Gdańsk GNSS Interference Steps Up — 82–99% of Aircraft Flagging Degraded Navigation, September 2026
- Gdańsk (GDN) is operating — its airport brief scores it normal for the weekday, though 3 and 4 November read the window's two lowest counts — both now settled — and unattributed; observed movements averaged about 159/day over 13 Aug–8 Nov; Tuesday 20 October settled at 117, one under the 118 of 6 October — the window's lowest settled day until 3 November; Thursday 22 October settled at 153 — the window's lowest settled Thursday, scored normal at −22% against its Thursday reference; Friday 23 October settled at 162 and Saturday 24 October at 142; Sunday 25 October, the first day of the winter timetable, settled at 120 — the window's lowest Sunday; Monday 26 October settled at 148 — the window's lowest Monday; Tuesday 27 October settled at 132, flagged partial for a one-hour network collection hole its settled row enshrines; Wednesday 28 October settled at 147 — the window's lowest Wednesday, by one; Thursday 29 October settled at 148 — the window's lowest Thursday; Friday 30 October settled at 141 — the window's lowest Friday; Saturday 31 October settled at 119 on a short network pass — the window's joint-lowest Saturday, read as a floor; Sunday 1 November settled at 118 on a short network pass — the window's lowest Sunday, read as a floor; Monday 2 November settled at 143 — the window's lowest Monday; Tuesday 3 November settled at 86 — the window's lowest day, low in both networks we read; Wednesday 4 November settled at 106, scored normal at −36% against its Wednesday reference — the window's lowest Wednesday and its second-lowest day; Thursday 5 November settled at 141 — the window's lowest Thursday; Friday 6 November settled at 149 — the window's second-lowest Friday; Saturday 7 November reads a recount-substituted 126, not yet final; Sunday 8 November reads a measured 148, scored normal at +4% against its Sunday reference, still filling; Wednesday 14 October settled at 148, the window's lowest Wednesday until 28 October; Thursday 1 October, at 216, is the busiest; check your airline on the day.
- The Gulf of Gdańsk sits in a persistent GNSS-interference zone that has run for well over a year, concentrated on the Baltic coast toward Kaliningrad — in September the share of aircraft flagging degraded navigation over Gdańsk’s own cell stepped up from 71–84% to 82–99%, and across October it ran 74–93% (86.2% on the month), with the weeks of 5 and 12 October both closing at 84.3%, in the August range, before the week of 19 October closed at 89.2% — back above September; the week of 2 November then closed at 79.2%, under the August mark, so on a weekly measure the step-up has unwound.
- The zone has a gradient, not a wall: over the last seven observed days (2–9 November; 6 November is a feed gap) 99.6% of tracked aircraft were flagged at 22°E, 91.8% at 21°E, 98.2% at 20°E, 89.0% at 19°E, 80.1% over Gdańsk at 18°E, 62.9% at 17°E, 40.7% at 16°E and 28.0% at 14°E over Szczecin’s side of the coast.
- GPS interference is a navigation-integrity issue, not a closure event — inertial systems and ground-based aids (ILS, VOR/DME) back satellite navigation up; the practical cost is precision and workload, occasionally a diversion in poor weather.
Advisory timeline — how active is this episode
Our detection layer reads the navigation-integrity field every ADS-B aircraft broadcasts — the Navigation Integrity Category, a self-reported measure of how far the aircraft trusts its own position. When satellite navigation is jammed or spoofed, receivers lower that figure, and the share of aircraft broadcasting a low NIC rises. In August we documented the 1°×1° cell centred on 54°N 18°E (Gdańsk and the Gulf of Gdańsk) as a steady state at 71.2–84.0% and closed the brief. September has not stayed in that band, and October opened in the new one, softened through its second and third weeks, and came back in its fourth; the first week of November closed under the August mark. From 1 September to 9 November the cell ran 74.1–99.4% on every observed day: 85.8% (97 of 113 aircraft) on 9 November, 75.6% (96 of 127) on 8 November, 76.1% (83 of 109) on 7 November, 80.0% (100 of 125) on 5 November, 78.9% (86 of 109) on 4 November, 80.6% (79 of 98) on 3 November, 83.7% (108 of 129) on 2 November, 81.5% (101 of 124) on 1 November, 90.4% (104 of 115) on 31 October, 91.8% (112 of 122) on 30 October, 85.2% (115 of 135) on 29 October, 79.5% (93 of 117) on 28 October, 91.4% (117 of 128) on 27 October, 90.6% (145 of 160) on 26 October, 85.7% (120 of 140) on 25 October, 85.7% (132 of 154) on 24 October, 92.0% (150 of 163) on 23 October, 93.1% (134 of 144) on 22 October, 85.4% (123 of 144) on 21 October, 92.7% (115 of 124) on 20 October, 89.7% (131 of 146) on 19 October, 87.7% (121 of 138) on 18 October, 82.1% (115 of 140) on 17 October — the softest since 12 October — 90.4% (141 of 156) on 16 October, 84.6% (137 of 162) on 15 October, 85.1% (120 of 141) on 14 October, 85.6% (119 of 139) on 13 October, 74.1% (109 of 147) on 12 October, 77.6% (121 of 156) on 11 October, 91.2% (124 of 136) on 10 October, 79.3% (111 of 140) on 9 October, 86.2% (125 of 145) on 8 October, 86.3% (132 of 153) on 7 October, 85.7% (102 of 119) on 6 October — then the thinnest daily sample since this series began, 85.0% (125 of 147) on 5 October, 83.8% (145 of 173) on 4 October, 82.1% (124 of 151) on 3 October, 87.0% (140 of 161) on 2 October, the same 140 of 161 on 1 October, and a peak of 99.4% (179 of 180 aircraft) on 11 September. 3 and 4 October, at 82.1% and 83.8%, were the first back-to-back days below 84% since 25–26 August, and 5–8 October came back to 85.0%, 85.7%, 86.3% and 86.2%. Then 9 October read 79.3% — at the time the softest day since 26 August — and 10 October came straight back to 91.2%, the highest since 27 September: a twelve-point swing in a day on 136–140 aircraft, wider than sampling alone explains. Then 11 and 12 October read 77.6% and 74.1% — each the softest day since mid-August (16 August read 76.6%, 15 August 71.2%), back-to-back, on ordinary samples of 156 and 147 aircraft. Two days are logged as two days: 74.1% replaces 79.3% as the floor of the run since 1 September, and the claim this brief rests on is the aggregate below, not the pair. 13 October then read 85.6% (119 of 139) — back above 85% in a day, an eleven-point rise that mirrors the 9–10 October swing in the other direction; the floor stands at 74.1%, and the rebound is logged as one day as the dip was logged as two. 14 October held at 85.1% (120 of 141) — a second day above 85%, so the rebound is now two days to the dip's two; the floor still stands at 74.1%, and neither pair is the claim. 15 October read 84.6% (137 of 162) — a third day in the mid-80s, a shade under the 85% line on the cell's largest sample since 4 October; three days now stand against the dip's two, the floor is still 74.1%, and none of them is the claim. 16 October then read 90.4% (141 of 156) — the highest since 10 October's 91.2%, on a day the whole western end of the row ran hot at once (below); a fourth day back above the dip, logged as one day. 17 October then read 82.1% (115 of 140) — the softest since 12 October's 74.1%, on the cell's second-thinnest sample since 6 October's 119, on a day the whole western end ran soft at once (below); a fifth day back above the dip's floor, logged as one day. 18 October read 87.7% (121 of 138) — back near the September mean on the cell's thinnest sample since 6 October's 119; a sixth day above the dip. 19 October read 89.7% (131 of 146) — the highest since 16 October's 90.4%, a seventh day above the dip. 20 October read 92.7% (115 of 124) — then the highest since 11 September's peak, on what was then the cell's second-thinnest sample since 1 September (the thinnest then, 119, was 6 October), so a single aircraft moves it by close to a point; an eighth day above the dip, logged as one day. 21 October read 85.4% (123 of 144) — a ninth day above the dip, seven points down from the day before on an ordinary sample. 22 October read 93.1% (134 of 144) — the highest since 11 September's peak, half a point above 20 October and on an ordinary sample, the same size as the day before; a tenth day above the dip, logged as one day. 23 October read 92.0% (150 of 163) — the third-highest since 11 September, on the cell's largest sample since 4 October's 173; an eleventh day above the dip. 24 October read 85.7% (132 of 154) — six points down from the day before on an ordinary sample, on a day 17°E, 16°E and 22°E all fell with it (below); a twelfth day above the dip, logged as one day. 25 October read 85.7% again (120 of 140) — the same share as the day before on different counts, a shared rounding rather than a repeated row; a thirteenth day above the dip. 26 October read 90.6% (145 of 160) — five points up on the day before, on the cell's largest sample since 23 October, the first day of the week of 26 October; a fourteenth day above the dip, logged as one day. 27 October read 91.4% (117 of 128) — a fifteenth day above the dip. 28 October then read 79.5% (93 of 117) — the softest since 12 October's 74.1%, on what was then the cell's thinnest daily sample since this series began (117 aircraft, two under 6 October's 119), on a day the whole 54°N row ran soft at once on thin samples (below); logged as one day, and 74.1% stays the floor of the run since 1 September. 29 October read 85.2% (115 of 135) — back above 85% in a day on an ordinary sample, as most of the row took back the day before's fall (below); logged as one day. 30 October read 91.8% (112 of 122) — the highest since 23 October's 92.0%, on what was then the cell's third-thinnest daily sample of the series (after 28 October's 117 and 6 October's 119), on a day the western cells rose with it while 22°E, at the zone's eastern end, fell to its lowest reading of the series (below); logged as one day. 31 October read 90.4% (104 of 115) — a second day above 90%, on what was then the cell's thinnest daily sample since this series began (115 aircraft, two under 28 October's 117), on a day the receiver network as a whole tracked fewer aircraft than on any day of the week before; logged as one day. 1 November read 81.5% (101 of 124) — the softest since 28 October's 79.5%, on a day 16°E and 17°E fell with it while the cells from 19°E east held at 91–100% (below); logged as one day. 2 November read 83.7% (108 of 129) — a second day under 85%, the first day of the week of 2 November; logged as one day. 3 November read 80.6% (79 of 98) — the softest since 28 October's 79.5% and a third day running under 85%, the first three-day run under that mark since 25–27 August, on the cell's thinnest daily sample since this series began (98 aircraft, seventeen under 31 October's 115), on a day most western cells also carried their thinnest samples since 1 September (below); logged as one day, and 74.1% stays the floor of the run since 1 September. 4 November read 78.9% (86 of 109) — then the softest since 12 October's 74.1% and a fourth day running under 85%, on what is now, with 7 November, the cell's joint second-thinnest daily sample of the series, on a day 17°E fell to its lowest since 11 October (below); logged as one day, and 74.1% stays the floor. 5 November read 80.0% (100 of 125) — a fifth day running under 85%, then the longest run under that mark since 10–17 August, on a fuller sample than the two days before, on a day 17°E held at its 4 November low (below); logged as one day, and 74.1% stays the floor. 6 November is a gap in our per-cell feed — no data in any cell — and is left out. 7 November read 76.1% (83 of 109) — then the softest since 12 October's 74.1% and a sixth observed day running under 85%, on a sample as thin as 4 November's, on a day 17°E came back to 61.0% (below); logged as one day, and 74.1% stays the floor. 8 November read 75.6% (96 of 127) — the softest since 12 October's 74.1% and a seventh observed day running under 85%, on a fuller sample than the two observed days before, on a day 17°E fell to 55.7%, its lowest since 16 August (below); logged as one day, and 74.1% stays the floor. 9 November then read 85.8% (97 of 113) — the highest since 31 October, ending the run under 85% at seven observed days (1–8 November), on a day 17°E came back to 70.1%, its highest since 3 November; logged as one day. The two October days carrying identical counts (1 and 2 October) is coincidence, not a copied row — the days are written separately and seven of the 2,628 cells with 100 aircraft or more repeat exactly between them, the same rate as the day before. Twenty-two of the twenty-nine observed September days sit at 85% or above; in the whole of August, seven of twenty-two did; in October, twenty-three of thirty-one; in November so far, one of eight. Weekly aggregates tell the same story without the noise: 76.8% in the week of 10 August, 84.2% and 84.7% in the following two weeks, 88.7% in the week of 31 August, 90.4% in the week of 7 September, 86.8% across the six observed days of the week of 14 September, 87.9% across the full week of 21 September, 85.2% across the full week of 28 September (940 of 1,103 aircraft), and 84.3% across the full week of 5 October (840 of 996 aircraft) — the softest complete week since that of 10 August, level with the August weeks of 17 and 24 August (84.2%, 84.7%) and the first since the step-up to fall back into the August range. The week of 12 October closed at 84.3% (862 of 1,023 aircraft) on all seven days — 74.1%, 85.6%, 85.1%, 84.6%, 90.4%, 82.1%, then 87.7% — the same figure the week of 5 October closed on, level with the August weeks of 17 and 24 August, so that made two consecutive weeks in the August range for the first time since the step-up. The week of 19 October then closed at 89.2% (905 of 1,015 aircraft) on all seven days — 89.7%, 92.7%, 85.4%, 93.1%, 92.0%, 85.7%, then 85.7% — above September's 88.1%: the first complete week back at the September level since the week of 28 September, and the highest since the week of 7 September (90.4%). The two August-range weeks did not become three. The week of 26 October then closed at 87.3% (787 of 901 aircraft) on all seven days — 90.6%, 91.4%, 79.5%, 85.2%, 91.8%, 90.4%, then 81.5% — above the 85% mark for a second consecutive week, so the reassertion is now two closed weeks deep, but 0.8 points under September's 88.1%, where the week of 19 October had closed above it. The week of 2 November then closed at 79.2% (552 of 697 aircraft) on six observed days — 83.7%, 80.6%, 78.9%, 80.0%, 76.1%, then 75.6%, with 6 November a gap in our per-cell feed — 3.2 points under the 82.4% the cell averaged across 10–31 August, the mark this brief set: on a weekly measure the September step-up has unwound. It is the softest closed week since that of 10 August (76.8%), under the August weeks of 17 and 24 August (84.2%, 84.7%), and it is one week on six observed days; we report it on the rule we set and read nothing beyond it. The week of 9 November opened at 85.8% on its first observed day; it is read on the same marks once it closes. On the month, October closed at 86.2% (3,842 of 4,457 aircraft) — under September's 88.1%, above the 82.4% of 10–31 August. 14 September and 6 November are not plotted: our per-cell feed holds no data for either day in any cell — collection gaps, not readings. Honesty note: this per-cell series begins on 10 August, so it is 90 observed days deep and we make no claim about a longer baseline; the cell saw 133–195 aircraft a day in September and 115–173 in October (115 on 31 October), then 124, 129, 98, 109, 125, 109, 127 and 113 on 1–5 and 7–9 November (98, on 3 November, the thinnest of the series, and 109 on 4 and 7 November the joint second-thinnest), so daily percentages move by a few points on sampling alone, which is why we lean on the weekly figures. Every count is a floor — only aircraft the crowdsourced receiver network received are included. Daily share of aircraft flagging degraded navigation in the cell:
Fig. 1 — daily share of tracked aircraft broadcasting a low Navigation Integrity Category (NIC) in the 54°N 18°E cell (Gdańsk / Gulf of Gdańsk), % — crowdsourced ADS-B network · Data as of 10 Nov 2026, 21:52 UTC · per-cell series complete through 9 Nov (6 Nov and 14 Sep are feed gaps) · FIR-level through 9 Nov (25 Oct missing) · traffic through 8 Nov (6 Nov latest settled; 31 Oct and 1 Nov settled on short network passes, read as floors; 7 Nov recount substituted for a flagged clipped row; 8 Nov still filling; 27 Oct and 29 Sep partial) · Source: FlySafe monitoring — crowdsourced ADS-B navigation-integrity data (public).
Airports in the exposure zone
| Airport | Size | Exposure (9 Nov) | FIR |
|---|---|---|---|
| Gdańsk Lech Wałęsa (GDN) | large | — · ≈85.8% of aircraft flagged (own cell, 97 of 113) · traffic at window lows 3–4 Nov, both settled | EPWW |
| Kaliningrad Khrabrovo (KGD) | large | — · ≈97.9% flagged (own cell, 46 of 47 — thin sample) · Kaliningrad FIR ≈32.6% over 7 days (FIR-level) | UMKK |
| Palanga International (PLQ) | medium | — · ≈85.3% flagged (own cell, 29 of 34 — thin sample) · Vilnius FIR ≈18.2% over 7 days | EYVL |
| Szczecin–Goleniów (SZZ) | medium | — · western reference point — ≈23.3% flagged (own cell, 45 of 193) | EPWW |
Distance alone does not determine impact — wind direction and the flight levels the ash reaches decide which airports and routes are affected on a given day. FIR = Flight Information Region.
What our monitoring shows: Gdańsk traffic at the window's lowest on 3–4 November — both now settled — and low in both networks we read, while the navigation layer still flags most aircraft over the cell — though its latest closed week fell under the August mark
FlySafe tracks observed departures and arrivals at 493 airports from crowdsourced ADS-B receiver data. Observed counts are a floor, not a total — receiver coverage varies — but an airport measured against its own baseline is a reliable shape. Gdańsk Lech Wałęsa's last 30 days:
Fig. 2 — Observed daily movements at GDN, 13 Aug – 8 Nov (latest complete UTC day). Data as of 10 Nov 2026, 21:52 UTC · per-cell series complete through 9 Nov (6 Nov and 14 Sep are feed gaps) · FIR-level through 9 Nov (25 Oct missing) · traffic through 8 Nov (6 Nov latest settled; 31 Oct and 1 Nov settled on short network passes, read as floors; 7 Nov recount substituted for a flagged clipped row; 8 Nov still filling; 27 Oct and 29 Sep partial) · Source: FlySafe monitoring (ADS-B receiver network).
- Across the 13 Aug–8 Nov window plotted above: ~172 observed movements/day is the window reference — the mean of the 37 measured days through 18 September, kept stable across updates; the 88 measured days now plotted average about 159. Every day in the run is measured — no blanks — but four of them carry a known hour-scale hole in the network feed, and we say so rather than smooth it: 27 October (12:50–13:50 UTC, below), 29 September (13:00–15:00 UTC, below), 8 September (13:00 UTC: 746 departures recorded worldwide against 8,135 and 8,298 in the same hour on the Tuesdays either side; GDN shows 1 movement in that hour against 9–13 on the other September Tuesdays, so its 129 reads roughly ten movements low) and 26 August (06:00 UTC missing worldwide; GDN usually logs 4–10 movements in that hour, so its 176 reads a few low). Two more days, 31 October and 1 November, carry longer shortfalls: both settled on network passes that ran short feed-wide and never backfilled (below), so their 119 and 118 are read as floors too. One GDN day carries a gap flag in the airport feed this cycle — 7 November: 16 October–6 November have settled at 162, 142, 142, 161, 117, 165, 153, 162, 142, 120, 148, 132, 147, 148, 141, 119, 118, 143, 86, 106, 141 and 149 (5 November at the 02:33 UTC pass on 9 November and 6 November at the 02:33 UTC pass today, each at exactly the recount-substituted figure we plotted); 7 November's stored row reads 2 (0 departures, 2 arrivals, refreshed 21:25 UTC today) and is flagged, while the recount gives 126 (75 departures, 51 arrivals), so the recount is substituted — departures undercounted by 75, arrivals by 49; 8 November's stored 148 agrees with the recount (87 departures, 61 arrivals) and is still filling; 9 November (4 movements so far) is not plotted. Against a 14-day worldwide median of 116,131 departures (26 Oct–8 Nov, counting 7 November on its raw count of 107,199 because its stored worldwide rollup reads 10,972), network-wide collection ran at 90% of that median or better on every settled day but two: Saturday 31 October at 89.6% and Sunday 1 November at 82.5% (below); Sunday 11 October reads 90.2%. The median held at 116,131 this cycle: 25 October (111,398 departures) rolled out of the window and 8 November (103,638, still filling) rolled in, both below its middle, which is still 4 and 6 November (112,991 and 119,271 departures); 6 November settled at the 119,271 it read last cycle, and 7 November rose from 103,856 to 107,199 as it filled. Nine of the fourteen days in the window — 31 October to 8 November — are short network passes, so the yardstick itself sits low, and every share below reads higher for it. Against it Sunday 6 September reads 95.5%, Tuesday 29 September (on its recount of 111,018 departures, which is also what its rollup settled at) 95.6%, Wednesday 26 August 96.6%, Saturday 10 October 96.2% and Saturday 17 October 96.0% — all above the line, each unchanged from last cycle, because the yardstick did not move. 10 October remains a light network Saturday on which no worldwide hour fell under 90% of the same hour a week earlier; 26 August is one of the hour-holed days above. Two settled days sit clearly under the line, and we say so: Sunday 1 November at 82.5% and Saturday 31 October at 89.6% — the network's collection passes for those days ran short feed-wide and never backfilled (below); Sunday 8 November, still filling, reads 89.2%, its worldwide hours from 09:00 to 11:00 UTC at 0.91–0.96 of the Sunday before, itself a short pass; Saturday 7 November, latest fully collected, 92.3%, its hours from 10:00 to 12:00 UTC at 0.77–0.81 of the Saturday before; Friday 6 November, now settled, 102.7%, its hours from 10:00 to 12:00 UTC at 0.80 of the Friday before; Thursday 5 November, settled, 102.8%, its hours from 10:00 to 12:00 UTC at 0.81–0.83 of the Thursday before; Wednesday 4 November, settled, 97.3%, its hours from 10:00 to 12:00 UTC at 0.75–0.77 of the Wednesday before; Tuesday 3 November, settled, 93.8%, its hours from 10:00 to 12:00 UTC at 0.69–0.76 of the Tuesday before; Monday 2 November, settled, 91.9%; Friday 30 October 105.3%; Thursday 29 October 110.1%; Wednesday 28 October 106.7%; Tuesday 27 October 104.0% — whole at day level despite its hour-long hole (below); Monday 26 October 103.3%; Sunday 25 October 95.9% — a thin network Sunday on the day Europe's clocks went back, not a hole; Saturday 24 October 100.8%; Friday 23 October 112.2%; Thursday 22 October 112.4%; Wednesday 21 October 107.7%, Tuesday 20 October 110.2%, Monday 19 October 109.2%, Sunday 18 October 102.9%, Friday 16 October 100.4%, Thursday 15 October 109.0%, Wednesday 14 October 106.2%, Tuesday 13 October 104.8% and Monday 12 October 102.4%. Friday 9 October reads 112.8%, Thursday 8 October 114.5%, Wednesday 7 October 112.1% and Tuesday 6 October 110.0%; 5 October 104.5%, 4 October 97.6% and 3 October 98.9%. A day-level share does not catch an hour-long hole — 8 September reads 102.2% and 27 October 104.0% — which is why we also check the hourly profile. Observed counts are a floor, not a total.
- Through the September step-up in the cell (1–30 Sep): 144 / 176 / 182 / 167 / 119 / 171 / 165 / 129 / 159 / 196 / 164 / 120 / 156 / 158 / 154 / 170 / 215 / 182 / 132 / 148 / 168 / 125 / 166 / 176 / 183 / 138 / 165 / 172 / 129 / 166 observed movements — a September mean of about 160/day over the 30 measured days (8 and 29 September partial) against about 180/day over 13–31 August. That step-down is broad across weekdays and lines up with the end of the summer schedule; it carries no signature of the navigation layer — the two lowest September days (119 on Saturday 5 September, 120 on Saturday 12 September) are ordinary Saturdays, and the busiest day of the whole window, 216 on Thursday 1 October (ahead of the two 215s of 27 August and 17 September), fell on a day the cell read 87.0% flagged. The thirty-one October days read 216, 186, 133, 165, 164, 118, 171, 196, 150, 130, 155, 166, 142, 148, 190, 162, 142, 142, 161, 117, 165, 153, 162, 142, 120, 148, 132, 147, 148, 141 and 119 — Thursday 1 October to Saturday 31 October — and 1–8 November read 118, 143, 86, 106, 141, 149, 126 and 148. Tuesday 3 November, now settled at 86, is the lowest day of the whole window, 31 under the 117 of 20 October — until then the lowest settled day, one movement under the 118 of 6 October and of Sunday 1 November — and Wednesday 4 November, now settled at 106 (below), sits second; 3 November, 20 October and 6 October all fell on a Tuesday: Tuesdays are the window's thinnest weekday and have slid with the season — 155 and 170 in August, 154 on 15 September, 125 on 22 September, 118 on 6 October, 142 on 13 October, 117 on 20 October, 132 on 27 October and 86 on 3 November (8 and 29 September are hole-partial at 129, and 27 October is hole-partial too) — while Wednesday 7 October came straight back to 171, Thursday 8 October to 196 and Wednesday 21 October to 165. Wednesday 14 October settled at 148 — then the lowest of the window's ten Wednesdays, scored normal by the airport brief against its 166 Wednesday reference — and Thursday 15 October came back to 190 (settled). That is the end-of-summer step-down showing on the lightest day of the week, not a navigation-layer signature: the cell read 85.7% flagged on 6 October, in line with the rest of its early-October run. Thursday 22 October, settled at 153, is the window's lowest settled Thursday (201, 212, 215, 182, 196, 215, 176, 216, 196, 190 and 153 across the eleven to that date), 23 under the 176 of 24 September; the airport brief scored it normal, at −22% against its 196 Thursday reference. The cell read 93.1% flagged that day, near its highest since 11 September — but it read 92.7% on 20 October and 90.4% on 16 October, when Gdańsk logged a low Tuesday and an ordinary Friday, so we report the low Thursday as measured rather than attribute it. Friday 23 October, settled at 162, ties 16 October as the window's second-lowest settled Friday (199, 186, 182, 167, 164, 182, 183, 186, 150, 162 and 162 across the eleven to that date), above the 150 of 9 October — on a day the cell read 92.0%. Saturday 24 October, now settled at 142, ties 17 October as the third-busiest of the window's eleven Saturdays (152, 150, 124, 119, 120, 132, 138, 133, 130, 142 and 142), on a day the cell read 85.7%. Sunday 25 October, now settled at 120, is the lowest of the window's eleven Sundays (190, 182, 175, 171, 156, 148, 165, 165, 155, 142 and 120), 22 under the 142 of 18 October and level with Saturday 12 September as the joint-fourth-lowest day of the whole window, on a day the cell read 85.7%; Monday 26 October, now settled at 148, is the lowest of the window's eleven Mondays (195, 202, 151, 165, 158, 168, 172, 164, 166, 161 and 148), three under the 151 of 31 August, on a day the cell read 90.6%; Tuesday 27 October, now settled at 132 and flagged partial for a network collection hole, is sixth of the window's eleven Tuesdays (155, 170, 144, 129, 154, 125, 129, 118, 142, 117 and 132) — sixth with or without the few movements the hole likely cost it — on a day the cell read 91.4%; Wednesday 28 October, now settled at 147, is the lowest of the window's eleven Wednesdays (206, 176, 176, 159, 170, 166, 166, 171, 148, 165 and 147), one under the 148 of 14 October, on a day the cell read 79.5%, its softest since 12 October; Thursday 29 October, now settled at 148, is the lowest of the window's twelve Thursdays (201, 212, 215, 182, 196, 215, 176, 216, 196, 190, 153 and 148), five under the 153 of 22 October, on a day the cell read 85.2%; Friday 30 October, now settled at 141, is the lowest of the window's twelve Fridays (199, 186, 182, 167, 164, 182, 183, 186, 150, 162, 162 and 141), nine under the 150 of 9 October, on a day the cell read 91.8%; Saturday 31 October, now settled at 119, is level with 5 September as the lowest of the window's twelve Saturdays on the count we have (152, 150, 124, 119, 120, 132, 138, 133, 130, 142, 142 and 119), on a day the cell read 90.4% — read as a floor, because the network's pass for the day settled short; Sunday 1 November, now settled at 118, is the lowest of the window's twelve Sundays (190, 182, 175, 171, 156, 148, 165, 165, 155, 142, 120 and 118), two under the 120 of 25 October and level with 6 October's 118, on a day the cell read 81.5% — read as a floor, because the network's pass for the day settled short; Monday 2 November, now settled at 143, is the lowest of the window's twelve Mondays (195, 202, 151, 165, 158, 168, 172, 164, 166, 161, 148 and 143), five under the 148 of 26 October, on a day the cell read 83.7%; Tuesday 3 November, now settled at 86, is the lowest of the window's twelve Tuesdays and the lowest day of the whole window (155, 170, 144, 129, 154, 125, 129, 118, 142, 117, 132 and 86), 31 under the 117 of 20 October, on a day the cell read 80.6%; Wednesday 4 November, now settled at 106, is the lowest of the window's twelve Wednesdays (206, 176, 176, 159, 170, 166, 166, 171, 148, 165, 147 and 106), 41 under the 147 of 28 October, on a day the cell read 78.9%; Thursday 5 November, now settled at 141, is the lowest of the window's thirteen Thursdays (201, 212, 215, 182, 196, 215, 176, 216, 196, 190, 153, 148 and 141), seven under the 148 of 29 October, on a day the cell read 80.0%; Friday 6 November, now settled at 149, is the second-lowest of the window's thirteen Fridays (199, 186, 182, 167, 164, 182, 183, 186, 150, 162, 162, 141 and 149), eight above the 141 of 30 October, on a day our per-cell feed holds no reading (a collection gap); Saturday 7 November reads a recount-substituted 126, not yet final, which would be the fifth-lowest of the window's thirteen Saturdays if it holds (152, 150, 124, 119, 120, 132, 138, 133, 130, 142, 142, 119 and 126), seven above the 119 of 31 October, on a day the cell read 76.1%; Sunday 8 November reads a still-filling 148, which would be level with 20 September as the joint-fourth-lowest of the window's thirteen Sundays if it holds (190, 182, 175, 171, 156, 148, 165, 165, 155, 142, 120, 118 and 148), thirty above the 118 of 1 November and the highest Sunday since 11 October, on a day the cell read 75.6%. 25 October was the first day of the winter timetable and the day European clocks went back an hour — in our hourly count Gdańsk's early-morning wave of movements has sat at 05:00 UTC rather than 04:00 on 25 October–8 November — so we note the timing and still attribute nothing: the first fifteen winter-timetable days read the window's lowest Sunday, its lowest Monday, a mid-table Tuesday, its lowest Wednesday, its lowest Thursday, its lowest Friday, a joint-lowest Saturday (a floor), a new lowest Sunday (a floor), a new lowest Monday, a new lowest Tuesday — the window low — a new lowest Wednesday, a new lowest Thursday, a second-lowest Friday and, if they hold, a fifth-lowest Saturday and a joint-fourth-lowest Sunday, eleven of the fifteen at the bottom of their weekday; the first full winter-timetable week, 25–31 October, totals 955 movements against 1,042 for 18–24 October (−8%), while the cell read 85.7%, 90.6%, 91.4%, 79.5%, 85.2%, 91.8%, 90.4%, 81.5%, 83.7%, 80.6%, 78.9%, 80.0%, 76.1% and 75.6%, inside its range since 1 September on all fourteen it has a reading for (6 November is a gap in our per-cell feed). The low days fall on cell readings from 78.9% to 91.8% — the two lowest, 3 and 4 November, on the cell's thinnest sample and its joint second-thinnest, and on two of its softer readings, the rest spread across its range — so we report the pattern as measured and attribute it to nothing until enough winter-timetable weeks are in to compare whole weeks with whole weeks.
- What moved since the last update: Friday 6 November has settled at 149 (85 departures, 64 arrivals) at the 02:33 UTC pass today, exactly the recount we substituted while its stored row was clipped — the thirty-eighth consecutive cycle in which a figure we plotted proved to be where the feed settled. It is the second-lowest of the window's thirteen Fridays, eight above 30 October's 141; we attribute it to nothing. Saturday 7 November is plotted at a recount-substituted 126 (75 departures, 51 arrivals) — one departure and one arrival above the 124 we plotted last cycle — because its stored row reads 2 (0 departures, 2 arrivals, refreshed 21:25 UTC today), a clip the airport feed flags. The network's day has filled to 107,199 departures, 3.0% above the Saturday before (itself a short pass), its hours from 15:00 UTC on at 1.01–1.41 of it, so it is the latest fully collected day, may still gain, and settles at its final pass on 11 November. If it holds it is the fifth-lowest of the window's thirteen Saturdays, seven above 31 October's 119; the cross-check network reads it level with the Saturday before (106 Gdańsk movements against 108). Sunday 8 November is plotted at its measured 148 (87 departures, 61 arrivals, stored row and recount agreeing at the 21:25 UTC refresh today) and is still filling: the network's day stands at 103,638 departures, 8.2% above the Sunday before (itself a short pass), its last hour at 0.76 of it. GDN's airport brief scores the day normal, at +4% against its 142 Sunday reference; against the flat line it is −14%. If it holds it is level with 20 September's 148 as the joint-fourth-lowest of the window's thirteen Sundays and the highest Sunday since 11 October, thirty above 1 November's 118; the cross-check network reads it above the Sunday before too (139 Gdańsk movements against 128), and the airport's weather reports show CAVOK from 09:00 to 19:00 UTC, with mist in the evening. Tuesday 27 October stays flagged partial at its settled 132: its 12:50–13:50 UTC network hole (4,820 departures worldwide in that hour against 7,140 and 7,594 on the days either side; GDN 3 movements against 8 and 9) is enshrined in the settled row, so 132 is a floor around five movements short, not a dip. Tuesday 29 September still reads the partial 129 (80 departures, 49 arrivals) with its two-hour hole enshrined rather than backfilled: a floor roughly twenty movements short — not a dip.
- A note on the baseline: against the weekday-independent ~172 window reference, Friday 16 October's settled 162 is −6%, while GDN's airport brief scores it normal at −11% against its 183 Friday reference: on a Friday the flat line understates the shortfall, because Fridays run above the window average — 162 is, with 23 October, the window's second-lowest settled Friday (199, 186, 182, 167, 164, 182, 183, 186, 150, 162 and 162 across the eleven to that date), which we report rather than explain away. Thursday 15 October's settled 190 reads +10% against the flat line, eighth of the window's ten Thursdays. Saturday 17 October's settled 142 reads −17% against the flat line and +7% against the 133 Saturday reference: on a Saturday the flat line overstates the shortfall by some twenty points. Sunday 18 October's settled 142 reads −17% against the flat line and −14% against the 165 Sunday reference: on a Sunday the flat line overstates the shortfall by a few points. Monday 19 October's settled 161 reads −6% against the flat line and −4% against the 168 Monday reference: on a Monday the two references agree to within a point or two. Tuesday 20 October's settled 117 reads −32% against the flat line and −9% against the 129 Tuesday reference: on a Tuesday, the window's thinnest weekday, the flat line overstates the shortfall by more than twenty points, and the rest is a genuinely light day — then the window's lowest settled day, by one movement — which we report rather than explain away. Wednesday 21 October's settled 165 reads −4% against the flat line and −1% against the 166 Wednesday reference: on a Wednesday the two references nearly agree. Thursday 22 October's settled 153 reads −11% against the flat line and −22% against the 196 Thursday reference: on a Thursday the flat line understates the shortfall, because Thursdays run well above the window average — 153 is the window's lowest settled Thursday, which we report rather than explain away. Friday 23 October's settled 162 reads −6% against the flat line and −11% against the 183 Friday reference: on a Friday the flat line understates the shortfall too — 162 ties 16 October as the window's second-lowest settled Friday. Saturday 24 October's settled 142 reads −17% against the flat line and +3% against the 138 Saturday reference: on a Saturday the flat line overstates the shortfall by some twenty points. Sunday 25 October's settled 120 reads −30% against the flat line; the airport brief did not score it, and against the window's own Sundays it is the lowest of eleven by 22 movements, which we report rather than explain away. Monday 26 October's settled 148 reads −14% against the flat line and −11% against the 166 Monday reference: on a Monday the two references agree to within a few points, and both say the same thing — the window's lowest Monday, which we report rather than explain away. Tuesday 27 October's settled 132, flagged partial for its network hole, reads −23% against the flat line and +2% against the 129 Tuesday reference: on a Tuesday, the window's thinnest weekday, the two references disagree in sign, and the whole of that gap is the weekday. Wednesday 28 October's settled 147 reads −15% against the flat line and −11% against the 166 Wednesday reference: on a Wednesday the two references nearly agree, and both say it is a light day — the window's lowest Wednesday, by one movement, which we report rather than explain away. Thursday 29 October's settled 148 reads −14% against the flat line and −24% against the 196 Thursday reference: on a Thursday the flat line understates the shortfall, because Thursdays run well above the window average — 148 is the lowest of the window's twelve Thursdays, which we report rather than explain away. Friday 30 October's settled 141 reads −18% against the flat line and −13% against the 162 Friday reference the airport brief now uses (it scored 16 and 23 October against 183): against that lower reference the flat line overstates the shortfall by a few points — 141 is the lowest of the window's twelve Fridays, which we report rather than explain away. Saturday 31 October's settled 119, read as a floor on a short network pass, reads −31% against the flat line; the airport brief did not score it, and against the window's own Saturdays it ties the lowest of twelve. Sunday 1 November's settled 118, read as a floor, reads −31% against the flat line and −24% against the 155 Sunday reference the airport brief used last cycle (it used 165 in mid-October): on a Sunday the flat line overstates the shortfall by some seven points, and the rest is a genuinely light Sunday — the lowest of twelve — which we report rather than explain away. Monday 2 November's settled 143 reads −17% against the flat line and −13% against the 164 Monday reference the airport brief scored it against (it used 166 for 26 October): on a Monday the two references agree to within a few points, and both say it is a light day — the lowest of twelve Mondays — which we report rather than explain away. Tuesday 3 November's settled 86 reads −50% against the flat line; the airport brief did not score it, and against the window's own Tuesdays it is the lowest of twelve by 31 movements. Wednesday 4 November's settled 106 reads −38% against the flat line and −36% against the 165 Wednesday reference the airport brief scored it against — which still scored it normal: on a Wednesday the two references nearly agree, and both put it far under every other Wednesday in the window, which we report rather than explain away. Thursday 5 November's settled 141 reads −18% against the flat line and −26% against the 190 Thursday reference the airport brief scored it against (it used 196 for 22 and 29 October): on a Thursday the flat line understates the shortfall, because Thursdays run well above the window average — 141 is the lowest of thirteen Thursdays, which we report rather than explain away. Friday 6 November's settled 149 reads −13% against the flat line and −8% against the 162 Friday reference the airport brief scored it against: against that lower Friday reference the flat line overstates the shortfall by a few points — 149 is the second-lowest of thirteen Fridays, which we report rather than explain away. Saturday 7 November's recount-substituted 126, not yet final, reads −27% against the flat line and −11% against the 142 Saturday reference the airport brief scored it against last cycle: on a Saturday the flat line overstates the shortfall by some fifteen points — 126 would be the fifth-lowest of thirteen Saturdays, which we report rather than explain away. Sunday 8 November's measured 148, still filling, reads −14% against the flat line and +4% against the 142 Sunday reference — which scores it normal: on a Sunday the flat line overstates the shortfall by some eighteen points — 148 would be level with 20 September as the joint-fourth-lowest of thirteen Sundays. Wednesday 14 October's settled 148 reads −14% against the flat line and −11% against the 166 Wednesday reference the airport brief scored it against: on a Wednesday the two references nearly agree, and both say the same thing — then the window's lowest settled Wednesday, until 28 October's 147. Tuesday 13 October's settled 142 reads −17% against the flat line — fifth of the window's nine Tuesdays (155, 170, 144, 129, 154, 125, 129, 118 and 142) — and was scored normal at +10% against its 129 Tuesday reference: on a Tuesday, the window's thinnest weekday, the two references disagree in sign, and the whole of that gap is the weekday. Monday 12 October's settled 166 reads −3% against the flat line — fifth of the window's nine Mondays (195, 202, 151, 165, 158, 168, 172, 164 and 166) — and was scored normal at −2% against its 168 Monday reference: on a Monday the two references agree to within a point or two. Sunday 11 October's settled 155 reads −10% against the flat line — second-lowest of the window's nine Sundays (190, 182, 175, 171, 156, 148, 165, 165 and 155), above the 148 of 20 September — and was scored normal at −6% against its 165 Sunday reference: on a Sunday the flat line overstates the shortfall by a few points; most of the gap is the weekday, and the rest is a genuinely light Sunday, which we report as the second-lowest rather than explain away. Saturday 10 October's settled 130 reads −24% against the flat line — sixth of the window's nine Saturdays (152, 150, 124, 119, 120, 132, 138, 133 and 130) — and was scored normal at −2% against the 133 Saturday reference: on a Saturday the flat line overstates the shortfall by some twenty points. Friday 9 October's settled 150 reads −13% against the flat line and is the window's lowest settled Friday; Tuesday 6 October's settled 118 reads −31% and was the window's lowest settled day until 20 October took that mark by one movement. The gap between the two references is mostly the weekday — and on 6, 9, 11, 14, 16, 20, 22, 23, 25, 26, 28, 29 and 30 October and 1, 2, 3, 4, 5, 6 and 7 November partly a genuinely light day, which we report as the former settled window low, the window's lowest settled Friday, a then second-lowest Sunday, its then lowest settled Wednesday, a joint second-lowest settled Friday, the settled window low one under the old, its lowest settled Thursday, the other joint second-lowest settled Friday, its lowest Sunday, its lowest Monday, a new lowest Wednesday by one movement, a new lowest Thursday, a new lowest Friday, a new lowest Sunday, a new lowest Monday, a new lowest Tuesday — the window low — a new lowest Wednesday, a new lowest Thursday, a second-lowest Friday and, if it holds, a fifth-lowest Saturday rather than explain away. We keep the window reference fixed so the bars stay comparable across updates, and quote the same-weekday figure beside it whenever the feed gives us one.
- The point: GNSS interference does not surface in the movement count. It surfaces in the navigation-integrity layer — aircraft broadcasting degraded position quality — not in whether flights depart. The bars show an ordinary late-summer profile, thinning as the season ends — with 3 and 4 November, both settled, the window's two lowest days, which we report and do not attribute — while the cell above ran at 74% or more on every observed day.
Live view: GDN airport brief.
What it means for flights
The news is the step, not the presence. The August brief on this cell closed on a finding of "no escalation": eight days inside a 71.2–84.0% band. That band is gone on the month. From 21 August to 10 October the cell did not post a single day below 77.9%, and from 1 September to 10 October not one below 79.3%; 11 and 12 October then read 77.6% and 74.1% — the first readings under that floor since mid-August — and 13–27 October came back to 85.6%, 85.1%, 84.6%, 90.4%, 82.1%, 87.7%, 89.7%, 92.7%, 85.4%, 93.1%, 92.0%, 85.7%, 85.7%, 90.6% and 91.4%, before 28 October read 79.5% on what was then the cell's thinnest sample of the series, 29 October 85.2%, 30 October 91.8%, 31 October 90.4% on a thinner sample still, 1–5 November 81.5%, 83.7%, 80.6%, 78.9% and 80.0%, the third and fourth on the thinnest samples yet, 7 November 76.1%, on a sample as thin as 4 November's, 8 November 75.6% and 9 November 85.8% (6 November is a gap in our per-cell feed); we log the pair as two days, the rebound as fifteen and 28 October–9 November as one day each, and return to them below. Aggregated over comparable samples — 3,520 tracked aircraft across 10–31 August, 4,636 across 1–30 September — the flagged share moved from 82.4% to 88.1%, and the weekly figure climbed in steps before flattening, easing and climbing again: 76.8% → 84.2% → 84.7% → 88.7% → 90.4% → 86.8% → 87.9% → 85.2% → 84.3% → 84.3% → 89.2% → 87.3% → 79.2%, the weeks of 5 and 12 October each closed at 84.3% on all seven days — the softest complete weeks since that of 10 August, back in the August range — and the week of 19 October back at 89.2%, above the September month, with the week of 26 October closing at 87.3%, above 85% but under it, and the week of 2 November at 79.2% on six observed days, under the 82.4% August mark; the October month closed at 86.2% (3,842 of 4,457 aircraft), between August and September. A six-point rise on matched samples of three and a half thousand aircraft or more is not noise; nor were two closed weeks 3.8 points under the September figure — and a third, closed 1.1 points above it, followed by a fourth at 87.3%, said those two did not become a trend — and a fifth, closed at 79.2%, under the August mark, unwinds the step-up on the weekly measure this brief set. It is also not a new zone: the southern Baltic around Kaliningrad has carried elevated GNSS interference for well over a year (background: Baltic GPS-jamming escalation and how GPS jamming works). What our detection layer has caught is an intensification at the zone's western end, over a large Polish airport, two closed weeks in which that end eased, a third in which it came back hotter than September, and a fifth in which Gdańsk's own cell closed under the August mark — which is why this brief reopens the file the August one closed (August brief) and keeps it open.
A gradient that runs east–west — and has crept west. Interference has a footprint, and on this coast it slopes rather than stops. On 16 October the flag rate along the 54°N row ran 99.1% at 22°E, 95.5% at 21°E, 97.6% at 20°E, 98.1% at 19°E, 90.4% over Gdańsk at 18°E, 77.6% at 17°E, 51.0% at 16°E, 43.4% at 15°E and 34.5% at 14°E — Szczecin's side of the coast, roughly 240 km west of Gdańsk. The cells between Gdańsk and the zone's eastern end are thin (22–52 aircraft that day at 19–21°E, so a single aircraft moves them by two to five points — on 3 October 21°E read 84.6% on 26 aircraft, below both of its neighbours, and two days later 100% on 34; 20°E read 37 of 37 on both 10 and 11 October, an identical pair that 48 of the 4,157 cells holding 30 aircraft or more also produced across those two days), but the 22°E cell reads 99.1% on 106 aircraft, and the 7-day aggregate across the whole row tells the same story without the thin-sample noise: 99.6% at 22°E, 91.8% at 21°E, 98.2% at 20°E, 89.0% at 19°E, 80.1% over Gdańsk, 62.9% at 17°E, 40.7% at 16°E, 30.3% at 15°E, 28.0% at 14°E (the seven observed days 2–9 November; 6 November is a gap). The September creep was in the August-to-September comparison one and two cells west of the city: 54°N 17°E rose from 67.6% to 69.9%, 54°N 16°E from 42.6% to 44.7%, and the inland row south of the coast moved too — 53°N 17°E from 38.6% to 44.9%, 53°N 18°E from 60.4% to 66.3%. Small steps individually; the same sign in every cell west and south of Gdańsk. Cells north across the water toward Sweden did not follow (55°N 17°E: 73.1% in August, 68.6% in September). October has run softer in every one of these cells, including Gdańsk's own, and the calendar week of 5 October — the first test this brief set itself — closed below September in each of them: 84.3% over Gdańsk against 88.1%, 64.7% at 17°E against 69.9%, 40.8% at 16°E against 44.7%, 41.0% at 53°N 17°E against 44.9%, 63.0% at 53°N 18°E against 66.3%, 64.1% at 55°N 17°E against 68.6%. Across October the figures closed at 86.2%, 70.9%, 45.0%, 44.0%, 64.6% and 70.2% — Gdańsk's own cell and both inland cells below September, while 17°E (70.9% against 69.9%), 16°E (45.0% against 44.7%) and 55°N 17°E (70.2% against 68.6%) closed the month back above their September figures, by 1.1, 0.3 and 1.6 points; at 17°E and 16°E the month also closed above August (67.6%, 42.6%), by 3.3 and 2.4 points, where across 1–16 October it had sat below both. Then the calendar week of 19 October closed above September in every one of these cells: 89.2% over Gdańsk against 88.1%, 79.8% at 17°E against 69.9%, 55.5% at 16°E against 44.7%, 52.1% at 53°N 17°E against 44.9%, 70.0% at 53°N 18°E against 66.3%, 80.0% at 55°N 17°E against 68.6% — at 17°E, 16°E and 55°N 17°E the highest weekly reading since our per-cell series began on 10 August (the previous highs were 73.5%, 50.0% and 79.4%), with the two inland cells a fraction under their week of 7 September (52.8%, 70.6%). So the easing at the western end, called on the closed week of 5 October and held through the week of 12 October, did not last a third week: on a closed week the western slope is back, and higher than in September. It is one week, and we read it as a reversal of the October easing, not yet as a new level. The calendar week of 26 October then closed split: 87.3% over Gdańsk, 73.7% at 17°E and 73.2% at 55°N 17°E above their September figures, while 16°E (41.4%), 53°N 17°E (41.9%) and 53°N 18°E (66.2%, a tenth under 66.3%) closed below theirs — so the western slope held at 17°E and fell back at 16°E and inland; we report it cell by cell rather than as a direction. The calendar week of 2 November then closed under September in every one of these cells, on six observed days: 79.2% over Gdańsk, 61.7% at 17°E, 39.6% at 16°E, 38.4% at 53°N 17°E, 56.8% at 53°N 18°E and 65.1% at 55°N 17°E — over Gdańsk, at 17°E and in both inland cells the lowest closed week since that of 10 August, at 16°E since the week of 28 September (38.7%) — while at the eastern end 20°E and 22°E came back to 98.3% and 99.7% and 21°E read 91.5% on thin samples. So the western slope that came back on the week of 19 October has fallen below its September figures in every watched cell as the eastern end recovered; one week, reported cell by cell. At the other end of the row the same week ran the other way: 20°E, 21°E and 22°E read 96.9%, 95.9% and 92.7% across 19–25 October — 22°E's lowest week since the series began (every earlier week 99.1–100%) and 20°E's lowest by a few tenths (97.3% in the week of 28 September) — as 21–25 October's 93.3%, 93.6%, 95.0%, 84.8% and 84.1% at 22°E (126 of 135, 132 of 141, 134 of 141, 128 of 151, 116 of 138) became the first five days under 97% in that cell since 1 September, back to back, with 25 October's 84.1% then the lowest that cell had read since our per-cell series began, on an ordinary sample; 26 October's 87.3% (103 of 118) made it six days running, the third in a row under 90%, and 27 October's 97.5% (115 of 118) ended the run at six. 28 October then read 68.2% (75 of 110) — sixteen points under 25 October's 84.1% and then the lowest that cell had read since the series began, on a day the whole row ran soft at once (below), logged as one day; 30 October has since gone lower still, to 64.1% (below), and the week of 26 October closed with 22°E at 86.1% (621 of 721 aircraft), under the week of 19 October — that cell's lowest closed week in the series. Higher in the west and lower in the east in the same week is a flatter slope over that week; we report both ends rather than read a direction into one week. Day to day the western cells still swing, in both directions and across the whole row at once: 17°E read 59.6% on 8 October — then its lowest since 17 August — 61.8%, 74.2% on 10 October, its highest since 12 September, 56.0% on 11 October, its lowest since 16 August, 59.3% on 12 October, 71.1% on 13 October, 65.4% on 14 October, 70.5% on 15 October and 77.6% on 16 October, its highest since 11 September; 16°E ran 32.5% → 35.0% → 60.1% → 39.4% → 41.2% → 33.1% → 44.3% → 43.1% → 51.0% over the same nine days; inland, 53°N 18°E read 68.5% on 10 October, then 54.8% and 47.8% on 11–12 October, the latter its lowest since 15 August, 69.7% on 13 October, 60.1% on 14 October, 64.8% on 15 October and 67.6% on 16 October; north across the water, 55°N 17°E read 76.2%, 67.5%, 62.2%, 65.8%, 75.2%, 64.5% and 75.7%. 10 October ran hot across the whole western end at once, 11–12 October ran soft across it at once, 13 October split it — Gdańsk's cell, 17°E and the inland cell south of the city came back while 16°E, 15°E and 14°E fell — 14 October split it the other way, 16°E, 15°E, 14°E and the cell north across the water rising while 17°E and the inland cell gave back part of the day before's rise and Gdańsk's own cell held, and 15 October split it back again, 17°E and the inland cell up, 16°E, 15°E, 14°E and the cell north across the water down, Gdańsk's own cell half a point lower, 16 October ran hot across the whole western end at once again, as 10 October had — 17°E at its highest since 11 September, 15°E since 26 September, the inland 53°N 17°E cell since 12 September, Gdańsk's own cell at 90.4% — and then 17 October ran soft across the western end at once: 17°E dropped to 65.1%, 53°N 18°E to 57.1%, 55°N 17°E to 58.4%, and Gdańsk's own cell to 82.1%; 18 October brought 17°E back to 70.8%, 55°N 17°E to 70.3% and Gdańsk's cell to 87.7%; 19 October ran hot across the western end again — 17°E 77.9%, 16°E 55.4%, 55°N 17°E 78.4%, Gdańsk 89.7% — and 20 October hotter still, 17°E at 82.7%, its highest since 11 September, 16°E 56.7%, 53°N 17°E 61.1%, 55°N 17°E 84.1%, Gdańsk's own cell 92.7%; then 21 October gave part of it back across the row at once — 17°E 75.3%, 16°E 52.3%, 53°N 17°E 45.9%, 53°N 18°E 61.9%, 55°N 17°E 78.0%, Gdańsk 85.4% — and 22 October ran hot across the western end again, hotter than 20 October: 17°E 86.0%, 16°E 63.8% and the inland 53°N 18°E cell 79.5%, each its highest since 11 September, 53°N 17°E 62.3%, 55°N 17°E 80.8%, Gdańsk 93.1% — on a day the cells from 20°E to 22°E read 95.0%, 96.8% and 93.6%, logged as one day; 23 October held most of it — 17°E 85.5%, 16°E 61.6% and 53°N 18°E 74.7%, each second only to 22 October in the last six weeks, 55°N 17°E 84.9%, its highest in that span, and Gdańsk 92.0% on its largest sample since 4 October — logged as one day too; 24 October then gave much of it back across the row — 17°E 76.0%, 16°E 48.5%, 53°N 17°E 42.0%, 53°N 18°E 59.7%, 55°N 17°E 72.5%, Gdańsk 85.7% — while at the eastern end 22°E fell to 84.8% and 21°E to 81.8% (18 of 22, a thin sample), with 19°E and 20°E at 100% and 95.6%; logged as one day; 25 October held close to that — 17°E 75.3%, 16°E 51.0%, 53°N 17°E 49.4%, 53°N 18°E 70.5%, 55°N 17°E 81.8%, Gdańsk 85.7% — with 22°E at 84.1% and 19°E at 89.7%; 26 October split the western end — 17°E held at 75.1% and the inland 53°N 18°E cell rose to 72.3%, while 16°E fell to 40.8%, 53°N 17°E read 48.9% and 55°N 17°E 74.1% — as Gdańsk's own cell rose to 90.6% and 22°E read 87.3%, logged as one day; 27 October held the western end — 17°E 77.8%, 16°E 43.0%, 55°N 17°E 77.3%, and the inland 53°N 18°E cell 81.4%, its highest since 11 September — with Gdańsk at 91.4% and 22°E back to 97.5%; and 28 October ran soft across the whole row at once — 15°E 11.0% and 53°N 17°E 25.0%, each the lowest that cell has read since the series began, 14°E 16.1%, its lowest since 13 August, 16°E 30.3%, 17°E 67.2%, 53°N 18°E 50.8%, 55°N 17°E 69.7%, Gdańsk 79.5%, 19°E 87.1%, 21°E 83.3% and 22°E 68.2%, while 20°E alone held at 96.7% — on what were then the thinnest samples since 1 September: 27 or 28 October was then the thinnest day in every western cell we watch (76 aircraft at 16°E on 28 October against 157 two days earlier), and since then 31 October has run thinner over Gdańsk and the inland 53°N 18°E cell, and 3 November thinner again in every one of those cells but 16°E (below). Logged as one day, with the thin samples noted and nothing attributed. 29 October then took back most of it across the row — 92.3% at 22°E, 95.8% at 21°E, 100% at 20°E, 93.0% at 19°E, 85.2% over Gdańsk, 74.4% at 17°E, 44.6% at 16°E, 25.3% at 15°E and 21.6% at 14°E, with the inland 53°N 18°E cell back to 62.3% — while 53°N 17°E (36.2%) and 55°N 17°E (69.5%) stayed near their 28 October readings; logged as one day too, on a sample still thin at 16°E (92 aircraft). 30 October then split the row by its ends: the western cells rose — 78.5% at 17°E, 46.9% at 16°E, 33.7% at 15°E and 26.3% at 14°E, with Gdańsk's own cell at 91.8% — while at the eastern end 22°E fell to 64.1% (66 of 103), the lowest that cell has read since our per-cell series began, and 19°E to 77.1% (27 of 35, a thin sample), its lowest since 1 September; the inland cells and the cell north across the water held close to the day before (53°N 17°E 40.8%, 53°N 18°E 61.7%, 55°N 17°E 69.9%). Logged as one day. 31 October brought 22°E back to 100% (61 of 61) — on the thinnest sample that cell has carried since our per-cell series began, against 103 the day before — with 21°E at 100% (15 of 15) and 20°E at 96.6% (28 of 29), while the western cells held near 30 October — 73.5% at 17°E, 46.0% at 16°E, 34.6% at 15°E, 27.6% at 14°E and 90.4% over Gdańsk — and the inland and northern cells rose (53°N 17°E 46.9%, 53°N 18°E 70.6%, 55°N 17°E 73.3%). Thin samples at the eastern end; logged as one day. 1 November split the row: 16°E fell to 37.3% and 17°E to 68.3%, with Gdańsk's own cell at 81.5%, while 15°E and 14°E rose to 41.5% and 36.8% and the cells from 19°E east read 91.3%, 95.9%, 95.5% and 100% (81 of 81 at 22°E); 2 November softened the far west — 22.7% at both 15°E and 14°E, 32.1% at 16°E, 66.9% at 17°E — as Gdańsk read 83.7% and 20°E, 21°E and 22°E all read 100% (47 of 47, 25 of 25, 94 of 94). Logged as one day each. 3 November then ran thin across the western end — the thinnest daily samples since 1 September at 14°E (144 aircraft), 15°E (130), 17°E (97), over Gdańsk (98), at 19°E (30), in both inland cells (114 and 124) and north across the water (91) — on a day the receiver network as a whole tracked 4% fewer aircraft than a week earlier and the 53–55°N, 14–22°E box 11% fewer; the cross-check network's own count of Gdańsk movements that day also ran low (79 against 128 the Tuesday before, while Warsaw's ran 4% under), so the thin samples looked local to Gdańsk — a receiver-coverage or traffic dip we could not tell apart. A cycle on, the network feed reads the day low independently — 86 Gdańsk movements against 132 the Tuesday before, none recorded between 15:25 and 17:04 UTC, in clear weather at the airport — and it was not Gdańsk's alone: the cross-check network logged Wrocław 19% and Kraków 9% under their Tuesday before, Warsaw 4% under. We still cannot tell receiver coverage from traffic, and attribute nothing. On those samples 17°E rose to 75.3% and 16°E to 43.9%, 15°E read 34.6% and 14°E 28.5%, Gdańsk 80.6%, 19°E 83.3% (25 of 30), and 20°E, 21°E and 22°E 93.9%, 95.2% and 99.1% (107 of 108 at 22°E); 53°N 17°E read 41.2%, 53°N 18°E 66.9% and 55°N 17°E 76.9%. Logged as one day, the thin samples noted, nothing attributed. 4 November ran thin again over Gdańsk (109 aircraft, the second-thinnest of the series) and softer in the west: 17°E fell to 57.7% (64 of 111), its lowest since 11 October, 16°E to 38.7%, 15°E read 29.8% and 14°E 27.3%, Gdańsk 78.9%, 19°E 86.7% (26 of 30), 21°E 83.3% (15 of 18), while 20°E and 22°E read 100% (31 of 31, 107 of 107); 53°N 17°E read 34.3%, 53°N 18°E 53.6% and 55°N 17°E 64.2%. The 53–55°N, 14–22°E box tracked 5% fewer aircraft than a week earlier, in line with 4% fewer worldwide, so the thin day was not a regional coverage drop. Logged as one day. 5 November held the western end soft on a fuller sample: 17°E read 57.8% (89 of 154) — with 4 November, its two lowest readings since 11 October — 16°E 40.0%, 15°E 30.1% and 14°E 29.9%, Gdańsk 80.0% (100 of 125), the inland 53°N 18°E cell 51.6%, its lowest since 28 October, 53°N 17°E 36.0% and 55°N 17°E 61.3%, its lowest since 17 October, while 19°E to 22°E read 95.3%, 100%, 90.0% (18 of 20) and 99.2% (123 of 124). The 53–55°N, 14–22°E box tracked 5% fewer aircraft than a week earlier, against 3% fewer worldwide. Logged as one day. 6 November is a gap in our per-cell feed, in every cell. 7 November read 76.1% over Gdańsk (83 of 109), the softest since 12 October, while 17°E came back to 61.0% (75 of 123), 16°E to 44.1%, 15°E read 34.7% and 14°E 33.5%; the inland 53°N 18°E cell read 56.4% and 53°N 17°E 38.1%, 55°N 17°E 59.8%, its lowest since 17 October, and 19°E to 22°E 90.2%, 100% (32 of 32), 89.5% (17 of 19) and 100% (93 of 93). The 53–55°N, 14–22°E box tracked 6% fewer aircraft than a week earlier, against level worldwide. Logged as one day. 8 November read 75.6% over Gdańsk (96 of 127), the softest since 12 October, as 17°E fell to 55.7% (78 of 140), its lowest since 16 August, 16°E read 41.2%, 15°E 28.8% and 14°E 23.6%; the inland 53°N 18°E cell read 51.8% and 53°N 17°E 37.6%, 55°N 17°E 63.8%, and 19°E to 22°E 85.4%, 96.1% (49 of 51), 88.5% (23 of 26) and 100% (116 of 116). The 53–55°N, 14–22°E box tracked 2.6% more aircraft than a week earlier, against 5.5% more worldwide. Logged as one day. 9 November read 85.8% over Gdańsk (97 of 113), the highest since 31 October, as 17°E came back to 70.1% (89 of 127), 16°E read 46.4%, 15°E 32.6% and 14°E 30.1%; the inland 53°N 18°E cell read 63.4% and 53°N 17°E 36.8%, 55°N 17°E 72.7%, and 19°E to 22°E 91.7% (33 of 36), 97.9% (46 of 47), 93.1% (27 of 29) and 99.1% (114 of 115). The 53–55°N, 14–22°E box tracked 1.5% more aircraft than a week earlier, against 1.9% more worldwide. Logged as one day. Which is exactly why the call rests on the closed week and the month, and not on any run of days.
FIR-average hides the coast — why the cell-level number matters. By the FIR-wide measure, the whole Warsaw FIR (EPWW) sits at 3.5% over the last 7 days, against its 3.8% 90-day average, reading 4.90%, 3.54%, 3.23%, 3.17%, 2.99%, 3.53% and 3.45% on 3–9 November — 25 October is missing from our FIR-level feed — after 19–23 October at 4.97%, 5.63%, 5.19%, 4.81% and 5.19%: 20 October the highest single day in this series, above 11 September's 5.59%, and the five together the first consecutive days above the 3.35–4.39% band since it formed in late September, and a longer run above 4.39% than the three days of 10–12 September — with 24 and 26–29 October back inside the band, 30 October a fraction under its 3.35% floor, the lowest day since 21 September, 31 October back inside it, 1 November's 4.15%, the highest since 23 October, inside it too, and 3 November's 4.90% back above it — the first day above the band since 23 October, on 12,291 tracked aircraft, the FIR's thinnest daily sample since 1 September, then 4 November's 3.54% back inside it, 5 November's 3.23% under its floor, the lowest day since 21 September, 6 November's 3.17% under it again, the lowest since 26 August, and 7 November's 2.99% under it a third day running, the lowest since 25 August — three consecutive days under the floor, the low-side test this brief set, so a low-side break, back at the level the FIR read in August, before 8 November's 3.53% came back inside the band, ending the run at three days — as its two highest days of October (16 and 20 October) also fell on thin samples — on 12,300 to 20,100 tracked aircraft a day (FIR-level, high confidence). The August-to-September movement at that scale is 3.3% → 3.9% — real, but a fraction of a point, because the average pools a hot Baltic coast with quiet inland Poland. Zoom to the 54°N 18°E cell and the degraded share is some twenty times the FIR figure. Both numbers are true; only the cell-level one tells a dispatcher what the Gulf of Gdańsk looks like today. The neighbouring FIRs at the same 7-day scale: Kaliningrad (UMKK) ~32.6% against a ~29.6% 90-day average, and Vilnius (EYVL) ~18.2% against ~19.8% — Palanga's FIR. UMKK's figure rests on 74–106 tracked aircraft a day over the last week (45–150 since September), up from ~31.5% a cycle ago, and carries low confidence in our feed on four of its seven observed days (7, 8 and 9 November medium), so treat it as indicative rather than as a move. One FIR-wide figure hides the pocket; the pocket alone overstates the FIR. We label which scale each number belongs to for exactly that reason.
Interference degrades navigation; it does not ground flights. The figure counts aircraft broadcasting downgraded navigation integrity in their ADS-B position-quality fields — the consistent fingerprint of GNSS interference. It does not mean those aircraft are lost or off course. Airliners cross-check satellite positioning against inertial reference systems and ground-based aids — ILS, VOR/DME — and fall back to them when GNSS degrades, with published contingency procedures for GNSS loss. The real cost is precision and workload: satellite-based (RNP/RNAV) approaches can become unavailable, approach minima rise, and in poor visibility that can mean holding or a diversion to an alternate. That is exactly why Gdańsk's departure board shows nothing: the traffic section above reads an ordinary late-summer profile — a September mean of about 160 observed movements a day, and the window's busiest day of all, 216, falling on Thursday 1 October — while nearly nine in ten aircraft over the cell flagged degraded GNSS across the month.
Honest arithmetic on a mid-sized cell. The Gdańsk cell has seen 98–195 tracked aircraft a day in our feed since 1 September — large enough that a weekly aggregate on roughly 1,000 aircraft is a solid number, small enough that a single day can swing five points on sampling alone. That is why the 99.4% of 11 September (179 of 180 aircraft) is reported as a peak day and not as the level, why 3 and 4 October's 82.1% and 83.8% were logged rather than called a softening, with 5–8 October back at 85.0%, 85.7%, 86.3% and 86.2% (the 6th on 119 aircraft, then the thinnest day of the series), and why 9 October's 79.3% on 140 aircraft was logged as a floor rather than a break when 10 October came straight back to 91.2% on 136. 11 and 12 October then read 77.6% (121 of 156) and 74.1% (109 of 147) — two consecutive days below every reading since 16 August, on ordinary samples — and 13–27 October came back to 85.6% (119 of 139), 85.1% (120 of 141), 84.6% (137 of 162), 90.4% (141 of 156), 82.1% (115 of 140), 87.7% (121 of 138), 89.7% (131 of 146), 92.7% (115 of 124 — then the highest since 11 September, on what was then the second-thinnest sample since 1 September), 85.4% (123 of 144), 93.1% (134 of 144 — the highest since 11 September), 92.0% (150 of 163), 85.7% (132 of 154), 85.7% (120 of 140), 90.6% (145 of 160) and 91.4% (117 of 128), before 28 October read 79.5% (93 of 117 — then the thinnest sample of the series), 29 October 85.2% (115 of 135), 30 October 91.8% (112 of 122), 31 October 90.4% (104 of 115 — then the thinnest of the series), and 1–5 November 81.5% (101 of 124), 83.7% (108 of 129), 80.6% (79 of 98 — now the thinnest of the series, on a day Gdańsk's own movement count also fell to the window's lowest in both networks we read), 78.9% (86 of 109) and 80.0% (100 of 125), 7 November 76.1% (83 of 109) 8 November 75.6% (96 of 127) and 9 November 85.8% (97 of 113). The pair is logged as two days, the rebound as fifteen and 28 October–9 November as one day each; a move of eleven or twelve points in a day is more than sampling alone, and this cell has now produced one in each direction more than once inside a week, which is why the brief claims nothing on single readings. What it does claim is on aggregates: the step-up on the September month (88.1% against 82.4%), the easing on the closed weeks of 5 and 12 October (84.3% and 84.3%, back in the August range), and its reversal on the closed week of 19 October (89.2% — 89.7%, 92.7%, 85.4%, 93.1%, 92.0%, 85.7%, then 85.7%), held above 85% on the closed week of 26 October (87.3%), and its unwinding on the closed week of 2 November (79.2%, under the 82.4% August mark, on six observed days), with the October month closing at 86.2% (3,842 of 4,457 aircraft), between the August and September months. A day with no data at all, like 14 September and 6 November, is left out rather than filled in. The same goes for an odd-looking coincidence: 1 and 2 October carry identical counts in this cell, 140 of 161 both days, and rather than quietly smooth one of them we checked — the two days are written independently, and seven of the 2,628 cells holding 100 aircraft or more repeat exactly across them, the same rate as the pair of days before. Likewise the identical pairs at the Kaliningrad cell (54°N 20°E), which read 35 of 37 aircraft on both 6 and 7 October and 37 of 37 on both 10 and 11 October: 42 of the 4,146 and 48 of the 4,157 cells holding 30 aircraft or more repeat exactly across those pairs, so on samples that thin a repeat is ordinary — as was the pair one cell west, at 54°N 19°E, which read 40 of 43 on both 7 and 8 October, one of 59 exact repeats among the 4,197 cells holding 30 aircraft or more across those two days. The traffic section is kept to the same standard in both directions. Saturday 31 October and Sunday 1 November settled at exactly the recounts we substituted, 119 and 118, but the network's short passes for those days never backfilled (104,085 and 95,760 departures worldwide, 89.4% and 82.3% of the 14-day median), so the settled rows enshrine them and both are read as floors. Monday 2 November settled at 143, one arrival above the measured 142 we plotted while it was still filling. Tuesday 3 November settled at exactly the 86 we substituted for its clipped stored row — the window's lowest day, with the afternoon gap it carried (no Gdańsk movement between 15:25 and 17:04 UTC) kept in the settled row — Thursday 5 November settled at exactly the 141 we substituted for its clipped row, and Friday 6 November has settled at exactly the 149 we substituted for its own — the thirty-eighth consecutive cycle in which a figure we plotted proved to be where the feed settled. Tuesday 27 October stays flagged partial at its settled 132: the network feed lost about a third of its departures in the hour from 12:50 to 13:50 UTC that day and never backfilled them, so the settled row enshrines the hole (GDN: 3 movements in that hour against 8 and 9 on the days either side). Tuesday 20 October's settled 117 is now the window's third-lowest settled day. Saturday 7 November's stored row now reads 2 (0 departures, 2 arrivals), a clip the airport feed flags; we substitute the recount, 126, as on every previous clipped day, and do not call it final — it settles at the final pass on 11 November. Sunday 8 November is plotted at its measured 148 and still filling. 5 November is the lowest of the window's Thursdays, 6 November its second-lowest Friday, 7 November would be its fifth-lowest Saturday if it holds and 8 November its joint-fourth-lowest Sunday; the cross-check network read 3, 4 and 5 November low too (79, 94 and 134 Gdańsk movements against 128, 127 and 147 a week earlier), holds no data at all for 6 November, reads 7 November level with the Saturday before (106 against 108) and 8 November above the Sunday before (139 against 128), so we report them as measured and attribute nothing. Tuesday 29 September remains plotted at its measured 129 and flagged partial: its two-hour network hole (13:00–15:00 UTC) never backfilled, and the settled stored row enshrines it. Two older hour-scale holes stay disclosed — 8 September (13:00 UTC) and 26 August (06:00 UTC) — beside the new one on 27 October. Agreement between a stored row and a recount is not finality, as 1 October showed earlier this month. Every figure here is an aggregate of crowdsourced receiver telemetry: a floor, not a total.
What would change the picture. Three measured things are watched continuously by our automated multi-signal analysis. First, the western edge: the 54°N 17°E cell (70.1% on 9 November, after 55.7% on 8 November, its lowest since 16 August, 61.0% on 7 November, 61.7% across the closed week of 2 November, 73.7% across the closed week of 26 October, 79.8% across the closed week of 19 October, 64.7% across the closed week of 5 October, 70.9% across October, 69.9% across September) and 54°N 16°E (46.4%, 41.2%, 44.1%, 39.6%, 41.4%, 55.5%, 40.8%, 45.0%, 44.7%) are the tell-tales — a September-style step in those cells would put the zone's centre of mass over the Polish mainland rather than the gulf. On the closed October month that has not happened, at 1.1 and 0.3 points above September; on the closed week of 19 October both cells read ten points or more above September, on the closed week of 26 October they split — 17°E 3.8 points above September, 16°E 3.3 points below — and on the closed week of 2 November both closed below it, 17°E by 8.2 points and 16°E by 5.1, so a western step is not confirmed. The first test was the calendar week of 5 October, which closed below September at 17°E and 16°E and in every other watched cell — so the western-edge easing was called on a closed week, and it was never a retreat: the cells from 20°E east read 98–100% over that week. The week of 19 October has now closed above September in every one of those cells, so that call is reversed on the same measure; the cells from 20°E east read 93–97% over it. The next test was Gdańsk's own cell, and it has been run: the week of 12 October closed at 84.3% (862 of 1,023 aircraft) — 74.1%, 85.6%, 85.1%, 84.6%, 90.4%, 82.1%, then 87.7% — between the two marks this brief set, so the September step-up has neither unwound on a weekly measure (that needed a close below the 82.4% the cell averaged across 10–31 August) nor been reasserted (that needed a close above 85%); it matched the week of 5 October exactly. The week of 19 October has now closed on the same two marks: 89.2% (905 of 1,015 aircraft) — 89.7%, 92.7%, 85.4%, 93.1%, 92.0%, 85.7%, then 85.7% — above 85%, so on a weekly measure the September step-up has reasserted itself: the first complete week back at the September level since the week of 28 September (85.2%), above the 88.1% September month, and the highest since the week of 7 September (90.4%). The week of 26 October has now closed on the same marks: 87.3% (787 of 901 aircraft) — 90.6%, 91.4%, 79.5%, 85.2%, 91.8%, 90.4%, then 81.5% — above 85%, so the reassertion is two closed weeks deep, though 0.8 points under the 88.1% September month, where the week of 19 October closed above it. The week of 2 November has now closed on the same marks: 79.2% (552 of 697 aircraft) on six observed days — 83.7%, 80.6%, 78.9%, 80.0%, 76.1%, then 75.6%, with 6 November a gap in our per-cell feed — below 82.4%, so on a weekly measure the September step-up has unwound: 3.2 points under the mark, the softest closed week since that of 10 August (76.8%). It is one closed week on six days, and we call it on the rule we set and nothing more; the week of 9 November is read on the same two marks — a close above 85% would reassert the step-up, a second close below 82.4% would make the unwinding two weeks deep. It opened at 85.8% on its first observed day. Second, the FIR-level EPWW ratio breaking decisively out of the band it has held since late September rather than oscillating inside it: 10 October's 4.71% was the first day above the 3.35–4.39% of 26 September–9 October and the highest since 17 September, and we said it would become a break only if the following days held above 4.39% — they did not, reading 3.85%, 3.68%, 3.58%, 3.92% and 3.90%, so it stayed a one-day excursion. 16 October then read 5.36%, the second day above that band in a week and the highest since 11 September, and pulled the 7-day average to 4.1%; 17 October read 3.83% and 18 October 3.72%, both inside the band, so 16 October stayed a one-day excursion as 10 October did — then 19 October read 4.97%, 20 October 5.63% — the highest single day in this series, above 11 September's 5.59% — and 21 October 5.19%: three consecutive days above 4.39%, the condition we set, so the FIR-level ratio has broken out of its late-September band on the high side; 22 and 23 October added a fourth and a fifth day at 4.81% and 5.19%, and 24 October read 3.75%, back inside the band, ending the run at five days. The days since have stayed inside it or just under it — 3.68%, 3.48%, 3.44% and 3.42% on 26–29 October, then 3.29% on 30 October, a fraction under the band's 3.35% floor and the lowest since 21 September's 3.22%, and 3.58% on 31 October, back inside, with 25 October missing from our FIR-level feed — and the 7-day average eased from 4.8% to 3.5% and now stands at 3.5%, three tenths under the 3.8% 90-day average: a five-day break that has not become a new level. We said we would call a break on the low side only on the test we set on the high side — three consecutive days under 3.35% — and 31 October's return inside the band means that test was not met: 30 October stays a one-day reading. 1 November then read 4.15% and 2 November 3.66%, both inside the band, and 3 November 4.90% — the first day above it since 23 October, on the FIR's thinnest daily sample since 1 September; on the test we set, a new high-side break needs three consecutive days above 4.39%, so it is logged as one day — and 4 November's 3.54%, back inside the band, means that test was not met either. 5 November then read 3.23%, under the 3.35% floor and the lowest since 21 September, 6 November 3.17%, under it again and the lowest since 26 August, and 7 November 2.99%, under it a third day running and the lowest since 25 August, on 13,629 tracked aircraft: three consecutive days under 3.35%, the condition we set, so the FIR-level ratio has broken out of its late-September band on the low side. It is a return to August levels rather than a new low — the FIR averaged 3.3% across August, when days at 2.85–3.25% were common — and a FIR-level figure that pools the coast with quiet inland Poland, while the cell over Gdańsk read under 85% on each of those days it was observed; 8 and 9 November then read 3.53% and 3.45%, back inside the band, ending the run at three days; the 7-day average stands at 3.5%, three tenths under the 3.8% 90-day average. We report the break on the rule we set and read nothing into it beyond that. Third, a shift from jamming (signal loss) toward spoofing (a coherent false position), or interference reaching approach paths at GDN in low-visibility conditions. A fourth signal — regulatory action, meaning NOTAMs suspending satellite-based approach procedures at Polish coastal airports — would be the clearest operational marker, and we report what our feed now shows: after not refreshing between 4 and 27 October, our NOTAM set refreshed on 28 October and again on 1 November and now carries Warsaw FIR (EPWW) items it did not carry before — 30 when it first refreshed, 23 still in force by 30 October, 32 after the 1 November refresh, 33 after a further refresh on 9 November and 35 after the latest on 10 November — while it still carries none for the Vilnius (EYVL) or Kaliningrad (UMKK) FIRs. One of them is a standing FIR-wide GNSS notice, in force from 11 September to 11 December and replacing an earlier one, which says GNSS jamming and spoofing occurrences can be expected within the Warsaw FIR, asks crews to remain vigilant and report to ATS, and notes that conventional navigation aids are available. That is an advisory, not the procedural marker this test looks for: none of them mentions satellite-based (RNP or RNAV) approaches or Gdańsk. Because the set holds only notices currently in force, a notice issued and withdrawn while it was not refreshing would not show, so silence on the procedural marker — and on EYVL and UMKK altogether — is still partly a gap in our coverage, not evidence that nothing has been issued. This page updates from the same monitoring cycle as the GDN brief and the live regional GPS-interference map.
Passenger questions, answered from the data
As of 10 November 2026, the airspace cell over Gdańsk and the Gulf of Gdańsk (54°N 18°E) has run 74–99% of aircraft flagging degraded navigation on every observed day since 1 September — 85.8% on 9 November, the highest since 31 October, ending a run of seven observed days under 85%, the longest such run since 10–17 August, 75.6% on 8 November, 76.1% on 7 November, 80.0% on 5 November, 78.9% on 4 November, then the softest since 12 October, on the cell's joint second-thinnest sample of the series, 80.6% on 3 November, on its thinnest, 83.7% on 2 November, 81.5% on 1 November, 90.4% on 31 October, 91.8% on 30 October, the highest since 23 October, 85.2% on 29 October, after 79.5% on 28 October, the softest since 12 October, 91.4% on 27 October, 90.6% on 26 October, 85.7% on 25 and 24 October, 92.0% on 23 October and 93.1% on 22 October, the highest since 11 September — up from the 71–84% band documented in August on the month, but the latest closed week, that of 2 November, closed at 79.2% on six observed days, under the 82.4% August mark, so on a weekly measure the September step-up has unwound; the week of 26 October had closed at 87.3% and the week of 19 October at 89.2%, back above September, after the weeks of 5 and 12 October had both closed at 84.3%, in the August range. Observed traffic at Gdańsk (GDN) stayed within what its airport brief scores normal for the weekday through 2 November, then read the window's two lowest days on 3 and 4 November, both now settled, in both of the networks we read, with no cause we can attribute; Tuesday 20 October settled at 117, one under Tuesday 6 October's 118 — the window's lowest settled day until 3 November; Thursday 22 October settled at 153 — the window's lowest settled Thursday, scored normal at −22% against its Thursday reference; Friday 23 October settled at 162 and Saturday 24 October at 142; Sunday 25 October — the first day of the winter timetable — settled at 120, the window's lowest Sunday; Monday 26 October settled at 148, the window's lowest Monday; Tuesday 27 October settled at 132, flagged partial for a one-hour network collection hole its settled row enshrines; Wednesday 28 October settled at 147 — the window's lowest Wednesday, by one; Thursday 29 October settled at 148 — the window's lowest Thursday; Friday 30 October settled at 141 — the window's lowest Friday; Saturday 31 October settled at 119 on a short network pass — the window's joint-lowest Saturday, read as a floor; Sunday 1 November settled at 118 on a short network pass — the window's lowest Sunday, read as a floor; Monday 2 November settled at 143 — the window's lowest Monday; Tuesday 3 November settled at 86 — the window's lowest day, low in both networks we read; Wednesday 4 November settled at 106, scored normal at −36% against its Wednesday reference — the window's lowest Wednesday and its second-lowest day; Thursday 5 November settled at 141 — the window's lowest Thursday; Friday 6 November settled at 149 — the window's second-lowest Friday; Saturday 7 November reads a recount-substituted 126, not yet final; Sunday 8 November reads a measured 148, scored normal at +4% against its Sunday reference, still filling; Wednesday 14 October settled at 148, the window's lowest Wednesday until 28 October; Thursday 1 October, at 216, is the busiest day of the whole window. Aircraft in the affected area broadcast degraded navigation but continue operating on back-up systems. See the live GDN brief, and check your airline's status on the day of travel.
Over Gdańsk's own cell, yes, measurably, on the month: 88.1% of tracked aircraft flagged across 1–30 September against 82.4% across 10–31 August, with the daily floor rising from 71% to 82% and a 99.4% peak on 11 September. The cells one and two degrees west (54°N 17°E, 54°N 16°E) and the inland cells south of the coast all rose by two to six points over the same comparison, while cells north across the water did not — the zone pushed west and inland along the Polish coast in September. October ran softer for its first three weeks: across October Gdańsk's own cell closed at 86.2%, below September, while 17°E (70.9%) and 16°E (45.0%) closed 1.1 and 0.3 points above their September figures — and both the week of 5 October and the week of 12 October closed at 84.3% over Gdańsk, two consecutive weeks in the August range; 11 and 12 October read 77.6% and 74.1%, the softest days since mid-August. Then the week of 19 October closed at 89.2% over Gdańsk, above September, with 17°E (79.8%) and 16°E (55.5%) at their highest weekly readings since our per-cell series began on 10 August — so on that week the answer at the western edge was yes again; the week of 26 October closed at 87.3% over Gdańsk with 17°E (73.7%) still above September and 16°E (41.4%) back below it. The cells from 20°E east read 93–97% over that week, so the zone has not retreated; its slope has flattened, higher in the west and lower in the east. The week of 2 November then closed at 79.2% over Gdańsk, under the 82.4% the cell averaged across 10–31 August, with 17°E (61.7%) and 16°E (39.6%) both below September while 20–22°E read 91.5–99.7% — so on that week the answer over Gdańsk is no: the September step-up has unwound on a weekly measure. Averaged across the whole Warsaw FIR (EPWW) the August-to-September change is 3.3% → 3.9% — a FIR-level number, deliberately much lower than the cell, because it pools the coast with quiet inland Poland. Deeper in the zone the FIR-level picture barely moved: the Kaliningrad FIR (UMKK) averaged 29.2% across 10–31 August and 30.6% across 1–30 September — under two points on a feed of just 45–150 tracked aircraft a day at low confidence, which we do not read as a step, and its 28.2% across October is on the same thin feed and reads the same way.
Aircraft carry independent navigation systems — inertial reference and ground-based aids such as ILS and VOR/DME — that crews and air-traffic control use when satellite positioning degrades, and regulators publish procedures for interference-prone airspace. We publish the measured picture: where interference is concentrated, how persistent it is and how it is moving. Operational and go/no-go decisions belong to operators and authorities.
NIC is the Navigation Integrity Category — a value each ADS-B aircraft broadcasts describing how much it trusts its own position. When GNSS is jammed or spoofed, that value falls. We aggregate NIC reports collected by crowdsourced ADS-B receiver networks into a per-cell daily share of aircraft reporting low integrity, on 1°×1° cells. Because it only counts aircraft the network received, the share is a floor — real exposure may be higher, not lower. On the Gdańsk cell that has been 98–195 aircraft a day since September, so we report the step-up on weekly and monthly aggregates rather than on single days.
Because the two measure different layers. The 74–99% figure counts aircraft broadcasting degraded position quality in a specific airspace cell; the traffic figure counts departures and arrivals at the airport. Interference degrades a navigation source with documented back-ups — it does not close a runway — so it leaves no signature in the movement count. Gdańsk averaged about 159 observed movements a day over the 88 measured days from 13 August to 8 November, about 160 a day in September against about 180 in the second half of August — a broad late-summer step-down with no link to the navigation layer — Tuesday 20 October settled at 117, one under Tuesday 6 October's 118 — the window's lowest settled day until 3 November, on the weekday that has thinned most with the season; Thursday 22 October settled at 153 — the window's lowest settled Thursday, scored normal by the airport brief at −22% against its Thursday reference; Friday 23 October settled at 162 and Saturday 24 October at 142; Sunday 25 October — the first day of the winter timetable — settled at 120, the lowest of the window's eleven Sundays; Monday 26 October settled at 148, the lowest of the window's eleven Mondays; Tuesday 27 October settled at 132, flagged partial for a one-hour network collection hole its settled row enshrines; Wednesday 28 October settled at 147 — the lowest of the window's eleven Wednesdays, by one; Thursday 29 October settled at 148 — the lowest of the window's twelve Thursdays; Friday 30 October settled at 141 — the lowest of the window's twelve Fridays; Saturday 31 October settled at 119 on a short network pass — level with the lowest of the window's twelve Saturdays, read as a floor; Sunday 1 November settled at 118 on a short network pass — the lowest of the window's twelve Sundays, read as a floor; Monday 2 November settled at 143 — the lowest of the window's twelve Mondays; Tuesday 3 November settled at 86 — the window's lowest day — and Wednesday 4 November settled at 106 — its second-lowest — both low in both networks we read, in clear weather at the airport, and attributed to nothing, the navigation layer included; Thursday 5 November settled at 141, the window's lowest Thursday, Friday 6 November at 149, its second-lowest Friday, Saturday 7 November reads a recount-substituted 126, not yet final, and Sunday 8 November a still-filling 148. Wednesday 14 October settled at 148, the window's lowest Wednesday until 28 October. Thursday 1 October, at 216, remains the busiest day of the whole window. Tuesday 29 September stays at its measured 129, flagged partial — the network feed's two-hour collection hole is baked into its settled row, so 129 is a floor roughly twenty movements short, not a dip.
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“Over Gdańsk and the Gulf of Gdańsk, 82–99% of tracked aircraft broadcast degraded navigation integrity on every observed day from 1 to 30 September 2026 — 88.1% across the month against 82.4% across 10–31 August, with the interference gradient creeping west and inland along the Polish coast — even as the wider Warsaw flight-information region averaged 3.5% over the latest week and Gdańsk airport’s observed traffic stayed normal for the weekday, according to flight-monitoring service FlySafe.zone.”
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FlySafe.zone monitors airspace risk and observed airport activity worldwide: 334 flight-information regions scored daily, GPS-interference signals, volcanic-ash exposure and daily observed movements at 493 airports from the crowdsourced ADS-B receiver network. Methodology: flysafe.zone/methodology.
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