FlySafe was not operational during this event. This analysis reconstructs publicly available signals — to demonstrate how predictive airspace intelligence could have provided advance warning.
Etna–Stromboli Dual Eruption
July 2024 — 90 Flights Cancelled, Catania Closed
On July 4, 2024, Mount Etna launched a paroxysmal eruption, sending an ash column to 9.5 km over eastern Sicily. Within hours, Stromboli — 150 km to the northeast — intensified its own eruption with a major explosion raising the Civil Protection alert to Red. Catania-Fontanarossa Airport (CTA), Sicily's busiest with 10+ million annual passengers, closed on July 4 and again on July 14 during a second Etna paroxysm. Over 90 flights were cancelled. ENAV restricted airspace across LICZ FIR as ash clouds from two separate volcanoes created overlapping hazard zones.
What Happened
On 4 July 2024, Mount Etna — the 3,357-metre stratovolcano dominating eastern Sicily — entered a paroxysmal eruptive phase, sending an ash column to 9.5 km above sea level and directly into airspace used by high-density Mediterranean traffic. Within hours, Catania-Fontanarossa Airport (LICC/CTA) — Sicily's busiest airport and the primary gateway for summer tourist season — was closed by ENAV. What made this event unusually complex was that it did not occur in isolation: Stromboli (924 m), the perpetually active island volcano in the Aeolian archipelago roughly 200 km to the northeast, simultaneously produced a major explosive episode that triggered Italy's Civil Protection to raise its alert level to Red — the highest on the national scale.
The convergence of two active volcanic systems within the same Flight Information Region — LICZ (Rome ACC) — produced overlapping ash hazard zones that aviation meteorologists rarely encounter in a European context. Toulouse VAAC (Volcanic Ash Advisory Centre), the body responsible for volcanic ash advisories across the EUR-NAT region, issued multiple advisories covering flight levels from surface to above FL350 across the affected sectors. Catania was closed a second time on 14 July during a repeat Etna paroxysm, confirming this was a sustained, multi-event crisis rather than a single isolated eruption. By the end of summer 2024, Etna had produced at least six discrete paroxysms, each requiring reassessment of the airspace around LICC and the broader LICZ FIR.
- —Elevation: 3,357 m (Sicily, Italy)
- —Paroxysm onset: 4 July 2024
- —Ash column height: 9.5 km ASL
- —LICZ FIR airspace restrictions activated
- —Repeated paroxysms: 6+ through summer 2024
- —Monitored by INGV Catania Observatory
- —Elevation: 924 m (Aeolian Islands)
- —Major explosion: concurrent with Etna event
- —Civil Protection alert raised to Red
- —~200 km NE of Etna — overlapping ash zones
- —Also within LICZ FIR coverage
- —Compounded hazard assessment complexity
Warning Signs
Etna's paroxysmal eruptions are rarely without precursor signals. INGV's Catania Observatory — one of the most densely instrumented volcanic monitoring networks in the world — continuously tracks seismic tremor amplitude, infrasound, SO₂ flux, ground deformation, and thermal anomaly data across Etna's summit craters. In the days and hours before the 4 July 2024 paroxysm, multiple indicator streams showed escalating values consistent with pre-paroxysmal behaviour documented in prior events. For Stromboli, seismicity and explosive intensity had been elevated in the preceding weeks, a pattern that preceded the late-June 2019 major eruption and has since been incorporated into Italian Civil Protection's watch criteria.
From an aviation risk perspective, the critical pre-event data window was well-defined. SIGMET issuance protocols require Toulouse VAAC to issue advisories within one hour of confirmed ash cloud detection, but the lead time between INGV escalation and actual airspace impact is typically 2–4 hours for Etna events, depending on eruption column height and prevailing upper-level winds. On 4 July, upper-level wind patterns directed the 9.5 km ash plume southward and eastward — directly across the standard arrival and departure corridors for LICC. This was not an unpredictable wind scenario; the synoptic pattern was visible in 12-hour NWP output hours before the eruption peaked.
INGV real-time tremor data showed amplitude in the high range for 6–8 hours before the paroxysm onset on 4 July, matching the signature of prior Southeast Crater eruptive events. This data is publicly accessible via INGV's monitoring bulletins.
Sulphur dioxide flux from Etna's summit is a leading indicator of ascending magma. Pre-paroxysm SO₂ flux values in the hours before 4 July significantly exceeded baseline, providing a quantifiable chemical precursor to the ash-generating eruption column.
Stromboli's baseline explosion rate had increased in the weeks prior, and lava field activity on Sciara del Fuoco was elevated. Italian Civil Protection's progressive alert system had already moved above the standard operational baseline before the Red alert declaration.
NWP model output for 4 July showed upper-level airflow over eastern Sicily directed southward and eastward — the precise vector to carry a 9.5 km ash column across LICC's approach paths. This wind regime was forecastable 12–24 hours ahead, enabling proactive airspace impact modelling.
Toulouse VAAC maintains situational awareness for Italian volcanic activity year-round. The VAAC's watch status for Etna and Stromboli was already elevated prior to the dual-eruption event, reflecting heightened activity levels documented by INGV in June–July 2024 bulletins.
Timeline
INGV observes elevated seismicity and increasing lava field activity on Stromboli's Sciara del Fuoco. Italian Civil Protection places Stromboli under heightened watch. Etna's Southeast Crater shows recurring Strombolian activity, with INGV bulletins noting increased degassing and tremor at moderate levels. Toulouse VAAC notes uptick in Italian volcanic monitoring signals.
INGV Catania Observatory records escalating tremor amplitude and SO₂ flux at Etna's summit craters through the evening and overnight hours. Seismicity on Stromboli remains elevated. Upper-level wind forecasts for 4 July over Sicily indicate southward-eastward airflow at FL250–FL350 — conditions that would carry an ash plume directly into LICC approach corridors if an eruption occurs.
Mount Etna enters paroxysmal eruption. The ash column reaches 9.5 km above sea level, confirmed by INGV real-time monitoring and satellite detection. Toulouse VAAC issues Volcanic Ash Advisory for LICZ FIR, covering multiple flight levels. Ash cloud advances toward Catania-Fontanarossa Airport (LICC/CTA). ENAV issues NOTAM activating airspace restrictions and closes LICC to arriving and departing traffic.
Catania-Fontanarossa Airport closes. Ryanair, Wizz Air, easyJet, and ITA Airways begin cancelling flights to and from LICC. Palermo Falcone-Borsellino Airport (LICJ) is activated as the primary diversion and alternative for displaced passengers. Airlines operating the busy summer leisure routes from Northern Europe — UK, Poland, Germany, the Netherlands — announce mass cancellations. Total cancellation count begins to accumulate past 90 flights.
Stromboli produces a major explosive episode during the same period. Italy's Civil Protection raises the Stromboli alert level to Red — the highest tier in the national volcanic alert framework. The dual-eruption scenario creates overlapping ash hazard zones within the LICZ FIR, a configuration without precedent in recent European aviation history. Toulouse VAAC's advisory polygon must account for two independent ash plumes in the same FIR simultaneously.
LICC reopens as Etna's initial paroxysm subsides. Toulouse VAAC downgrades ash advisory coverage. Airlines attempt to restore normal summer schedules. INGV continues elevated monitoring of Etna, issuing activity bulletins that note the volcano remains in an active eruptive cycle. Stromboli alert level is assessed for potential reduction. Passenger disruption continues as rebooking and recovery operations extend several days beyond the initial closure.
Etna undergoes a second paroxysm. Ash column again reaches hazardous heights. ENAV issues a second wave of NOTAMs and LICC closes for a second time. Toulouse VAAC reissues ash advisory for LICZ FIR. Airlines face a repeat cycle of cancellations — the second major disruption within eleven days, compounding the operational and commercial impact of the summer season disruption. Palermo again serves as the diversion airport.
Etna continues an elevated eruptive cycle through the summer, producing at least six discrete paroxysms. Each event requires INGV to issue updated activity bulletins, Toulouse VAAC to assess ash advisory applicability, and ENAV to evaluate NOTAM status for LICC. Airlines operating Sicily routes maintain contingency planning throughout the season. The 10+ million annual passengers served by CTA represent ongoing exposure to recurrent operational risk for the duration of the cycle.
Etna's paroxysmal cycle declines in intensity. LICC returns to sustained normal operations. Italian Civil Protection reduces Stromboli alert level from Red. Toulouse VAAC advisory frequency decreases. Airlines complete post-event disruption review and update volcanic contingency protocols for LICC and LICZ FIR. INGV Catania Observatory maintains continuous monitoring as standard operational posture.
Aviation Impact
The compounding effect of the dual-eruption scenario was felt most acutely in the low-cost carrier sector, which dominates CTA's traffic mix. Ryanair, Wizz Air, and easyJet collectively account for the majority of Catania's summer international movements — routes primarily serving leisure travellers from the UK, Poland, Germany, Hungary, and Scandinavia whose summer holiday bookings provide minimal schedule flexibility. ITA Airways, operating domestically and internationally, faced the same constraints. With Palermo as the only viable alternative Sicilian airport, LICJ absorbed significant overflow demand that strained its own ground handling and gate capacity during the peak disruption windows.
Over 90 flights cancelled across the July 4 and July 14 closure events, affecting Ryanair, Wizz Air, easyJet, and ITA Airways. Represents a significant share of CTA's daily movements during peak summer schedule.
Catania-Fontanarossa (LICC/CTA) closed on both 4 July and 14 July 2024 — two separate paroxysmal events within eleven days, creating a double disruption cycle during the busiest period of the aviation calendar.
Catania-Fontanarossa handles over 10 million passengers annually, making it Italy's fifth-busiest airport. Disruptions during July — the peak inbound month for Sicily tourism — carry disproportionate commercial and passenger welfare impact.
Etna produced at least six paroxysmal eruptive episodes through summer 2024, sustaining operational uncertainty across the LICZ FIR for months. Each event required fresh NOTAM assessment, VAAC advisory evaluation, and airline contingency decisions.
Beyond the headline cancellation figures, the dual-eruption scenario introduced a qualitative complexity that standard airline disruption procedures are not designed to handle. When two volcanic sources produce simultaneous ash hazards within the same FIR, the combined advisory polygon can cover airspace geometries that isolate an airport from multiple approach directions simultaneously. Catania, situated in the eastern shadow of Etna, has limited alternative approach geometries in any case; a southward and eastward ash plume from a 9.5 km column eliminates standard instrument approach paths and pushes the closed-airport threshold well before ash concentrations reach dangerous levels at the surface.
For network carriers, the disruption cascade extends beyond the immediate cancellations. Aircraft and crew displaced from LICC require repositioning, often from Palermo (LICJ) or mainland Italian hubs, generating knock-on delays across the network for 24–48 hours after the immediate closure resolves. The cost of a single major LICC closure day in July — in terms of refunds, rebooking, hotel accommodation, staff positioning, and slot recovery — runs into millions of euros for the carriers most exposed to Sicily leisure traffic.
Takeaway
The July 2024 Etna–Stromboli dual-eruption event exposes a structural gap in conventional airline risk management: the assumption that volcanic hazards are single-source, episodic events rather than multi-source, sustained cycles. Standard NOTAM-and-SIGMET workflows are designed around individual closures — a single airport, a single VAAC advisory, a single recovery timeline. When two active volcanic systems within the same FIR escalate simultaneously, and when the primary affected airport serves 10 million annual passengers during peak season, the reactive model fails operationally and commercially.
The critical insight from this event is that the data required to anticipate the July 4 closure — and to identify the 14 July second closure as highly probable — was available hours to days in advance. INGV's continuous monitoring output, Toulouse VAAC's advisory history for the LICZ FIR, upper-level wind NWP forecasts, and the seismic and geochemical precursor signals preceding Etna's paroxysms are all public or near-real-time data streams. The operational failure was not one of data availability; it was one of integration, interpretation, and proactive alerting — precisely the gap that an airspace risk intelligence layer is designed to close.
For flight operations teams, network planners, and slot coordinators managing summer Sicily schedules, the lesson is clear: LICC and the broader LICZ FIR carry persistent volcanic risk that repeats on a multi-week cycle during active Etna eruptive periods. Contingency planning should be pre-positioned at the start of each such cycle, not re-initiated reactively each time a NOTAM is issued. Palermo (LICJ) diversion capacity, crew positioning, and passenger communication protocols should be on standby as a continuous posture during elevated Etna activity windows — not activated as an emergency response.
This retrospective analysis examines signals present in public data before the event. It is provided for educational context only and does not claim predictive capability for future events.
A retrospective analysis suggests FlySafe's indices may have indicated LICC as entering an elevated closure-risk window on 3 July — approximately 12–18 hours before the first airport closure on 4 July. The model may have identified the convergence of high seismic tremor amplitude, elevated SO₂ flux, and a southward-eastward upper-level wind regime as a high-confidence precursor pattern matching prior Etna paroxysmal events. A separate signal track on Stromboli's concurrent escalation may have indicated a dual-source advisory flag for the LICZ FIR — alerting operations teams to the unusual complexity of simultaneous overlapping ash hazard zones. Following the July 4 event, FlySafe's sustained-risk tracking may have maintained an elevated risk score for LICC throughout the six-paroxysm summer cycle, providing pre-positioned warning for the July 14 second closure with sufficient lead time for proactive capacity management at both LICC and the Palermo diversion airport.
Sources
- — Toulouse VAAC — Volcanic Ash Advisories July 2024, LICZ FIR coverage, issued for Etna and concurrent Mediterranean volcanic activity
- — INGV (Istituto Nazionale di Geofisica e Vulcanologia) — Etna Activity Bulletins July 2024; Stromboli Activity Bulletins July 2024; Catania Observatory real-time monitoring data
- — ENAV — NOTAM archive LICC (Catania-Fontanarossa), July 4 and July 14 2024 closure NOTAMs; LICZ FIR airspace restriction records
- — Italian Civil Protection (Dipartimento della Protezione Civile) — Stromboli Red Alert declaration, July 2024; volcanic alert level framework documentation
- — Reuters — "Sicily flights cancelled as Mount Etna erupts," July 4 2024; reporting on Catania airport closure and airline cancellations
This is a retrospective analysis of publicly documented events. FlySafe's prediction system was not operational during this event. All information is sourced from public records, aviation authority publications, airline statements, and open data.