Can Planes Land in Fog?
Sources: FAA, EASA, ICAO Annex 10 · Updated May 2026
Yes — modern airliners routinely land in dense fog using Instrument Landing System (ILS) precision approaches. CAT I, CAT II, and CAT III approaches each allow progressively lower visibility minima, with CAT IIIb autoland permitting touchdown at runway visual range (RVR) as low as 75 metres (about 250 feet). The aircraft, the crew, and the airport must each be approved for the relevant category. CAT III approaches typically use autoland — the autopilot flies the aircraft to touchdown and rollout. The pilots monitor and take over only if a fault is detected. Major hubs like London Heathrow (LHR), Frankfurt (FRA), Paris CDG, and Amsterdam (AMS) operate CAT III routinely; smaller airports often top out at CAT I.
What the ILS categories mean
The Instrument Landing System sends radio beams that define a precise approach path to the runway. The lower the visibility a category allows, the more redundancy is required in the aircraft, the runway lighting, the ground equipment, and crew training. ICAO Annex 10 defines the international standard; FAA and EASA implement it with minor regional variation.
Decision height 200 ft, RVR 550 m (1,800 ft). The standard precision approach available at most ILS-equipped runways worldwide. Hand-flown to decision height.
Decision height 100 ft, RVR 300 m. Requires approved aircraft, trained crew, and higher-integrity ground equipment with additional runway lighting.
Decision height below 100 ft (or no DH), RVR not less than 200 m. Typically flown with autoland; touchdown is automatic.
Decision height below 50 ft (or no DH), RVR as low as 75 m. Autoland mandatory; rollout assistance for taxiing off the runway in dense fog.
No DH, no RVR limit. Defined in standards but not operationally used because surface movement in zero visibility cannot be assured.
How autoland works
For CAT IIIa/IIIb, the aircraft flies the entire approach, flare, touchdown, and rollout under autopilot control. The required airborne equipment includes dual or triple autopilots, dual ILS receivers, autothrottle, radio altimeter, and fail-operational (or fail-passive) automatic flight control. The system continuously cross-checks itself; any disagreement triggers a missed approach.
Pilots monitor instruments and external cues. They are trained to intervene only if a system fault is annunciated. Below alert height (typically 100 ft on CAT IIIb), a single fault no longer triggers go-around — the system is designed to land safely on the remaining channels.
Which airports support CAT III
Major hubs in fog-prone regions invest in CAT III ground infrastructure: dual transmitters, enhanced runway lighting (centerline, touchdown zone, edge), protected critical areas, and surface movement guidance. Common CAT IIIb runways include:
- →London Heathrow (EGLL/LHR) — multiple runways CAT IIIb
- →Frankfurt (EDDF/FRA) — CAT IIIb capability across main runways
- →Paris Charles de Gaulle (LFPG/CDG) — CAT IIIb
- →Amsterdam Schiphol (EHAM/AMS) — CAT IIIb
- →Zurich (LSZH/ZRH), Munich (EDDM/MUC), Milan Malpensa (LIMC/MXP) — CAT IIIb
- →Beijing Capital (ZBAA/PEK), Tokyo Narita (RJAA/NRT), Seoul Incheon (RKSI/ICN) — CAT IIIa/IIIb
Smaller airports typically support CAT I only. When fog sets in and visibility drops below CAT I minima at a non-CAT III field, traffic diverts.
Low-Visibility Operations (LVO)
When fog reduces visibility, airports activate Low-Visibility Procedures (LVP). Movement on the airfield slows: aircraft taxi one at a time on each route, ATC applies wider spacing on final, and protected ILS critical areas keep ground vehicles clear of the signal. Departure minima rise as well — even a CAT IIIb airport may pause takeoffs if RVR drops below the lowest takeoff minimum (typically 75–125 m).
The cost: throughput drops sharply. A runway that handles 40 movements per hour normally may handle 20 or fewer under LVP. That is why fog disrupts schedules even when individual landings remain safe.
When fog cancels a flight
A flight is held, delayed, diverted, or cancelled when any of the following apply:
- →Destination RVR drops below the lowest approved minimum for that runway
- →The specific aircraft is not approved for the required category (some smaller jets are only CAT I or CAT II)
- →One or both pilots are not current on autoland or low-visibility procedures
- →An onboard system needed for autoland (autopilot, ILS, autothrottle, radio altimeter) is inoperative
- →The runway ILS is degraded — for example, only single-transmitter CAT I service available because the standby is out
- →Strong crosswind or tailwind exceeds the autoland limit (typically tighter than visual landing limits)
A brief history
The first autoland in scheduled service was a BEA Trident in 1965 at London Heathrow. CAT IIIa entered routine European service in the 1970s; CAT IIIb followed in the 1980s. Modern fly-by-wire aircraft (A320 family, A330/340/350/380, Boeing 777/787, 737 NG/MAX with appropriate certification) include autoland as standard equipment. The technology is mature and statistically extremely safe — autoland is a daily routine at fog-prone European hubs every winter.
Sources
- ICAO Annex 10 Vol I — Aeronautical Telecommunications: Radio Navigation Aids
- FAA Order 8400.13 — Procedures for the Evaluation and Approval of Facilities for Special Authorization CAT I, CAT II and CAT III Operations
- EASA AMC and GM to Part-SPA — Approach Operations Including EFVS
- EASA Part-CAT Subpart D — Low Visibility Operations (LVO)
- FAA AIM Chapter 5 — Air Traffic Procedures: Approach