British Airways A320 stall warnings over London draw AAIB investigation

Two stall warnings sounded in the cockpit of a British Airways A320 on final approach to London Heathrow on 6 July 2026, after an air data reference failure during descent degraded the aircraft's flight control law and removed its automatic protection against exceeding the stalling angle of attack. The UK Air Accidents Investigation Branch is investigating and has placed the occurrence in the loss of control in-flight category, according to reporting published on 29 and 30 July by FlightGlobal, The Times, airlive.net, Simple Flying and PYOK.

The aircraft was an Airbus A320-232 registered G-EUUN, operating flight BA919 from Düsseldorf. Coverage put roughly 180 people on board. Nobody was injured and the crew completed a landing at Heathrow. The event became public only at the end of July, more than three weeks after it occurred.

Sequence over east London on 6 July

According to airlive.net, the failure developed during descent over east London when an air data reference unit stopped supplying usable information to the flight control computers. On the A320 family, three air data inertial reference units feed airspeed, altitude and angle of attack values to the elevator and aileron computers, which compare the three sources and reject an outlier. When the computers cannot resolve the disagreement, they downgrade the control law rather than act on suspect data.

The British Airways A320 reverted from normal law to alternate law. The crew continued the approach to runway 27L, received a stall warning, discontinued the approach and flew a go-around. At that point they declared a PAN PAN, the international urgency call that sits one level below distress.

On the second approach, at about 3,000 feet, a further stall warning sounded. The captain took control of the sidestick and flew the recovery. The aircraft descended to approximately 2,200 feet before the crew stabilised it, and the radio call was upgraded from PAN PAN to MAYDAY. The landing that followed was uneventful.

Geography sharpened the event. Runway 27L is served by an approach that carries arriving traffic westbound across east and central London, and upday News reported that the sequence unfolded over the Canary Wharf area. Aircraft on that track are in a phase of flight where altitude and airspeed margins are at their lowest and where a go-around must be flown into one of the busiest terminal control areas in Europe. Declaring an urgency call gives the crew priority handling from air traffic control before any distress call is made.

Alternate law and the protections it removes

The distinction between the two control laws is the technical heart of the occurrence. In normal law, an Airbus fly by wire aircraft will not permit the crew to exceed the angle of attack at which the wing stalls. High angle of attack protection commands a nose down input as the limit is approached, and on the A320 the autothrust system can apply take off or go around thrust automatically. The aircraft cannot be stalled through sidestick input alone.

Alternate law removes that hard envelope protection. Low speed stability may remain as a soft cue, but the aircraft can be stalled, and the crew must respond to the aural warning with a conventional recovery: reduce angle of attack first, then apply thrust and recover the altitude. European operators, British Airways A320 fleets included, have trained that response under the upset prevention and recovery training requirements introduced across commercial aviation following a run of loss of control accidents. The reported actions on BA919, breaking off the approach after the first warning and transferring control to the commander after the second, are consistent with that doctrine.

One further caution applies. A stall warning is not proof of an aerodynamic stall. Where air data is corrupted, computed angle of attack values can be spurious and the warning can be false. Establishing which occurred on 6 July is a task for the recorders rather than for contemporaneous accounts.

Investigation classification and the recorders in hand

Loss of control in-flight is the occurrence category associated with the largest share of fatalities in commercial aviation worldwide, and applying it to the 6 July approach is a decision about where the event belongs in safety statistics rather than a finding that control was lost. Investigators are examining why the air data reference failed and are reviewing flight data recorder and cockpit voice recorder information to assess the crew response, according to airlive.net. The AAIB, which is based at Farnborough in Hampshire and reports to the Department for Transport, publishes monthly bulletins alongside standalone reports for field investigations. Recent commercial fixed wing work on its published register includes an inquiry into incorrect take off performance figures used by a Boeing 737-8 registered G-CRUX at London Luton on 22 April 2025, and incorrect thrust used during take off by an Airbus A320-214 registered G-EZUK at the same airport on 13 June 2025. Both concern the accuracy of the data feeding a departure rather than a failure of the systems generating it in flight.

Crew status and operator position

PYOK reported that the captain has been grounded on stress leave. Several UK national outlets, among them The Sun, the Daily Express, the Daily Mail, the Mirror and GB News, framed the occurrence around pilot error, and Simple Flying described an intervention by the commander after the first officer's handling at around 3,000 feet. Those characterisations run ahead of an investigation that has published no findings, and the branch's remit under UK air accident regulations is to determine cause for the prevention of future occurrences, not to apportion blame or liability.

Coverage on 29 and 30 July did not carry a detailed technical statement from either British Airways or Airbus. That is the normal pattern once an AAIB inquiry is open: the branch becomes the source of record for a serious incident, and operators and manufacturers usually confine public comment to confirming cooperation.

Air data failures in the Airbus service record

Corrupted air data has produced two of the most closely studied events in modern airline safety, and both frame how investigators will read the recordings from the British Airways A320.

On 7 October 2008, Qantas flight 72, an Airbus A330-303 registered VH-QPA, suffered two uncommanded pitch down manoeuvres in cruise off Western Australia. One air data inertial reference unit mislabelled altitude data as angle of attack: the binary word representing an altitude of 37,012 feet was interpreted as an angle of attack of 50.625 degrees. The aircraft lost 650 feet in the first event and 400 feet in the second. Of 315 people on board, 12 were seriously injured and 107 sustained minor injuries. The Australian Transport Safety Bureau concluded in its final report of 19 December 2011 that a design limitation in the flight control primary computer software had combined with a failure mode affecting one of the aircraft's three units.

On 1 June 2009, Air France flight 447, an Airbus A330-203 registered F-GZCP, lost reliable airspeed indication when ice crystals blocked its pitot probes over the Atlantic. The autopilot disconnected at 02:10:05 UTC, the aircraft entered alternate law 2, and the stall warning behaved counterintuitively, stopping when the angle of attack became so extreme that the airspeed values were rejected as invalid. All 228 people on board died. The French investigation bureau published its final report on 5 July 2012, attributing the accident to inconsistent airspeed measurements and the crew's handling of the resulting stall.

Neither case resembles the outcome at Heathrow. Both explain why an air data failure that strips envelope protection from a British Airways A320 during a low altitude approach over a dense urban area is treated as a serious matter irrespective of the safe landing that followed.

Discrepancies in the published accounts

Reporting on the British Airways A320 differs on altitude. Airlive.net placed the second stall warning near 3,000 feet with a descent to about 2,200 feet before recovery. The Times, the London Evening Standard, India Today and several other outlets described the aircraft stalling at about 4,000 feet. Simple Flying referred to 3,000 feet in connection with the first officer's handling. Only the flight data recorder trace, published in the AAIB report, will settle the recorded values.

Passenger numbers are likewise approximate in current coverage, with about 180 the figure most often cited. The registration G-EUUN, the flight number BA919 and the Düsseldorf to Heathrow routing are consistent across the aviation trade reports, as is the sequence of one go-around, a PAN PAN and a later upgrade to MAYDAY.

Timetable and regulatory route

The AAIB does not commit to publication dates for individual investigations. Field investigations into serious incidents involving large transport aircraft typically conclude within about twelve months, and the branch issues a special bulletin earlier where it judges that safety action cannot wait for the final report. Interim safety recommendations can be made at any point.

If the inquiry identifies a systemic problem with the air data reference installation rather than a one off component failure, the route to mandatory action runs through the European Union Aviation Safety Agency, which holds type certificate responsibility for the Airbus A320 family and can require inspection or modification by airworthiness directive. The UK Civil Aviation Authority would then adopt or mirror that instruction for British registered aircraft.

Its findings will turn on the technical cause of the air data reference failure, on whether the two stall warnings were genuine or spurious, and on how the handling of a British Airways A320 in alternate law compared with the operator's published procedures and training. Until the branch reports, every other characterisation of the 6 July approach remains provisional.