A British Airways A320 stall warning on approach to London Heathrow on 6 July forced the crew of flight BA919 to declare a mayday, with the Airbus A320-232 registered G-EUUN carrying approximately 180 passengers from Düsseldorf before landing safely without injuries or damage.
How a Data Failure Cascaded Into a Mayday
The sequence began with a failure of the aircraft’s air data reference (ADR) system, according to the French Air Safety Investigation Authority (BEA), which triggered the first stall warning on approach to Runway 27L.
The crew initiated a go-around and declared a PAN PAN urgency call, then repositioned the aircraft for a second approach. At that point, they were flying in what is known as ‘alternate law’, a degraded flight mode that removes some of the automated protections the Airbus fly-by-wire system normally provides.
FlightGlobal, citing BEA preliminary information, reports that alternate law specifically removes angle-of-attack protection, which is standard when the aircraft operates in normal law. That matters because angle-of-attack protection is one of the primary guardrails against an aerodynamic stall.
On the second approach, a further stall warning sounded at 3,000 feet, just miles from the airport by most expert estimates. The crew’s recovery manoeuvre brought the aircraft down to approximately 2,200 feet before the approach was stabilised, according to Migflug, citing the Air Accidents Investigation Branch (AAIB). The PAN PAN was upgraded to a mayday at that point, signalling imminent danger.
The aircraft landed without further incident. No injuries were reported and no damage to the airframe was confirmed.
What the British Airways A320 Stall Warning Investigation Will Examine
The AAIB has classified this as a serious incident rather than an accident, and Simple Flying reports that the AAIB’s preliminary notification does not state the aircraft entered an actual aerodynamic stall. The distinction matters legally and operationally: a stall warning and an actual stall are different events, and investigators will be assessing what the aircraft’s energy state truly was at that moment.
The investigation has also been provisionally categorised as a Loss of Control In-flight (LOC-I) serious incident, which places the focus on both the systems failure and the crew’s handling of the degraded flight envelope. The AAIB said the probe will be conducted as a correspondence investigation, meaning no field team will be deployed to the site.
British Airways confirmed it was assisting the AAIB but said it was not legally able to comment further. There is an added jurisdictional wrinkle: the BEA published the preliminary event summary on its website, attributing it to the AAIB, but the AAIB declined to confirm the statement was theirs. Both agencies are notified under international aviation investigation protocols when an incident involves an aircraft of French manufacture.
Aviation safety investigator David Gleave offered some calibration on the mayday itself. ‘You could have sick passengers on board who need urgent medical attention… so it’s up to the captains’ discretion as to what they call, but its very unusual for it to be a significant failure on board the aeroplane,’ he said. The implication being that a mayday is not always the crisis it sounds from the outside. In this case, though, the sequence, ADR failure, alternate law, two stall warnings, a recovery manoeuvre to 2,200 feet, suggests the crew had good reason to use the strongest language available to them.
TechTimes reports the approximately 180 passengers on board were unaware of much of this; the aircraft landed without drama visible from the cabin. The AAIB’s correspondence investigation is expected to produce a final report in due course, and its findings on what caused the ADR failure in the first place will be the thing to watch.
