Serious incident — Boeing 787-9 instrument failure, international

Summary

A Qantas Boeing 787-9 experienced simultaneous failure of both left and right angle-of-attack sensors during cruise at FL390. The crew received multiple stall warnings and activated the unreliable airspeed procedure. The aircraft was returned to Sydney for engineering inspection. All 236 passengers and crew were uninjured.

Investigation Findings (4)

1. 01Both AoA sensors had been replaced during the preceding maintenance input and had been incorrectly calibrated to the same erroneous bias.
2. 02The simultaneous failure masked the normal disagreement alert.
3. 03Qantas revised its post-replacement test procedure to require an independent calibration verification check.
4. 04Boeing issued a service bulletin specifying a double-verification requirement after AoA sensor replacement.