What happened
On August 19, 2017, an Air France Airbus A340-300, registration F-GLZO, was preparing for a commercial flight from Bogotá El Dorado Airport to Paris. Due to high altitude and temperature conditions, the aircraft's takeoff performance was limited, requiring a reduction in payload to stay within safety margins.
During the takeoff roll on runway 13R, the aircraft experienced a rapid change in wind conditions. As the aircraft accelerated, the longitudinal wind shifted from a 3-knot headwind to an 11-knot headwind. Upon rotation at 138 knots, the wind transitioned from an 11-knot headwind to a 12-knot tailwind, accompanied by a downward vertical wind component.
Six seconds after liftoff, the aircraft's flight management computer detected windshear, triggering a red warning on the Primary Flight Display and an audible alarm. The airspeed dropped to 128 knots, which was 13 knots below the minimum selectable speed (VLS). The aircraft's angle of attack increased until the "Alpha Prot" protection mode was activated. Despite the encounter, the crew maintained the TOGA power setting and stabilized the aircraft, eventually clearing the runway threshold at 58 feet and reaching the required V2 speed of 145 knots.
The investigation
The BEA investigation focused on the meteorological conditions and the information available to the crew. Investigators examined the wind data from anemometers at the runway thresholds, which showed significant discrepancies in wind direction and intensity between the 13 and 31 runway ends.
The investigation also reviewed the communication between Air Traffic Control (ATC) and other aircraft. It was noted that while Spanish-speaking crews were receiving weather updates in Spanish, the Air France crew, which did not speak the language, was unable to follow these critical updates. Furthermore, the investigation examined why the aircraft's Predictive Windshear System (PWS) did not alert the crew to the approaching hazard.