What happened
On April 3, 2012, an Airbus A320-214, registration F-HEPE, operated by Air France, was performing a scheduled passenger flight from Paris Charles de Gaulle to Tel Aviv Ben Gurion. The flight crew was executing a RNAV VISUAL approach to runway 26.
During the descent, the crew transitioned to an OPEN DESCENT mode. While performing the final turn, the pilot flying (PF) applied a prolonged pitch-up command that contradicted the flight director instructions. This maneuver caused the aircraft's speed to drop from 135 kt to 122 kt, triggering the "SPEED, SPEED, SPEED" low-energy warning.
In response to the low speed, the PF initiated a go-around without notifying the pilot monitoring (PM). During this maneuver, the aircraft's angle of attack reached the threshold for ALPHA FLOOR protection, which automatically applied maximum TOGA thrust and engaged the "TOGA LOCK" mode. Because the thrust was locked at maximum, the crew struggled to manage the engine power. As the aircraft climbed, the speed increased to 223 kt, exceeding the maximum flap extension speed (VFE) for the current configuration and triggering an overspeed warning. The crew eventually disengaged the autothrust by moving the thrust levers to IDLE, allowing them to stabilize the aircraft and perform a second approach for a successful landing.
The investigation
The BEA examined flight data from the maintenance recorder (QAR), radio communications, and crew testimonies. The investigation focused on the crew's use of the OPEN DESCENT mode, the specificities of the RNAV VISUAL approach procedure at Tel Aviv, and the crew's management of the aircraft's automation during the low-speed event and subsequent go-around.
Findings
- The crew's lack of familiarity with the RNAV VISUAL approach, which was not explicitly detailed in their technical manuals at the time, contributed to inadequate preparation.
- The crew utilized the OPEN DESCENT mode, which maintains engines at idle; however, they failed to monitor the flight director instructions, leading to a loss of airspeed.
- The pilot flying's decision to configure the aircraft to FULL flaps early in the descent reduced the energy margin available for the final turn.
- Inadequate monitoring of flight parameters and a lack of communication between the pilots during the critical phase of the approach prevented the timely identification of the developing underspeed condition.
- The activation of the ALPHA FLOOR protection and the resulting TOGA LOCK mode caused confusion, as the crew did not immediately recognize that the thrust was being held at maximum despite their manual inputs.