What happened
On 2 May 2015, an Air France Boeing 777-228ER, registration F-GSPG, was performing a commercial flight from Malabo, Equatorial Guinea, to Douala, Cameroon. The flight was operating at a low altitude of FL90. Due to heavy storm activity in the region, the crew significantly deviated from the filed flight plan to avoid large cumulonimbus cells.
During the flight, the crew was managing high workloads involving intense air traffic control exchanges and complex weather monitoring. While attempting to join the DME arc for the Douala arrival, the pilot flying (PF) executed a right turn. Approximately 30 seconds into this turn, the Enhanced Ground Proximity Warning System (EGPWS) activated a "TERRAIN AHEAD" caution, followed shortly by a "P2ULL UP" warning.
The crew immediately executed the emergency maneuver, which included a nose-up input and maximum thrust. During the maneuver, the pilot in command (PM) requested that the climb be stopped at FL110 and then FL120 due to concerns regarding potential mid-air collisions with other traffic, despite the fact that the peak of Mount Cameroon stands at 13,202 ft. The aircraft eventually stabilized at FL130 and proceeded to land in Douala without further incident.
The investigation
The BEA investigation focused on the crew's loss of situational awareness regarding their position relative to the terrain. Investigators examined the use of the weather radar and the Navigation Displays (ND), noting that both pilots had set their displays to Weather mode rather than Terrain mode. The investigation also reviewed the flight preparation, specifically the use of a Douala arrival chart that featured Malabo as an insert, which was not to scale and contributed to a positioning error.
Furthermore, the BEA examined the operator's initial route study. While the airline had assessed risks for the departure and arrival airports, no specific risk assessment had been conducted for the en-route phase of this short leg, which often requires flying below the height of surrounding terrain.
Findings
Several contributing factors led to the near-collision:
- The crew's preoccupation with avoiding storm cells and managing ATC communications led to a significant deviation from the flight plan, rendering the flight's safety altitudes obsolete.
- The use of Weather mode on both NDs prevented the crew from clearly identifying the terrain.
- The navigation chart used for the arrival contained a non-scale representation of Malabo, which hindered the crew's ability to accurately judge their distance from Mount Cameroon.
- The lack of a formal en-route risk assessment meant the danger of flying below terrain peaks on this specific route was not identified during the initial route study.
- A brief attempt by the PF to use Terrain mode was insufficient to allow the radar to build a complete updated image of the terrain.