Air Algérie Flight 5017

Air Algérie Flight 5017 was a scheduled international passenger flight from Ouagadougou, Burkina Faso, to Algiers, Algeria, which crashed near Gossi, Mali, on 24 July 2014. The McDonnell Douglas MD-83 twinjet, operated by Spanish charter airline Swiftair for Air Algérie, disappeared from radar about fifty minutes after take-off. All 110 passengers and 6 crew members on board died.

The Malian authorities, assisted by the French Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA), published an investigation report in April 2016, concluding that, while the aircraft was cruising on autopilot, ice accretion on the engines caused a reduction of thrust that led to a high-altitude stall. The crew never tried to recover from the stall, and the aircraft crashed. The BEA issued several recommendations to Air Algérie, the US Federal Aviation Administration, and the Governments of Burkina Faso and Mali. Until final number of fatalities is confirmed for the 2023 Il-76 crash in Gao, the crash of Flight 5017 remains the deadliest accident in Malian aviation history. On the legal front, Swiftair was brought to trial before the Paris Criminal Court on 9 March 2026, nearly twelve years after the crash, on charges of involuntary manslaughter.

Accident

Flight 5017 departed from Ouagadougou Airport at 1:15 local time (UTC) on 24 July 2014. It was scheduled to land at Houari Boumediene Airport, Algiers, at 5:10 local time (4:10 UTC).

The aircraft reached cruise altitude, flight level 310 (31,000 ft), 22 minutes after departure and attained its target speed of 280 kn (IAS). About two minutes later, it began to gradually lose speed, and, though the speed did eventually drop to 200 kn, the aircraft maintained FL310. After an unspecified length of time had passed, the aircraft began to descend, and the speed dropped to about 160 kn. Afterwards, the aircraft entered a left-hand turn and began to lose altitude more rapidly, thus spiralling down. The flight data recording stopped at 1:47; at the time, the aircraft was at an altitude of 1600 ft and a speed of 380 kn. It crashed into the ground at 270 m above sea level about a second later.

On 28 July, it was revealed that the flight crew had asked to return to Burkina Faso, after first requesting to deviate from course because of bad weather. There was a mesoscale convective system in the area at the time, and the aircraft had deviated to the left of its course to avoid it. Satellite images apparently identifying the light flare from the aircraft impact at the margins of the thunderstorm were captured.

Initially there were conflicting reports of the location of the crash. The aircraft's flight route took it over Mali, and it was reported to have disappeared between Gao and Tessalit. French forces reported detecting wreckage of the aircraft in an area between Gao and Kidal, in a desert region that is difficult to access. France sent a military unit to secure the wreckage of the Air Algérie plane. Malian President Ibrahim Boubacar Keïta said wreckage had been found in the country's northern desert, between Aguelhok and Kidal. There were also reports of wreckage being found near the town of Tilemsi in Mali, with officials from Algeria, Burkina Faso, and France having issued conflicting details.

Sequence of events based on flight data recorder analysis

The following was the sequence of events based on the FDR analysis:

The crew had been prepared to fly to Algiers from Ouagadougou. Because the crew was flying to Algiers they should have known the weather condition in the area. The crew had arrived in Ouagadougou one hour earlier, and knew about the weather in the region. Therefore, they already knew the risks of turbulence and icing. After handling the ground clearance, AH5017 took off from Ouagadougou at 01:15 local time (same time as UTC). There were no incidents in the initial climb.

Thirteen minutes after takeoff, while climbing through flight level 215 (21,500 ft), outside temperature 9 C, AH5017 slightly deviated to the left to avoid a storm in the area, which they reported to Ouagadougou ACC. However, even though they knew of the storm, the flight crews did not activate the engine anti-icing system. The temperature in the area indicated a high risk of icing. According to procedures, the engine anti-ice system should have been activated below 10 C. Ice crystals may be difficult to visually detect, especially at night, and are not detectable on weather radar, plus the absence of significant turbulence, may have caused the crew to think that activating the engine anti-icing system was not necessary.

The plane levelled off at at FL310 (31000 ft) at 01:37, the temperature was -5 C, the autopilot and autothrottle were already engaged. Two minutes later the speed of the plane increased. The crew then selected the cruise thrust regime on the TRP (thrust rating panel).

Shortly after, the EPR (engine pressure ratio) values of the right engine became erroneous, probably due to ice crystals obstructing its pressure sensor. The autothrottle then adjusted the thrust to prevent the erroneous values from exceeding the EPR limit in cruise setting. The thrust delivered by the engines was then lower than the thrust required for level flight, and the speed of the plane continued to decrease. For about one minute, the gap between the EPR values of the left and right engines gradually increased and then stabilized between 0.2 and 0.3, and the autothrottle switched to MACH ATL mode three times. 55 seconds after the anomaly in the right engine, the left engine's EPR values also became erroneous and started to increase. Due to these incorrect readings, the crew realized that an anomaly had occurred. Five seconds later, and continuing for four seconds, this increase was interrupted by a decrease in both engines' RPM. This decrease could have resulted from the crew reducing the Mach target, or from manual decrease in engine RPM by over-riding the autothrottle. However, even though there were many anomalies in the engines, the speed of the plane was still at or near normal speed cruising, so the crew still did not activate the engine anti-icing system. They did not realize that the blockage in the pressure sensors was causing the engines to deliver insufficient thrust. The engine RPM then increased again until the erroneous left EPR values reached EPR limit. The thrust delivered by the engines remained lower than the thrust required in this phase of flight and the plane continued to decelerate. The gap between the right EPR and the left EPR became closer to the typical EPR values while in cruise. The N1 values were slightly lower than the typical cruise values (77% instead of 80 – 85%). The inconsistency between the EPR values and N1 values was therefore hardly noticeable to the crew, more so since their documentation did not have a table of correct actions between EPR and N1 and they had not been trained to observe the correct action between these two parameters. Additionally, the flight crew was busy trying to avoid a nearby storm system and trying to contact Niamey.

AH5017's speed then decreased further to 210 kn, nearly to its stall speed. The Mach indicator needle was close to vertical, and such a reading should have been noticed by the flight crew, who then should have put the plane into a descent. However, they only made an input on the thrust lever. This was the correct action when there was a problem with the EPR system, but this action alone was not the reaction expected of a crew in an approach to stall. They should have put the aircraft into a descent. They did notice that there was a problem in AH5017's EPR. The autothrottle then disengaged, at a speed of 203 kn. The "SPEED LOW" warning then appeared on the cockpit screen but the flight crew were slow to react because they were handling contact with Niamey ACC. At this point, the autopilot was still engaged.

When the speed reached 200 kn, the stick shaker triggered, followed three seconds later by the stall warning. From this time onwards, Captain Comerón's side loudspeaker only broadcast the "STALL" warning, while that on First Officer Gost's side alternated the "STALL" warning with the other warnings that were active. When a stall happens, the crew should disconnect the autopilot and execute the stall recovery procedure. Neither actions were taken by the crew, indicating that they did not know that a stall had happened in-flight. In order to maintain altitude, the autopilot then commanded a continuous nose-up movement of the trimmable horizontal stabilizer and the elevators. This resulted in an increase in the angle of attack of up to 24°, or 13° above the stall angle of attack in the event conditions, as well as the broadcast of several "STABILIZER MOTION" warnings. Both engines suffered a surge probably due to the plane's high angle of attack, their RPMs decreased to values close to idle. This surge may have been noticed by the crew. There was no sign of a reaction by the crew other than the throttle movements, until the disconnection of the autopilot which occurred 25 seconds after the triggering of the stick shaker. The speed was then 162 kn, and the altitude had decreased by about 1,150 ft. The plane was banking to the left and its pitch was decreasing. The crew applied input mainly to roll to the right to bring the wings level. At the same time they applied mainly nose up inputs, contrary to the inputs required to recover from a stall, and continued to do so until impact with the ground.