Boeing 737-300 F-GFUF Turbulence Incident at Antalya

Incident Overview and Flight Details On 2 May 2009, a Boeing 737-300 with registration F-GFUF, operated by Europe Airpost, was conducting a charter passenger flight from Marseille to Antalya, Turkey. The aircraft carried two flight crew members, three cabin crew members, and 110 passengers. The incident occurred at 07:13 UTC while the aircraft was on approach to Antalya, approximately 30 nautical miles north of the aerodrome. ## Sequence of Events The flight crew initiated descent at 06:55 UTC, with the co-pilot serving as pilot flying. The aircraft was using the autopilot and autothrottle, and the onboard weather radar was set to WX + TURB mode. At 07:09:27, engine anti-ice was activated as the aircraft passed flight level 130 at 240 knots. Shortly after, turbulence was recorded, with airspeed varying between 225 and 252 knots and vertical accelerations between +0.54 g and +1.62 g. The air traffic controller requested the crew to reduce speed toward the minimum approach speed. The crew selected 220 knots, which was 10 knots above the estimated clean configuration speed. At 07:13:12, the autopilot entered altitude acquisition mode, and at 07:13:19, it captured altitude hold at 11,000 feet. The recorded indicated airspeed was 210 knots. The crew observed a compact cumulus cloud approximately 2.5 nautical miles in diameter on the VOR-DME radial, about 25 nautical miles from the runway threshold. The cloud top was estimated at 12,000 feet and was clearly visible on the weather radar. The crew requested a left-hand deviation to avoid the cloud, but the controller granted a right-hand deviation. ## Loss of Control and Recovery At 07:13:33, approximately 30 nautical miles from the aerodrome, the aircraft, level at 11,000 feet at 210 knots, began a right-hand avoidance turn. The autopilot was in heading select mode with altitude hold, and the autothrottle was in speed hold mode. Engine N1 values were approximately 63.5 percent. Between 07:13:34 and 07:13:36, the aircraft entered a turbulent zone, with vertical accelerations varying between +0.5 g and +1.36 g. At 07:13:38, with indicated airspeed at 206 knots, a reduction in thrust levers was recorded, followed by a decrease in thrust. N1 values reached 36.8 percent and 32.8 percent at 07:13:46, with indicated airspeed at 199 knots and bank angle approximately 23 degrees. The thrust levers were advanced, likely manually, shortly after a vertical acceleration of +1.45 g was recorded. Airspeed continued to decrease while the engines responded to the lever advance. From 07:13:51, with airspeed at 187 knots, the bank angle increased to the right with a very high roll rate. The crew reported hearing the bank angle alarm and feeling the stick shaker activate. At 07:13:52, the bank angle was approximately 57 degrees and increasing, with N1 values reaching approximately 98 percent and 87 percent. A thrust lever reduction was recorded. The autothrottle disengaged at 07:13:53 as the pitch attitude decreased sharply. Recorded aileron deflection indicated a full left aileron input to counter the roll loss of control, accompanied by left rudder deflection. The autopilot entered CWS Roll mode and was disconnected approximately two seconds later. The bank angle reached a maximum of 102 degrees to the right, and the minimum airspeed of 181 knots was reached. The bank angle decreased to 90 degrees, which was maintained for 3 to 4 seconds, while the pitch attitude reached -24.8 degrees at 07:13:57 with the elevator in a nose-up position. Airspeed increased, and the descent rate was approximately -7,000 feet per minute. The crew reported being in instrument meteorological conditions at this point. The right bank angle then decreased, and the aircraft rolled to the left to approximately 35 degrees. The elevator moved to nose-down. The maximum recorded descent rate during the event was approximately 12,000 feet per minute. The thrust levers were advanced manually to full. The roll loss of control lasted 18 seconds. The minimum altitude reached during the event was 7,576 feet. The crew returned to the initial altitude of 11,000 feet and resumed the maneuvering speed in clean configuration plus 10 knots (220 knots). The autopilot was re-engaged at the end of the climb, followed by the autothrottle. ## Meteorological and Environmental Factors Satellite imagery showed a strong southwesterly flow and the presence of orographic waves. The crew did not have access to this satellite image, and the meteorological briefing provided did not allow for prediction of the orographic wave phenomenon. The southwestern part of the Taurus Mountains is located north of Antalya aerodrome. No official or operator documentation contained specific aerodrome instructions regarding meteorological phenomena associated with the aerodrome environment. ## Aftermath and Conclusions At the request of air traffic control, the crew described the severe phenomenon encountered. After landing at 07:27, departures were suspended, and arriving aircraft were held for approximately 30 minutes. The incident resulted in no damage. The investigation was conducted in accordance with ICAO Annex 13 and European Regulation No. 996/2010, with the sole objective of drawing lessons to prevent future accidents, not to establish fault or assign individual or collective responsibility.