West Caribbean Airways Flight 708 - Aftermath and Investigation

Aftermath and Investigation

The 160-person death toll made the accident the deadliest of 2005, and jointly (with China Northwest Airlines Flight 2303, which had an identical death toll) the 50th deadliest crash of all time. It followed the crash of Helios Airways Flight 522 on 14 August in Greece, which killed 121 people. The only other plane crashes in 2005 to kill over 100 people were that of Kam Air Flight 904 on 3 February in Afghanistan (104 deaths), and Sosoliso Airlines Flight 1145 on 10 December in Nigeria (109 deaths). West Caribbean Airways Flight 708 is the eleventh crash of an MD-80 with fatalities since the aircraft was brought into service in 1980. The Comité de Investigación de Accidentes Aéreos (CIAA, Aircraft Accidents Research Committee) of Venezuela led the investigation on the causes of the accident. United States' National Transportation Safety Board (NTSB) and French Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile (BEA) also took part. On 22 November 2005, the CIAA released a report suggesting that a buildup of ice inside each engine's PT2 probe was responsible for the accident. Analysis of the cockpit voice recorder showed that the crew discussed weather conditions, including icing, and continually requested and performed descents which is the usual response to a low power or low airspeed situation.

Analysis of the debris showed that both engines exhibited indications of high-speed compressor rotation at the time of impact, which enabled investigators to conclude that the engines were not previously damaged, and were functioning at the time of impact. Ground scars showed that the aircraft impacted with its nose up.

The aircraft had taken off from its origin in a slightly overloaded state. In fact, two flight attendants had to disembark to allow the flight to continue, under the instructions of the captain. This overloaded condition would allow the aircraft to fly at a top altitude of only 33,000 feet without stalling. Unfortunately, due to the poor weather the flight encountered on its way, the crew switched on the engine anti-ice system. The system uses power from the engines, thus reducing their maximum performance. With the anti-ice system on, the highest altitude at which the overloaded aircraft could fly - without stalling - was reduced to only 31,900 feet. The captain noticed the reduction in engine power, but he couldn't realize the source of the problem. Therefore, he started a rapid descent, as a precaution. At that time, the airspeed was already near stall speed and the autopilot had kept a nose-up attitude to maintain a constant height. When the airliner was pummeled by a sudden updraft, it finally entered a stall condition and the crew mishandled it. Although the CVR picked up the First officer correctly diagnosing the situation as a stall and attempting twice to communicate this to the captain, the captain was likely confused by the unusual behaviour of the engines, due to the anti-ice system and probably the air flow disruption caused by the updraft. The captain thought he was struggling with an engine flameout, which he told the first officer to communicate to the ground controller, and did not recognise the deep stall situation; he then mishandled the stall by maintaining nose-up attitude, which further decreased speed and deepened the stall until the plane eventually crashed.