Crew struggled to regain control   

of doomed West Caribbean MD-82

 
 
Crew struggled to regain control of doomed West Caribbean MD-82

Double engine flame-out was reported by the crew of the West Caribbean Airways Boeing MD-82 which crashed fatally on 16 August, according to preliminary data released by Venezuela’s air accident investigation committee (CIAA).

West Caribbean

 

From visual evidence at the scene, the Pratt & Whitney JT8D-200 engines both appear to have regained power shortly before impact, but investigators have been hampered by the flight data recorder’s failure to record a number of parameters – including the left engine pressure ratio (EPR).

The US National Transportation Safety Board (NTSB) in a notice today says it agrees with the CIAA’s initial findings, which confirm that the West Caribbean flight crew requested air traffic control (ATC) clearance to descend gradually from FL330 to 14,000ft (4,300m) before informing ATC of a dual engine flameout.

Information from the flight data recorder (FDR) indicates that the aircraft began a normal climb to FL330 before leveling off and accelerating to Mach 0.76.

“About 90sec after reaching Mach 0.76, the airspeed began to steadily decrease,” says the CIAA. “The horizontal stabilizer moved from about two units nose-up to about four units nose-up during this deceleration.”

Roughly 3.5min from the end of the recording, the Mach number fell to 0.60, the autopilot was disengaged and the aircraft began descending from FL330.

“As the airplane descended past about FL315, the airspeed continued to decrease and the right engine EPR [engine pressure ratio] decreased to about flight idle,” says the report.

Data recovered from the MD-82’s cockpit voice recorder shows that about 8min before the end of the recording, while the aircraft was level at FL330, the flight crew discussed weather conditions, including possible icing conditions.

“The flight crew also discusses turning on engine and airfoil anti-ice,” says the CIAA, which does not state whether the systems were in fact switched on.

About 3.5min before the end of the recording, the crew requests and is cleared to descend to FL310. After another 30 seconds “an audio warning similar to altitude alert is heard, followed 22s later by a sound similar to stick-shaker…and then an aural stall warning alert”.

The report adds that the flight crew “does not declare an emergency and they do not refer to any checklist during the descent”.

It continues: “About eight seconds before the end of the recording, a ground proximity warning system (GPWS) warning starts to be heard and continues to the end of the recording.”

The wreckage was confined to a relatively small triangular area – 205m long by 110m wide at its greatest extent. Both engine compressors showed signs of high-speed rotation, and the horizontal stabilizer was found at the full nose-up – 12 units – setting.

West Caribbean flight 708 crashed near Machiques, Venezuela during a charter flight from Panama to Martinique, killing all 160 on board. The CIAA says movement of the aircraft wreckage has been delayed due to heavy rain, but it will be moved to Maracaibo in the next few days.

Once there, additional inspections will be carried out.

 from this link

Press release distributed on November 22, 2005 Air crash of August 16, 2005

Following information was made public by the Committee of Investigación de Accidentes Aéreos of Venezuela. France, Colombia and the United States took part in the validation of these data. The BEA disseminates this information at the request of the designated Venezuelan investigator.

Wreck The removal of the wreck was delayed because of the strong rains in the area of the accident. However, it should be moved to a prepared area in Maracaibo in days to come. Once the wreck is moved, complementary examinations will be undertaken. According to the first observations on the site: The traces on the ground indicate that with the impact the plane adopted an attitude nose-up and a light bank to the right. The remains are distributed on a triangular a height of approximately 205 meters and basic zone of 110 meters. The two engines carry traces of being at a high compressor RPM  at the time of impact. The air intake of the engines, the empennage and the leading edges do not present any sign of damage prior to the impact. The trimmable horizontal stabilizer was found in maximum nose-up position. (approximately twelve units nose-up)

Flight recorder The cockpit voice recorder (CVR) and the flight data recorder (FDR) were stripped at the laboratory of the Office of Investigations and Analyses for the Safety of the Civil aviation, near Paris, during the week of September 5, 2005. The FDR and CVR cases were strongly damaged by the impact. The two recorders functioned until impact.

Recorder of data (FDR) The protected part of the FDR was in good condition as well as the extracted magnetic tape. The data recorded made it possible to advance the investigation, even if several parameters were not recorded correctly. Several parameters were not valid, in particular the report/ratio of pressure of engine (EPR) of the left engine, pitch attitude, roll attitude, magnetic heading, and column position.

The following events are recorded on the FDR: The accident flight lasted approximately an hour from takeoff until the end of the recording. The flight reached its initial cruising level of flight 310 at approximately 0625 UTC (coordinated universal time). At approximately 0641 UTC, i.e. approximately 20 minutes before the end of the recording, the plane started to climb normally towards flight level 330. It achieved this level at approximately 0643 and accelerated up to Mach 0,76. The EPR parameter of the right engine corresponds well to the normal values for climb and cruise. Approximately 90 seconds after having reached Mach 0,76 (0649 UTC), the airspeed started to slowly decrease. The trimmable horizontal stabilizer moved from approximately two units nose-up towards approximately 4 units nose-up during this deceleration. At 0657 UTC, approximately 3 minutes and 30 seconds  before the end of the recording, the Mach number had slowed to 0,60. The autopilot was then disconnected and the plane started to descend from flight level 330. While descending through flight level 315, airspeed continued to decrease and the EPR parameter for the right engine decreased to flight idle. The rate of descent increased after passing flight level 310. Airspeed reached a minimum of about 150 knots at approximately Flight Level 250. The EPR of the right engine remained at flight idle during the descent. It even increased several times, including just before the end of the recording. Once the plane began its descent, the trimmable horizontal stabilizer moved by stages until reaching approximately twelve units nose-up while passing flight level 200 in the descent. This corresponds to a position close to the maximum nose-up.

The Cockpit Voice Recorder (CVR)

The CVR cover was slightly opened up by the impact. Generally the magnetic tape was in a good condition. However, the tape was partially cut by the impact. The overall quality of the recording was bad, with many bursts of static and high background noise. However useful information could be obtained. Almost all the conversations between the pilots and with ATC (in Colombia and in Venezuela) were in Spanish. The CVR contained the last thirty-two  minutes of the accident flight. The following events are recorded on the CVR:

To approximately 0653 UTC, approximately 8 minutes before the end of the recording (when the plane was at flight FL 330) the crew discussed the weather conditions, including the possibility of icing. The crew also reviewed the possibility of starting the engine and aerofoil anti-icing systems. Approximately 3 minutes and 30 seconds (0657 UTC) before the end of the recording, the crew asked for and obtained ATC clearance to descend to flight level 310. Approximately 3 minutes before the end of the recording, an altitude alert is heard followed, 22 seconds later (0658 UTC), and stick shaker, then of the stall warning indicator. These alarms continue until the end of the recording. The crew regularly asks for lower flight levels, for flight level 290, flight level 240, and finally for 14 000 feet. The crew did not declare an emergency and did not make mention of a checklist during the descent. Approximately a minute after the stickshaker began, the crew announces a double engine flame-out after ATC asks whether the flight has a problem. The last radio transmission of the crew to ATC was around 7 a.m. 00 min 11 S UTC. Approximately eight seconds before the end of the recording, a (GPWS) ground proximity alarm began and continued until the end of the recording. Time between the first stick-shaker alert and the end of the recording was approximately 2 minutes and 46 seconds. The end of the recording was at approximately 7. 00 min 31 S UTC.

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