Some weeks ago I read the first interim report from the “Bureau d’Enquêtes et d’Analyses” (BEA) on the accident suffered by the Swiftair MD-83 matriculated EC-LTV on July 24th in Mali (find the report here, PDF 5.2MB). The last 1’30” of that flight must have been scary.
Take a look at the records of altitude, attitude, bank angle:
Probably you are familiar with this other graphic that has appeared in the press:
Today, at lunch while on a training course, I had the chance to discuss about the accident with the course instructor (a retired former Airbus senior vice president in customer services) who pointed me at a similar accident undergone by a MD-82 HK-4374X in Venezuela in August 2005.
I went to the BEA website to check for the report of that other accident (here, PDF 20MB, in Spanish). While the investigation of the EC-LTV will most probably reach to the conclusions of the root causes of the accident, the are many similarities between the cases:
- Hot weather conditions (ISA+10 or above, that is temperatures not below -30 degrees at FL31),
- proximity of thunderstorms,
- use of anti ice (inducing a penalty measured in about 3,000ft penalty for available engine thrust),
- autopilot engaged in “Speed on Thrust” mode in “Altitude Hold” (making the aircraft pitch upwards when losing speed due to the lack of available power at FL310 due to hot weather and use of anti ice),
- engine EPR close to maximum values for both engines (followed by a oscillations when the airplane starts to lose speed),
The report of the 2005 accident included a study from NASA and a presentation by Boeing then chief pilot covering similar incidents and showing a 2002 Boeing Flight Operations Bulletin warning flight crews of this kind of situations.
I’m looking forward for future reports from the BEA to see what are the findings they reach.