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Air Traffic Monitoring => Aviation Audio Clips => Topic started by: kea001 on April 17, 2009, 10:49:18 AM

Title: ACA926 - CYUL to KFLL - Apr. 14th, 2009 - Loss of Control In Flight
Post by: kea001 on April 17, 2009, 10:49:18 AM

An Air Canada Airbus A320-200, registration C-FTJQ performing flight AC-926 from Montreal Trudeau,QC (Canada) to Fort Lauderdale,FL (USA), was enroute at FL360 about 170nm south of Montreal about 30 minutes into the flight, when the crew requested to return to Montreal and reported problems with the flight controls. The airplane was on final approach to runway 06L about one nautical mile before touchdown, when the crew declared emergency and requested emergency services to standby. The airplane continued for a safe touch down and stopped on the runway for about 10 minutes. The crew reported, that they had experienced "severe mechanical turbulence" and had lost control of the airplane momentarily.

Aviation Herald:
http://avherald.com/h?article=4181e1c9&opt=0 (http://avherald.com/h?article=4181e1c9&opt=0)

(http://map3.flightaware.com/flight_track_map.rvt?ident=ACA926-1239655860-37611-15;airports=CYUL+CYUL;key=4dadc58f60361c2ca5d4775a1c0d59a563735ca5;keytime=1239979643;height=340;width=400;departuretime=1239743280;arrivaltime=1239747049)

NOTE: No transmission captured of initial problem. I've compiled whatever I could find.

Title: Re: ACA926 - CYUL to KFLL - Apr. 14th, 2009 - Loss of Control In Flight
Post by: joeyb747 on April 18, 2009, 10:34:10 PM

"severe mechanical turbulence"...can't say as I've heard that one before.

Do you think they mean pourposing?
Or rapid, uncommanded flight control movements?
I'm a bit unclear on what the means exactly... :|

Title: Re: ACA926 - CYUL to KFLL - Apr. 14th, 2009 - Loss of Control In Flight
Post by: kea001 on April 19, 2009, 10:09:41 AM

According to the 'Workbook of Atmospheric Dispersion Estimates - An Introduction to Dispersion Modelling ' Second Edition,
Chapter 1, 1.4.3:

wind passing vegitation or building structures creates mechanical turbulence. The stronger the wind, the greater the degree of mechanical turbulence. Also, the larger the roughness of the surface of the object, the greater the turbulence. Mechanical turbulence can also be created by wind shear; a slower moving air stream next to a faster moving one.
http://books.google.ca/books?id=0GP2fgVfzQsC


ALSO SEE: Aviation Weather - Terry T. Lankford
http://books.google.ca/books?id=kSSn7vPgmUQC&pg=PT373&dq=aircraft+"mechanical+turbulence"&ei=9i_rSZ7BAYqKNNvCrbEB

Google Book Search
http://books.google.ca/books?q=mechanical+turbulence&btnG=Search+Books


NOTE: Mechanical turbulence is a descriptor of the airflow the pilot is encountering and has nothing to do with the mechanical integrity of the airplane, not to say that it might have entered the back of his mind.   :|

Title: Re: ACA926 - CYUL to KFLL - Apr. 14th, 2009 - Loss of Control In Flight
Post by: joeyb747 on April 19, 2009, 12:51:21 PM

Hmmm...interesting name for it...guess you learn somthinng new everyday!  :wink:

Thanks for the info!  :-)

Title: Re: ACA926 - CYUL to KFLL - Apr. 14th, 2009 - Loss of Control In Flight
Post by: kea001 on April 22, 2009, 01:06:16 PM

(http://tbn3.google.com/images?q=tbn:FbmvpKMF5Sr9MM:http://wwwimage.cbsnews.com/images/2004/09/01/image640056x.jpgg)

O.K. Here's our final answer Alex. What is severe vibration of the airframe?:

"The Canadian TSB reported on Apr 20th, that the crew received a "SPOILER FAULT" message on the electronic centralized aircraft monitoring system (ECAM) and noticed, that the ground spoilers were partially removed from the display. After consultation with the airline's maintenance department the crew decided to return to Montreal. On short final the crew declared emergency due to severe vibration of the airframe. The aircraft had undergone maintenance during which the ground spoilers had been disabled and were not reactivated. The airframe vibrations came from the spoilers, that started to flutter after the landing flaps were deployed."

http://avherald.com/h?article=4181e1c9&opt=0 (http://avherald.com/h?article=4181e1c9&opt=0)