"The National Transportation Safety Board determines that the probable cause of the accident was the flightcrew's failure to use the taxi checklist to ensure the flaps and slats were extended for takeoff. Contributing to the accident was the absence of electrical power to the airplane takeoff warning system which thus did not warn the flightcrew that the airplane was not configured properly for takeoff. The reason for the absence of electrical power could not be determined."
After liftoff, the wings of the airplane rolled to the left and the right about 35” in each direction.
The flight characteristics used to determine the stall speed of the DC-9-80 series airplanes are, in part, “A roll that cannot be readily arrested.. ”
The CVR recording showed that the flightcrew neither called for nor accomplished the TAXI checklist. The first item on the TAXI checklist required both pilots, in response to the checklist’s challenge, to check and verify orally that the flaps and slats were positioned correctly. This item was
not performed, and the flightcrew did not discover that the airplane was configured improperly for takeoff. The omission of the TAXI checklist was further corroborated by the flightcrew’s inability to
engage the autothrottles at the start of the takeoff because they did not, as required by the TAXI checklist place the TCI in the “T.O.” mode. However, they were able to rectify this omission by the time the airplane accelerated to 100 KIAS. Once the takeoff began, however, there was little chance they would detect any of the visual cues--the flap indicators in the up position, the absence of the blue takeoff light on the slat indicator light panel, and the absence of the ART ready light--that
might have alerted them to the fact that the airplane was not configured properly. All of the visual cues relating to the flaps and slats were located outside, or on the perimeter of, those areas normally
monitored by the captain and the first officer during takeoff. The Safety Board concludes that the failure of the flightcrew to accomplish the TAXI checklist in accordance with required procedures
was the probable cause of this accident.
Quotes from the NTSB report on NWA 255,a DC-9 that crashed on takeoff August 1987 in Michigan,USA.
Evidence against engine failure at Madrid is growing so maybe the answer lies in the past with this DC-9 crash?Is there any connection between the MEL work carrried out and disabling of takeoff config warning system??
I know practically nothing about the MD but the report spoke of 2 automated stall protection systems for the DC9;autoslat and stick-pusher,but both are disabled with slats retracted.Stall recovery technique is to apply and call for MAX POWER,FLAPS 15,release back pressure and avoid secondary stall.
The report speaks of six lines of defence against such an omission(failure to perform a checklist) :
The first line of defense was human vigilance; the second, another crewmember detecting error; the third, secondary indications, such as cockpit displays and instrumentation; the fourth, warning and alerting devices;the fifth, persons other than crewmembers detecting the error, i.e., ATC personnel or ground personnel; and the sixth, machines that take action on their own to rectify the error, i.e., the DC-9-82’s autoslat and stick pusher systems.
If you apply it to the Madrid case you can see how each line of defense could easily have been breached:
-vigilance-the tech problem and return to gate may have distracted crew and lowered vigilance levels
-another crew member detects the problem-"Do you want the before takeoff checklist?" or even "Did we do the checklist?"-again the tech problem could have upset their natural rhythm
-cockpit displays-the blue slat light or ART ready light-TCI not in TO mode distracts them and they miss all the signs and theyd be looking outside mostly anyway.
-warning device-takeoff warning system may have been disabled without the crew realising-was it checked pre-flight?Who checks it?both pilots?Its a major item..in my book,the skipper must check it but many airlines now have the First Officer checking these vital systems pre-flight while the skipper enters the flightplan in the computer!wrong way round.
-ATC-wouldnt apply here
-automated systems-autoslat/stickpusher disabled because slats retracted.
If it wasnt a takeoff warning system fault,then the other possibilities might be:
-blown tire at high speed..improved climb takeoff at hot/high airport,tailwind,slope.. all present at Madrid..
-thrust reverser deployment..but then why the bank left and then right?
- overweight or improper loading...with 2 engines working and correct takeoff configuration,less likely unless the discrepancy was sizeable..combined with another problem,like an engine failure or tire blowout,would be deadly.