Chris,
Forgive me for not researching the Fokker 100 accident, Green-dot (am on that dail-up connection again); but was the aeroplane airborne, and was its speed close to Vmca?
Yes the aircraft had just become airborne.
With reference to the Fokker 100 AFM performance section (an outdated copy I must add) I quote: "For the Fokker 100 Vmca is less than the stalling speed Vs for all take-off flap settings."
From the information available to me, the aircraft took off with flaps 8. Entering the Vs graph with a rough estimation of the aircraft gross weight and information of the actual airspeed recorded, the aircraft reached an airspeed well above Vmca. I estimate that Vs would have been somewhere between 108-112kt, hence Vmca is below this. The aircraft reached a speed of approx. 140kt which reduced to just below 120kt after the #2 reverser deployed. See links below.
krujje,
I would say that point is debatable. Please correct me if I'm wrong, but there is no requirement to prove that uncommanded TR deployment at take-off is controllable, therefore airframers don't... preferring, as I said, to show 10-9 instead. Is there proof through test or analysis that the event is controllable in all normal take-off scenarios? If yes, does it hold for all modern aircraft, or only certain types?
I don't know if there is or is no specific requirement at take-off. I do know that abnormal procedures exist for (uncommanded) TR deployment on the ground and in flight and the aircraft has demonstrated to be controllable with one TR deployed in flight as part of the certification process. I am also aware that with a failure chance of 10-9 (if I recall correctly it was even 10-11 for the Fo100), the emphasis should be on proper maintenance and operational procedures.
Can we really say that the accident could have been prevented had the crew known what the problem was? I think that that may venture too far into speculation. Although I say this not having read the report. I have only a cursory knowledge of the circumstances of the accident (I have not been able to find an english translation of the official report.)
As is usually the case with hind sight, it is easy to judge from a comfortable chair how things could have been handled differently. The surprise effect and the short time to analyse such a problem during a critical phase of flight obviously have contributed to the outcome. Especially when the remoteness of an uncommanded TR is taken into consideration. Would it, even today, be routinely in the back of the minds of pilots as one of the anticipated possibilities of this occurring during the take-off phase? Is such a scenario trained for on a regular interval?
The answers put emphasis on human factors and CRM.
To shed some light on what happened on that flight:
Here are 2 graphic presentations based on CVR/ATC/FDR data. The first without CVR/ATC text, the second including text. Please note #2 thrust lever position retarding to idle at moment of TR deployment and the subsequent thrust lever increase as explained in my previous post. Also note aileron/rudder inputs.
YouTube - TAM 402 -
YouTube - TAM 402 de 1996 com legenda - transcrição caixa preta + FDR
Regards,
Green-dot