Originally Posted by Sdruvss
No one answer me?
What is behind the logic of not deploying armed spoilers, even after manual braking is applied, if TLA is not in idle? I don't understand that. Please, I would like to understand.
I think this is a very good and valid question. I have also discussed this with PBL, and we made the following observations (PBL, feel free to correct me):
1/ Using manual braking alone as a signal to deploy ground spoilers will not work, as brakes may inadvertently be pressed in flight when making rudder inputs.
2/ Combined with any of the "on-the-ground" conditions (wheels spinning or (MLG struts compressed and RA <6ft)) it looks like a good idea. We'd still need to consider the late-go-around ("touch and go") scenario, in which rudder inputs may be needed, and brake inputs may occur, and ground spoiler deployment would be fatal.
3/ We consider it useful, as a previous poster said (I'm sorry I can't remember the name), to think of the thrust levers as "Stop"-levers. I want the aircraft to stop: I pull the thrust levers back. Although they are not really brake-levers, they work as such after touchdown: they are the only directly flight-crew-controlled inputs to the ground-spoiler extension logic, which in turn activates automatic braking.
The "LOSS OF BRAKING" memory item has as the first point after "If no braking available" (when using manual brakes):
REV ...... MAX
I have remarked before that it looks like the crew in this accident did not think they had "lost" braking, and did not fully and immediately apply the memory item.
It is also a question of whether or not they considered the less-than-satisfactory performance of the manual brakes to be "No braking available", in which case they would have gone to the next item on the list(REV: MAX), and taken a second look (touch) at the thrust levers.
I had asked experienced A320 flight crews for what situations exactly said memory item was trained:
- Only failure of autobrake after it had initially been active?
- And/or failure of manual brake if no autobrake was selected?
- Also in a case like this where autobrake fails to engage because of failure of GS deployment?
For the third case the memory item would to be more aptly called "NO BRAKING"
As has also been suggested, it might be useful to do some data mining through collected flight data (properly anonymised) to find out how often one T/L was "forgotten" at a position above "near idle" without dire consequences.
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Originally Posted by marciovp
Going back to my road analogy...just a little modification. We have three accidents in a road turn with a specific brand of automobile.
This one doesn't hold water.
1/ This is the first such accident at this corner (airport)
2/ there have actually been
more accidents of this kind with the other brand of car, than the one involved in this accident: there have been more runway excursions on landing with B737-300/400/500 than there have been with A320, as shown by PBL in post #1316 (p.66).
So this is like saying: A Mercwagen has crashed here, so let's look at what is wrong with Mercwagen cars, when in fact more BMGs have crashed in the same way. But still people insist that there is something wrong with Mercwagen, but not so with BMG.
Bernd