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707 Captain >> 707 Captain >> Takeoff Performance
https://www.captainsim.org/forum/csf.pl?num=1286472861

Message started by VulcanB2 on Oct 7th, 2010 at 5:34pm

Title: Re: Takeoff Performance
Post by CoolP on Oct 8th, 2010 at 4:15am
I've just read the report you posted a bit. Interesting.

The transcript of the Cockpit Voice Recorder is interesting, the conclusions are too of course.

"Vee one!"

"(Sound of Power Levers hitting Stops)"
"(Sound of reverse thrust noise starts)"
"(Sound of full reverse thrust)"

Not as expected if you calculate V1 for good reason and state that you're already above it with calling out loud "Vee one!"

A doubt that the modern way of loosing an engine on the 4 engine driven planes will cause a Captain to stop the bird, even when still below V1 and even on the two engine machines I doubt that (being close to V1).

First rule is to "fly the airplane" and those modern rockets can take the loss of an engine but they still brake dramatically bad when at high loads and already having eaten some large amount of runway. So the danger of an overrun is very high while the lost engine usually can be equalized and does not lead to an unsafe flight and landing.

I've read reports that state that an engine wasn't lost, it just stalled and FADEC brought it back to live but was interfered by an unsure crew that interpreted the engine readings somehow wrong, concentrated on that lost engine instead of flying, shut the engine down although it would be functional again and then got into real problems because their aircraft already ran into some "extra power need situation".

I think they nowadays even train to be real calm if "engine fire" comes up as it could indicate a soon passing condition and thereafter everything returns to normal values or at least workable ones while the emergency shutdown would give you a definitely inop windmill at one wing.

The cost factor might be another reason for continuing takeoffs because the aborted TO causes huge wear on the undercarriage elements and especially the brakes. Again, when done at high gross weights.

You also need to cool those brakes down for a very long time if high gross weights had to be stopped to zero. I remember the Concorde (which had a very advanced braking installation, first carbon on commercial planes) had to pause for hours then, with the brake fans running!

But we have to be fair. It's so easy to be clever after watching some guys fail.
I've read some minutes, nobody annoys me, everything is calm, I'm sipping on my tea .. while they were discussing the FO's technique, suddenly heard "bang" (those stalls are loud) and then the warnings to come up.
So decision time was a very small value here and you have to train and train to fight the impulse of human beings to stop every machine when it has a malfunction. Seems to be our nature somehow.

Might be the reason for this loud "Vee one" is to counteract this tendency and to make clear to everybody, that "we will fly from now on, whatever happens".
As you see, strong impulse on stopping even for the professionals.

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