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wongben4

rwy length and V speed

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Hi guys, I have a stupid question, does pmdg 744 takes runway length into consideration when caculates the V speed? and IF I tried to T/O in a rwy which length is not enough, would the FMC say RWY TOO SHORT (both in real 744 and pmdg 744)I know it sounds kind of stupid, but I just want to know...thxben

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Guest D17S

I have the same question. I spoke to a 744 test pilot and was told the Vspeeds are not auto-entered on the TO page. I've worked through the actual drill that the MD11 flight planners go through to get those Vspeeds and the final Vspeed chart is runway specific. Every single runway has its own MD11(-model/engine specific) Vspeed chart (as would a 7XX (-model/engine). Those Vspeeds (especially V1) may not be based only on runway length. Just taking the runway length into account is never the only consideration when calculating Vspeed. For instance, there may be plenty of runway to stop at a V1, but the airplane still may have to get airborne sooner because of an obstacle clearance issue down range. Remember that especially V2 has nothing whatever to do with all engines operating performance. A V2 will provide obstacle clearance by lots and lots with all engines operating (all these big jets are massively powered with all engines running) . . . . but if you loose an engine just beyond V1, that V2 climb speed is calculated to allow you to miss that limiting downrange obstacle by . . are you ready for this . . . . 35 feet. That's why that Vr event is so critical. With all engines operating, just pull on back (Let's be sensible though). So why does it matter? If you loose an engine, this all becomes critical. The entire TO sequence is about loosing and engine. I spoke to an MD80 pilot that characterized himself as "cocked and armed" to loose an engine on every TO. He hits the Vspeeds on the nose, not (so much) that he can have a successful all engines operating TO. He is in the constant process of setting up for an engine to fail. He flys the TO as if the engine failure is going to happen . . . for sure. If he makes the GO decision at V1, then is on the nose with VR, he can fail an engine at any moment from V1 on out and he's already perfectly on target and ready to handle it. Remember too, if the TO is obstacle limited, he's playing with a 35 foot clearance down range. I really don't think the FMC's database is updated to include these runway Vspeed charts . . . but that why I have the same question, because I'm really not sure. That 744 test pilot seemed to think, "no." (I was about to open my mouth and say

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