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Jeff Nielsen

Windshear abort

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Our local airport had an interesting time last week. Apparently a 737 had to abort its take-off because of a 'possible windshear' warning. I assume this was via an audible cockpit warning, and it must have occurred before V1. My question is does anyone know what the procedures might be had the warning come after V1 or even on the point of V2 or Vr?

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>Our local airport had an interesting time last week.>Apparently a 737 had to abort its take-off because of a>'possible windshear' warning. I assume this was via an audible>cockpit warning, and it must have occurred before V1. My>question is does anyone know what the procedures might be had>the warning come after V1 or even on the point of V2 or Vr?I would think that would depend on the length of the runway, and if the pilot had enough room to stop even past V2 or VR. This possibly could be done at one of the larger airports like KJFK, KLAX, KORD etc.. For the vast majority though I think the plane would be committed at that point and it would have to takeoff. I'm sure there would be a lot of hail Mary's in the cockpit though!! It would be the difference between an increased chance of an accident, vs a definite chance of one.

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the correct terminology is a "stagnating airspeed" aborted takeoff.basically if it was an electric cockpit, the airspeed trend vector disappears and the airspeed simply hovers or reverses at its current speed (instead of accelerating). since it is before V1 (if it was after V1 you GO no matter what) but takes awhile to decipher you could in theory be past the point of no return on the runway.pilots judgement then takes over whether to abort and stop with max braking or to takeoff (below V1). the pilots will have done both scenarios in their wind shear training in the simulator. climbing out below V1 (or rather shakily flying than climbing) is a weird feeling in the sim.generally an increasing performance sheer generates a winshear caution, but a stagnating or reduced performance sheer generates a warning and the "WIND SHEAR" aural announcement.

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To answer the posters actual question. If the crew was stationary on the ground they were most likely alerted by the AIRPORT's widshear system through ATC.What you do not state however is WHAT AIRPORT (some major airports have windshear detection systems on the ground), and was the aircraft already rolling. In other words, who actually rejected or denied the takeoff clearance, or was it really a rejected takeoff.Those are 2 very important factors.If it was an ACTUAL aborted takeoff where the aircaft was actually rolling and crew intervention was required it purely depends on where the aircraft was to determine whether or not they were at the point of no return.You also have to know where the wind shear was located on the field.All these factors come into play before the PIC/PF processes all that information then goes through his aircraft and airline's RTO procedures (probably memorized).We do not seem to have NEAR enough information to make a conclusion here...LOL. Not even close.Sorry.

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well he did say aborted takeoff.....i have never heard of an aborted taxi, etc. :-)

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Well, if he was at the hold short point or "in position". You above anyone else should know better...lol.The question is; was it an actual aborted/RTO on the roll or was it a last minute "do not go" by ATC?Where did the wind shear warning come from? ATC or the aircraft?I've flown through low level windhsear in the sowndowner before. I knew this because of the airspeed indicator jumping all the way past the Vne rapidly then back down...hehe. Funny note about that is that when I landed my ground roll was so short I was able to take the first taxiway physically closest to the end of the approach end which prompted a notice by ATC to all airport facilities not to taxi back on that particular taxiway...lol. I think I threw them off gaurd a little with that landing. My actual groundspeed over the numbers must not have been more than 30kts with about 55kts indicated...hehe. It felt like I was just hovering and simply landed comfortably to a stop! It was quite a fun flight with our other company aircraft over the missouri river and they hit their heads on the roof of the aircraft. I came out unscathed because I knew not to fly over the river on a hot day near downtown KC. I simply flew a tad north over worlds of fun.

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