Thrust to flare?
Join Date: May 1999
Location: Unionville, PA, USA
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There are three ways to reduce the sink rate landing the MD11 or MD10 1) Power, 2) Power, 3) More Power. Save a hard landing with pitch will only give you a very hard landing.
there was one airline that used to call "100ft" on the radar altimeter, at which point the pilot (almost always an ex F-5A major) would start running the trim fully back on the pickle switches. Yes, eventually the aircraft would land, in spite of the technique, usually also even on the runway, although there were many skidmarks passing across the piano keys, referred to as "Kong trails". Go arounds were not frequent but apparently very exciting.
If you need to add power on the aircraft in the flare from a stable approach, and you are not a helicopter... then it is hard to see that it complies with the certification standard, and I would doubt that it is in the FCTM for the type. For a decaying airspeed or increasing sink rate, keeping power on or adding power is a fair alternative to a hard impact, but by definition would not be considered as a stable approach.
B727: pitch down/deflare, power up etc, yes they get done, but oddly enough, the plane also lands very nicely with a gentle flare as per the FCTM, and reducing thrust to ide by touchdown, odd but true. MD11, seen many variations, like the B767, but the outcome from a normal approach and flare is about as nice and far less exciting. The MD does like to sink though...
If you need to add power on the aircraft in the flare from a stable approach, and you are not a helicopter... then it is hard to see that it complies with the certification standard, and I would doubt that it is in the FCTM for the type. For a decaying airspeed or increasing sink rate, keeping power on or adding power is a fair alternative to a hard impact, but by definition would not be considered as a stable approach.
B727: pitch down/deflare, power up etc, yes they get done, but oddly enough, the plane also lands very nicely with a gentle flare as per the FCTM, and reducing thrust to ide by touchdown, odd but true. MD11, seen many variations, like the B767, but the outcome from a normal approach and flare is about as nice and far less exciting. The MD does like to sink though...
Join Date: Jan 2011
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I'm very new in this profession with only 260h on type. On steep GP-angles with headwind reducing abruptly it works great around the threshold not to lose the bugspeed, otherwise I don't see the point.
I've flown with a couple of captains (all ex military) who uses this technique even in perfectly normal conditions. Some also tend to jerk the yoke stick back very intermittently during the flare. They land the aircraft smoothly in general but in the far end of the TDZ.
I just move my eye-focus to the far end of the runway and try to coordinate 0 sink with one meter below the runway using my peripheral sight. That way I don't end up with these PA28-floats (the 737 floats like a fat lady in a tub of salt water) that many of my mates do
less brake wear, reversing and backtracking. Also a faster vacation of the runway.
It keeps my acc. manager, Boeing, captains and maintenance happy. The only one taking a turn is my ego, haven't managed to get one yet though
I've flown with a couple of captains (all ex military) who uses this technique even in perfectly normal conditions. Some also tend to jerk the yoke stick back very intermittently during the flare. They land the aircraft smoothly in general but in the far end of the TDZ.
I just move my eye-focus to the far end of the runway and try to coordinate 0 sink with one meter below the runway using my peripheral sight. That way I don't end up with these PA28-floats (the 737 floats like a fat lady in a tub of salt water) that many of my mates do
less brake wear, reversing and backtracking. Also a faster vacation of the runway. It keeps my acc. manager, Boeing, captains and maintenance happy. The only one taking a turn is my ego, haven't managed to get one yet though
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This is how the C-17 "Flares". However, there is a shedload of flight control law mechanics also working in the background, in particular alpha hold functions and using the trim switch to control IAS (so I am told).
If you had a HUD with a flight path vector displayed, you would see the mechanics of it.
I used this technique on the herc J, it provides extra lift and an upward motion of your flight path vector especially as you approach ground effect (which is also visible through a hud). We used it as an untought technique on some of the longer strips in afghanistan to prevent the aircraft slamming in on what would otherwise be a needlessly agressive touchdown (the manual is written for short field performance). The effect is instantaneous and does not result in a speed increase, its done literally as you enter ground effect and thus the extra thrust does not have time to accelerate the aircraft.
Whether it would work on an aircraft without barn door type flaps I dont know (not sure if it is blown lift or due to the thrust affecting circulation).
Biggest problem with it is the gentle touchdowns it generates can delay spoiler deployment and potentially invalidate your TOLD calcs. Its also almost impossible to judge touchdown point and if you overdo it, you can end up climbing!
If you had a HUD with a flight path vector displayed, you would see the mechanics of it.
I used this technique on the herc J, it provides extra lift and an upward motion of your flight path vector especially as you approach ground effect (which is also visible through a hud). We used it as an untought technique on some of the longer strips in afghanistan to prevent the aircraft slamming in on what would otherwise be a needlessly agressive touchdown (the manual is written for short field performance). The effect is instantaneous and does not result in a speed increase, its done literally as you enter ground effect and thus the extra thrust does not have time to accelerate the aircraft.
Whether it would work on an aircraft without barn door type flaps I dont know (not sure if it is blown lift or due to the thrust affecting circulation).
Biggest problem with it is the gentle touchdowns it generates can delay spoiler deployment and potentially invalidate your TOLD calcs. Its also almost impossible to judge touchdown point and if you overdo it, you can end up climbing!
Last edited by VinRouge; 20th Nov 2012 at 07:31.
