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OPS1

Question about headwinds at high altitudes

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Hi there, Yesturday i was climbing out in the Qw757 with a heavy-ish payload of 206,000 ibs. About FL280 i looked at the FMC data page, and it indicated 56kt headwinds. I was climbing at CLB-1 setting in the 75, and usually i have to decrease my vertical speed to around 1400-1700fpm around FL280. However the aircraft shot up to my initaial cruising FL of FL390 with a vertical speed of 1700-2000fpm at CLB-1, and i was keeping at mach 0.75 for the climb. Took me about 15 minutes to get to FL390 from takeoff. So may question is, does headwind increase the climb rate of an aircraft through high altitudes? Sorry if this sounds stupid, but ive only been flying with REX for about 2 weeks, so im expericening all this new weather activity.

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I could be wrong but I always thought the VNAV automatically calculated and executed the best rates given the conditions. Maybe something to do with your cost index? Your throttles might have been up all the way, without regard to fuel burn, to achieve that kind of climb rate. I dunno. I have the Captain Sim 757 and usually it also climbs pretty damn fast...sometimes almost 4000fpm if I'm pretty light on fuel on shorter flights for example. But I pretty much never have to manually set a V/S in the AP, the FMC/VNAV always takes care of that.

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I could be wrong but I always thought the VNAV automatically calculated and executed the best rates given the conditions. Maybe something to do with your cost index? Your throttles might have been up all the way, without regard to fuel burn, to achieve that kind of climb rate. I dunno. I have the Captain Sim 757 and usually it also climbs pretty damn fast...sometimes almost 4000fpm if I'm pretty light on fuel on shorter flights for example. But I pretty much never have to manually set a V/S in the AP, the FMC/VNAV always takes care of that.

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Hi there, Yesturday i was climbing out in the Qw757 with a heavy-ish payload of 206,000 ibs. About FL280 i looked at the FMC data page, and it indicated 56kt headwinds. I was climbing at CLB-1 setting in the 75, and usually i have to decrease my vertical speed to around 1400-1700fpm around FL280. However the aircraft shot up to my initaial cruising FL of FL390 with a vertical speed of 1700-2000fpm at CLB-1, and i was keeping at mach 0.75 for the climb. Took me about 15 minutes to get to FL390 from takeoff. So may question is, does headwind increase the climb rate of an aircraft through high altitudes? Sorry if this sounds stupid, but ive only been flying with REX for about 2 weeks, so im expericening all this new weather activity.
The answer is no, headwinds do not increase rate of climb or have any affect on aerodynamics. They are a navigation/fuel planning issue only and in some rare situations can pose a safety problem with clear air turbulence. They affect ground speed but have no affect on performance.The only exception is what is sometimes referred to as "mountain wave." If a strong wind blows at right angles across a mountain range it can set up as "wave" of air slightly to the lee side of the mountain. Imagine a saucer upside down. If you are flying at at the right altitude you can "hitch a ride" if your course is parallel to the mountains. You get into the upside of the invisible "saucer" and it is pushing the aircraft up. You can either use that for increased rate of climb or if you are flying level, you can use the energy to allow you to lower the nose to maintain altitude and either increase air speed or reduce power for the same air speed. It can be amazingly smooth and quite exhilirating to be flying at max cruising speed with thrust reduced... Of course, the flip side happens if you are silly enough to fly parallel to a mountain on the "down side" of the wave. It will be very turbulent and you will have to increase thrust to maintain altitude or air speed.The only time when wind becomes a performance or aerodynamic issue is during take off or approach and landing. Windshear can be a serious hazard during approach and when your wheels are on the ground or immediately after liftoff, then wind will affect lift and dragMy guess is that it's a flight model (FDE) issueCheersIan

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