The same than if you have a stiff tailwind, a stiff crosswind, or a stiff no-wind.
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Air France 447 - On topic only!
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Originally posted by EconomyClass View PostHas someone answered what happens when you have a stiff headwind and then the airspeed sensors fail?Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.
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Originally posted by 3WE View PostAvoid turning downwind because as the stiff headwind shifts to a stiff tailwind you will lose airspeed and risk stalling if your speed was slow to start with.
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Originally posted by 3WE View PostAvoid turning downwind because as the stiff headwind shifts to a stiff tailwind you will lose airspeed and risk stalling if your speed was slow to start with.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
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Originally posted by Peter Kesternich View PostWell - that would only occur during low speed maneuvering.
At altitude there is no such thing as windshear.
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
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Originally posted by Gabriel View PostSay again? Exactly what would happen during low speed maneuvering but not faster?
Say again? Fly through a nice Cb (aka cumulus-nimbus, aka thunderstorm) at altitude and then repeat that (if you survive). Windshear is by definition a change in wind velocity (i.e. in its speed or direction) in a narrow zone. (still not sure what does it have to do ith your previous line or what you qoted from 3WE)
Avoid turning downwind because as the stiff headwind shifts to a stiff tailwind you will lose airspeed and risk stalling if your speed was slow to start with.
Sorry for the confusion, Gabriel
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Originally posted by Peter Kesternich View PostActually, I think the misunderstanding lies already in 3WE's lines
--- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
--- Defend what you say with arguments, not by imposing your credentials ---
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Originally posted by Evan View PostOf course it's just speculation, but perhaps they never actually stalled, just sunk. try this out:
1) They underestimate or misread the weather system, a fatal error, and fly into extreme turbulence, lightning, what have you. Unable to divert or otherwise avoid the system at this point, they command reduced speed and commit to traversing it. No big deal for the A330.
2) Suddenly, the AP is out, the AT is out, the ADIRU's are shutting down, the yaw damper is out, TCAS is out, a lot of crazy sh*t is happening.
3) The last thing they expect is pitot failure at that altitude, so they work the problem not as unreliable airspeed, but as a systems malfunction and place their focus there.
4) They are in alternate (or abnormal alternate) law. They are in hard turbulence, and perhaps electrical discharge as well. Chaos essentially. There is not even attention to spare to issue a mayday call.
5) Therefore, while assuming that there is no imminent need to address basic flight parameters at cruise level coming off, say M.82, they neglect to realize how much speed has decayed (as they have no reference for this) nor how much sink rate is rapidly increasing. The PF is focused on manually controlling attitude in the turbulence, and they are distracted by ECAM messages.
6) At some point, they notice the altimeter or the vertical speed. They have forgotten in the confusion that they had been commanding a lower airspeed before things got hairy (The AT would have kicked off with thrust in a retarded position), and not wanting to overspeed in the turbulence, the PF initially adds pitch, not power, to regain lift. Possibly while not accustomed to the altered sidestick sensitivity.
7) In actuality, the airspeed is much lower than they realize, and therefore, with the high sink rate the airflow is coming at a steeper upward angle than they expect. In a matter of seconds they reach critical angle of attack at a surprisingly low pitch angle and suddenly stick shaker kicks in.
At wits end, they firewall the thrust levers and bring the nose down, but the engines are slow to respond and the lower pitch increases the sink rate without decreasing angle of attack, due to the steeper airflow vector. They are falling out.
9) Perhaps they begin to recover by pitching down, maintain aileron authority, wings level, but can't slow the rate of descent in time... pitch up at the last moment and impact in that attitude.
All this occurring in degraded control law and while descending through a violent storm.
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