Windshear on T.O

[A Squared]

At first I thought that they were nuts but then I tried it in the sim and it works really well.

Not to take away from your comments at all, that's a different way of looking at windshear and it certinly has some merit. But, I wanted to point out that the fact that something works in a sim doesn't necessarily prove anything either way. Sims of course are an approximation of reality. True, some are really good approximations of reality, but they all have thier limits.

 

[HS125]

Dassault sees it a little differently. They suggest that you keep your nose level with the horizon and try to get out of the windshear as fast as possible. At first I thought that they were nuts but then I tried it in the sim and it works really well. If you are pitched up say 20 degrees and flying 130 knots across the ground it will take you alot longer to get out of the windshear than if you are pitched closer to the horizon but going 250 knots across the ground. You might be losing quite a bit more altitude but again you will fly out of the shear faster.

The theory is the same as what I do when I am flying my glider. When I am in very very nice lift I fly L/D, 1 knot above a stall to maximize my exposure to the lift in the thermal. HOWEVER, when I am in heavy sink I fly as fast as I can to get out of it.

When you use this manuver you probably have some altitude to work with and are not less than 1000' AGL.

Like I said I thought those folks at Dassault and Flightsafety were nuts but after doing it in the sim I am beginning to question if pulling up to the shaker is always the best way to escape.

Not saying one is better than the other just thought I would bring this into the discussion.

When did FSI start to teach this procedure? I've been to 1 initial and 4 recurents on the 900 and have yet to be taught this procedure. The only thing that I remember beign different from what I have been taught in the past is that Dassault tells you to raise the landing gear in a windshear. Every other manufacture says to leave the configuration alone until the aircraft is flying.

Furthermore, I can't imagine pushing the nose over to get back the 10 -20+ kts of airspeed that I just lost on takeoff when I'm only a few hundred feet off the ground. You are already in a situation where you may have a sink rate that you cannot recover from. Why would you want to push the nose over and increase that sink rate.

From what I remember from training many years ago is that, you pull the nose up to stop the sink as needed, and if necessary up to stick shaker always respecting stick shaker. This gets the wing pointed more into the relative wind from the down burst increasing lift.

I'm curious as to who the FSI instructor was that taught you this procedure. Big Al isn't teaching the 50EX also is he?

 

[Peanut gallery]

I think there may be some confusion here

Most manufactures that I have flown recommend pitching to 15 degrees nose up and holding that through the entire encounter. The shaker should not deter you from maintaining 15 degrees as the target but the shaker is not the target. This goes for Boeing and Mcd.

 

[FN FAL]

Dassault IS the manufacturer.

yea, but they are not the maker.

 

[mar]

Same here

From our FOM:

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Disengage the autopilot and autothrottles.​

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Aggressively advance the thrust levers to the mechanical stops and call “Firewall Thrust”.​

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Simultaneously roll wings level and rotate to an initial pitch attitude of 15 degrees. (Pitch attitudes as high as 20 degrees may be required to silence the “Pull Up” warning and/or avoid terrain.)​

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If the vertical flight path or altitude loss is still unacceptable, smoothly increase pitch attitude in small increments (2 degrees) until an acceptable flight path has been achieved.​

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Respect stick shaker. Use intermittent stick shaker as the upper pitch limit.​

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Maintain gear and flap position until windshear and terrain clearance is no longer a factor.​

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Accelerate to maneuvering speed, call for climb thrust and resume normal procedures.
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[FONT=Arial,Bold]

NOTE:​

[/FONT]Do not use flight director commands.​

 

[Hugh Johnson]

Just got back from 900EX recurrent at FSI TEB. The excape maneuver is leave flaps and gear where they are, firewall the throttles, pitch up and ride the stick shaker/stall warning system until you exit the windshear. Period, end of sentence.

 

[HS125]

Just got back from 900EX recurrent at FSI TEB. The excape maneuver is leave flaps and gear where they are, firewall the throttles, pitch up and ride the stick shaker/stall warning system until you exit the windshear. Period, end of sentence.

The 900EX has some operating differences from the 900A/B even though they are the same airframe. I can't figure out the French.

Not to change the topic of the thread but, does the 900EX have publised X-wind limits for wet and slippery runways?

 

[Hugh Johnson]

Supp 2 of the performance manual, operations on contaminated runways, has a limitation of 5KT on "icy" runway. It defines icy as "contaminated by ice", "A runway surface condition where braking action is expected to be very low, due to the presence of wet or dry ice."

 

[bigsky]

As I understand it the stick shaker is max L over D. This is based on Angle of attack so it is the most accurate.
One thing I have noted when studying windshear accidents is the last thing on the voice recorder is " watch your speed" (In all cases they were slow as one would expect in windshear) As is our habit when we see a slow airspeed we want to lower the nose to prevent a stall. This is where they all released back pressure - lowered the nose and the airplane crashed into the ground..... most experts seem to believe if they had maintained their attitude they would have flown out of it.

 

[flatspin7]

The ERJ has 2 windshear escape modes ---
Yellow (increasing performance) calls for immeadite go around and reconfigure (gear up, flaps 9) There is a WindShear flight guidance mode but in this case it only comes active with the TOGA buttons.


A RED windshear (decreasing performance) call for immediate go-around with out re configuring and that flight guidance is set up for max performance... it is not necessarily "riding the shaker" in an severe encounter in the sim it seems to be going on and off a lot.


Either way the best protection you have in a windshear situation is to get your self as far from the ground as quickly as possible... in a severe down draft lowering the nose to increase ground speed will get your self killed.

Thing a severe downdraft can be upwards of 4000 fpm (really bad case) you need to find 4000 fpm of climb just to stay level!

 

[millhouse21]

I'm going to have to go ahead and kind of disagree with you on that....yeah...Windshear Escape Guidance mode will come on automatically any time it detects decreasing performance. It will also come on when the TOGA buttons are pressed in the yellow windshear mode.