737 FD off in wind shear

[president]

If you do a FD off take off and get a wind shear warning, will the FDs appear when you press TOGA after airborne similar to what happens when you do a FD off go around with FDs off? Put in other words. Will you only get FDs commands in wind shear with the FD switches in the on position?

[ImbracableCrunk]

You'd get the "pop-up" mode, no? It'll disappear when another mode becomes active, I believe.

[president]

Perhaps but I could not find any reference to this feature in the FCOM. FD guidance during a FD take off in wind shear is well described though.

[de facto]

If you do a FD off take off and get a wind shear warning, will the FDs appear when you press TOGA after airborne similar to what happens when you do a FD off go around with FDs off

YES

Put in other words. Will you only get FDs commands in wind shear with the FD switches in the on position?

NO
Following a no FD approach,if TOGA is pressed and below RA 2000ft the FD will guide you until level off (alt hold) via a pop up mode as mentioned above.

[president]

De facto: I was not talking about the automatic pop up for GA. Only wind shear escape manoeuvre on a non FD take off - after pressing TOGA. Do you have any reference to this feature in the FCOM ?

[de facto]

Only wind shear escape manoeuvre on a non FD take off - after pressing TOGA

After you press TOGA you will get FDs ON even if OFF during take off.windshear or not.
TOGA is one thing ,winshear escape is another.
If toga pitch is not satisfactory,ie you aint climbing,pitch must be adjusted to the PLI which is THE reference limit to your pitch during windshear.

PLI (pitch limit indicator) was designed for windshear recovery not TOGA.
If you take off with no FD selected and enter windshear,apply max thrust and pitch for 15 deg,if not enough pitch until max (pli) and firewall.
If you take off with fds ,follow fds..and firewall as necessary(ie approaching ground contact).

Read about TOGA in your fcom and windshear maneuver in your qrh?
If i misunderstood your question again,try writing a clearer question.

[president]

Thanks it's clear now. But on a normal take off with FDs off you don't get FDs pop up when you press toga to set take off thrust. That's a fact. So you are saying that if I press toga again after TO (wind shear or not) they will pop up?

[de facto]

But on a normal take off with FDs off you don't get FDs pop up when you press toga to set take off thrust. That's a fact

Not exactly.

So you are saying that if I press toga again after TO (wind shear or not) they will pop up?

After 80 kts,the pop up function will work if you press TOGA so to answer your question:yes.

[president]

Ok thanks for your help. Will this feature be described anywhere in the FCOM or is it something you have observed in the aircraft? I had a look of course but could not find it.

[172_driver]

Reference for the FD pop-up is in FCOM 4.20.5

What I cannot figure out is if their is any good reason to re-cycle the FDs on final following a raw data approach. The pop-up feature is there.

De-facto, you said:

Following a no FD approach,if TOGA is pressed and below RA 2000ft the FD will guide you until level off (alt hold) via a pop up mode as mentioned above.

I can't find that in the books… maybe it is like that? You're basically saying the pop-up FD's retract when you reach ALT HOLD if the FD switch is in OFF position?

[president]

That's right 172. They retract at alt hold. The only reason to recycle is not to lose them later on.

De facto: I found it now

"TOGA can be engaged for take off with FDs off if a TOGA switch is pushed after 80 kias below 2000 ft and prior 150 s after lift-off"

[de facto]

TOGA can be engaged for take off with FDs off if a TOGA switch is pushed after 80 kias below 2000 ft and prior 150 s after lift-off

Well done