B757 Windshear go-around?

[Lembrado]

Hi,

New to the aeroplane and airline flying, FI background. LPC/OPC next week.

My company manual says that changes to flap/gear position should not be attempted until positively clear of the shear and Vref+5 or greater.

On short final, with gear down and flap 30. After windshear EGPWS warning, one selects max thrust and pitches up to the PLI. My question is that shouldn't this be accompanied by immediate selection of gear up and flap 20 - as per a normal go-around? Why delay getting rid of the extra drag?

Maybe a minor point, but something that crossed my mind whilst revising.

Thanks for any clarification.

L

[shlittlenellie]

Pitch and directional stability and minimal actions from the flightcrew other than to fly the aircraft (particularly when close to the ground).

[BizJetJock]

If it's only a "minor" windshear (if there is such a thing), then you have plenty of performance available and it wouldn't make much difference. However, the procedure is devised for the worst case where you're pitching to the shaker/eyebrows - depending on avionics fit. In this case retracting the flap risks a configuration stall, as well as reducing the available lift. Even that small amount of lift could be the difference between arresting the descent in time or not. You leave the gear down to act as a shock absorber for the impact...

[banana head]

Bizjetjock,
You leave the gear down to act as a shock absorber for the impact...

While this may be a positive consequence of leaving the gear down, the actual reason for not retracting the gear is far more straight forward. On most larger A/C the gear doors open to lower the gear, then close again with the gear down. Selecting gear up requires the doors to sequence open again - and this causes additional drag right when you don't need it!

In a w/s go-around situation we make NO config changes until safely away and perf recovered.

B

[757manipulator]

Just to back up Banana, he has it on the money, although its just as important to have something hanging down should you touch the ground.

My company SOP's are TOGA thrust (double click on the TOGA switch) pitch to 15 initially, then to the eyebrows if required. The eyebrows are based on each config, they do however lag slightly.

Ive actually done a live one for real going into Malaga, at about 87 tonnes we were still going up at 3000fpm.

:ok:

[Frank Poncherello]

Spot on with the comment about leaving Gear Down.

Another reason, perhaps, for leaving flap configuration the same could be the increase in stall speed (with less flap selected). So, by reducing the flap setting, one increases the stall speed, at a time when the speed trend could be a very large negative.

Just a thought!

FP

[stansdead]

You also leave the gear down because:

When you retract gear the gear doors open on the 757. They are HUGE and increase drag for a few crucial moments until the gear is fully retracted and the doors closed..... this process increases drag and hence reduces aerodynamic stability and thrust availability.

Leave the config alone until clear of any windshear.

[Lembrado]

Thanks, thats cleared things up in my mind. Especially with regard to the gear doors - good point that I missed!

L

[None]

...My company SOP's are TOGA thrust (double click on the TOGA switch) pitch to 15 initially, then to the eyebrows if required. The eyebrows are based on each config, they do however lag slightly.
Ive actually done a live one for real going into Malaga, at about 87 tonnes we were still going up at 3000fpm....
:ok:
757m,
Your company wants you to firewall the thrust in a windshear, don't they?
push-push (TOGA & thrust levers)
click-click (click-off the A/P and A/T's)
look-look (Look at the ADI to make sure the A/T's are off)

[wingletflyer]

In a w/s go-around situation we make NO config changes until safely away and perf recovered.
I would also be careful not to call this W/S recovery precedure as Go Around!
While we all pilots are preprogrammed to move the flaps and the gear-up when we hear " Go Around"
I would call it either "Maximum climb" - analog to hard GPWS recovery - or "Windshear Recovery" but no Go Around!
Happy landings