747-400 Flap schedule
 

Hi,

Just wondering if anyone could explain in very simple terms the flap schedule for the 747-400. Alternatively, tell me if i have it correct or incorrect! It feels slightly different to the bus way of doing / displaying things!

As i understand it, for flap extension:

select the stage of flap you are approaching as you decelerate. Ie at a few KTS above "5" on the speed tape, decelerating towards it, select flap 5 (from flap 1).

for retraction:

select the stage of flap as you pass the respective number and are accelerating. i.e. when you reach the speed '10' is displayed at, and are accelerating, select flap 10 (from flap 20)

Thanks,

H

The 747 is different to other types of Boeings, so your interpretation is incorrect.

The flap manoeuvre speeds are flown as minimum speeds for that flap setting. For extension of flaps, you shouldn’t be slower than the flap marker for that present flap setting (ie no slower than Up with flaps up, no slower than 20 with flaps 20.)

For retraction, the flap can be retracted once above the next flap speed. I.e. with flaps 10 extended, once above 5, then flaps 5 can be selected.

Apologies, I'm probably still confused: is what you say not the same as what I said?

During flap extension, selection of the flaps to the next flap position should be made when approaching, and before decelerating below, the maneuver speed for the existing flap position.

Here's an example :)
https://cimg0.ibsrv.net/gimg/pprune....afa3ab21fe.jpg

For acceleration, you are correct.

I think I've understood it now:

for flap extension, before you reach the number on the speed tape you call for the next flap setting as you can't go slower in the current config.

for retraction, as you pass the number on the speed tape you call for that flap stage.

Cheers everyone