Speed limit, LE flaps and slats
 

Hey guys

We have a speed restriction on the 737-800 on departure of 230 kts. with the LE flaps and slats extended.

On approach you may extend the LE flaps and slats if you're below 250 kts.
Why is there different speeds here?

Is it because the LE flaps and slats can only handle 230 kts. during retraction?

Who are "we" ?

- mainly as i havnt heard of that one before, on a normal departure...
- normally wouldnt go there anyway, but guess what the "approx" min clean speed is for NG max T/O mass.
- is it "only" a company recommendation / SOP, or is it listed in the limitations chapter.
- what does your speed tape say, (the red bar)
- what does Vnav command on flap retraction...( if you use it)

The 230kts until retracted is a boeing recommendation and VNAV schedules 230 until all leading edge devices are retracted. It is done to cover a possible stuck flap situation and keep within the speed limitation for that case. During approach one is usually decelerating and therefore the airspeed is decreasing anyway. However even in that case boeing recommends to select the next flap setting only 10kts above the current flap limit speed, which for example means flaps 1 at speed up plus 10kts.