B737 Autoland Flap Setting

[BangorBoy]

Hi a question on the flap setting for the B737 700 autoland. Our Company manual(EZY) states that we should use flap 30 or 40. Is there a reason why we cannot use say flap 15 ? I do not know (I'm sure I should !) if this is a certification issue or relates to slant range using the higher flap settings.

Thanks in advance for any help with this query

Regards BB

[Rainboe]

Flap 15 is a significant failure configuration for landing, not authorised for autoland. It probably just boils down to it was not checked in the certification process as it was probably not judged a realistic scenario in view of the failures that would discourage autoland.

[BangorBoy]

Thanks Rainboe

Lots of theories at work today most thought it might be a certification issue as we use flap 15 for certain events ie. single engined landing. Your answer is appreciated.

BB

[Cough]

[Info based on 737 classic ops....may apply, or not, you decide!]

I find the aircraft lands with a significantly higher nose attitude when autolanding, (due to much earlier reduction of power compared to the manual technique). Hence I would have thought tail clearance may become more marginal if you carried out an autoland with flap 15.

Just my initial thought anyhow....

[CaptainSandL]

It is an AFM limitation:

"Autoland capability may only be used with flaps 30 and 40 with both engines operative."

Ref D631A001, Section 1, Page 13C.

[Hold position]

Performance considerations as will as certification. which take in to account the visual contact with the runway and the go around procedure in case of auto pilot failure, and no contact given the trim position and its impact on the above situation specially at the last stage before touch down.

[Denti]

It depends really on your ordered options (as usual). For those 737s that are CAT IIIb capable is autoland with flaps 15 possible since that includes CAT IIIa single engine capability.

Apart from that we had to use flaps 30 or 40 in an autoland on the classics and flaps 40 only in real CAT III approaches. On the NG it was changed to either flaps 30 or 40 in either circumstances except for single engine operation.

[Johnny F@rt Pants]

The higher flap setting also provdes a lower nose attitude and therefore increases your chances of seeing the required elements of the runway/approach lights at DA. (737-300)

[BangorBoy]

Thanks guys for your information, all very interesting. Happy flying.

BB