Engaging VNAV at 400ft in 737NG

[reverserunlocked]

Is it done or not done?

Seems like a good idea to me, gives you protection against overspeeding the flaps.

Or do you clean up first, and then engage it?

Just curious :hmm:

[alexban]

Speed limit for flap 5 is 250 kt's,I think it's not something to worry on take off.
Unlike classic where is 230 kts.
You can select vnav,but how will you handle the noise procedure,for ex. 1000' N1 ,then 3000' up. You'll have N1 at 400' . Not such a big thing on a 737,but if you want to follow the rules....

[crvm]

Hummm why is it that SWA's Efis MASI for a flaps 5 TO has a **LIMIT** speed arc of 190 to 250? I mean the yellow limit arc that is not present on the standard PFD. This is removed once you go flaps 1 in clb but does not make any sense seeing that limit for 5 is 250!

Any SWA pilots who can comment on this strange limit arc?


crvm

[LEM]

Flaps 5 limit on the 400 (classic) is also 250 kts.

As Alex has pointed out, how are you gonna handle noise abatement?

[quietwing]

LEM

You could enter a speed restriction on the climb page to comply with noise abatement.

[LEM]

quietwing,

yes that could work, but when you pass the acceleration altitude, isn't it going to accelerate unrestricted?

You'd loose 250 below 10...

Anyways, not a good practice. Also not applicable for a flaps 15 takeoff.

:hmm:

[capt.topgun]

We in our airline, stick to VNAV only after cleanup due to LE flaps extended speed restriction. It is very easy to exceed the LE FLAPS ext. speed in the VNAV mode if one of them is stuck during retraction due the FCC only monitoring the TE FLAP position. Once the Crew confirms FLAPS UP NO LIGHT, VNAV is all yours.:ok:

[Hudson]

Capt.topgun. Good point about LED speed limit. Does the SOP of your airline require a specific call by the PNF of "flaps up-no lights", as soon as the action is complete (confirmed later by the After Takeoff Checklist). Some operators follow the Boeing SOP meaning no specific call as the flaps hit up and the LED light goes out. This has led to neither pilot monitoring the flap retract sequence of events until some time later when the After Takeoff Checklist is called for. By that time it may be too late to prevent overspeed of the LED if in fact they are still extended for some reason or another.

[Lucky Angel]

In my company at acceleration we BUG UP then Flaps1. Then we select Flaps UP and when the lights go out the standard call is Flaps UP no lights then engage VNAV above 3000'.

[capt.topgun]

Hudson,
Our SOP procedure is ditto as Angel's except there is no restriction of 3000' for engaging VNAV (with no noise abetment required). The moment PNF calls "Flaps UP No Light", PF verifies it and then asks for VNAV as the climb mode. Passing TA, "After T/o C/L" is carried out which confirms the above once again ( Though its a tad late for the LED speed to be observed as u are already doing 250 K ) Pretty satisfactory procedure IMHO. :D
Keep it safe out there, :ok: