Takeoff climb gradient

[G-CIVA]

would anyone use V/S here?

Does V/S give you speed protection?

Is it wise to use such a 'coarse' mode of automation during such a crucial phase of flight?

[Britjet]

Always remember that once you select VS you lose speed protection. At low altitude and when maybe still retracting flaps,  trying to VS out of a situation can have serious consequences. If you must use basic modes then use FLCH.
Peter.

[Will]

Thanks, Peter, but so I understand you, you're talking about FLCH and then dialing the airspeed down so that the aircraft doesn't pitch down to accelerate? When I go to FLCH SPD, the IAS/Mach window opens and shows 225 kts. The aircraft, now in FLCH SPD, still pitches down to accelerate, and the rate of climb drops to 500 fpm and we miss the crossing altitude by 1000 feet.

But if I switch to FLCH SPD and dial the airspeed back to 180, now the aircraft climbs at a solid 1400 fpm and we make the crossing restriction, after which I go back to VNAV and accelerate from there. That's what you mean, right?

Or do you mean pressing FLCH and then moving the thrust levers forward?

[Martin Baker]

Will, do you have a .situ file for this so I can try it and see what you mean? Martin

[Will]

Situ is at the link below.

https://www.dropbox.com/s/te1ntdqflsl9y2b/WJC%20Climb%202.situ?dl=0

It's set up with the aircraft at about 500', gear up, autopilot on, so all you have to do is watch, and retract the flaps on schedule.

Please let me know what you think.

[Britjet]

Will,
Your second paragraph is correct. You would be using FLCH and then selecting an appropriate safe speed in a rather roundabout way to stop further acceleration and so increase the climb rate. And you still have speed protection which is the most important thing.
Peter.

[emerydc8]

Always remember that once you select VS you lose speed protection. At low altitude and when maybe still retracting flaps,  trying to VS out of a situation can have serious consequences. If you must use basic modes then use FLCH.
Peter.

Although it's a different airplane, on the 767 with an engine fail on takeoff, the first call at flap acceleration height (usually 1000') is "vert speed 200, center autopilot to command." If you're really heavy you call "vert speed zero, center autopilot to command." Then accelerate and clean up the flaps on schedule. Once clean and at V2+80, we call "FLCH, continuous, VNAV Engine-out prompt execute" and do the memory items.

The -400 is so much nicer!

[simonijs]

As I mentioned earlier: in the LIDO Airport Operational Information [AOI] page 5 of RJBB, there is a speed restriction of 200 kts up to 3000 ft within RJBB CTR (circular with a 5 NM radius).

In this case I would just enter 200/3000 in LSK4L on the VNAV CLB page.

In KLM's AOM it says that "selection of the ENG OUT prompt overrules the speed/altitude restriction if entered on the climb page. However, speed/altitude constraints on the LEGS page will remain in effect (...)."

Regards,
Simon

[Will]

Thank you very much, everyone. I appreciate the info and the suggestions.

[Hardy Heinlin]

I just split two posts from Simon and me regarding E/O speed restriction to a new thread:

http://aerowinx.com/board/index.php?topic=5813.0