I have a question how things should work, as after take off thrust do not automatically change into CLB regime. Is it correct that regimes must be changed manually?

Beardyman wrote on Dec 25^th, 2021 at 6:33pm:

I have a question how things should work, as after take off thrust do not automatically change into CLB regime. Is it correct that regimes must be changed manually?

Yes, CLB thrust only happens one of 3 ways: manually pressing CLB on the thrust mode selection panel, by selecting VNAV, or selecting FLCH.

Alex, so i understand that having Lnav and Vnav engaged thrust should automatically change to CLB regime, but i cannot see such action, so if i do not change it manually then plane climbs like a rocket. I always take off with lnav and vnav engaged.

The B767 still has a few quirks with the A/T...not nearly as bad as the CS757.

My procedure on take-off...manually follow pitch on the flight director. Once stable (above 1000 ft), engage the autopilot. Reset the V/S lower to maintain speed. Engage the A/T, then engage LNAV and VNAV.

So far, no issues with this procedure, CLM thrust works as it should.

Beardyman wrote on Dec 26^th, 2021 at 9:23am:

Alex, so i understand that having Lnav and Vnav engaged thrust should automatically change to CLB regime, but i cannot see such action, so if i do not change it manually then plane climbs like a rocket. I always take off with lnav and vnav engaged.

Correct.

My procedure is engage VNAV at the acceleration altitude (800AFE usually, sometimes 1000AFE, sometimes 1500AFE). and CLB always comes on automatically. Can you take a video of your example and show us how yours is working? Mine works as expected.

I do not know how system should work, trying to watch some YT movies but cannot figure out.
My procedure is that during taxi i engage L&V NAV modes, FD and AT is on, then i press TO/GA and choose '1' for derated take off. During take off advance throttle until derated thrust marker position and press THR. After lift off engage AP, aprox 1500 AGL. Thrust mode remains same as for take off, then i have to press CLB mode. Having experience from other Boeing planes done by another company i know that take off power automatically changes into climb power as u reach 1500ft AGL, so my question is if 767 is different or is it a bug?
Next flight i will test ur way of engaging VNAV after passing 1500 ft AGL.

Don't set VNAV and LNAV before takeoff. Both should be off. This is a 1980's B767. At 400' AFE set LNAV on and then at 1500' AFE set either VNAV or FLCH. Power will reduce to CLB power. The correct way is to set FLCH and set speed to 220KIAS and then continue climbing to 3000' AFE while retracting flaps. AT 3000'AFE set VNAV.

trevors wrote on Dec 27^th, 2021 at 6:26pm:

Don't set VNAV and LNAV before takeoff. Both should be off. This is a 1980's B767. At 400' AFE set LNAV on and then at 1500' AFE set either VNAV or FLCH. Power will reduce to CLB power. The correct way is to set FLCH and set speed to 220KIAS and then continue climbing to 3000' AFE while retracting flaps. AT 3000'AFE set VNAV.

I agree with this. I know some operators engage VNAV on the ground, but my airline doesn't allow it.

trevors wrote on Dec 27^th, 2021 at 6:26pm:

Don't set VNAV and LNAV before takeoff. Both should be off. This is a 1980's B767. At 400' AFE set LNAV on and then at 1500' AFE set either VNAV or FLCH. Power will reduce to CLB power. The correct way is to set FLCH and set speed to 220KIAS and then continue climbing to 3000' AFE while retracting flaps. AT 3000'AFE set VNAV.

Trevor - appreciate detailed description. Works well as u wrote, thank u

As the manual I have, LNAV could be armed on ground, and VNAV could not, VNAV or FLCH are both selectable on thrust reducing altitude, and it's recommended by Boeing to use VNAV.
On TAKE OFF page 2 you can input acceleration height, if doing NADP1, you can set it to 3000, so at 1500 (or anything above 400) you press VNAV, thrust reduced (sometimes increased) to CLB, but AP or FD will keeps you on V2+15~25 until 3000 as you inputted
Works on both CS757 and 767.

And for non-VNAV:

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