Trigger for climb power?

[Will]

What conditions have to be met for the thrust to change from Takeoff to Climb?

I'm asking because I've noticed that it doesn't always make the transition, and I can climb all the way to cruising altitude with the thrust still reading TO or TO-1. I know about the FMC entry on the TAKEOFF page, and I am manually entering 1000 feet (for example), or 400 feet, or Flaps 5, so it's not a matter of not having a defined point for the transition. Rather, there must be some other criterion that I'm missing, that prevents the aircraft from switching at the defined point.

Thanks.

[double-alpha]

Hi Will,

Do you use VNAV during your climb?

If VNAV is not used, at THR REDUCTION (When reaching Flaps 5, or 1000 ft or anything you have manually entered), you have to select manually Thrust reduction to climb thrust limit CLB by pressing the MCP THR switch.

[Will]

I'm using VNAV, but I'm seeing it only when 400 is the height entered in THR REDUCTION on the TAKEOFF REF page.

You can see it by loading the Basic 004 - Cleared for takeoff.situ.

1. Load the situ.
2. Load the TAKEOFF REF page.
3. Ener 400 in LSK 3L.
4. Release the parking brakes.
5. Perform a normal takeoff.

Climb thrust won't engage until you press the THR switch on the MCP.

Is that how it's supposed to work?

[double-alpha]

According to FCOM, valid entry is an height from 400 to 9999 feet AAL.

I tried several takeoff from your situ...

It works well with 415 ft for exemple, but like you at 400 ft CLB doesn't come on...

I am not an expert but I understand like you. Seems to me a bug???

Anyway, I think in real life 400 ft is never selected.

[Hardy Heinlin]

I haven't tried 400 in the past two years. That's probably too low for my trigger system now because VNAV engages a few milliseconds after 400 -- and VNAV is required for this.

I'll check it during the next update project (June or July).


Cheers,

|-|ardy

[Will]

Two questions.

1. Does any operator perform a takeoff with VNAV not armed? If so, how and why?

2. In PSX, if you takeoff with VNAV unarmed (like with just TO/GA mode annunciated but no subsequent mode armed), and then climb through the trigger point set on the TAKEOFF REF page for the transition from TAKEOFF thrust to CLB thrust, and then engage VNAV, the thrust setting remains at the takeoff setting and doesn't change to the climb setting. Is that how the real 747 functions?

Thanks, everyone.

[Hardy Heinlin]

Is that how the real 747 functions?

I don't think so.