Step Climb question

[Dewey8524 0]

Hey everyone,

 

I must be screwing something up. Can someone please explain to me in detail how to program and execute a step climb. I read the pdf manual, tried it, and it's not working. Do I have to program the step in the legs section? Thanks

[PHXMD-11 86]

Hey everyone,

 

I must be screwing something up. Can someone please explain to me in detail how to program and execute a step climb. I read the pdf manual, tried it, and it's not working. Do I have to program the step in the legs section? Thanks

 

The 744 will automatically calculate step climbs if the FMS is set up correctly (PERF INIT page set, route is set up correctly, winds inserted (optional). Step climbs default to 4000 feet. You can choose to change this number on the PERF INIT page by replacing ICAO with a number (i.e., 2000). You can see the distance and time to the step climb point on the VNAV Cruise page and the PROGRESS page if I remember correctly.

 

Once at the step climb point, change the altitude in the MCP window and the cruise altitude on the VNAV Cruise page if needed. I would recommend conducting the climb by setting a VS of +500 fpm. That way the engines won't spool up to max climb thrust. It's more comfortable for the passengers and easier on the engines. Just re-engage VNAV at the end of the climb.

[Dewey8524 0]

Hey Kenny,

 

Thanks for the reply. I figured out what the problem was. I would be lazy and enter the STAR before takeoff. This would cause all al**udes for waypoints (LEGS) to be less than the al**ude for the proposed step climb...hence, the countdown would stop. Now I enter the STAR at some point after the last S/C and it works like a charm. Thats what I get for trying to cheat. What you said about the 500fpm step climb makes sense, I'll have to give it a try. VNAV is a bit zealous at times. Thanks much

[richardnobes14 13]

Two ways of step climbing. 1. Changing the MCP altitude and pressing the ALT intervene button 2. Changing MCP altitude, then swapping to V/S for a climb rate of about 300-400fpm, while this is happening change the CRZ ALT in the FMC and then place back into VNAV after climb

[Richard McDonald Woods 168]

and 3. Changing MCP altitude and pressing it (which also updates the CRZ ALT), then pressing FL CH for a smoothe climb.

[richardnobes14 13]

and 3. Changing MCP altitude and pressing it (which also updates the CRZ ALT), then pressing FL CH for a smoothe climb.

 

That was actually number one on my list, FL CH will not give you a "smooth climb", it will be the same as an VNAV step climb

[YMMB 234]

On the question of smooth climbs am I right in suggesting using FL CH to initiate the climb uses the aircraft's pitch to maintain the set airspeed while initiating the climb and so you could potentially go from a very shallow climb, say 200-500fpm if already flying fast and heavy to say 6000fpm if light and slow ...and then... If V/S is used to initiate a climb you can get a much smoother climb rate as this is the parameter being controlled and you can limit/won't get a sudden jump to max thrust or the potential to shoot up to the stars. I once got an overheat of N2 because of my inattention when the Queen went to 4500fpm, max thrust etc.. and using FL CH

[PHXMD-11 86]

On the question of smooth climbs am I right in suggesting using FL CH to initiate the climb uses the aircraft's pitch to maintain the set airspeed while initiating the climb and so you could potentially go from a very shallow climb, say 200-500fpm if already flying fast and heavy to say 6000fpm if light and slow ...and then... If V/S is used to initiate a climb you can get a much smoother climb rate as this is the parameter being controlled and you can limit/won't get a sudden jump to max thrust or the potential to shoot up to the stars. I once got an overheat of N2 because of my inattention when the Queen went to 4500fpm, max thrust etc.. and using FL CH

 

I would recommend climbing in V/S mode. It may increase the engine thrust a bit but it will be a smoother experience for your passengers. If I remember correctly the FL CH mode will increase the engines to full climb. By the way I think the 744 will stall if step climbing at 6,000 FPM.

[kevinh 409]

In the 747, for small flight level changes FLCH does not cause thrust to go to CLB power. It increases enough to make the altitude change in a defined time. Thus FLCH can as work smoothly as VS and in a better controlled manner.