Will the pmdg 777 automatically perform step climbs like the MD-11, or do you have to press the altitude intervention button to initiate a step climb?

 

Thanks-

Fred Miller

I'm almost sure you'd have to change the altitude on the MCP ALT window then press the switch. Every time I've seen 777's do steps in DVD's they've always contacted ATC for a climb, then climb in V/S once approved.

 

You enter the step(s) in the legs like; 360S. Then once you're airborne and past T/C it will make a countdown in NM and give the ETA at next point to climb in the Progess & VNAV page.

 

That's pretty cool that the MD-11 does it automatically!

Automatic step climbs seem very convenient. Fortunately, my flights are usually short enough not to require fuel panel changes or step climbs during cruise.

Automatic step-climbs are actually not a very good feature in a real aircraft. Normally you are assigned a particular level to maintain by ATC. When the aircraft starts climbing without you noticing, you're going to get some pretty stern words over the radio and possibly a phone number to call

 

As far as I know, the 777 does NOT have this function. Once the aircraft enters altitude capture and then hold in VNAV (FMAs "VNAV ALT" or "VNAV PTH", depending on whether it's capturing an intermediate level or the current FMC constraint/cruise level), adjusting the altitude bug doesn't do anything. You must press altitude intervene (pushing in the ALT knob) for the aircraft to do any further climbing. This logic is consistent through modern Boeing aircraft.

 

The only time that I'm aware of, in which a Boeing AFDS will command a level change from altitude hold in VNAV without the altitude intervene/FMC execute is when the aircraft reaches T/D with a lower level set in the MCP altitude window.

I was about to post pretty much what David has said. It's not exactly a useful function in the MD-11 and doesn't reduce workload in any way really pre-inputting step climbs into the MD-11 FMS because no pilot is going to be stupid enough to set the MCP above their cleared cruise altitude.

I was about to post pretty much what David has said. It's not exactly a useful function in the MD-11 and doesn't reduce workload in any way really pre-inputting step climbs into the MD-11 FMS because no pilot is going to be stupid enough to set the MCP above their cleared cruise altitude.

 

But you would set it shortly before your next step climb.

But you would set it shortly before your next step climb.

 

Obviously, once you've got clearance to step climb (and so you're not longer going to risk being above your cleared level).

This talk of setting MCP above cleared is a bit meaningless, since on ascent, just like descent, the AP will hold at the which ever limit it hits first, whether it is FMC or MCP. In the MD-11, if there is a planned step climb, and the MCP is higher then the current altitude, then the AP will initiate the step climb without further pilot intervention. If the pilot does not want this behaviour, they simply do not set the MCP to an altitude above their current cruise.

 

I would expect the 777 to have the same behaviour.

It's actually a valid point.

Because the FAA so widely defines pilot responsibilities, it's very easy for the blame in many situations to be pinned on the pilot. With that, part of being a pilot is being good at CYA. I'd consider it poor practice to have the ALT selected on anything other than what you intend to maintain most immediately (even if temporarily), for two reasons:

1 - "Well the FMC's intermediate cruise altitude should've kicked in and stopped the climb at FL330" is not going to get you out of FAA action when - for whatever reason - the plane busts right through it on the way to the altitude in the window causing a CA on your controller's scope, and a subsequent RA in both of your aircraft.

2 - Even when it stops at the initial cruise altitude as was assigned, you still need clearance from your current level to the next one above it. Even though your flight plan may show that you'd like to climb at a certain point (often noted in plans as M###F###: M082F350), your clearance on your route is not implicit clearance that you will be able to climb at that point. So, if you weren't paying attention and the plane hit the step and automatically climbed up into the aircraft above it (or near it), you're going to get the book thrown at you (as in the case above).

It's actually a valid point.

Because the FAA so widely defines pilot responsibilities, it's very easy for the blame in many situations to be pinned on the pilot. With that, part of being a pilot is being good at CYA. I'd consider it poor practice to have the ALT selected on anything other than what you intend to maintain most immediately (even if temporarily), for two reasons:

1 - "Well the FMC's intermediate cruise altitude should've kicked in and stopped the climb at FL330" is not going to get you out of FAA action when - for whatever reason - the plane busts right through it on the way to the altitude in the window causing a CA on your controller's scope, and a subsequent RA in both of your aircraft.

2 - Even when it stops at the initial cruise altitude as was assigned, you still need clearance from your current level to the next one above it. Even though your flight plan may show that you'd like to climb at a certain point (often noted in plans as M###F###: M082F350), your clearance on your route is not implicit clearance that you will be able to climb at that point. So, if you weren't paying attention and the plane hit the step and automatically climbed up into the aircraft above it (or near it), you're going to get the book thrown at you (as in the case above).

 

Yeah, couldn't agree more! And nothing interferes with proper autopilot operation like A) a heavy workload and you fail to notice something happening, and B) in the times when things are not going that wildly and your concentration begins to slip a little. That sort of feature is cool though if you are flying through the night and need to get some sleep :LMAO:

 

Kind regards

Could PMDG make it an option for the FMC to perform automatic step climbs (like the MD-11)? On longer flights, when I am often away from the computer, I can get incorrect fuel predictions if I do not initiate the step climb at the optimum time. This is especially important in the T7, when flights can be up to 18 hours!

 

 

Fred Miller-

Could PMDG make it an option for the FMC to perform automatic step climbs (like the MD-11)? On longer flights, when I am often away from the computer, I can get incorrect fuel predictions if I do not initiate the step climb at the optimum time. This is especially important in the T7, when flights can be up to 18 hours!

 

 

Fred Miller-

 

The FMC will give you an ETA for the step climb so you could always just keep an eye on the time and return roughly when the FMS says you should step climb.

If it isn't on the real 772 it will probably not be on the PMDG model. I would just like to have the plane, My birthday just past days ago and I am waiting patiently because my wife knows this is what I want. So she is going to buy it for me out of my checking account. How ironic. Good luck guys sitting on my hands waiting for my time. Cpt out.

Could PMDG make it an option for the FMC to perform automatic step climbs (like the MD-11)?

 

I think this is a good idea also. It's not always practical to come back at the FMC predicted time especially with significant others and kids. If they did it in the MD-11 then it's not like they do not know how to implement it here.

 

It does not bother me that something like this is not on a real 777. Opening doors from the CDU in not either.

I think this is a good idea also. It's not always practical to come back at the FMC predicted time especially with significant others and kids. If they did it in the MD-11 then it's not like they do not know how to implement it here.

 

It does not bother me that something like this is not on a real 777. Opening doors from the CDU in not either.

 

I think the issue arises in how to implement it. Sure, there's no such "FS ACTIONS" menu on a real 737 FMC or "PMDG OPTIONS" but those two functions of the FMC are fairly independent from the rest of the aircraft. If they were to incorporate automatic step-climbs it'd have to be integrated into the otherwise highly accurate FMS.

 

I'm not sure if this works in the 777, but you might be able to pre-programme the STEP climbs into the FMC on the LEGS page and leave the MCP at the highest altitude. For example, if you're optimum initial cruise is FL300 you can find a waypoint ~1500nm further along and set the altitude in the LEGS page to FL320 (1500nm is roughly the intervals between step climbs given in the B744 FMS - I'm estimating the 777's intervals will be slightly less than this) and you might be able to do this for the entire flight and just set the MCP to the altitude you'll end up at. Obviously you could also use a step of 1,000ft if flying on the NAT. It wouldn't be done this way in the real world, since the pilots would increase the MCP after getting clearance to step climb, but for the purpose of leaving the flight unattended this will probably work.