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Konterhalbe

747 LR flights without being at the PC

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Gents,

 

You're trying to outsmart the code here and in the process waaaaay overthinking it...

 

Think of it this way:

 

The auto functions are "you." When you are flying, you wouldn't set the MCP altitude anywhere other than your cruise FL when you're established at cruise. When you set auto cruise, you're telling the computer "you are now me - function as me." When you, personally, would go to step climb, you would manually roll the wheel up from current cruise to new cruise and then allow the plane to climb. The auto cruise function does the same thing, but in order to make sure it doesn't do all kinds of weird stuff, we programmed it with the (reasonable) assumption that you would behave like a normal crew would and have the cruise alt at the current cruise alt.

 

Literally treat the aircraft exactly as you would if you were to hand the plane over to the relief crew while you hit the bunk. "Hey, I know we'll be at FL370 by the time I'm done with my bunk time, so I left the MCP alt 4000 above current" said no crew handing an aircraft off, ever. :wink:

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Kyle Rodgers

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Ref. the posts above with auto step descend.

 

My experience so far is that the auto step function does not handle step descends. It poses a problem when for instance transiting between Russia, Mongolia and China where you sometimes may be to heavy to go to next level (in e.g. Mongolia or China) so you rather want to descend less than 1,000 feet to find a more appropriate level there (or optimal winds if more favourable winds at lower altitudes).

 

As this is an artificial function the auto step funcion should go both ways so I hope this will be included in a future update please.

 

In addition I experienced a situation where the auto step function did not make the subsequent step climb after I manually had descended the aircraft (probably as mentioned above the a different altitude disables the function). On PERF page I had 2000 as step value but I suppose that should not be an issue(?). Should I encounter this issue again I will submit a ticket.

Søren Geertsen


Søren Geertsen

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If I understand well (as described in the manual), it's NOT a real feature, it's just a PMDG feature, an invisible hand that dials the MCP altitude for you while you are away from the computer...

That's my understanding as well. Sort of a "virtual first officer" who handles the MCP (and tank-to-engine switchover) during auto cruise.


Jim Barrett

Licensed Airframe & Powerplant Mechanic, Avionics, Electrical & Air Data Systems Specialist. Qualified on: Falcon 900, CRJ-200, Dornier 328-100, Hawker 850XP and 1000, Lear 35, 45, 55 and 60, Gulfstream IV and 550, Embraer 135, Beech Premiere and 400A, MD-80.

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Søren,

 

If you descended, you needed to reset your cruise altitude on the cruise page of the FMC. Since the function did not work, I'm assuming that you did not accomplish this extremely important step. Your current cruise altitude needs to match your current flown altitude, and the altitude in the MCP.

 

As I've mentioned before, step descents are such a corner case that I don't think we'd go back and alter a function to accommodate that. It could open up a Pandora's box that I think is best left closed (think about it: not even the FMC will accept a negative step value - even Boeing and other aircraft manufacturers accept this as a manual override of normal logic).


Kyle Rodgers

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Kyle,

 

You are probably right - that is why I would like to test it again - there is usually a good explanation to it. ;-)

 

- and it may be that other issues will arise with allowing step descend in the logic; however, I guess that a simple function should allow you to do  FL 310, 330, 350 370, 364, 361, 381. The test should simply be that Crz page FL is identical to Legs page FL which is identical with MCP altitude from the outset. When a step climb/descend comes up the system changes both MCP and Crz page to the new value which should be identical to subsequent Flight Level on your Legs pages and the plane performs the climb or descend and so on.

 

If you do not mess with these pages - and why should you if you are not at the controls - then I suppose that it would be doable and that should be an acceptable solution. In any case I do hope that you would consider such a function for a future update.

 

Søren Geertsen


Søren Geertsen

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Søren,

 

You're welcome to submit a ticket and recommend it, but I really don't see it happening. It's a niche issue, in a very specific segment of airspace, and the FMC itself doesn't even handle what you're asking to do without pilot intervention to manually override the default FMC functions (steps are always assumed to be positive, based on the PERF INIT or CRZ page step size, and so on - our auto step interacts heavily with the default logic of the FMC).


Kyle Rodgers

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Thanks Kyle, I will consider submitting a ticket.

 

You are absolutely right. Step climbs are assumed to be positive but in the real world step descends do happen and are entered into the Legs pages. Especially as most western bound (US - China flights and Europe - Asia flights go through this region).

 

So this suggestion is purely based on having the automatic (!) relief pilot to do the manual override of the FMC - and I appreciate that it may interfere with the logic that you have based the auto step function. Hence my suggestion of a simplified logic.

 

However, it would just be another of those really nice features to have and use in your impressive 747! :-)

 

Søren Geertsen


Søren Geertsen

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My last couple of trips into metric altitudes was very easily accomplished without the need for any auto step feature.  I don't understand the logic used, the difference is usually just 100 feet such as FL311 instead of FL310 and when I depart the metric altitude all I do is enter 310S on the LEGS page at the waypoint I want to step down and she does exactly as asked.  Keep it simple.


Dan Downs KCRP

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On 21/2/2017 at 2:45 PM, jgoggi said:

Sorry, just read page 0.00.99 of PMDG_747_Introduction.pdf:

 

"PAGE 6/10 AUTO STEP CLIMBS: Automatically increase the MCP altitude at step climb points and climb to the new altitude. Useful if you are flying long haul while not at your computer."

It should read:

"PAGE 6/10 AUTO STEP CLIMBS: Automatically increases the MCP altitude at step climb points and climbs to the new altitude. Useful if you are flying long haul while not at your computer."

Without the s's it indicates that YOU do it ;-)


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14 minutes ago, Kyprianos Biris said:

It should read:

"PAGE 6/10 AUTO STEP CLIMBS: Automatically increases the MCP altitude at step climb points and climbs to the new altitude. Useful if you are flying long haul while not at your computer."

Without the s's it indicates that YOU do it ;-)

Typo, sure. The claim that it implies that the operator does is contradicts the entire point of the function, so...no.


Kyle Rodgers

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