StanP

A bunch of questions about the Queen

23 posts in this topic

 

12 hours ago, pcubine said:

On more than several occasions PFPX's recommended initial altitude has been above the maximum altitude of the airplane be it the NGX, 777, or 744. The PFPX step climbs in their OFP package are done earlier than what the FMC recommends. PFPX has a tendency to fly right below the maximum altitude rather than the optimum altitude. I have never paid any attention to PFPX's initial altitude or step climb schedule. Two members from the PFPX forum got into this issue back in January hot and heavy and them dropped it like a hot potato and disappeared into the woodwork. I can't even get them to reply to PMs anymore. I would go with the recommendations in the FMC. I trust PMDG more than FlightSimSoft.

Noted! 

Although a part of me wants to trust the planning software, since the FMC does not use winds in neighbouring levels to define the "recommended" altitude, like the 777 does. 

11 hours ago, Budbud said:

Hi,

Using the profiles from Flyprecisely, I found the initial cruise level to be pretty spot on.
For the climb steps, there may be some small discrepancies (without being completely off though) but I'm tempted to put that on the small discrepancies being expected winds aloft and experienced ones that I can notice when comparing the values throughout the flight.

In PFPX, I always select optimization=none.

Noted, thanks guys. 

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8 hours ago, StanP said:

Although a part of me wants to trust the planning software, since the FMC does not use winds in neighbouring levels to define the "recommended" altitude, like the 777 does. 

As far as I know both the 777 and 744 handle winds aloft at cruise in the same manner. What is the difference between the two FMCs.

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1 hour ago, pcubine said:

As far as I know both the 777 and 744 handle winds aloft at cruise in the same manner. What is the difference between the two FMCs.

744: 

OPT level based on GW / Cost index

MAX level based on GW 

 

777 

OPT level based on GW / Cost index

MAX level based on GW / Cost Index

RECMD level based on GW / Cost Index and winds aloft 

 

Or I am getting this wrong? 

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By the way, what was the "easter egg" feature which PMDG said they will not tell us until we guess it? Has it already been revealed?

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2 hours ago, StanP said:

777 

OPT level based on GW / Cost index

MAX level based on GW / Cost Index

RECMD level based on GW / Cost Index and winds aloft 

The 744 also has a recommended level. Press VNAV button. It is on Page 2 of 3. It will not appear on that page until performance data is entered. The way I do it is to set the cruise altitude 2000 feet below what PFPX shows as initial altitude. During the climb I change the initial cruise altitude if I set it to low.

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12 hours ago, StanP said:

FMC does not use winds in neighbouring levels

What do you mean by "neighboring levels"?

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8 hours ago, pcubine said:

The 744 also has a recommended level

I stand corrected. The 744 does not have a recommended level. I confused it with the optimum level. In both the 777 and 744 I base the cruise level and step climbs based upon what the optimum altitude is. I just started a 744 flight EDDP-KIAH. PFPX shows an initial cruise of FL320. The FMC indicated max altitude was FL322 and the optimum was FL300. So I started with an initial altitude of FL300. When the optimum reaches FL310 I will do a climb to FL320. Basically you spend half of the time below and half of the time above optimum altitude.

A word about winds aloft. When they are requested the winds are loaded for FL270, 290, 330, and 370. Since I am flying westbound and the winds are for east bound levels I change the levels to FL300, 320, 340, and 360 and request, load, and execute the winds ago.

 

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20 hours ago, pcubine said:

A word about winds aloft. When they are requested the winds are loaded for FL270, 290, 330, and 370. Since I am flying westbound and the winds are for east bound levels I change the levels to FL300, 320, 340, and 360 and request, load, and execute the winds ago.

I usually just do that anyway, using altitudes that I'm more likely to be at.

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