FMCs and transition altitudes

[Anthony Atkielski 985811]

How do you account for changes in transition altitudes on a FMC? On the PMDG FMCs that I have (737 and 747), there's only one spot that I can see for entry of a transition altitude, and while this works for take-off and climb, the FMC seems to "forget" the transition altitude and sets it back to 18000 thereafter in the flight, with no apparent way to change it. Any ideas on how to handle this? Also, is this the way the real FMCs work, or are they more flexible?

[Alan Sutherland]

I think that if you type in the transition altitude then select the key next to where it says transition altitude, it will change it.

 

Alan

[Bill Casey]

Once you've pressed the STD button it takes no notice of the FMCs TA anyway so on climbing through TA press STD and away you go. On the way back down you'll get descended to FLs initially then get an instruction to 'descend to altitude x,000ft QNH yyyy", hit the STD button again and adjust the QNH. The TA in the FMC doesn't really come into play at all so why worry about it?

 

Alan is correct for the FMC though, put the actual TA in the scratchpad then RSK next to the TA, it'll change it.

[Anthony Atkielski 985811]

It seems to automatically change back to 18000 at some later point, though.

 

I asked pilots in another venue and I was told that normally the FMC database contains transition altitudes for every airport. It looks like PMDG doesn't simulate this aspect of the FMC, though.

 

I do use the STD button to override the FMC, but it's not very elegant.

[Paul Byrne]

Hello,

 

This is how the PMDG 737 does it. Not sure about the 747. But it's Boeing FMC so the principle should be the same.

 

In the descent page, go to forcast. On the top left you'll see Transition Level. That's what you want. Set the TA for the departure airport in PERF INIT and the TL for the arrival airport in the forcast page.

 

Hope this helps.

 

Cheers!

Paul.

[Bill Casey]

It seems to automatically change back to 18000 at some later point, though.

 

On which FMC screen? I've never seen this happen in my 737 but we may well be looking at different pages. Let me know where you see it switch back to 18,000 and I'll check the same page later on today while flying it.

[Bill Casey]

It seems to automatically change back to 18000 at some later point, though.

 

On which FMC screen? I've never seen this happen in my 737 but we may well be looking at different pages. Let me know where you see it switch back to 18,000 and I'll check the same page later on today while flying it.

 

OK, you didn't bother replying to my kind offer but I checked anyway and no, it didn't revert to 18,000ft any time, any page. Hope this helps.

[Anthony Atkielski 985811]

I'll try the forecast thing, thanks.

 

I can never remember which page has the transition altitude, I think it's perf init, but I'm not in the cockpit right now. Anyway, setting that one alone doesn't seem to help, but I'll try the forecast page instead.

[Anthony Atkielski 985811]

I tried setting the transition level in the PMDG 747-400 on the DES FORECAST page, but it says INVALID ENTRY no matter what I do. Has anyone else got this to work? If so, what's the secret?

[Ivan Kovacevic 920456]

All you should write is "70" and nothing else. It always worked for me....

[Anthony Atkielski 985811]

Thanks, that did the trick! I saw five dashes so I figured it had to be some sort of five-character field, but 2-3 digits works just fine.

[Christopher Waldo 860237]

For a US guy, EU transition alt's are 7k correct?

[Ivan Kovacevic 920456]

Incorrect.

 

In UK, they are 5000 or 6000 if I remember well, in Belgrade FIR it's 10.000, in Amman FIR the transition altitude is 13000ft.

 

The TA and sometimes TL is written on the chart for every airport out there. Just consult the charts when you fly.

[Anthony Atkielski 985811]

How do you know the TA and TL between airports?

[Andreas Fuchs]

Exactly, in Europe the Transition Altitudes vary between 3,000ft and 16,000ft so you always need to check on the respective airport, SID, STAR or approach charts.

 

The TRL (Transition Level) is usually published on the ATIS (the chart will say "by ATC"), in some places the TRL is always the same and published in the charts together with the Transition Altitude.

 

The good thing of pilots being able to set the correct transition level/or altitude as well in the descent to the destination airport is that e.g. the Honewell FMZ will come up with a warning "CHECK BARO" if you descend through the TRL with 1013/29.92 set and thus may catch your failure to adjust your altimeters to QNH/local altimeter setting.