Hi Captainscan you please verify this:Default Transition Altitude is not saved / loaded when set in FMC/MENU/SETUP/ Save StatesI prepared my aircraft for COLD and DARK also setting the Default Transition Altitude to 5000ft.When loading its back to 18000ft, rest of the setup is fine.I remember this working prior SP1B.I am not in front of my NGX right now, but there's two entries for the Default TA, one for departure and arrival, if i recall that correct.Why?Oliver Kohl

Departue TA can be different from the arrival one. Simple as that...

Hi Captainscan you please verify this:Default Transition Altitude is not saved / loaded when set in FMC/MENU/SETUP/ Save StatesI prepared my aircraft for COLD and DARK also setting the Default Transition Altitude to 5000ft.When loading its back to 18000ft, rest of the setup is fine.I remember this working prior SP1B.I am not in front of my NGX right now, but there's two entries for the Default TA, one for departure and arrival, if i recall that correct.Why?Oliver Kohl

I have the same issue Oliver. And I think mine was also working pre SP1b... I have not been able to find a solution though, and since the problem is not very big, I've decided to let it rest... But let us know if you find a solution!Mas

Departue TA can be different from the arrival one. Simple as that...

There was never a doubt about that, question was, why is there only one option to define a default one and why it is not saved with panel statesOliver

I have the same issue Oliver. And I think mine was also working pre SP1b... I have not been able to find a solution though, and since the problem is not very big, I've decided to let it rest... But let us know if you find a solution!Mas

So it is a open bug, thanks for the confirmation.I was wondering why it was not mentioned here so far ;-)Oliver

Edited January 6, 201214 yr by JetNoise

Departue TA can be different from the arrival one. Simple as that...

TA is not as useful as the Transition Level(TRL) when arriving. So when you go to DES page - Forecast, then you insert the TRL for arriving airport, which is given by ATC, as it depends on the barometric situations of the day (in Europe at least). I find it to be one of the hardest things to explain, but here goes:Transition Level is the lowest FLIGHTLEVEL on standard altimeter/QNH (2992/1013) in the controlled area and is given by ATC.So in other words, when above the TRL your height above the sealevel is a FLIGHTLEVEL and is messured on the standard altimeter/QNH setting (2992/1013). When continuing descent below the TRL, height above sealevel is now an ALTITUDE messured in FEET on a local altimeter/QNH setting... Passing TRL means setting local altimeter/QNH.And vice/versa climbing: Passing the TA, means that you go from height messured in altitude on local altimeter setting, to FL messured on standard altimeter setting. Passing TA means setting standard altimeter/QNH.I could ramble on like this for hours, but I'll spare you ;)Mas

Mas,There is no way in explaining it better ;-)Oliver

Nice to know ;)... I remember studiyng for controller exam at IVAO in my younger days, that I had some difficulty getting this one into my head. So now that I know how to explain it, I never pass an oppertunity to bragg about my knowledge - haha!Mas

If you want to calculate the transition level (TL) yourself it's a bit of calculation but no rocket science. As Mas said it's dependent of the barometric pressure at the arrival aerodrome and the transition altitude (TA) at that aerodrome. The TA doesn't change with pressure so it's always the same for respective aerodrome.Now, between the TA and the TL you have the transition layer. This layer is 0-499 ft depending on pressure, and the 0-499ft is above the TA. So TA+"0-499 ft" gives you the TL.And here is where the calculation part gets in, to calculate how 'thick' the transition layer is going to be.As I'm from Sweden I'll do an example using hectopascal.I'll take Stockholm-Arlanda (ESSA) as an example and calculate the TL.Todays QNH is 998 hPa.ESSA has a TA of 5000 ft.First we need to calculate how much the difference in height between the local QNH and the standard setting (1013 hPa). Each hPa is equivalent to 30 feet. That gives us:1013-998=1515*30= 450 ft.Since pressure drops with height, 998 hPa must be above 1013 hPa.So then we can say an altitude of 5000 ft on QNH 998 hPa is the same as 5450 ft on QNH 1013 hPa.As you know QNH 1013 hPa is the standard setting and the one used when flying on flight levels (Actually the standard setting is 1013.25 hPa but this small difference we can neglect when calculating).If we would rephrase those 5450 feet, we could say FL54.5. But that is not a valid flight level and the next one above is FL55 so we add 50 feet.And there you have your transition level, FL55.The transition layer is 50 feet because of those 50 feet we added in the end.The result with TA 5000 ft, QNH 998:Transiton level (TL): FL55Transition layer: 50 feetI've attached a little drawing to try and get a better grip of it all.I remember back when I was studding at the ATC academy and we did these kind of calculations. You can get screwed up quickly if you don't make a drawing of it all. Luckily the teacher said that we are not trusted to do these calculations in real life because it's easy to get a number wrong if you don't pay attention. And today when I work I just look at the radar screen to see what the TL is. :smile:With that said; Sorry, I know it wasn't what the topic was about but I felt that I wanted to continue spinning on Mas reply.Now I only hope I didn't screw up when calculating the example.

Edited January 6, 201214 yr by Hillblom86

Excellent explanation Stefan!I remember trying to understand this - how to dertermine the TL based on baro, but I must admit never quiti understand the behind maths, based on IVAO's "self-study-documents" - I do now - thx!Mas

... Now, between the TA and the TL you have the transition layer. This layer is 0-499 ft ...

Stefan...I came to wonder the other day, that in f.ex. EHAM, the TRL is often FL045, and the TA is always 3000'.This means that the transition Layer is 1500'? Did I misunderstand something in regards to what defines the TL?Mas

Edited January 8, 201214 yr by mas618

Mas, not really. Since TA 3000 ft is based on local QNH and TRL FL045 is based on std QNH, 1013 hPa. You have to look what the difference in height between the two pressures are.If we as an example take QNH 972. The difference is 41 hPa. That is equivalent to 1230 ft (41*30). 972 hPa is above 1013 so we have to add 1230 ft to 3000 ft to get what flight level correlates with 3000 ft on QNH 972. FL042.3 is as we know not valid and the next above is FL045. And then the transition layer is 270 ft.If we instead take a higher QNH, for instance 1035 hPa the TRL will be totally different.Since the local QNH now is below the std. QNH (remember pressure drops with altitude) it gets the other way around. We won't add the difference but subtract it.1035-1013=2222*30=660 ft.This makes a TA of 3000 ft the same as FL023.4 since we have subtracted 660 ft from 3000 ft. And the next valid flight level above is FL025. Transition layer is 160 ft.There is a table at http://en.wikipedia....ki/Flight_level where you can see the different TRL for any given hPa.Of course there can be national differences. On the link above I noticed some aerodromes in Norway require a larger transition layer because of the mountainous terrain.I can do a sketch for the two different examples if you want. :smile:My bet for why FL045 often is the TRL at EHAM is because you've checked during autumn and winter when we experience a lot of low pressures in central and northern Europe.

Edited January 8, 201214 yr by Hillblom86

Mas, not really. Since TA 3000 ft is based on local QNH and TRL FL045 is based on std QNH, 1013 hPa. You have to look what the difference in height between the two pressures are.If we as an example take QNH 972. The difference is 41 hPa. That is equivalent to 1230 ft (41*30). 972 hPa is above 1013 so we have to add 1230 ft to 3000 ft to get what flight level correlates with 3000 ft on QNH 972. FL042.3 is as we know not valid and the next above is FL045. And then the transition layer is 270 ft.If we instead take a higher QNH, for instance 1035 hPa the TRL will be totally different.Since the local QNH now is below the std. QNH (remember pressure drops with altitude) it gets the other way around. We won't add the difference but subtract it.1035-1013=2222*30=660 ft.This makes a TA of 3000 ft the same as FL023.4 since we have subtracted 660 ft from 3000 ft. And the next valid flight level above is FL025. Transition layer is 160 ft.There is a table at http://en.wikipedia....ki/Flight_level where you can see the different TRL for any given hPa.Of course there can be national differences. On the link above I noticed some aerodromes in Norway require a larger transition layer because of the mountainous terrain.I can do a sketch for the two different examples if you want. :smile:My bet for why FL045 often is the TRL at EHAM is because you've checked during autumn and winter when we experience a lot of low pressures in central and northern Europe.

Ah - Ok - now I see the point... When I thought there was a transition layer of 1500ft, it was merely a nomianl value of numbers, rather than acutal height ;) Thx Stefan for clearing that up...So just to get i right: -besides from Norway (and I guess other mountain-heavy areas?), a transition layer (by definition that is) cannot exceed a vertical volume of more than 500ft? Correct?Mas

Hi Oliver,I have the same problem, worked fine prior SB1b. Default Transition Altitude in New Zealand is 13000 but this always turns back ot 18000 even after being saved in the FMC. This has to be a bug.

I'm absolutely no expert on how it is in other countries. I can only speak for how it is in Sweden. But according to the wiki link, Norway is the only country that add an additional 1000ft to the transition layer.I'm guessing that apart from Norway and also New Zealand and North America which has a fixed TRL, the TRL is 0-499 ft above TA.

Edited January 8, 201214 yr by Hillblom86

Good enough for me;) Thx Stefan!Mas