I note the CAA are consulting on raising the Transition Altitude to 18000ft in both the London and Scottish FIRs.
Does the LAA have a view on this and can anyone think of any potential problems?
Transition Altitude
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John Brady
- Posts: 284
- Joined: Tue Jan 08, 2008 8:39 pm
1. Having different TA's around the UK is stupid - it is quite difficult to sort out where you should be when flying at say 4000ft from a 3000 ft TA area into a 6000ft TA area. Can make a big difference when pressure is high or low. Apparently there are hundreds of different TAs throughout Europe.
2. When the Midlands TA went to 6000ft it introduced a problem for gliding in that when pressure was high and the weather good, the base of CAS (now an altitude not a FL) was closer to the ground and effectively took away their ability to gain energy. So gliding may not like this new move.
3. Looking at the major airfield TMAs, the first level off on a Standard Instrument Departure is always at an altitude (ie below the TA) not a FL to reduce the chance of a level bust if the crew forget to set 1013 after take-off. Airspace designers always assume that there will be a level segment at a stop altitude so the boundary of CAS has to be extended to cater for that and the appropriate protection distance even though aircraft are normally cleared to a higher level. This makes TMAs bigger than they need to be and with a 6000ft TA, the base of CAS is extended at 5000ft or lower because of that. Once the TA goes to a higher altitude, the stop altitudes can go up and the volume of CAS at lower levels can reduce. Airlines like that too as direct climbs reduce fuel consumption and get above 10,000ft quickly so speed can be increased reducing the cost of sector time and fuel consumption. We (the LAA) went through this with airspace designers during the last London TC North redesign proposal which in the end did not run. So for GA flying in class G airspace, a TA somewhere above 11,000ft is a good thing. Above that the actual number does not matter to us so whatever works for international air transport should be fine.
4. The Future Airspace Strategy work (ok wake up out there) expects to provide continuous climb to cruise where airspace complexity allows and having a really high TA is one of the keys to achieving that. Again, good for GA as continuous climbs and descents for airliners means less spread of CAS at lower levels
5. The 18,000 ft TA change is going to spread through Europe and it is good to see EASA/Eurocontrol not trying to invent a different number to that already in use in the USA and elsewhere. But they still have time.
If you have any comments or thoughts on this consultation please write them here and we will compile them in the LAA response.
John
2. When the Midlands TA went to 6000ft it introduced a problem for gliding in that when pressure was high and the weather good, the base of CAS (now an altitude not a FL) was closer to the ground and effectively took away their ability to gain energy. So gliding may not like this new move.
3. Looking at the major airfield TMAs, the first level off on a Standard Instrument Departure is always at an altitude (ie below the TA) not a FL to reduce the chance of a level bust if the crew forget to set 1013 after take-off. Airspace designers always assume that there will be a level segment at a stop altitude so the boundary of CAS has to be extended to cater for that and the appropriate protection distance even though aircraft are normally cleared to a higher level. This makes TMAs bigger than they need to be and with a 6000ft TA, the base of CAS is extended at 5000ft or lower because of that. Once the TA goes to a higher altitude, the stop altitudes can go up and the volume of CAS at lower levels can reduce. Airlines like that too as direct climbs reduce fuel consumption and get above 10,000ft quickly so speed can be increased reducing the cost of sector time and fuel consumption. We (the LAA) went through this with airspace designers during the last London TC North redesign proposal which in the end did not run. So for GA flying in class G airspace, a TA somewhere above 11,000ft is a good thing. Above that the actual number does not matter to us so whatever works for international air transport should be fine.
4. The Future Airspace Strategy work (ok wake up out there) expects to provide continuous climb to cruise where airspace complexity allows and having a really high TA is one of the keys to achieving that. Again, good for GA as continuous climbs and descents for airliners means less spread of CAS at lower levels
5. The 18,000 ft TA change is going to spread through Europe and it is good to see EASA/Eurocontrol not trying to invent a different number to that already in use in the USA and elsewhere. But they still have time.
If you have any comments or thoughts on this consultation please write them here and we will compile them in the LAA response.
John
Last edited by John Brady on Fri Feb 03, 2012 5:25 am, edited 1 time in total.
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Bill Scott
- Posts: 137
- Joined: Sat Mar 28, 2009 6:25 pm
John, thanks for explaining it to us mere mortals 
I think it would be a real safety improvement if we can have a higher, common TA. There is real potential for unwittingly infringing at times, perhaps more so when you don't have the luxury of a second altimeter.
To me, the biggest question revolves around just which QNH setting do you use at a given time? The sooner the whole thing gets simplified, the better.
I think it would be a real safety improvement if we can have a higher, common TA. There is real potential for unwittingly infringing at times, perhaps more so when you don't have the luxury of a second altimeter.
To me, the biggest question revolves around just which QNH setting do you use at a given time? The sooner the whole thing gets simplified, the better.