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UK may be going for 18000ft transition altitude

The great benefit of raising the Transition Altitude in the UK is ridding ourselves of the plethora of altimeter settings which now prevail. If we could prise the RAF away from their addiction to QFE, there would be no need for a subscale change when crossing any MATZ and we would save communication time from those GA airfields which still insist on passing the QFE. The RPS should be consigned the same way as the signal square. The RPS was there to ensure terrain separation for aircraft flying IFR non radio. Nowadays there is no need to know the lowest forecast pressure in a given area over the next but one hour. (RPS is valid for an hour and available one hour in advance). Listening to ATIS or Volmet or indeed any local Approach control is all that is required. Of course there will still be an area QNH but at least it will be actual not forecast lowest and there is a better chance of everyone flying on the same one in a given area.

I agree with everything topoverhaul said above. Well said

Listening to ATIS or Volmet or indeed any local Approach control is all that is required. Of course there will still be an area QNH but at least it will be actual not forecast lowest and there is a better chance of everyone flying on the same one in a given area.

Just out of interest I checked eight automated airport altimeter settings in my area (on line with VFRMAP). Its a nice day here so one could assume that they should all be same. All eight of them were between 30.08 and 30.10 (both values would be 1019 hPa in those units). Assuming sources of aviation data are controlled, I see no particular issues with aircraft getting their altimeter data from anywhere independently available in the area.

If an uncontrolled field has no automated altimeter data, it can be obtained on approach from somewhere else nearby. That's how we do it anyway, resetting to field elevation before takeoff and occasionally along the way with some place's ASOS or ATIS. Then, even if somebody neglects to reset the altimeter to the ATIS value on approach to a controlled field, its still likely that everybody has an indicated altitude pretty close to their actual MSL altitude. From first principles, isn't that what an altimeter is for? And why should ATC personnel be involved in making sure our altimeters are kept accurate during flight? Keeping all of them indicating relative to sea level just requires real time access to altimeter data that wasn't feasible 70 years ago, but is today.

The great benefit of raising the Transition Altitude in the UK is ridding ourselves of the plethora of altimeter settings which now prevail.

You don't have to raise the TA to 18 000ft for that, just do it like your neighboring countries. TA in France is 3500ft and 5000ft in Germany usually. I find that to be the most practical setup. All my IFR flying is done with 1013hPa, no messing with altimeter settings before the approach. When flying VFR, FIS hands out regional QNHs when flying below 5000ft.

The UK system is totally weird and non standard but that's not because of the TA. The best way to set the TA is to choose the lowest level where IFR is common. In IFR your terrain clearance is 1000ft (2000ft mountainous) so plenty of margin for 1013 vs real QNH.

The best way to set the TA is to choose the lowest level where IFR is common

In the UK, the lowest level where IFR is common is 500ft (legally) and 0ft (otherwise).

That's because UK allows IFR in Class G. Germany doesn't.

The level at which "proper IFR" is possible in the UK is whatever Eurocontrol will accept the flight plan for (which is nowadays not restricted e.g. you could file a route right across the UK at 2000ft, busting all major airports on the way) AND the IFR controlling authority (London Control for much of the UK) will not chuck in the bin when they receive it from Eurocontrol (which basically means it has to be an obvious "airway" route, with the right MEAs, typically FL070 plus, but higher in some places e.g. Scotland. London Control won't accept a flight plan which lies "obviously" partly or wholly in Class G.

So that criterion won't work in the UK.

I don't see a problem with having a 18k (or some other high figure) TL, because for obstacle avoidance you have exactly the same issues with both altitude or flight level.

With altitude you need the QNH (unless you are "obviously well above" anything possible) and with a flight level you cannot do obstacle clearance at all (unless you are "obviously well above" anything possible).

The UK has had a horrid mixture of stuff like one piece of CAS with a 4500ft base and right next to it another piece with a FL045 base.

Administrator
Shoreham EGKA, United Kingdom

The UK has had a horrid mixture ...

Without any doubt. But by introducing US procedures as only country in Europe this horrid mixture will then become part of the European sky. Why not just do what everybody else in Europe is doing?

EDDS - Stuttgart

Raising the TA to 18000 feet does not make sense at all to me and makes everything more complicated, not simpler.

Take for example an aircraft flying at 10.000 feet on the QNH 1018. Another aircraft departed from elsewhere with the local QNH still set to 1016. Both will think they are flying at 10.000 feet, but are flying on different altimeter settings. So, you would still need to regularly get the regional QNH to fly that level properly. That simply does not work.

The reason we fly flightlevels is to not have to bother with setting the altimeter anymore and to all fly at one altimeter setting of 1013. Then, when 2 aircraft fly at FL100, they are flying at the same altitude, which might not be 10.000 feet on the QNH.

The only reason we are flying QNH below the flight levels is so that we can see our separation from obstacles and ground.

Also, the pressure can change rather quickly during flight, e.g. when passing a pressure/weather front.

EDLE, Netherlands

Indeed, nobody needs QNH for obstacle clearance nowadays. Every GPS uses black, yellow and red should you be below 1000ft AGL. When IFR in CAS, obstacle clearance is 1000ft on 1013hPa, that is enough.

Most European countries have CAS very low (class E). In Germany, E starts from where radio contact is possible (2500ft AGL or lower). The more class E the better because CAS means ATC/FIS are available. Of course class E means higher visibility requirements than G but that makes hardly a difference in real life.

So as part of Euro harmonization, the UK should finally start offering ATC/FIS at low altitudes (turn G to E).

Why does the relatively small country of Germany have a 'typical' TA of 5,000 ft with the Alps at its southern border?

Yes, GPS works. What would also work is what ATC does - having MSL altitude data calculated from encoder output plus local pressure data that could be continuously downloaded from available local sources, along with other weather data. That way you'd have two largely independent sources of altitude data, neither needing any knob twiddling as you go up and down.

I remain quite happy for now only to need to deal with one altimeter setting, and to have no exposure to the archaic TA concept. Unless the flight is long, I set the altimeter before takeoff and then reset with ATIS before landing, not touching the knob in between since TA is above the absolute ceiling of anything I fly, anywhere I fly.

Why does the relatively small country of Germany have a 'typical' TA of 5,000 ft with the Alps at its southern border?

Probably because the bit of the Alps that belongs to Germany is not that high (<10.000ft) and the few airways that actually cross the alpine territory from Germany have such high MEAs that there is plenty of safety margin with most pressures and temperatures. I know of no accident where an aircraft flew IFR into mountains due to flying at flight levels instead of altitude.

EDDS - Stuttgart
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