Why is the TL not given on UK ATIS

[mcdhu]

A question being kicked around the Airline currently is why the Transition Level is not given on UK ATISs? Is there anything in UK ATC Manuals that might provide an answer or is it simply seen as being unnecessary?

Cheers
mcdhu

[Diaz]

It's probably seen as unnecessary as ATC give an instruction to descend to altitude giving the QNH, so you change to the QNH once vacating the current FL or vacating the last FL ATC wanted you to report passing.

http://www.ead.eurocontrol.int/eadba...2010-02-11.pdf

Section 5.3 details this. Essentially, pilots don't need to know the transition level, so why add even more to the long ATIS messages

[5milesbaby]

Its written on all the SID & STAR charts in the top left corner.

[spekesoftly]

Originally Posted by 5milesbaby

Its written on all the SID & STAR charts in the top left corner.

That's the Transition Altitude (in the top left corner of SID charts).

The OP is asking about the TL (Transition Level).

[samotnik]

It's probably seen as unnecessary as ATC give an instruction to descend to altitude giving the QNH, so you change to the QNH once vacating the current FL or vacating the last FL ATC wanted you to report passing.

Oh, is it really done like this in the UK? In this case there may be aircraft in the same space, at the same level, that fly on 1013 in level flight and some that fly at some totally different QNH while descending. How do you achieve vertical separation in this case? The whole idea of the QNE/QNH story is that all aircraft below certain level fly on QNH, and all above a certain level use QNE.

[DFC]

To respond to the last post - if one aircraft is level and another is passing through it's level then I hope that something other than vertical separation is being provided.

I suspect that the original poster is one of the many that have SOPs requiring that the FMS is given the TA on the ay up and the TL on the way down so that among other things there will be a little reminder if the altimeters are not on standard when the TA has been passed and not on QNH when the TL has been passed.

This in general is a good idea as it is yet another posibility of preventing an incident / accident due to for example an altimeter remaining on STD when it should be on QNH.

However, one has to remember that the interpretation of the definition of Transition Level varies from place to place. Many places interpret the situation and provide a TL that is a minimum of 1000ft above the TA. i.e. an aircraft at the TL is always vertically separated from the TA.

Some places have fixed TA and TL.

The UK interprets the TL as being the lowest level above the TA as meaning there is no requirement for the TA and TL to be separated. Therefore it is possible that the TL could be only 1ft above the TA. Yes that was "one".

Therefore in the UK, feeding the TL into the FMS is not going to provide any safety benefit unless the cleared level on the way down is below the TA (in which case you may as well input the TA!!).

In the UK, many places where the holding is at flight levels will have a "minimum stack" level and this level will indeed be a minimum of 1000ft above the TA. Unfortunately while this level is also not on the ATIS, there is a nice table both in the AIP and in the MATS which will enable any crew to calculate what the firtst FL at least 1000ft above the TA is.

[5milesbaby]

Fair point spekesoftly, I had misread the question!!

However, take the transition altitude stated on the SID/STAR charts and then apply it to the table that can be found in the UK MATS Part 1: Appendix A (Pressure Setting Tables)
Available free here: http://www.caa.co.uk/docs/33/CAP493Part1.pdf

[samotnik]

To respond to the last post - if one aircraft is level and another is passing through it's level then I hope that something other than vertical separation is being provided.

In theory, yes. But there are moments, when things go wrong. Let's say you have to stop the descent for some reason, or the crew stopped it. Which altimeter setting should they have? I presume that until they are at or above min stack level they should still use QNE, but do the crew remember that they should change altimeter setting just because they stopped the descent? And how do you descend another aircraft above in case a low QNH? I had a tough evening yesterday, so correct me if I'm wrong, but in this case the aircraft may be indicating 10000 altitude, but it is in fact at FL110. If crew is supposed to change to QNH at TL, then this problem is experienced only in proximity of TL. If crew changes it immediately after receiving descent instruction below min stack level, then you must remember about it all the time!

In my FIR there is fixed TA and broadcasted TL which always provides at least 1000ft of transition layer, so your system looks quite odd for me. I can't think of any advantage of your system, while there do exist some problems that I pointed out above.

[HEATHROW DIRECTOR]

Just as an aside.... in 32 years working in UK ATC no pilot ever asked me what the TL was... and I estimate that I dealt with well over a million flights.

[Talkdownman]

Me neither in 43.
But I have been asked what the Transition Altitude is. Hardly surprising with such dangerous inconsistency of Transition Altitudes within UK airspace...at least one of which is not terrain-safe....

[ford cortina]

Samotnik, lets look at your theory.

If a aircraft is given a descent from FL170 to 8000 feet QNH 1005. Both pilots set QNH and announce it following whatever your company SOP's are.

For some reason they stop at 11000 feet on the QNH.
Now if they instigate this they will contact ATC and tell them that they have stopped at 11000 feet.

If ATC have stopped them they will tell them to stop at FL110 or 11000 feet.
Either way ATC will immediately be in the loop as will any other aircraft in the vicinity.

I have no idea what your company SOP's are about transitioning to and from flight levels, but the Three companies I have been in all have the same rule, When you are given your first flight level by ATC you set standard and when you are given your first Altitude you set QNH. I was also taught this when I did my IR.

This way you never have any problems and yes, I find this works all over Europe and even in non radar controlled Africa, which I have had the pleasure of flying in.
It is only a problem if you make it so.

[Cough]

at least one of which is not terrain-safe

Many airfields have TA's below the local MSA. Most of Northern Italy, Switzerland, parts of France. Its not a problem! Even when climbing above the TA, there will normally still be an altimeter set to QNH, so that MSA can be called when it is reached.

[Cartman's Twin]

I don't doubt that to be the case HD, but it's not really something the Approach / Tower unit would be asked. In the TMA we're probably asked for the TL about once a week, although normally by American crews. Tis no problem to find it as it's on the info display with Regional Pressure settings etc

[samotnik]

I have no idea what your company SOP's are about transitioning to and from flight levels, but the Three companies I have been in all have the same rule, When you are given your first flight level by ATC you set standard and when you are given your first Altitude you set QNH. I was also taught this when I did my IR.

This way you never have any problems and yes, I find this works all over Europe and even in non radar controlled Africa, which I have had the pleasure of flying in.
It is only a problem if you make it so.

In EPWW AIP it's cleary stated, that you should stick to QNE until passing transition level. Exactly as in ICAO doc 8168, with one exception - ICAO says, that when you are cleared for approach and in continous descent, you may switch to QNH immediately. I presume it's not common to be cleared for approach while flying well above TL... Is your SOP against ICAO rules?

But maybe in fact it's not so critical. We all know that the whole idea of flight levels was designed to simplify things during level flight. But anyway, does your company SOP have precedence over AIP of the FIR that you're currently flying in?

[mcdhu]

Thanks for all the replies.

It seems, therefore, that in UK we don't 'publish' the TL on the ATIS because our altimeter setting procedures make its knowledge irrelevant ie in descent, we set QNH when cleared to an altitude?

Cheers
mcdhu

[DFC]

samotnik,

The setting of altimeters is a critical operation and when done correctly in accordance with SOP will take time. Here is an example of what the SOP could be;

PF = Pilot Flying and PM = Pilot Monitoring

PF - "Set QNH 996" sets altimeter to 996
PM - sets altimeter to 996 and reports "QNH 996 set passing 6 thousand 1 hundred feet
PF - checked.

Now in the UK, at somewhere like Heathrow the transition altitude is 6000ft. If the QNH is 996 the transition level will (under UK rules) be FL65

So let's look at where they really are. The TA is 6000ft AMSL and (using 28ft per milibar) the TL is 6024ft AMSL.

Do you think that if the aircraft is cleared to descend to 6000ft QNH 996, the crew can wait until the transition level and carry out a safe SOP for setting altimeters as well as avoiding a level bust?

--------

mcdhu,

correct and as I say above, waiting until the TL to change over could be very dangerous.

[samotnik]

DFC, in case when transition layer is not provided to be at least 1000ft, you are perhaps right. In my FIR it's always at least 1000ft. I'm just against changing to QNH too early.

[PointMergeArrival]

It seems time has come to standardize this and do like the yanks.
There is a nordic initiative to have a common TA. They're looking at either 10.000 or 18.000ft. To me the lower seems futile as it would not be suffucient in the mountaineous areas of Europe.
And in my thinking how to determine the TL should also be common. If it is a "safe" 1000+ft or not is not important as both ways seem to work, but it should be done the same way everywhere to avoid confusion.

[fireflybob]

In close on 40 years of airline flying across a number of different airlines in different countries I have never needed to know the Transition Level! Ok some FMS have an input for this, I agree.

I find the inclusion of the TL on ATIS a blessed nuisance as it wastes time on what I consider to be irrelevant information!

[Z10]

TL/TA Norway

Even though the question was about TL in the UK, I feel the discussion did become a bit more general, and I therefore add some information about Norway;

Even though the pilot is given in a descend altitude at/below TA, the pilot shall not change altimeter setting to QNH before passing through the TL.
Same goes for departures, pilot shall remain on QNH untill passing TA climbing, even though he/she is cleared a flightlevel.

AIP Norway - ENR 1.7:

During climb to and when flying at the transition
altitude, the vertical position of the aircraft shall be
expressed in terms of altitudes.
After passing the transition altitude, aircraft during
climb shall change the altimeter setting to 1013.2
hPa, and thereafter the vertical position of the aircraft
shall be expressed in terms of flight levels.

Flights conducted at or above the transition level
shall express the vertical position of the aircraft in
terms of flight levels.

During descent, aircraft passing the transition level
shall change the altimeter setting to the current QNH
value for the aerodrome and thereafter express the
vertical position in terms of altitudes.

However, due to personal interest and my involvement in the Norwegian air traffic controllers association, I've discovered the following from the three main operators in Norway:

During descend;
- 2 operators set QNH upon receiving the QNH from the controller (and therefore a descend clearance below TA)
- 1 operator set QNH whenever they do their "descend-checklist", which might be in FL150, or FL100 or any level. (After receiving the QNH and a descend below TA from controller)

During climb;
- 2 operators set standard altimetersetting once they receive a clearance for a flightlevel,
- 1 operator fly on QNH until they climb through TA, or are above MSA (if higher) for the current airport, then changes to standard altimeter if received a clearance above TL

So one might wonder how this can happen, since their checklists are approved by the Norwegian CAA, and the same about the AIP..