Altimeter Setting, Transition

[scud]

Hello,

This question is for anybody other than North Americans (no discrimination intended).

You're outside North America, and you're cruising at FL260, approaching your destination airport, and you're talking to Terminal control.

The controller says that "you're cleared to descend to 6000 feet, QNH 1015".

Published transition is FL090.

Do you reset your altimeter to QNH:

1. As you're reaching the transition layer, or

2. As you're leaving your cruise altitude of FL260?

For anyone answering 2, is there anything specifically in the applicable country's AIP or in your company's flight operations manual that prescribes this?

Thanks,

Scud

[GoneWest]

Scud...I don't qualify to answer your question...but...

...forgive the pedantics (but we are all here to learn??)...controller should say "you're cleared to descend to altitude 6000 feet, QNH 1015"....and...you can't have a cruise altitude that is a flight level. It would be a cruise level

<<edit for rogue typo>>

[Agent86]

I would say set the QNH at transition. In that way if the controller asks "Report passing F200" you would give a REAL report ...Esp if the QNH differs from 1013 markedly.

ops wise I set QNH on the standy alt once assigned an ALT vs FL and then set all alts to QNH at transition ( or a few 1000 above if you get busy on MBZ/Area/HF/..... :( )

MAx

[scud]

GoneWest,

6000 feet would not normally be a cruise level because it is below, in this case, to the published transition layer.

Scud

[Offchocks]

Scud if you are cleared to an altitude in a country that has a published transition level, then you set QNH at or just before transition level.
It has been a while since I have operated into a country with "transition level by ATC" stated on the chart, however in this case I believe that if you are cleared an altitude from a flight level you then set the QNH on starting descent.
The information for altimetry in your country would be in its AIP (ours is). I know that for the UK this information is also in the Jeppesen ATC section.

[Checkboard]

In Australia, at least, the AIP states that you set the QNH at the transition level on descent. Not so much for the "report passing", but more for a sudden clearance to maintain a level during the descent for unexpected traffic.

The Ansett procedure was to set QNH at the transition checks, which were typically after passing F150 (transition is a standard F110 throughout Australia). Descending at 5-6000 fpm in a jet, the difference was minor.

[scud]

Offchocks,

You've provided a very important factor: "Transition Level by ATC". A brief review of European approaches indicates that for descents/STAR's and approaches, all transition levels are "As assigned". This includes:

Schiphol, Dublin, Frankfurt, Glasgow, London LHR, Madrid, Manchester, Milan, Munich, Paris, Rome, Shannon, Zurich.

All SID's/departure have a transition altitude.

Oddly enough, Tel Aviv is opposite: Transition Level is specified on the STAR (F115) and approach plates, whereas transition altitudes are "As assigned" for all SID's except for DEENA, PURLA and SOLIN (10500 feet). Can someone confirm this? I'm not using Jeppesen. Larnaca, just next door, is like Europe above.

I found a reference to your statement:

"if you are cleared an altitude from a flight level you then set the QNH on starting descent"

in case of a transition level assigned by ATC;

and this would have been taken from the UK AIP. References that I have to other European AIP's seems conflicting, although all European airports above have transition levels assigned by ATC.

Can anyone who is familiar with other European AIP's confirm that the quote above applies equally to the other European airports mentionned above?

The ICAO PANS-RAC, in the section about altimeter setting procedures, doesn't refer to this specifically. Only when a turbine aircraft has been cleared for an approach when still above the transition level, can it refer it's altitude to QNH. Does anyone know of another ICAO reference that alludes to the situation above?

Thanks,

Scud

[Max Angle]

It seems to me that the only really important thing is to make sure you have the correct setting when you LEVEL OFF. The best way to do that is to set both main altimeters to QNH/FL when you are cleared to that altitude/level. If a report or reference of the previous setting is needed use the standby altimeter.

The published or assigned trans. alt or level is really an ATC tool to allow correct separation between traffic operating on QNH and FL's. At airfields that have assigned trans. levels the lowest allocated flight level varies with the pressure and ensures that there is always at least a 1000' between the highest allocated altitude and the lowest allocated level.

[Bally Heck]

If you don't set QNH as soon as you are cleared to an altitude, then you are going to regularly bust that altitude.

[scud]

Max Angle,

Yes, I agree with you. What you describle makes most sense, it's the easiest to apply, and to me, it's the safest. In fact, that's what I used to apply in a previous life. However, in the context of working in a large organisation, you can't go around half cocked doing your own thing. It's important that everyone do the same thing at the same time. That's what I'm getting at.

So I'm trying to find out what Europeans do in Europe in this regard, and based on documented State procedures and regulations.

Just wondering.... In the context of EU and Eurocontrol, have the individual State AIP's and ATS procedures been amalgamated into unified EU documents? If so, then I would expect that there would not be any difference between various European states on this issue.

Scud

[Offchocks]

Scud I operated into all those places you mentioned (and more) for about 12yrs but can't remember being cleared to an altitude from a cruise level. (note I am talking about jet cruise levels)
A clearance would normally be to a low intermediate flight level (say Fl120) followed at a later stage with a clearance down to an altitude, the latter is when QNH was set. Never had problems with busting altitudes with this procedure.
Now if you are really keen, your airlines NAV department may well have the AIPs for the places you go to!!!;)

[scud]

Offchocks,

I used F260 to illustrate a point. It's still possible to be cleared from this jet cruise level to an altitude during low activity quiet hours, where the ATC sectors tend to be large in volume. But there's no real difference to my point whether it's from F120 or F260. In fact, I was cleared from 260 to 6000 feet recently, but the place had a transition level, and the local rules do say that you go to QNH approaching transition level (this was not in NA). But that's besides the point. What do locals do in Europe, within the context of European State procedures and regulations?

Thanks,

Scud

[Offchocks]

Scud I actually worked in Europe for those years with a local airline and that was the procedure then.
Now different airlines/countries may have different procedures and since it has been 15yrs since I've worked over there, things may have changed. Good luck with your inquiry.

[DeltaTango]

True, the controler should say "altittude" when referring to a hight UNDER the transition layer.
A transition layer is a transition layer so you must stay at 1013/29.92 above it and change to the region QNH as you cross it.
Logic behind it:
Say there is a big difference between QNH and QNE and the controller stopes your descent atFL100, you will have to chenge back to QNE(29.92) and you might forget it aswell and this is no orderly way to conduct a flight.

hope my answer makes any sense.

DT

[GoneWest]

Scud - and Delta Tango...

Despite knowing the answer for once (not usual for me :( ) I was not authorised to play with this one...however, there is a thread running on ATC about pilot R/T phraseology...and this thread is about non-USA altimeter settings....

The point I was trying to make was that there are three distinct phrases to be used for the various altimeter settings - height, altitude and flight level.

Irrespective of the "vertical distance of the aircraft above the Earths surface", you cannot have a cruise altitude which is refered to as a flight level (Option 2 in Scuds original post.)

When cleared from FL260 to a vertical distance using a QNH (as per the example) it should be "descend to altitude 6000 feet, QNH 1015.

...and' likewise, if in D.T.'s example of being cleared to a "height UNDER the transition layer", the word altitude should not be used - the word height, should.

[Duke of Burgundy]

Hello scud - The position in the UK is that when an aircraft is descended from a Flight Level to an Altitude preparatory to commencing an approach for landing, ATC will pass the appropriate aerodrome QNH.

On vacating the Flight Level, the pilot will change to the aerodrome QNH unless further Flight Level vacating reports have been requested by ATC, in which case, the QNH will be set following the final Flight Level vacating report.

Similarly, when cleared to climb from an Altitude to a Flight Level vertical position is referred to in terms of Flight Level unless intermediate altitude reports have been requested by ATC.

The latter procedure was introduced a few years ago in an attempt to reduce the number of level busts caused when pilots forgot to change to the Standard Pressure Setting on
passing the Transition Altitude for reasons of workload, distraction etc. the trigger for changing to Standard Pressure now being the clearance to climb to a Flight Level.

In my sphere of operations which is one of the London Airports the Transition Level does not have much relevance so it is not routinely promulgated, but I cannot speak for other locations.

Hope this helps ;) ;)

[BEagle]

D of B - that's certainly what I teach!

If ATC clear you to "Descend altitude 5000 ft" from FL wotever and subsequently ask you to advise passing FL something else, that request should be made with sufficient time for you routinely to reset SPS; surely they should assume that you have already set QNH in accordance with your clearance?

Similarly Transition Level is surely the latest point at which QNH should be set during descent, not the defining point?

[M.Mouse]

Deltatango

Sorry to be pedantic but from:

http://www.kloth.net/informations/qcodes.htm

QNE - What indication will my altimeter give on landing at ... (place) at ... hours, my sub-scale being set to 1013.2 millibars (29.92 inches)?

[scud]

DeltaTango,

In the case of Israel, a transition level is specified for descent, so yes, you should go to QNH when approaching the transition layer.

However, many SID's out of Tel Aviv have assigned transition altitudes. This would mean to me that if you're at 3000 feet, and the controller clears you to climb to FL260, then you would immediately reset your altimeter to QNE. Otherwise, the controller would have to tell you where the transition altitude is, and I've never heard this before.

What you are saying is right, you may be recleared to a flight level after being cleared to a lower altitude, and you would have to reset your altimeter to QNE again. However, IMO, that's no big deal, since you're cued to do it. As others have pointed out, there is often no cue as to when to reset your altimeter at a specified transition layer, especially in areas there the transition layer varies from airport to airport; chances are that you'll forget to do so. What's more, the transition layer may be below the 10000 ft/In range checklist. You may not discover that you forgot to reset to QNH until quite low, depending on your company SOP's. There is risk here of CFIT, or at least an altitude bust.

I'm pretty certain now that in the UK, altimeters are reset immediately to QNH upon being cleared to descend from a flight level to an altitude, and it would appear that the UK AIP specifies this. What about the rest of Europe?

Scud

[Spitoon]

The D of B is quite correct.

As far as the UK is concerned it's clear and described in the AIP (http://www.ais.org.uk/uk_aip/pdf/enr/20107.pdf).

[fireflybob]

It's a very good question and I researched same many years ago!

Things might have changed since but the UK AIP used to say that you set the QNH immediately unless "further flight level reports were required" ie cleared altitude 2,500 QNH 1015, advise passing FL 50.

The ICAO PanOps said that the QNH should be set straightaway unless level flight above the TL was anticipated.

From a terrain point of view (esp if pressure less than 1013) set QNH asap but bear in mind ATC might want the FL passing reports.