View Full Version : I think this is a dumb procedure

13th Jul 2004, 03:40
My company has a procedure where by when cleared for climb to a flight level we set alt's to std even well below the transition level or on decent we set dest qnh when way above transition. no one in the company can tell me why we do it. my frustration arises when cleared to an alt on decent with a low/high qnh then atc ask us to report passing flight level - pnf has to do mental conversion before being able to respond.

does any other company have to do this

13th Jul 2004, 03:58
Our Altimeter procedures are as follows

Climb to FL - PF sets STANDARD, PNF stays with QNH until passing trans altitude

Descent to Altitude - PF sets QNH, PNF keeps STANDARD until passing TL

So, all passing FL /ALT are readable easily.


13th Jul 2004, 07:48
This procedure is a standard by now in all Europe,at least.
If the controller will tell you to descent at ,for ex. 4000' ,with TL at 60 ,when you are at FL 150,you should set QNH,no matter what TL is.
Then if he asks you what level are you passing,just tell him your altitude -8500' for ex.He just wants to verify his transpoder indication on the screen.
The only problem is if the ATC want's you to mantain FL 90 for ex.Then you should reset Standard and hold at FL indicated.
Brgds Alex

13th Jul 2004, 08:03
Slightly off the point of the question - why is it not possible in Europe to have a standard transition altitude of say 18,000 ft?

13th Jul 2004, 08:08
it is under discussion right now,it will be soon.Maybe not 180,probably 100 or 150

13th Jul 2004, 09:54
Slightly off topic, but I suppose an additional benefit of a TL above FL100 would be to reduce level busts where crews inadvertantly muddle FL100 and FL110.

Bail out
13th Jul 2004, 10:07
Climb - " Cleared to FL --- " PF and PNF set Altimeters to STD
Leaving the stanby on QNH for reference.

Descent " Cleared ALT ---- " PF and PNF set Altimeters to QNH
Leaving the stanby on STD for ref.

Its been a very long night so I hope this makes sense...

13th Jul 2004, 14:28
FatEric is right , the procedure is dumb!
My company [and as far as I know ALL companies in this half of the world] changes the altimiters AT transition! [that is why it is called "transition" ] This means that here in oz we both change from QNH to STD/1013.2 @ 10000' on climb and from 1013.2/STD to QNH @ FL110 on descent [in the states we change @18000' on climb and FL180 on descent] - in Europe we change on descent to QNH when told ["desc to 7000' on QNH 1008" etc]:D
Why make it more complicated?

763 jock
13th Jul 2004, 15:21
We set 1013 when cleared to a FL and QNH when cleared to and altitude. Both main altimeters are set together and the STBY can be used for "passing" reports to ATC if required.
The danger of waiting until passing transition is that it gets missed (distracted by someting else perhaps?). Take BHX Sids as an example. Transition altitude of 4000' and a SID block of FL60. QNH is 980 so you "wind on" about 990 when you pass 4000', hence you have 1000' to go when you may have thought 2000' to go.

Also bear in mind that it depends on how your aircraft works. Your SOP's should take into account that perhaps the Right Autopilot gets it's data from the Right ADC. The other A/P's might get their data from the Left ADC. No good having the R A/P engaged if the R altimeter is not set appropriately!

The more you dig, the more complicated it gets.:{

13th Jul 2004, 17:55
We had a combination of the methods above:
- when climbing to FL we set 1013 at trans alt.
- when descending we changed to QNH upon getting the first descent clearance below the TL.

Recently there was a change in the SOP and we are now required to change at TL, EXCEPT when we've been cleared for approach earlier - then may change to QNH above TL. Simple, isn't it? :}

I was told (and even checked it, but don't remember now), the change in the SOP followed changes in the ICAO DOC 4444. I don't have it at home now, but I think that's wher you can find "the truth" :8


CJ Driver
14th Jul 2004, 00:12
We operate pretty much as Bail Out says:

Climb - " Cleared to FL --- " PF and PNF set Altimeters to STD
leaving the standby on QNH for reference (until terrain separation is assured, then it goes to STD as well).

On Descent " Cleared ALT ---- " we set all three altimeters (PF, PNF and standby) to QNH.

This appears to be pretty much the procedure that Fat Eric is complaining about , but it looks fine to me.

It always baffles me when pilots get exercised over where the transition level/alt is. Why do you care? The concept of transition level is an abstraction for the benefit of ATC in managing separation, and - other than the change of wording for the altitude clearances - is of little interest to pilots. So, if ATC wants to clear me to 37,500 feet on the QNH, that's what I'll fly. If they clear me to FL023, I can do that too.

Of course, any time that I am responsible for terrain separation - like flying an approach - I'm always going to use QNH, but that's a different story.

14th Jul 2004, 03:38
Actually, I am not complaining. I dont particularly care which way its done - I was just trying to gauge what others do.

I still think its dumb. Our company SOP's do not involve using the SBY alt set differently to the main alts. Therefore, when descending to 3000 for example, when still passing 20000 and ATC ask you "passing FL", the pnf is required to do mental maths to figure what our FL actually is. Unless you just read the alt in which case you are passing on incorrect info to atc - once again if atc is fine with that then i dont care.

also, in OZ, the AIP clearly states - "when passing the TL, set qnh ....."etc. Is this similar to the wording in other countries.

Also, as someone stated, what happens when atc revise the alt/lvl you have been cleared to. the crew is then is required to reset the altimeters at a rather inconvenient point and could easily miss the required change - especially considering that this last minute change by atc is often with min traffic separation(this has occured to me numerous times in asia)

I fly in asia where the tl/ta is high and no one in my company can explain why we do it.

14th Jul 2004, 10:38
When told to got to a FL our company changes to STD, however the SBY ALT remains on QNH until through FL100 on the way up. The reverse happens on the way down. So you have visibility of both FL and ALT. The problem as already mentioned, on a low day out of BHX, with trans ALT at 4000ft and block FL of FL60, you need to go over as soon as cleared else you will bust. And the issue with this is that this part of airspace to the south of BHX would be one of the busiest in Europe, so you cant afford to mess around. True a transition level of 10,000ft may be suitable, but when you have significant terrain at many destinations, and also with a higher ATC work load It is much easier for a controller to say climb FL70 than seven thousand on QNH, especially if the QNH is changing rapidly which happens in the UK and you pass through 6 zones before crossing the channel. In Australia where you efectively have two area controlers outside of the TMA, ie MEL and BNE, it is much simpler. Imagine trying to handover in london to state ALT and QNH. Its hard enough to get a word in now. For the moment, I can handle setting STD and monitoring ALT on the SBY.

Captain Airclues
14th Jul 2004, 12:05

This has been discussed before here (www.pprune.org/forums/showthread.php?s=&threadid=56742) and here (www.pprune.org/forums/showthread.php?s=&threadid=89867)


14th Jul 2004, 18:12

When you are climbing you use the "Transition Altitude", not Level as your first post indicates. "Transition Level" is used on the way down. This "dumb procedure" will probably save you from altitude busts when the QNH is lower than standard. Not so dumb in my book.;)

17th Jul 2004, 12:25
Fateric + Tankengine

LEM, you know better than this.

I'll tell you why you must set 1013 as soon as cleared to a FL, and QNH as soon as cleared to an altitude: in not doing so, you create a disagreement between two values, the figure set in the altitude selector and your alimeter setting; you open a trap in which you might fall quite easily if "distracted" by something else.

Do you know that the most frequent excuse after mistakes in the sim is "...we were distracted by..."?

So, in other words, if you forget to change you will bust the altitude assigned, and that can be very dangerous.

It is a must to always make the two values agree, academics notwithstanding.

Just make a habit of it, and if ordered to level at an intermediate altitude/level, just apply the same: cleared to a level=1013, cleared to an altitude= QNH.

If requested to say passing level or altitude, use the standby, or even your brain if it's still producing some useful work ;)


Captain Stable
17th Jul 2004, 13:25
To add to the debate, and this is purely my own personal opinion, below climb MSA, the standby should always be set to QNH. Whether you extend that to "below TA" is a matter of personal choice (or SOPs where dictated).

If you are cleared to a FL, the altimeter that is slaved to the AP/FDS or AFCS or whatever you call it should ALWAYS be on standard. If anything distracts you, as LEM points out, that distraction should, at least, not be the cause of a level bust because you forgot to change from QNH. Whether it is the standby or the PNF's altimete you leave on QNH is a matter of debate.

square leg
17th Jul 2004, 19:56
Have fun setting the altimeter to 1013.25 at TL when the QNH is 990 in a busy environment.

The procedure you might call "dumb" might prevent you from using your TCAS and busting your level.

Don't forget that this procedure might not work in the same way for a C172 and an A320 or any other high performance A/C.

Adapt to the given conditions.