Altimeter Set Up
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Altimeter Set Up
Hi all ,
Whem do you all set your altimeters from QNE to QNH ? When cleared to an altitude or passing the TL?
On the QRH 3.06 states "When cleared to altitude: Baro ref - Set/x check" while on FCOM 3.03.17 states "Baro ref: Set QNH (or QFE) on the EFIS control panel and on the standby altimeter, when approaching the transition level and when cleared for an altitude"
I`ve always set my altimeter when cleared to an altitude , but now I am flying to an airlene which states we should do it only when passing the TL.
I fly in Europe.
A-3TWETY
Whem do you all set your altimeters from QNE to QNH ? When cleared to an altitude or passing the TL?
On the QRH 3.06 states "When cleared to altitude: Baro ref - Set/x check" while on FCOM 3.03.17 states "Baro ref: Set QNH (or QFE) on the EFIS control panel and on the standby altimeter, when approaching the transition level and when cleared for an altitude"
I`ve always set my altimeter when cleared to an altitude , but now I am flying to an airlene which states we should do it only when passing the TL.
I fly in Europe.
A-3TWETY
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On the way up we switch passing the transition altitude, on the way down when cleared to an altitude which can be much higher than the transition level. Since switching nowadays is only a single button action instead of twiddling around it is easy enough to switch back to standard when we get recleared to a flightlevel.
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Hi,
I totally agree with you and it is what I have done for years,, actually all my life.
But look down what airbus replied whem questioned about that:
ANSWER:
On the QRH 3.06, the procedure aims to inform that the flight crew must change the barometric reference when crossing the transition altitudes. This procedure is generic and has to be applied during climb at transition altitude and during descent when the ATC authorises to keep on the descent.
In the FCOM 3.03.17, we detail this procedure when the flight phase is descent. When the ATC gives clearance to an altitude and when the aircraft reaches the transition level (also given by the ATC), set the barometric reference corresponding to the approach/terrain (QFE or QNH). In addition, the flight crew should crosscheck the altitude on the PFD and the baro reference displayed on FCU.
As a conclusion, we recommend to refer to the FCOM 3.03.xx procedures to have more complete information.
We hope this satisfactorily responds to your request. We encourage you to provide us with your feedback using the questionnaire below, and we remain available for any additional information and assistance.
Best Regards,
David MARCONNET
Flight Operations Engineer
A320/A330/A340 FMGS Operational Standards - STLS AIRBUS Customer Services
I totally agree with you and it is what I have done for years,, actually all my life.
But look down what airbus replied whem questioned about that:
ANSWER:
On the QRH 3.06, the procedure aims to inform that the flight crew must change the barometric reference when crossing the transition altitudes. This procedure is generic and has to be applied during climb at transition altitude and during descent when the ATC authorises to keep on the descent.
In the FCOM 3.03.17, we detail this procedure when the flight phase is descent. When the ATC gives clearance to an altitude and when the aircraft reaches the transition level (also given by the ATC), set the barometric reference corresponding to the approach/terrain (QFE or QNH). In addition, the flight crew should crosscheck the altitude on the PFD and the baro reference displayed on FCU.
As a conclusion, we recommend to refer to the FCOM 3.03.xx procedures to have more complete information.
We hope this satisfactorily responds to your request. We encourage you to provide us with your feedback using the questionnaire below, and we remain available for any additional information and assistance.
Best Regards,
David MARCONNET
Flight Operations Engineer
A320/A330/A340 FMGS Operational Standards - STLS AIRBUS Customer Services
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I think it right to say most airlines now do as follows:
In the climb, when cleared to a flight level, set standard immediately, whatever the transition altitude. Standby altimeter remains on QNH until passing Climb MSA.
In descent, whenever cleared to an altitude, set QNH immediately, whatever transition level. Standby altimeter set to QNH before descent commences.
The problem with lower transition altitudes and a low cleared flight level is if you have a low pressure area and wait for transition to change to standard, you may instantly exceed your cleared flight level. Rates of climb are so high now that great care has to be taken.
In the climb, when cleared to a flight level, set standard immediately, whatever the transition altitude. Standby altimeter remains on QNH until passing Climb MSA.
In descent, whenever cleared to an altitude, set QNH immediately, whatever transition level. Standby altimeter set to QNH before descent commences.
The problem with lower transition altitudes and a low cleared flight level is if you have a low pressure area and wait for transition to change to standard, you may instantly exceed your cleared flight level. Rates of climb are so high now that great care has to be taken.
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We have a slightly different procedure - in the climb, set standard once above 3000' AGL AND cleared to climb to a FL. Standby Alt stays on QNH til above the MSA. On the way down, once cleared to an altitude.
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A320 the answer to your question is given in the SOP:
– BARO REF......................................................... ....................................SET
• Passing transition attitude and cleared for flight level (baro setting flashing on PFD) set STD on EFIS control panels and on standby altimeter.
• Cross check baro settings and altitude readings.
The reason for this modification is given TR No 046 - 1
SUBJECT: ATC WITH ENHANCED SURVEILLANCE
REASON FOR ISSUE:
The temporary revision is issued to advise operators that the transition level, when the flight crew selects ‘“STD” on the FCU, the last QNH or QFE barometric pressure settings is transmitted to the ground, instead of the standard pressure value(1013 hpa). Only the FCU selected altitude, if used
by the ATC on ground, may be misinterpreted. The real aircraft altitude transmitted to the ground is not affected, because the standard barometric altitude is transmitted, regardless of the barometric setting selected on the FCU. In addition, the “STD” value is correctly transmitted to the other aircraft systems.
VALIDITY:All A320 equipped with an ATC certified with the enhanced surveillance (Mod 35240)
FILING INSTRUCTION:Updated the record of temporary revision and insert the following pages:
Page 1 of 2 following 00-01 Page 1
Page 2 of 2 facing 3.03.14 Page 2
Always worthwhile to read your books gents.
Cheers,
– BARO REF......................................................... ....................................SET
• Passing transition attitude and cleared for flight level (baro setting flashing on PFD) set STD on EFIS control panels and on standby altimeter.
• Cross check baro settings and altitude readings.
The reason for this modification is given TR No 046 - 1
SUBJECT: ATC WITH ENHANCED SURVEILLANCE
REASON FOR ISSUE:
The temporary revision is issued to advise operators that the transition level, when the flight crew selects ‘“STD” on the FCU, the last QNH or QFE barometric pressure settings is transmitted to the ground, instead of the standard pressure value(1013 hpa). Only the FCU selected altitude, if used
by the ATC on ground, may be misinterpreted. The real aircraft altitude transmitted to the ground is not affected, because the standard barometric altitude is transmitted, regardless of the barometric setting selected on the FCU. In addition, the “STD” value is correctly transmitted to the other aircraft systems.
VALIDITY:All A320 equipped with an ATC certified with the enhanced surveillance (Mod 35240)
FILING INSTRUCTION:Updated the record of temporary revision and insert the following pages:
Page 1 of 2 following 00-01 Page 1
Page 2 of 2 facing 3.03.14 Page 2
Always worthwhile to read your books gents.
Cheers,
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In our bookwork it says TA and TL on the way up and down respectively, but it also says that when cleared to an altitude and the use of FL is no longer expected, QNH may be set. We also use setting of QNE and QNH as triggers for climb and approach checklists respectively.
Common practice is TA on the way up and when cleared to an altitude on the way down.
Common practice is TA on the way up and when cleared to an altitude on the way down.
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10W: unsure of what you are asking?
It may not be 100% accurate by definition, but in this thread atleast, I understand the term "QNE" to be the same as the standard pressure setting.
Edit: Google finds 2 definitions of QNE:
1) In radio communication, the baseline pressure setting is referred to by the Q code QNE.
2) QNE: reading in feet on an altimeter set to 1013.2 millibars (standard pressure) when the aircraft is at aerodrome elevation.
It may not be 100% accurate by definition, but in this thread atleast, I understand the term "QNE" to be the same as the standard pressure setting.
Edit: Google finds 2 definitions of QNE:
1) In radio communication, the baseline pressure setting is referred to by the Q code QNE.
2) QNE: reading in feet on an altimeter set to 1013.2 millibars (standard pressure) when the aircraft is at aerodrome elevation.
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Picture this. QNH is 980Mhz or millipascals or whatever we are meant to call them now. TA is 3000' (yes- there are such places! But you can use higher numbers to illustrate). You are cleared to TO and checking in to radar at 1500', you are cleared to maintain FL50. Dutifully, passing 3000'TA with a ROC 2500fpm, you reset 1013. By the time you look up passing 3000', your altimeter change trigger, you see your altimeter has immediately jumped 33mb x 30'=1000'. After registering the trap you fell in, you realise you are climbing at 2500fpm with 700' to go! What if you had only been cleared to FL40? You would have busted your perfect record by 1000'.
Not a good scenario. There is no reason when cleared above TA to delay setting 1013 as soon as possible to prevent the possibility of an altitude bust. Indeed, if we are cleared to take off with an initial FL restriction, as the last flap is selected up, we go to 1013 without delay, before even the After Take-off check. Delaying it means forgetting it. Taking it as early as possible means you have fewer cues to miss doing it. If your standard procedures have not already changed to this, they will do! Altitude busts are not 'cool'. I was nearly taken out in a 747 by a berserk Learjet over Dayne, probably doing just such a thing- I never found out what his excuse was, but it was close.
Not a good scenario. There is no reason when cleared above TA to delay setting 1013 as soon as possible to prevent the possibility of an altitude bust. Indeed, if we are cleared to take off with an initial FL restriction, as the last flap is selected up, we go to 1013 without delay, before even the After Take-off check. Delaying it means forgetting it. Taking it as early as possible means you have fewer cues to miss doing it. If your standard procedures have not already changed to this, they will do! Altitude busts are not 'cool'. I was nearly taken out in a 747 by a berserk Learjet over Dayne, probably doing just such a thing- I never found out what his excuse was, but it was close.
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10W: unsure of what you are asking?
It may not be 100% accurate by definition, but in this thread atleast, I understand the term "QNE" to be the same as the standard pressure setting.
Edit: Google finds 2 definitions of QNE:
1) In radio communication, the baseline pressure setting is referred to by the Q code QNE.
2) QNE: reading in feet on an altimeter set to 1013.2 millibars (standard pressure) when the aircraft is at aerodrome elevation.
It may not be 100% accurate by definition, but in this thread atleast, I understand the term "QNE" to be the same as the standard pressure setting.
Edit: Google finds 2 definitions of QNE:
1) In radio communication, the baseline pressure setting is referred to by the Q code QNE.
2) QNE: reading in feet on an altimeter set to 1013.2 millibars (standard pressure) when the aircraft is at aerodrome elevation.
ICAO PANS Doc8400 has more formal weight with the authorities and agencies around the world. Hence QNE (although commonly referred to as such) is not the same as Standard Pressure Setting.
ICAO defines it in this document as a question to a ground station meaning ''What indication will my altimeter give on landing at ... (place) at ... hours, my sub-scale being set to 1013.2 millibars (29.92 inches)?'' or a message from a ground station meaning ''On landing at ... (place) at ... hours, with your sub-scale being set to 1013.2 millibars (29.92 inches), your altimeter will indicate ... (figures and units).''
My questions stands, is there anywhere in Europe with the geography to require the use of this to overcome the limits of altimeter setting scales ? I would think not.
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ICAO procedures
ICAO PANS OPS Altimeter setting procedures , Part III, section 1, state that you change the baro reference setting to STD in the climb at TA. In descent, if cleared to an altitude you can set QNH, but you may wait until the TL, at the latest.
Any other procedures are simply not ICAO compliant.
However, as you say there are reasons for setting STD before TA because of that level bust problem when cleared to a FL very close to the TA when RoCs are high (at low altitudes). Maybe they should increase the transition layer. If I recall correctly, in the UK it can be pretty narrow (500 ft?).
In other countries the TA is very high, maybe 13,000 ft and/or the TL is fixed (at say FL150) rather than given by ATC. In these, there would no problem with ICAO procedure.
There have been numerous level busts due to stopping a descent at a FL after having been cleared to an altitude. It is in the human nature to forget things when unexpected things happen. In my opinion, there is no use in setting QNH at FL410 if cleared to 5,000. You can always wait a little bit, say until FL100 when TA is 5,4 or 6 thousand, or FL200 if TA is very high.
But my point is: can an airline lay down a procedure in its SOPs that is not compliant with ICAO PANS OPS?
Any other procedures are simply not ICAO compliant.
However, as you say there are reasons for setting STD before TA because of that level bust problem when cleared to a FL very close to the TA when RoCs are high (at low altitudes). Maybe they should increase the transition layer. If I recall correctly, in the UK it can be pretty narrow (500 ft?).
In other countries the TA is very high, maybe 13,000 ft and/or the TL is fixed (at say FL150) rather than given by ATC. In these, there would no problem with ICAO procedure.
There have been numerous level busts due to stopping a descent at a FL after having been cleared to an altitude. It is in the human nature to forget things when unexpected things happen. In my opinion, there is no use in setting QNH at FL410 if cleared to 5,000. You can always wait a little bit, say until FL100 when TA is 5,4 or 6 thousand, or FL200 if TA is very high.
But my point is: can an airline lay down a procedure in its SOPs that is not compliant with ICAO PANS OPS?
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In other countries the TA is very high
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When do you all set your altimeters from QNE to QNH ? When cleared to an altitude or passing the TL?
Related questions, why do the Europeans persist in needlessly complicating the issue by sticking with a variety of TA/TL's and why would anyone follow their lead?
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"But my point is: can an airline lay down a procedure in its SOPs that is not compliant with ICAO PANS OPS?"
Yes it can, but only if the governing authority of its country of origin is too lazy to spot it in the Operations Manuals which it is supposed to proof-read before approving! Many of these odd-sentenced statements have slipped through the net before.
Yes it can, but only if the governing authority of its country of origin is too lazy to spot it in the Operations Manuals which it is supposed to proof-read before approving! Many of these odd-sentenced statements have slipped through the net before.
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10W: Thank you, I learned something new then.
However I think that for the purpose of this discussion, one should read QNE as SPS, otherwise the whole thread would be nonsensical. And the thread itself, is highly relevant, in my opinion, definitions aside.
However I think that for the purpose of this discussion, one should read QNE as SPS, otherwise the whole thread would be nonsensical. And the thread itself, is highly relevant, in my opinion, definitions aside.
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Icaoicaoicaoicaoicaoicao....
There are many ways to do things, of which many are sensible and good, but... ICAO states the way it must be done quite clearly, so...
Can we just ignore the rule?
If, god forbid it, one day there was a mid air colision due to non ICAO standard altimeter setting procedures on the part of one (or two) airplanes, what would happen?
I don't think that setting 1013 just after take off is a good operating practice, even if you keep stand by altimeter in QNH till MSA. If one airfield has a very low TA and you are cleared to a FL very close to it because of a too narrow transition layer it is OK, but it is not OK doing it with a 18,000 ft TA, is it?
Can we just ignore the rule?
If, god forbid it, one day there was a mid air colision due to non ICAO standard altimeter setting procedures on the part of one (or two) airplanes, what would happen?
I don't think that setting 1013 just after take off is a good operating practice, even if you keep stand by altimeter in QNH till MSA. If one airfield has a very low TA and you are cleared to a FL very close to it because of a too narrow transition layer it is OK, but it is not OK doing it with a 18,000 ft TA, is it?
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Most European countries have somewhere in the region of 6000' TA. The UK is not unusual. Does Pans Ops still apply?
Cheers
Last edited by 9.G; 6th Sep 2009 at 21:03.