Cold weather altimetry & seasonal changes to minimum altitudes
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Cold weather altimetry & seasonal changes to minimum altitudes
In the low altitude approach environment how does ATC take into account the differences in height above the ground caused by flying the same indicated altitude when the temperature gets very cold (-33C and colder)?
I understand the phenomenon of how cold weather affects uncompensated barometric aircraft systems. What I want to know is how you men & women at ATC factor this in when handling aircraft or whether you correct for this at all?
The first time I came across this phenomenon I was a FO flying a CAT III approach to an airport where the surface temperature was -46C. Everything was “right” with the jet and the way we had the approach set up. However going by the published glideslope crossing height point on the approach we were some 360’ higher than the published figure. At the time I didn’t understand why.
If we have a sea level island airport and it is ISA (+15C & 29.92) and you (ATC) assign me 5,000’ - I will be at 5,000 indicated altitude and 5,000’ above the sea below me. If the temperature drops to -50C and you assign me 5,000’ and I fly 5,000’ indicated altitude (altimeters correctly set and no onboard system failures) I will be only 3,500’ above the surface of the sea.
The vast majority of the people I fly with do not understand how significantly cold surface temperatures affect the distance/room/clearance the jet has over the underlying terrain when they fly assigned or published altitudes that are not compensated for the existing low temperatures. Surprisingly: when the altimeter indicates several hundred feet higher at the FAF than the published values (cold temperatures at the aerodrome: -33C and colder) and they go through the normal mantra: “outer marker (or equivalent) altitude checks no flags” I have yet to have a FO question the discrepancy between the indicated altitude and the published altitude on the chart. Nor have I had a FO brief the expected change in indicated altitude.
Are the following views of ATC fairly accurate (low altitude approach airspace)? In Canada ATC assigned altitudes are compensated for temperatures. In the United States at some military airports altitudes assigned are compensated for temperature, at civilian airports they are not. I don’t know about Europe-never flown there. Africa/Middle East/SE Asia temperatures never get low enough to have any significant operational consequence.
When you handle us, what do you do different operationally when the temperature is much colder than ISA?
Best wishes to all for a safe and wonderful New Year! Thanks for all the work you do keeping us safe, apart, and away from the ground!!!!
I understand the phenomenon of how cold weather affects uncompensated barometric aircraft systems. What I want to know is how you men & women at ATC factor this in when handling aircraft or whether you correct for this at all?
The first time I came across this phenomenon I was a FO flying a CAT III approach to an airport where the surface temperature was -46C. Everything was “right” with the jet and the way we had the approach set up. However going by the published glideslope crossing height point on the approach we were some 360’ higher than the published figure. At the time I didn’t understand why.
If we have a sea level island airport and it is ISA (+15C & 29.92) and you (ATC) assign me 5,000’ - I will be at 5,000 indicated altitude and 5,000’ above the sea below me. If the temperature drops to -50C and you assign me 5,000’ and I fly 5,000’ indicated altitude (altimeters correctly set and no onboard system failures) I will be only 3,500’ above the surface of the sea.
The vast majority of the people I fly with do not understand how significantly cold surface temperatures affect the distance/room/clearance the jet has over the underlying terrain when they fly assigned or published altitudes that are not compensated for the existing low temperatures. Surprisingly: when the altimeter indicates several hundred feet higher at the FAF than the published values (cold temperatures at the aerodrome: -33C and colder) and they go through the normal mantra: “outer marker (or equivalent) altitude checks no flags” I have yet to have a FO question the discrepancy between the indicated altitude and the published altitude on the chart. Nor have I had a FO brief the expected change in indicated altitude.
Are the following views of ATC fairly accurate (low altitude approach airspace)? In Canada ATC assigned altitudes are compensated for temperatures. In the United States at some military airports altitudes assigned are compensated for temperature, at civilian airports they are not. I don’t know about Europe-never flown there. Africa/Middle East/SE Asia temperatures never get low enough to have any significant operational consequence.
When you handle us, what do you do different operationally when the temperature is much colder than ISA?
Best wishes to all for a safe and wonderful New Year! Thanks for all the work you do keeping us safe, apart, and away from the ground!!!!
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In the UK we don't get extremes of temperature that will make any significant difference to ATC procedures but as a general rule I have always understood that it is the pilot's responsibility to apply any cold-temp corrections that may be required. IIRC the reference is ICAO Doc 8168 PANS-OPS.
PANS-ATM 8.5.6.2 says: "When necessary, the minimum radar vectoring altitude shall include a correction for low temperature effect" with a further note that it is the responsibility of the ATS authority to provide the controller with this data.
In the UK, while MATS Part1 does not explicitly mention low temp correction, the phrasing used suggests that it would be an ATC responsibility
"Controllers are to ensure that levels assigned to:
a) IFR flights in receipt of a Radar Control Service
b) flights in receipt of a RAS and
c) flights in receipt of a RIS and receiving vectors;
provide adequate terrain clearance for the phase of flight as shown below."
I would be surprised if the MATS Part 2 for units/aerodromes where terrain is an issue does not include some provision for this. E.g. Inverness has been ISA -20 degC on the surface for a while now. It has a minimum altitude chart with 5600 ft not far away. That's about 5200 ft true in ISA -20, though in reality there's an inversion so the true altitude is likely to be more like 5400 ft. That's still going to keep you above Ben Macdui, but it is significant.
In the UK, while MATS Part1 does not explicitly mention low temp correction, the phrasing used suggests that it would be an ATC responsibility
"Controllers are to ensure that levels assigned to:
a) IFR flights in receipt of a Radar Control Service
b) flights in receipt of a RAS and
c) flights in receipt of a RIS and receiving vectors;
provide adequate terrain clearance for the phase of flight as shown below."
I would be surprised if the MATS Part 2 for units/aerodromes where terrain is an issue does not include some provision for this. E.g. Inverness has been ISA -20 degC on the surface for a while now. It has a minimum altitude chart with 5600 ft not far away. That's about 5200 ft true in ISA -20, though in reality there's an inversion so the true altitude is likely to be more like 5400 ft. That's still going to keep you above Ben Macdui, but it is significant.
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bookworm, I take it all back and bow to your greater breadth of reading.
As far as I am aware there are no local ATC procedures in the UK in which temperature corrections are applied - I stand to be corrected, perhaps from someone working at one of the northern Scottish airports. Certainly those I've worked at in southern Scotland (albeit it was a good few years ago now) did not apply any corrections and I recall a good many rather chilly nights! I trotted out what I understood to be the UK policy following a brief flirtation on the topic a few years ago. Maybe I misunderstood the discussion????? Maybe procedures are designed with corrections for the 'UK worst case' already applied (although the levels in procedures do not suggest this is the case)?
As you point out the difference can be significant, even in the UK's temperate climate. The AIP does not indicate that the UK has filed a Difference for the application of temperature corrections so, in theory anyway, the corrections should be applied somewhere.
As an aside, the UK is subject to an ICAO USOAP audit in the next couple of months - it will be interesting to see whether this topic is picked up. Actually, it will be interesting to see all the topics that are picked up....
As far as I am aware there are no local ATC procedures in the UK in which temperature corrections are applied - I stand to be corrected, perhaps from someone working at one of the northern Scottish airports. Certainly those I've worked at in southern Scotland (albeit it was a good few years ago now) did not apply any corrections and I recall a good many rather chilly nights! I trotted out what I understood to be the UK policy following a brief flirtation on the topic a few years ago. Maybe I misunderstood the discussion????? Maybe procedures are designed with corrections for the 'UK worst case' already applied (although the levels in procedures do not suggest this is the case)?
As you point out the difference can be significant, even in the UK's temperate climate. The AIP does not indicate that the UK has filed a Difference for the application of temperature corrections so, in theory anyway, the corrections should be applied somewhere.
As an aside, the UK is subject to an ICAO USOAP audit in the next couple of months - it will be interesting to see whether this topic is picked up. Actually, it will be interesting to see all the topics that are picked up....
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What about the USSR
I posted a question on a similar thread on Tech Log, so will not repeat it all here:
What about pressure correction, is 1042, at Sea Level, and -22c.
Are there two corrections, and I assume the Russians will not bother to correct these numbers.?
spitoon: applied somewhere: thats what worries me.
glf
What about pressure correction, is 1042, at Sea Level, and -22c.
Are there two corrections, and I assume the Russians will not bother to correct these numbers.?
spitoon: applied somewhere: thats what worries me.
glf
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I've got to go out for a while but this topic has piqued my interest.
gif, I have specifically cited the UK in my responses because I don't know what happens elsewhere.
And I'm sticking to the UK - in years gone by, the CAA designed all IAPs and airspace etc. I'm not sure of the current situation but a few years ago they sought to pass responsibility for the design work to 'industry' and to simply perform an approval role. This required, amongst other things, some UK policy to be made public - one example where, I presume, temperature corrections would apply is ATC Surveillance Minimum Altitude Charts (RVAs in old money).
The UK CAA published CAP777 on the topic. I haven't had time to look through it in any detail but it doesn't seem to mention anything about temperature corrections. I does mention ICAO references, but again after a quick look, doesn't seem to say that unless otherwise specified in the document, the ICAO PANS apply.
A very quick search through the Canadian AIP didn't find anything to explain about different charts for different temperatures as mentioned by Scooby - which lends weight to the idea that it should be transparent to the pilot.
Don't know whether this helps at all.
GTG now (as kids say!)
gif, I have specifically cited the UK in my responses because I don't know what happens elsewhere.
And I'm sticking to the UK - in years gone by, the CAA designed all IAPs and airspace etc. I'm not sure of the current situation but a few years ago they sought to pass responsibility for the design work to 'industry' and to simply perform an approval role. This required, amongst other things, some UK policy to be made public - one example where, I presume, temperature corrections would apply is ATC Surveillance Minimum Altitude Charts (RVAs in old money).
The UK CAA published CAP777 on the topic. I haven't had time to look through it in any detail but it doesn't seem to mention anything about temperature corrections. I does mention ICAO references, but again after a quick look, doesn't seem to say that unless otherwise specified in the document, the ICAO PANS apply.
A very quick search through the Canadian AIP didn't find anything to explain about different charts for different temperatures as mentioned by Scooby - which lends weight to the idea that it should be transparent to the pilot.
Don't know whether this helps at all.
GTG now (as kids say!)
Many of the Radar Vectoring Charts for airports in countries such as Poland and Latvia etc include a note concerning cold weather correction to altitudes. Either the chart lists two different values for (I think) ISA and ISA - 20 deg C or there is a statement that the altitudes shown assume ISA - 20 deg C.
The Ops Manual of the company I fly for contains guidance and instructions to correct for low temperature.
Incidentally corrections should be made to Decision Altitudes/Heights, Procedure Altitudes and Minimum Flap Retraction Altitudes as well.
The Ops Manual of the company I fly for contains guidance and instructions to correct for low temperature.
Incidentally corrections should be made to Decision Altitudes/Heights, Procedure Altitudes and Minimum Flap Retraction Altitudes as well.
The basic advice we are given is that if you read it on a plate or a chart you need to correct it and if you are told it by ATC then it will have already been corrected or the min. altitudes normally used will have taken into account the worst case. Have to say I don't really trust some of places we go to have done it so keep an even more careful eye on terrain and clearances if the temp is really low. Some of the corrections required to approach fixes, base turns and high MDAs can be pretty large if the surface temp is way below ISA, watch out.
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When 3,000' is NOT 3,000'
Max Angle,
Agreed if the temperatures are significantly below ISA then the printed MSL altitudes on the approach chart need to be adjusted. My impression is that this is not a well understood phenomenon by many pilots.
Your second statement regarding ATC is exactly my question. I am not at all sure ATC compensates for non standard temperatures. It’s a big world and I am sure some do. However, if you find yourself flying someplace that is experiencing sub zero frigid temperatures it is a real concern. Under those circumstances flying non temperature corrected altitudes (the ones printed on the approach plate or issued by ATC {possibly}) will result in significantly decreased separation from the underlying terrain.
My general impression is that I am not in fact “protected” by ATC when extremely cold temperatures exist at the aerodrome I am landing at. Last winter I was vectored to an ILS at the same assigned final altitude prior to intercepting the glide slope that they use during the summer. With no surprise we intercepted the glide slope well past (inside) the glideslope intercept point or the FAF. I was really surprised as this aerodrome is just outside the Arctic Circle and frequently experiences such conditions and the airport has been in operation for 60+ years. Here is their current weather, I just checked it: 031915Z 0000 1/16sm R01L/2400v2800ft FZFG BKN001 M41/ 29.97 RMK A02 FG BKN000. We were in VMC and I had the terrain in sight so I accepted it because the experience provided a good “teaching moment”.
I think the Canadians have this figured out. I’m learning about Europe from the responses.
I have been told that at some military airports in the U.S.A. altitudes are temperature compensated. I do not believe ATC assigned altitudes are corrected in the U.S.A. at civilian airports-we are on our own. Ya’ll be careful out there.
Agreed if the temperatures are significantly below ISA then the printed MSL altitudes on the approach chart need to be adjusted. My impression is that this is not a well understood phenomenon by many pilots.
Your second statement regarding ATC is exactly my question. I am not at all sure ATC compensates for non standard temperatures. It’s a big world and I am sure some do. However, if you find yourself flying someplace that is experiencing sub zero frigid temperatures it is a real concern. Under those circumstances flying non temperature corrected altitudes (the ones printed on the approach plate or issued by ATC {possibly}) will result in significantly decreased separation from the underlying terrain.
My general impression is that I am not in fact “protected” by ATC when extremely cold temperatures exist at the aerodrome I am landing at. Last winter I was vectored to an ILS at the same assigned final altitude prior to intercepting the glide slope that they use during the summer. With no surprise we intercepted the glide slope well past (inside) the glideslope intercept point or the FAF. I was really surprised as this aerodrome is just outside the Arctic Circle and frequently experiences such conditions and the airport has been in operation for 60+ years. Here is their current weather, I just checked it: 031915Z 0000 1/16sm R01L/2400v2800ft FZFG BKN001 M41/ 29.97 RMK A02 FG BKN000. We were in VMC and I had the terrain in sight so I accepted it because the experience provided a good “teaching moment”.
I think the Canadians have this figured out. I’m learning about Europe from the responses.
I have been told that at some military airports in the U.S.A. altitudes are temperature compensated. I do not believe ATC assigned altitudes are corrected in the U.S.A. at civilian airports-we are on our own. Ya’ll be careful out there.
Last edited by Northbeach; 3rd Jan 2009 at 19:04.
Last winter I was vectored to an ILS at the same assigned final altitude prior to intercepting the glide slope that they use during the summer
Roll on summer!.
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And Max has highlighted a second real problem. If the ATC procedures have already taken account of the temperature but the pilot also applies a correction, the separation between aircraft will be eroded. Taking the extreme example of -40 that is given, the nominal 1000ft vertical separation from the next higher allocated level will, in fact, be just 30ft.
Northbeach's original question and glf's input therefore become pertinent - it's important for the pilot to know who has responsibility for applying the correction. Another hunt through the books suggests that it's not clear.
I presume that when faced with this question in an operational situation, pilots will ask ATC whether temperature corrections have been incorporated in the procedures being used. What sort of answers do you get?
Northbeach's original question and glf's input therefore become pertinent - it's important for the pilot to know who has responsibility for applying the correction. Another hunt through the books suggests that it's not clear.
I presume that when faced with this question in an operational situation, pilots will ask ATC whether temperature corrections have been incorporated in the procedures being used. What sort of answers do you get?
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When the published MSA will not provide terrain clearance.
I know this is the ATC forum but I just realized another ramification of cold weather altimetry. On our approach charts (Jeppesen) we have published MSAs that provide terrain separation within 22NM/25SM of the stated reference point. The published MSAs are not valid when the aerodrome is significantly colder than ISA. If the MSA for a sector is 4,000’ the clearance above the underlying terrain will decrease as the temperature decreases if you fly the same indicated altitude.
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jar is slowly introducing this
PROC REGARDING OBST CLEARANCE AND CORRECTION FOR LOW TEMP EFFECT WERE
INTRODUCED IN NORWEGIAN TMA WEF 050929. THE NEW PROC STATES THAT THE
RADARCONTROLLER SHALL ISSUE CLEARANCES SUCH THAT THE PRESCRIBED OBST
CLEARANCE WILL EXIST AT ALL TIMES WHEN GIVING AN IFR FLIGHT A DCT
ROUTING WHICH TAKES THE ACFT OFF AN ATS-RTE. THE NEW PROC ALSO STATES
THAT THE RESPONSIBILITY FOR CORRECTION FOR LOW TEMP EFFECT WHEN
VECTORING AN IFR-FLT AND WHEN GIVING AN IFR-FLT A DCT ROUTING ARE
TRANSFERED TO THE RADARCONTROLLER. OSLO TMA AND FARRIS TMA ARE
TEMPORARILY EXEMPTED FM THE ABOVE MENTIONED PROC AND THE PILOT'S
RESPONSIBILITY IN THESE TMA WILL REMAIN UNALTERED
https://www.ippc.no/ippc/notambyid.j...d=ENAV-0019/09
What about corrections for strong winds in mountainous area (venturi effect) anyone used it in commercial flight?
INTRODUCED IN NORWEGIAN TMA WEF 050929. THE NEW PROC STATES THAT THE
RADARCONTROLLER SHALL ISSUE CLEARANCES SUCH THAT THE PRESCRIBED OBST
CLEARANCE WILL EXIST AT ALL TIMES WHEN GIVING AN IFR FLIGHT A DCT
ROUTING WHICH TAKES THE ACFT OFF AN ATS-RTE. THE NEW PROC ALSO STATES
THAT THE RESPONSIBILITY FOR CORRECTION FOR LOW TEMP EFFECT WHEN
VECTORING AN IFR-FLT AND WHEN GIVING AN IFR-FLT A DCT ROUTING ARE
TRANSFERED TO THE RADARCONTROLLER. OSLO TMA AND FARRIS TMA ARE
TEMPORARILY EXEMPTED FM THE ABOVE MENTIONED PROC AND THE PILOT'S
RESPONSIBILITY IN THESE TMA WILL REMAIN UNALTERED
https://www.ippc.no/ippc/notambyid.j...d=ENAV-0019/09
What about corrections for strong winds in mountainous area (venturi effect) anyone used it in commercial flight?
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What about the USSR I posted a question on a similar thread on Tech Log, so will not repeat it all here:
What about pressure correction, is 1042, at Sea Level, and -22c.
Are there two corrections, and I assume the Russians will not bother to correct these numbers.?
….I thinks you are wrong about RU and the post SU space.
Published SAs at the charts along SID/STAR here are not estimated with Standard atmosphere data. They are corrected with the average annual temperature and minimum pressure of several years' standing at APP sectors at the local aerodrome. SAs at RADAR sector and MSA at the aerodrome area within R50km for safety reasons corrected with minimum temperature on long-term observations.
----------------------------------------------------------------------------------
Doc 8168OPS/611 Chapter 4 ALTIMETER CORRECTIONS
Note.— This chapter deals with altimeter corrections for pressure, temperature and, where appropriate, wind and
terrain effects. The pilot is responsible for these corrections, except when under radar vectoring. In that case, the radar
controller issues clearances such that the prescribed obstacle clearance will exist at all times, taking the cold
temperature correction into account.
…may be I am not understood something?
What about pressure correction, is 1042, at Sea Level, and -22c.
Are there two corrections, and I assume the Russians will not bother to correct these numbers.?
….I thinks you are wrong about RU and the post SU space.
Published SAs at the charts along SID/STAR here are not estimated with Standard atmosphere data. They are corrected with the average annual temperature and minimum pressure of several years' standing at APP sectors at the local aerodrome. SAs at RADAR sector and MSA at the aerodrome area within R50km for safety reasons corrected with minimum temperature on long-term observations.
----------------------------------------------------------------------------------
Doc 8168OPS/611 Chapter 4 ALTIMETER CORRECTIONS
Note.— This chapter deals with altimeter corrections for pressure, temperature and, where appropriate, wind and
terrain effects. The pilot is responsible for these corrections, except when under radar vectoring. In that case, the radar
controller issues clearances such that the prescribed obstacle clearance will exist at all times, taking the cold
temperature correction into account.
…may be I am not understood something?
By my tables you would need to add 970ft to a 4000ft platform at -40 which is a huge error if not being corrected. -20 is about as cold as I have to deal with but it's still enough to need a 90ft correction to a 600ft MDA.
Nevertheless, like Spitoon, I'm intrigued by the apparent absence of guidance in the UK and some other places as to whether ATC should correct assigned altitudes to preserve terrain clearance.
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Still confusion re corrections
All we have managed to do so far is agree that there is no published 100% solution.
ALATOWERS: as you are based in Almati, and my original question relates to Almati, and Asana.
I was in both last week, and had mins approach both times. As a result of the lack of information, and no ATC reference to any corrections, we factored our mins by correcting as per the Glf check list, for the -20c.
IF we had missed our approach, as a result of adding an unrequired correction, I bet the company would not be happy, to say nothing of the passengers comments.
I have never been vectored in Moscow, for example at anything other than the "published" intercept heights, so feel that even this is open to confusion.
Lastly, It is not acceptable to compute an average figure on average temperatures, Irkutz, (spl), has a vast temperate range, and still something like -30c in winter.
Regards from +20C (this week).
Which brings up the other side of the coin: Middle East in Summer.......
glf
ALATOWERS: as you are based in Almati, and my original question relates to Almati, and Asana.
I was in both last week, and had mins approach both times. As a result of the lack of information, and no ATC reference to any corrections, we factored our mins by correcting as per the Glf check list, for the -20c.
IF we had missed our approach, as a result of adding an unrequired correction, I bet the company would not be happy, to say nothing of the passengers comments.
I have never been vectored in Moscow, for example at anything other than the "published" intercept heights, so feel that even this is open to confusion.
Lastly, It is not acceptable to compute an average figure on average temperatures, Irkutz, (spl), has a vast temperate range, and still something like -30c in winter.
Regards from +20C (this week).
Which brings up the other side of the coin: Middle East in Summer.......
glf
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Under “similar threads” below there are two good discussions. I think the bottom line is; there is no universally applied and accepted standard for non standard ISA, vectoring altitude corrections.
For the pilots, published instructions exist but generally they are not well understood. This is an education problem. Pilots need to understand the phenomenon, make the required corrections and then notify ATC of their actions. It’s interesting to me that there have been no U.S.A. or Canadian controllers join in the discussion (I think).
From my observation of the flight deck the vast majority of pilots have little understanding of the phenomenon therefore do not understand its ramifications nor do they apply any correction to the published or assigned altitudes.
On the other side of the coin (the point that was brought up in a recent post); yes if it is hotter than ISA, then flying the published altitudes will result in the aircraft being higher than it would be under ISA conditions.
I just received the following quoted response from the U.S. ATC facility where I first experienced this phenomenon. "We do not make any adjustments to our Minimum Vectoring Altitude due to temperature variations. Personal controller experience and technique may keep some flight higher but generally speaking we adhere to the requirement in FAA Order JO 7110.65."
The document referenced is some 605 pages in length. Having searched it I have not yet come across any mention of modifying assigned altitudes due to lower than ISA temperatures. I will keep looking but I doubt it is there. It seems I have the answer to my original question. In the U.S. altitudes assigned by ATC are not modified due to higher or lower than ISA temperatures.
For the pilots, published instructions exist but generally they are not well understood. This is an education problem. Pilots need to understand the phenomenon, make the required corrections and then notify ATC of their actions. It’s interesting to me that there have been no U.S.A. or Canadian controllers join in the discussion (I think).
From my observation of the flight deck the vast majority of pilots have little understanding of the phenomenon therefore do not understand its ramifications nor do they apply any correction to the published or assigned altitudes.
On the other side of the coin (the point that was brought up in a recent post); yes if it is hotter than ISA, then flying the published altitudes will result in the aircraft being higher than it would be under ISA conditions.
I just received the following quoted response from the U.S. ATC facility where I first experienced this phenomenon. "We do not make any adjustments to our Minimum Vectoring Altitude due to temperature variations. Personal controller experience and technique may keep some flight higher but generally speaking we adhere to the requirement in FAA Order JO 7110.65."
The document referenced is some 605 pages in length. Having searched it I have not yet come across any mention of modifying assigned altitudes due to lower than ISA temperatures. I will keep looking but I doubt it is there. It seems I have the answer to my original question. In the U.S. altitudes assigned by ATC are not modified due to higher or lower than ISA temperatures.
Last edited by Northbeach; 8th Jan 2009 at 01:14.
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Spitoon, on the matter of separation particularly, the instructions to pilots contain the line:
"When pilots intend to apply corrections to the FAF crossing altitude, procedure turn or missed approach altitude, they must advise ATC of their intention and the correction to be applied."
That's in the Aerad supplement, certainly used to be in the Jepp guide, and is also contained in our company manuals.
--
Interestingly, our company make a blanket statement that when under radar all assigned altitudes can assume to be tempereature corrected. PANS-OPS (Doc 8168), as well as discussing ATCs responsibility to provide corrections when radar vectoring, talks about the State's requirement to publish in their AIPs the criteria used to determine minimum flight altitudes and notes that where nothing is published it should be assumed that no corrections have been made.
I doubt very much that someone has trawled all the AIPs to check compliance!
Interestingly, the UK AIP in GEN 3.3.6 Minimum Flight Altitude (which is where the criteria should be) simply says 'to be developed'. So, do we now assume that the UK is to be treated as '... where nothing is published it should be assumed that no corrections have been made.' I think we should be told.
"When pilots intend to apply corrections to the FAF crossing altitude, procedure turn or missed approach altitude, they must advise ATC of their intention and the correction to be applied."
That's in the Aerad supplement, certainly used to be in the Jepp guide, and is also contained in our company manuals.
--
Interestingly, our company make a blanket statement that when under radar all assigned altitudes can assume to be tempereature corrected. PANS-OPS (Doc 8168), as well as discussing ATCs responsibility to provide corrections when radar vectoring, talks about the State's requirement to publish in their AIPs the criteria used to determine minimum flight altitudes and notes that where nothing is published it should be assumed that no corrections have been made.
I doubt very much that someone has trawled all the AIPs to check compliance!
Interestingly, the UK AIP in GEN 3.3.6 Minimum Flight Altitude (which is where the criteria should be) simply says 'to be developed'. So, do we now assume that the UK is to be treated as '... where nothing is published it should be assumed that no corrections have been made.' I think we should be told.
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Robin,
Here is a link to some of the resources I've compiled on the topic of Cold Weather Altimetry. I also made a quick video explaining the problem.
Cold | Robin's Roost
tailwinds,
Robin
Here is a link to some of the resources I've compiled on the topic of Cold Weather Altimetry. I also made a quick video explaining the problem.
Cold | Robin's Roost
tailwinds,
Robin