When to change to 1013mb?
Join Date: Jun 2000
Location: UK
Posts: 683
Likes: 0
Received 0 Likes
on
0 Posts
ferris, I still believe we are at cross-purposes. yy said:
This is quite clearly incorrect as TCAS cannot be affected by a wrongly set altimeter. TCAS uses Mode C (or Mode S) to assess the vertical position of the other aircraft. Thus there is no way that "the integrity of TCAS" can be affected if QNH is set on the altimeter, rather than Standard, i.e. 1013mb. That was what I was referring to ...
By the way, my transponder does give a visual indication of the Mode C data that is being transmitted (i.e. FL), so this data is not necessarily invisible to the pilot, as you say.
I am reluctant to prolong this thread creep, so if you think I am still missing your point, please PM me ...
JD
By the way, my transponder does give a visual indication of the Mode C data that is being transmitted (i.e. FL), so this data is not necessarily invisible to the pilot, as you say.
I am reluctant to prolong this thread creep, so if you think I am still missing your point, please PM me ...
JD
Last edited by Jumbo Driver; 20th May 2008 at 16:21. Reason: typo
Join Date: Apr 2001
Location: Adrift upon the tides of fate
Posts: 1,840
Likes: 0
Received 0 Likes
on
0 Posts
A few things (and I think it's relevent);
1. The info dipslayed to you, and the info transmitted, are not neccessarily the same thing (have seen this several times).
2. The integrity of TCAS relies on the integrity of the transponder, and the manner of determining the intregrity of the transponder is reliant on correct altimeter setting. So, I disagree, and think that altimeter setting can affect TCAS.
Make sense?
3. If clearance instructions, hence separation, hence whether you will experience a TCAS event, rely on correct altimeter setting, then the two (three) are permanently tied.
1. The info dipslayed to you, and the info transmitted, are not neccessarily the same thing (have seen this several times).
2. The integrity of TCAS relies on the integrity of the transponder, and the manner of determining the intregrity of the transponder is reliant on correct altimeter setting. So, I disagree, and think that altimeter setting can affect TCAS.
Make sense?
3. If clearance instructions, hence separation, hence whether you will experience a TCAS event, rely on correct altimeter setting, then the two (three) are permanently tied.
Join Date: Jun 2000
Location: UK
Posts: 683
Likes: 0
Received 0 Likes
on
0 Posts
No, I'm afraid it doesn't make sense ferris.
Altimeter subscale setting cannot affect TCAS. It is irrelevant. Neither can it affect the Mode C response.
I respectfully suggest you re-read the theory of TCAS and Mode C encoding.
JD
Altimeter subscale setting cannot affect TCAS. It is irrelevant. Neither can it affect the Mode C response.
I respectfully suggest you re-read the theory of TCAS and Mode C encoding.
JD
Join Date: Apr 2001
Location: Adrift upon the tides of fate
Posts: 1,840
Likes: 0
Received 0 Likes
on
0 Posts
Altimeter subscale setting CAN affect TCAS. Not in the sense that adjusting the subscale directly does anything to either the TCAS unit or the transponder, but I'm sick of explaining myself over and over.
I respectfully suggest that you have a look at the relationships between radar displayed alt, radar data processing, and mode c, as described in this thread. The key point being that the RDP expects you to have the correct subscale setting.
I respectfully suggest that you have a look at the relationships between radar displayed alt, radar data processing, and mode c, as described in this thread. The key point being that the RDP expects you to have the correct subscale setting.
Join Date: Jun 2000
Location: UK
Posts: 683
Likes: 0
Received 0 Likes
on
0 Posts
Thanks, Vercingetorix - I was beginning to lose the will to live there ... 
Perhaps we can now get back to the thread? Hoover Pilot has asked two questions; I hope ENR 1.7 has answered his first question. His second question was:
As he seems to be talking about the London area, perhaps someone from TC may be able to enlighten him?
JD
Perhaps we can now get back to the thread? Hoover Pilot has asked two questions; I hope ENR 1.7 has answered his first question. His second question was:
JD
Join Date: Apr 2001
Location: Adrift upon the tides of fate
Posts: 1,840
Likes: 0
Received 0 Likes
on
0 Posts
Hey JD, you had better watch whose support you receive. Vercingetorex is the clown who, after the Uberlingen accident, thought that it was correct for pilots to follow atc instructions over TCAS.
So, yeah, he's a TCAS expert.
As to the second part of your post- a question: What happens if the FMS is flying, and you are on a SID (which has altitude restrictions), but you are cleared to a FL and change the subscale? I take it the FMS is deriving it's data from the panel altimeters?
So, yeah, he's a TCAS expert.
As to the second part of your post- a question: What happens if the FMS is flying, and you are on a SID (which has altitude restrictions), but you are cleared to a FL and change the subscale? I take it the FMS is deriving it's data from the panel altimeters?
Join Date: Jan 2007
Location: Dunno ... what day is it?
Posts: 273
Likes: 0
Received 0 Likes
on
0 Posts
yakkity yak
I think you have answered your own point, in that your scenario couldn't happen where the transition levels are as low as they are in the UK, so UK procedures are appropriate here. However I think you have invented a problem that should not occur. As I was taught I change to SPS as soon as I was cleared to a flight level and have no need to use my primary altimeter for reference to altitude before reaching that flight level.
So if I was in a busy area, and asked to climb to say FL80, expediting through 5000 feet, then I would change to 1013 at 5000 feet. If all was quiet and I was on a steady track on autopilot, I might use the secondary altimeter (which I habitually leave on QNH until the cruise, as I was also taught) as the required altitude reference. Note that the worst that could happen in the UK by setting 1013 early is that I climb faster than I want to, or slower than ATC has requested I do, for a short time - no incident.
I think you have answered your own point, in that your scenario couldn't happen where the transition levels are as low as they are in the UK, so UK procedures are appropriate here. However I think you have invented a problem that should not occur. As I was taught I change to SPS as soon as I was cleared to a flight level and have no need to use my primary altimeter for reference to altitude before reaching that flight level.
So if I was in a busy area, and asked to climb to say FL80, expediting through 5000 feet, then I would change to 1013 at 5000 feet. If all was quiet and I was on a steady track on autopilot, I might use the secondary altimeter (which I habitually leave on QNH until the cruise, as I was also taught) as the required altitude reference. Note that the worst that could happen in the UK by setting 1013 early is that I climb faster than I want to, or slower than ATC has requested I do, for a short time - no incident.
Join Date: Apr 2001
Location: Adrift upon the tides of fate
Posts: 1,840
Likes: 0
Received 0 Likes
on
0 Posts
I gather that by posting those bulletins you are trying to say that you weren't aware that pilots were instructed to follow TCAS over ATC instructions, and that these were the first guidance on the matter.
At the time you made your statement of ignorance (July 2, 2002)- it was pointed out to you that that the instruction already existed in the AIP (where it had been the rule since the late 90's). Your response was "this country is a tin-pot little country with a rubbish AIP- proper countries dont have it". It was then pointed out that the "tin-pot country's" AIP was a cut and paste of the UK CAA document. To which you shuffled off to your office to check. Of no real consequence- except you were the SATCO at the time. Management by buffoon.
Yet another example of your shining brilliance. Said brilliance being the reason you were shown the door, no doubt.
At the time you made your statement of ignorance (July 2, 2002)- it was pointed out to you that that the instruction already existed in the AIP (where it had been the rule since the late 90's). Your response was "this country is a tin-pot little country with a rubbish AIP- proper countries dont have it". It was then pointed out that the "tin-pot country's" AIP was a cut and paste of the UK CAA document. To which you shuffled off to your office to check. Of no real consequence- except you were the SATCO at the time. Management by buffoon.
Yet another example of your shining brilliance. Said brilliance being the reason you were shown the door, no doubt.
Join Date: Apr 2001
Location: Adrift upon the tides of fate
Posts: 1,840
Likes: 0
Received 0 Likes
on
0 Posts
and was not a cut and paste of the UK CAA
Go on, tell us, why did you post those bulletins with dates highlighted, unless you are trying to say they are the first TCAS guidance? I dont think the wider audience is so easily fooled, and will recall when ACAS guidance was first about. It may be the trait of a manager to lie and deceive, but when the facts are in black and white, it's easy enough to see thru.
The fact that you were not aware that TCAS was/is to be followed above ATC instructions, despite the fact you were a "manager", remains. As I said, management by buffoon. Then again, lots of us in ATC know that.
Join Date: Jun 2000
Location: UK
Posts: 683
Likes: 0
Received 0 Likes
on
0 Posts
Thread creep
ferris, why don't you take your vitriolic personal attacks somewhere else? You are coming across as one who is obsessed with your own opinion, irrespective of the facts.
In case you have forgotten, this thread is about the setting of 1013mb when climbing throught TA and the Transition Layer.
If you think you have something useful to contribute to the topic, by all means do so - but good manners to the thread owner dictates it should be within the subject. Alternatively, you are free to start your own thread with the subject of your own choice (you could perhaps start with TCAS ... ). In any event, it is inconsiderate - and, in fact, rather boring - to take over someone else's thread with your own obsessive axe-grinding wanderings. It seems that your profile, at least, is pretty accurate.
Any chance of getting back to the topic?
JD
In case you have forgotten, this thread is about the setting of 1013mb when climbing throught TA and the Transition Layer.
If you think you have something useful to contribute to the topic, by all means do so - but good manners to the thread owner dictates it should be within the subject. Alternatively, you are free to start your own thread with the subject of your own choice (you could perhaps start with TCAS ... ). In any event, it is inconsiderate - and, in fact, rather boring - to take over someone else's thread with your own obsessive axe-grinding wanderings. It seems that your profile, at least, is pretty accurate.
Any chance of getting back to the topic?
JD
Join Date: Apr 2001
Location: Adrift upon the tides of fate
Posts: 1,840
Likes: 0
Received 0 Likes
on
0 Posts
I've tried to contribute, JD, but as my opinion differs to yours, clearly you dont like it. If someone has a different opinion, they are "obsessed with it"? I have tried to save you some embarrassment by identifying the depth of knowledge of the clown supporting you, but hey, you come across as an arrogant **** yourself, if you want to cast aspersions. Not only that, you haven't refuted a single thing I've said. I'd be looking in the mirror regarding obsessions and opinions.
I asked you a question (on topic) about altimeter setting and the FMS, which you have studiously ignored.
I asked you a question (on topic) about altimeter setting and the FMS, which you have studiously ignored.
Thread Starter
Join Date: Jul 1999
Location: North
Posts: 30
Likes: 0
Received 0 Likes
on
0 Posts
Hi BOAC still here (though work beckons in a day or so) and have watched the demise (or drift) of this one.
I was literally on the point of trying to bring it back the other day but JD beat me to it (thanks for that, by the way) but his efforts were in vain.
Seriously though thanks for all the responsible opinions but all I really wanted was the answer to one question. I do know what the regs say and have discussed my thoughts over my Company’s SOPs in this area, but their answer has been that if we are ever instructed to “stop climb” while we are still below the transition altitude then that instruction will be:
“stop climb altitude 4,000ft” and not
“stop climb FL50” – (or FL48 or FL52 or FL what-ever to maintain separation).
Therefore I was hoping for an answer from an ATC chap(ess) to the question:
“The tricky thing would be to have to stop the climb after having changed to 1013mb. Would ATC instruct me to stop the climb at an altitude or a flight level? (bearing in mind, in this case, I am still below the transition altitude)”
Here’s hoping……………….
Cheers HP
I was literally on the point of trying to bring it back the other day but JD beat me to it (thanks for that, by the way) but his efforts were in vain.
Seriously though thanks for all the responsible opinions but all I really wanted was the answer to one question. I do know what the regs say and have discussed my thoughts over my Company’s SOPs in this area, but their answer has been that if we are ever instructed to “stop climb” while we are still below the transition altitude then that instruction will be:
“stop climb altitude 4,000ft” and not
“stop climb FL50” – (or FL48 or FL52 or FL what-ever to maintain separation).
Therefore I was hoping for an answer from an ATC chap(ess) to the question:
“The tricky thing would be to have to stop the climb after having changed to 1013mb. Would ATC instruct me to stop the climb at an altitude or a flight level? (bearing in mind, in this case, I am still below the transition altitude)”
Here’s hoping……………….
Cheers HP
Guest
Posts: n/a
OK, here's an answer from a UK approach controller - i.e. TA/TL is day-to-day business. It's a personal view so you may get other answers from other posters!
I know what the UK rules are. I know that other States have different rules. I know that some SOPs do not adhere to UK rules whilst within UK airspace. I am aware that some pilots do their own thing regardless of the rules (and, sometimes, SOPs). In short, I am very aware of the issues involved - both for controllers and pilots.
Consequently, I will never clear an aircraft to climb to a FL knowing that I am going to want to stop the climb at an altitude. Frankly, if there's the possibility that I'll need to stop the climb because of other traffic then I'll only clear the aircraft to the safe level and then, as it approaches the level change, I decide whether I can clear it further. Same principles apply for descending traffic.
Some may say this is inefficient but it's fail-safe - and I've been in this game long enough to know how easy it is to get distracted.
But stuff happens and plans sometimes have to change. Working around the TA I'm always aware of the relationship between the TA and the next safe level. Therefore it is fairly easy to work out what level (be it a FL or altitude) will be safe relative to whatever the problem is if it really is necessary to change the plan. I'll use whatever level datum the pilot should be using according to UK rules first but if there's any hesitation or question I'll have the level referenced to the other datum ready. If it's all turning to a heap of manure there's always the 'stop climb now and advise the level' and I've got the mode C to help also.
In truth, particularly where the TA is 3000ft or 4000ft, it's not a common problem because it so rarely happens that a clearance needs to be changed whilst an aircraft is climbing through altitudes because it happens so quickly for most commercial ops type aircraft. Perhaps it's more frequent when descending but I haven't seen it done often. Of course, if TA is 10,000ft or 18,000ft it's going to be a different story.
I know what the UK rules are. I know that other States have different rules. I know that some SOPs do not adhere to UK rules whilst within UK airspace. I am aware that some pilots do their own thing regardless of the rules (and, sometimes, SOPs). In short, I am very aware of the issues involved - both for controllers and pilots.
Consequently, I will never clear an aircraft to climb to a FL knowing that I am going to want to stop the climb at an altitude. Frankly, if there's the possibility that I'll need to stop the climb because of other traffic then I'll only clear the aircraft to the safe level and then, as it approaches the level change, I decide whether I can clear it further. Same principles apply for descending traffic.
Some may say this is inefficient but it's fail-safe - and I've been in this game long enough to know how easy it is to get distracted.
But stuff happens and plans sometimes have to change. Working around the TA I'm always aware of the relationship between the TA and the next safe level. Therefore it is fairly easy to work out what level (be it a FL or altitude) will be safe relative to whatever the problem is if it really is necessary to change the plan. I'll use whatever level datum the pilot should be using according to UK rules first but if there's any hesitation or question I'll have the level referenced to the other datum ready. If it's all turning to a heap of manure there's always the 'stop climb now and advise the level' and I've got the mode C to help also.
In truth, particularly where the TA is 3000ft or 4000ft, it's not a common problem because it so rarely happens that a clearance needs to be changed whilst an aircraft is climbing through altitudes because it happens so quickly for most commercial ops type aircraft. Perhaps it's more frequent when descending but I haven't seen it done often. Of course, if TA is 10,000ft or 18,000ft it's going to be a different story.
Join Date: Oct 2005
Location: here and there
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
HP
I am an ATC enroute and approach controller and have worked in different worldwide jurisdictions. other than london where the TA is so low it barely matters, I would still expect PIC to have local/areaQNH set till passing TA on climb or passing TL on descent, especially in north america, australia, ME(for you intl pilots who fly there).
a late stop at an altitude on climb to FL's could happen at any time for any reason, so thus your co SOP's if memory serves me correctly are correct and QNH on the scale until TA. Tis also good airmanship as well as far as I am concerned .... and I also fly too.
hope that wraps it up!
cheers
I am an ATC enroute and approach controller and have worked in different worldwide jurisdictions. other than london where the TA is so low it barely matters, I would still expect PIC to have local/areaQNH set till passing TA on climb or passing TL on descent, especially in north america, australia, ME(for you intl pilots who fly there).
a late stop at an altitude on climb to FL's could happen at any time for any reason, so thus your co SOP's if memory serves me correctly are correct and QNH on the scale until TA. Tis also good airmanship as well as far as I am concerned .... and I also fly too.
hope that wraps it up!
cheers
Per Ardua ad Astraeus
Join Date: Mar 2000
Location: UK
Posts: 18,579
Likes: 0
Received 0 Likes
on
0 Posts
yy - from HP's post #10
Basically in the type I fly we have 2 main altimeters and 1 standby. The standby is ALWAYS set to 1013mb and the mains adjusted as we climb in accordance with SOPs (both mains are always sets the same).
So if we were to go to 1013mb when cleared to a flight level then we would have no altimeter set to QNH should ATC wish to stop our climb at an altitude. By keeping the main altimeters on QNH we can “express our vertical position in terms of FL” by reading off the standby AND stop the climb at any altitude as required.
....and thence the problem and why JD and I (at least) think his airline should review the SOPs.
Edit: Now we can add 'Max Angle'
Basically in the type I fly we have 2 main altimeters and 1 standby. The standby is ALWAYS set to 1013mb and the mains adjusted as we climb in accordance with SOPs (both mains are always sets the same).
So if we were to go to 1013mb when cleared to a flight level then we would have no altimeter set to QNH should ATC wish to stop our climb at an altitude. By keeping the main altimeters on QNH we can “express our vertical position in terms of FL” by reading off the standby AND stop the climb at any altitude as required.
....and thence the problem and why JD and I (at least) think his airline should review the SOPs.
Edit: Now we can add 'Max Angle'
Last edited by BOAC; 25th May 2008 at 07:00.
Blimey, three pages and counting. I am great believer in KISS (keep it simple stupid) and fortunately my airlines SOP agrees. Set 1013 as soon as you are cleared to FL no matter what the transition and set QNH as soon as you are cleared to altitude regardless of what FL you are at. If ATC want a check of alt. or FL when you have the other set use the standby and in the unlikely event that you are asked to stop at a intermediate level then just change the setting and level off.
I would suggest that the original posters airline are out of step with majority of other operators in this respect and are asking for a level bust.
I would suggest that the original posters airline are out of step with majority of other operators in this respect and are asking for a level bust.
