Mil rotary IR precision approach tolerances
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Moggie,
Just for my understanding, bear with me please!
How many civilian airfields are equipped with PAR, I haven't found many, hence my query regarding whether there would be widespread civilian use of a precision radar approach.
I assume, and it is a big assumption as i am not procedurally trained, that ILS and GPS approaches are both non-precision therefore DA(H) does not apply and therefore MDH(A) does. Am I wrong?
If I am right then does that not mean that there would not be widespread use of DH(A) by civilians?
Just for my understanding, bear with me please!
How many civilian airfields are equipped with PAR, I haven't found many, hence my query regarding whether there would be widespread civilian use of a precision radar approach.
I assume, and it is a big assumption as i am not procedurally trained, that ILS and GPS approaches are both non-precision therefore DA(H) does not apply and therefore MDH(A) does. Am I wrong?
If I am right then does that not mean that there would not be widespread use of DH(A) by civilians?
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HEDP
You are incorrect in your assumption. ILS and GPS are precision approaches. Where did you get the "radar" bit from?
DDW
Whilst I recognise your sarcasm, quite frankly, yes!
You are incorrect in your assumption. ILS and GPS are precision approaches. Where did you get the "radar" bit from?
DDW
Whilst I recognise your sarcasm, quite frankly, yes!
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The platform I operate is not cleared for ILS or GPS approaches. Hence I am answering from a radar approach perspective.
GPS approaches are practiced but emergency only and have to have a non-precision minima applied.
GPS approaches are practiced but emergency only and have to have a non-precision minima applied.
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Tourist, rest assured you are my first port of future call.
I have a reasonable grasp of the proceduresof an IRT though. My point is merely that the civvies seem do it better on this occasion, because in terms of precision approaches JSP 550 arguably leaves itself open to interpretation, Lasors section E does not.
Simples.
I have a reasonable grasp of the proceduresof an IRT though. My point is merely that the civvies seem do it better on this occasion, because in terms of precision approaches JSP 550 arguably leaves itself open to interpretation, Lasors section E does not.
Simples.
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Tourist: spot on with DH/MDH - operating to a DH/DA is a piece of cake and really doesn't need a lot of thought. An MDH/MDA is much more tricky if it involves the "fly level to the MAPt" section. That's why most of the UK airlines modify the MDA into a DA (as I posted earlier).
DDW: LASORS Section E still leaves a grey area because when I looked at it yesterday it only gave limits for an IMC test, not the (more stringent) IR test. Without seeing a copy iof the UK CAA examiners handbook, you are left to assume that the tolerances are the same.
HEDP: the only civilian airport at which I've done a PAR approach was Keflavik, Iceland (PAR provided by the US Navy). Their talkdown was less accurate than the VOR/DME (non-precision) approach that I'd just flown.
Civilian pilots are very unlikely to do a PAR approach but the staple diet is the ILS which is a precision approach, of course - and therefore the use of DA is almost universal. That's why I say that precision approaches are the staple diet of the civilian world.
DDW: LASORS Section E still leaves a grey area because when I looked at it yesterday it only gave limits for an IMC test, not the (more stringent) IR test. Without seeing a copy iof the UK CAA examiners handbook, you are left to assume that the tolerances are the same.
HEDP: the only civilian airport at which I've done a PAR approach was Keflavik, Iceland (PAR provided by the US Navy). Their talkdown was less accurate than the VOR/DME (non-precision) approach that I'd just flown.
Civilian pilots are very unlikely to do a PAR approach but the staple diet is the ILS which is a precision approach, of course - and therefore the use of DA is almost universal. That's why I say that precision approaches are the staple diet of the civilian world.
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Yeah DDW,
I also think you're confusing yourself into a point that doesn't exist.
The 200' (or 150' IIRC for rotary approaches) absolute minima is the lowest DH that can be used. That and the figures on the plates takes into account the descent post discussion. I'm sure someone will correct me but civvies can have much lower limits therefore it's safe to assume we're nowhere near the actual surveyed minima for an approach. So your concerns about busting a minima are unfounded.
I reckon you should worry about other things that your IR candidate is doing as I've yet to meet a pilot who couldn't make a decision at DH (I have however had a student who made he wrong decision - it turns out that basic studes are seldom still IMC at 200 feet and he'd kinda learned "200ft - decision - land" by rote, and promptly went quiet whilst attempting to land sans seeing.......)
HEDP - Are you really a Mil IRE and don't know what is a precision and non-precision approach, you might not have the kit to do it but that is a shocking lapse in knowledge - I bet your ground cat is a piece of........
I also think you're confusing yourself into a point that doesn't exist.
The 200' (or 150' IIRC for rotary approaches) absolute minima is the lowest DH that can be used. That and the figures on the plates takes into account the descent post discussion. I'm sure someone will correct me but civvies can have much lower limits therefore it's safe to assume we're nowhere near the actual surveyed minima for an approach. So your concerns about busting a minima are unfounded.
I reckon you should worry about other things that your IR candidate is doing as I've yet to meet a pilot who couldn't make a decision at DH (I have however had a student who made he wrong decision - it turns out that basic studes are seldom still IMC at 200 feet and he'd kinda learned "200ft - decision - land" by rote, and promptly went quiet whilst attempting to land sans seeing.......)
HEDP - Are you really a Mil IRE and don't know what is a precision and non-precision approach, you might not have the kit to do it but that is a shocking lapse in knowledge - I bet your ground cat is a piece of........
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Talk Reaction,
A bit barbed there mate. You can only IRE on the kit fitted, hence no procedural rating therefore no ILS. I fully know what constitutes a precision or non-precision radar approach thanks. Never done an ILS, if I ever do then I guess then would be the time to know the minima and approach.
No lapse involved, not fitted, not trained, no need to be!
HEDP
A bit barbed there mate. You can only IRE on the kit fitted, hence no procedural rating therefore no ILS. I fully know what constitutes a precision or non-precision radar approach thanks. Never done an ILS, if I ever do then I guess then would be the time to know the minima and approach.
No lapse involved, not fitted, not trained, no need to be!
HEDP
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I'm not confused actually but my point is not concerning approach minima or differences between mil/civvie etc. My point merely relates to JSP550 and the fact that the height limits for a mil instrument rating test are laid out oddly, stating "+/-100ft (but +100/-0ft on an MDH)" or very similar. Nothing more, crucially, for DH. So if a candidate on a white IRT flys a precision approach and calls 'decide' 50ft below HIS minima (but above the procedure minima) has he failed? Yes according to most mil pilots I speak to, no according to others as he is within the +/-100ft stipulated in JSP550 for IRT height limits.
And yes I know civvie rules are different but if one would care to look in Lasors section E and indeed JAR 2.210 then one would find that it is clearly laid down: +50ft/-0ft is the window to commence an overshoot for BOTH precision and non-precision approaches if you wish to gain an IMC rating or an IR. Much clearer.
Anyway, id much rather have a drink and a chat rather than engage in barbed exchanges for nil gain so cheers and good night all!
And yes I know civvie rules are different but if one would care to look in Lasors section E and indeed JAR 2.210 then one would find that it is clearly laid down: +50ft/-0ft is the window to commence an overshoot for BOTH precision and non-precision approaches if you wish to gain an IMC rating or an IR. Much clearer.
Anyway, id much rather have a drink and a chat rather than engage in barbed exchanges for nil gain so cheers and good night all!
Last edited by drugsdontwork; 7th Feb 2011 at 22:00.
I'm a civvy pilot and I've done a PAR (at Lyneham for a cloudbreak - bloody stupid idea though considering I had a coupled autopilot that could have done the ILS for me!)
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DDW,
A white rating adds 200' to the published minima for the pilot concerned therefore he flies to minima +200' with a tolerance of +100/-0 therefore a fail if he calls at 50' below the minima calculated with his rating added in.
A white rating adds 200' to the published minima for the pilot concerned therefore he flies to minima +200' with a tolerance of +100/-0 therefore a fail if he calls at 50' below the minima calculated with his rating added in.
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HEDP,
Show me where the tolerance is laid down for a precision approach! The +100/-0ft is mentioned ONLY for MDH (non precision) not DH (precision). My entire problem with this is that JSP550 does not specify a tolerance for precision approaches, only non precision. There appears to be confusion between accepted practice and what the book actually says in present form.
Show me where the tolerance is laid down for a precision approach! The +100/-0ft is mentioned ONLY for MDH (non precision) not DH (precision). My entire problem with this is that JSP550 does not specify a tolerance for precision approaches, only non precision. There appears to be confusion between accepted practice and what the book actually says in present form.
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The precision minima requires a decision at DH not 50 feet below it hence fail. Having taken the decision at (or before) DH you may transiently go below DH whilst re-establishing the climb.
Your entire problem seems to be that the precision minima requires a precise decision at DH, if you had a tolerance then it would not be a precise procedure with a precise decision as is required of a lower height during the go around.
You are quite correct in that a precise procedure requires a precise decision. Introduce tolerance then it becomes non-precise.
IMHO
Your entire problem seems to be that the precision minima requires a precise decision at DH, if you had a tolerance then it would not be a precise procedure with a precise decision as is required of a lower height during the go around.
You are quite correct in that a precise procedure requires a precise decision. Introduce tolerance then it becomes non-precise.
IMHO
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Erm...a couple of posts ago you mentioned a tolerance of +100/-0 yourself when we were talking about a precision approach.
If precision is to be just that and tolerance-free why do civvies have a +50/-0 tolerance?
And anyway I don't mind zero tolerance, it just needs to be stated so that Examiners can act accordingly. Yes, examiner discretion is good and proper but the lack of guidance here requires sorting out. The overiding mil regs document has guidance that currently splits opinion among our pilots and that is not ideal when the subject is instrument rating tests when consistency and uniformity are crucial.
I'm really done now: back to SAR H thread!!
If precision is to be just that and tolerance-free why do civvies have a +50/-0 tolerance?
And anyway I don't mind zero tolerance, it just needs to be stated so that Examiners can act accordingly. Yes, examiner discretion is good and proper but the lack of guidance here requires sorting out. The overiding mil regs document has guidance that currently splits opinion among our pilots and that is not ideal when the subject is instrument rating tests when consistency and uniformity are crucial.
I'm really done now: back to SAR H thread!!
Although this doesn't answer any of your burning questions re what is the mil tolerance, the following link may be of interest as it gives an insight into how one mil to Civ examinee and examiner saw things on one particular occasion:
http://www.pprune.org/rotorheads/391...l?highlight=IR
http://www.pprune.org/rotorheads/391...l?highlight=IR
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I had an amber, non-procedural IR as a student on the JP3 in the early 80s - it just meant that I had to be vectored onto the ILS rather than self positioning (procedural). I got a procedural rating on the Jetstream because that had enough kit for me to be able to find my way around without help from ATC.
You do seem a bit confused because at one point you said to me that you assumed that an ILS was "not a precision approach" and at another point you tell Talk Reaction that you "fully know what constitues a precision or non-precision approach".
I assume that your "if you introduce a tolerance it becomes imprecise" comment was intended to be tongue in cheek - but of course it's not correct! A precision approach DOES have a tolerance because no-one can fly the localiser and glideslope 100% accurately and, depending on how fast you speak, your "decide" call will not be exactly at DA/DH - but it must not be late. The term "precision" means that you get guidance in both azimuth and elevation, whereas non-precision approaches only give azimuth guidance and require you to sort our your own elevation.
Hence PAR and ILS are precision approaches, but NDB/DME, VOR/DME or SRA (for example) are non-precision approaches.
DDW: you don't need to set a -0' tolerance for a DA/DH because the definition says that they are the LOWEST Altitude/Height at which you make the decision. Whilst JSP550 may not say -0' the definition makes it clear.
The upper limit is set because the examiner doesn't want to see you break off the approach early - he needs to see you go to/almost to DA/DH because that's what you will have to do in marginal conditions.
Last edited by moggiee; 8th Feb 2011 at 09:52.
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Moggiee,
Incorrect. Mil AIP definition of DH makes no mention of lowest (unlike MDH). Therefore I refer back to JSP 550 which gives a height tolerance of +/-100 with the only caveat specified for an MDH. Ergo, call decide up to 100ft below your minima (assuming still above procedure minima) and pass your IRT.
I am of course playing devils advocate but it illustrates the ambiguity. What 550 needs is a line saying call "decide" not below your DH minima. Ideally, to make the test objective, a plus height tolerance should be inserted too to minimize unnecessary examiner discretion.
I'm actually boring myself now with all this!
Incorrect. Mil AIP definition of DH makes no mention of lowest (unlike MDH). Therefore I refer back to JSP 550 which gives a height tolerance of +/-100 with the only caveat specified for an MDH. Ergo, call decide up to 100ft below your minima (assuming still above procedure minima) and pass your IRT.
I am of course playing devils advocate but it illustrates the ambiguity. What 550 needs is a line saying call "decide" not below your DH minima. Ideally, to make the test objective, a plus height tolerance should be inserted too to minimize unnecessary examiner discretion.
I'm actually boring myself now with all this!
