DME arc maximum speed?
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DME arc maximum speed?
Is there an ICAO published maximum speed to fly a DME arc beyond the IAF? Similarly does anyone know of arc maximum speeds in USA, Europe, UK?
Many thanks in advance.
Many thanks in advance.
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A DME arc is, I think, a part of the arrival/approach procedure. New PANS Ops distinguishes between aircraft categories, but typically, a cat C aircraft (Vat 121-140kt) will have a speed range of 160/240t during initial approach. A cat D aircraft (Vat 141/165) has a speed range of 185/250kt.
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A valid question....I guess, if you're taking an academic test.
But in the real world flying jets...
210IAS for inital approach manuevers clean,
180IAS (intermediate flap) for intercept and manuevers final approach outside marker,
160IAS approaching marker (gear down/another flap)
APP+10 1000ft agl Final flaps
Never lose sight of the big picture...If you practice the ignorant art of "measuring with a micrometer", I can assure you .....you will lose your flying skills, your confidence, and your air sense.
For you new pilots.....Make sure that you place a good deal of common sense between theory and practice.
But in the real world flying jets...
210IAS for inital approach manuevers clean,
180IAS (intermediate flap) for intercept and manuevers final approach outside marker,
160IAS approaching marker (gear down/another flap)
APP+10 1000ft agl Final flaps
Never lose sight of the big picture...If you practice the ignorant art of "measuring with a micrometer", I can assure you .....you will lose your flying skills, your confidence, and your air sense.
For you new pilots.....Make sure that you place a good deal of common sense between theory and practice.
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flying-elvis: thanks for your input. However, I've been flying jets for many years and I had a reason for asking the question. Any other answers, including any references would be very much appreciated.
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My apologies. I should've made my "micrometer" comments a separate thread on CRM. But I see to many fine piloting skills ruined by the politicis of company check airmen.
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A DME arc can be used within an Arrival segment, or Initial Approach, or even Intermediate Approach. Pans Ops speeds are different for each performance category, of course, and might differ in each of these segments. I say "might differ" because, while the Intermediate segment has no specific speed limit, it is assumed that pilots will be slowing down from Initial approach speed to the Final approach speed in this segment.
In some countries, speed in any of these segments might be further restricted by local rules, or even modified by a restriction on the particular chart.
Rules relating to "being established" on the arc can differ from State to State, based on their own interpretation of the protection parameters in Pans Ops, or on other factors that might be unique to a particular State. Off hand, I think that Australia allows a pilot to be established when within 2NM of the nominal radius. Here in PNG, it's necessary to be within 1NM.
Hope this helps.
In some countries, speed in any of these segments might be further restricted by local rules, or even modified by a restriction on the particular chart.
Rules relating to "being established" on the arc can differ from State to State, based on their own interpretation of the protection parameters in Pans Ops, or on other factors that might be unique to a particular State. Off hand, I think that Australia allows a pilot to be established when within 2NM of the nominal radius. Here in PNG, it's necessary to be within 1NM.
Hope this helps.
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Sorry I can't give you an ICAO answer, but a practical one may help. I have flown arcs at 210 kts in small turboprops but the turn on to the Final Approach Track / Localiser really is a knife edge well over max AoB to make the turn in time, and is far too gung-ho.
The same arcs I have flown in jets and would never recommend flying clean at 210. Initial approach flap for yor type and a speed of no more than 180kts. 160kts I have seen published in the standard profiles for two of the types I've flown, both jets.
And yes, I go with a mile either side of the arc and a sensible heading for being "established".
As a previous poster said, you can fly this too much on definitive theory rather than natural experience based skill. I would say however, that you won't go wrong flying the profile printed in your ops manual.
The same arcs I have flown in jets and would never recommend flying clean at 210. Initial approach flap for yor type and a speed of no more than 180kts. 160kts I have seen published in the standard profiles for two of the types I've flown, both jets.
And yes, I go with a mile either side of the arc and a sensible heading for being "established".
As a previous poster said, you can fly this too much on definitive theory rather than natural experience based skill. I would say however, that you won't go wrong flying the profile printed in your ops manual.
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As far as I am aware there is no maximum speed for flying a DME arc. Obviously the speed would depend on what you are flying and how close the arc is to the airport. If it leads straight into the IAF then fly the speed as you would do on any other intermediate approach. Adjusting the speed and configuration depending on the distance from the airport the IAF is.
Lead and lag and if you get confused aim at the IAF.
Lead and lag and if you get confused aim at the IAF.
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If you're flying in Europe - get a copy of New Pans OPS.
TERPS, if flying in the States.
As for "established", I'd say you're well within limits if inside +/- 2.5NM of the published arc. The primary obstacle clearance area includes a 2.5NM sector on either side of the arc, where the obstacle clearance is minimum 300m. From there on, the obstacle clearance decreases linearly to zero, when reaching 5nm either side of the arc. According to NPO.
TERPS, if flying in the States.
As for "established", I'd say you're well within limits if inside +/- 2.5NM of the published arc. The primary obstacle clearance area includes a 2.5NM sector on either side of the arc, where the obstacle clearance is minimum 300m. From there on, the obstacle clearance decreases linearly to zero, when reaching 5nm either side of the arc. According to NPO.
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Ojuka
I don't know what the official publications say in your part of the world but, here, they say that the 2NM lead for the turn off the DME arc will only work if your radius of turn is 2NM. Thus, if your speed produces a greater radius of turn, you need to start the turn sooner, to account for the radius. Of course, if you're going like a bat out of hell at the time, your turn radius could be so large as to take your aircraft out of the protection area.
Here's some figures, using Pans Ops calculations, to give you an idea of how it works out :-
Associated conditions :
Altitude : 4000 FT
Temp : ISA +15
AoB : 25 degrees
Wind : Assumed zero.
At 160 KIAS (174 KTAS) = 0.95 NM (rounded adversely)
At 180 KIAS (196 KTAS) = 1.21 NM (rounded adversely)
At 200 KIAS (218 KTAS) = 1.49 NM (rounded adversely)
At 220 KIAS (240 KTAS) = 1.80 NM (rounded adversely)
At 240 KIAS (261 KTAS) = 2.14 NM (rounded adversely)
Obviously some additional allowance might be wise, if you expect a tailwind during the turn, but the above figures should give you an idea of the base amount by which you need to lead the turn. As a matter of interest, the speed that comes closest to a 2NM turn radius in the above conditions is 232 KIAS (253 KTAS).
Thus, in zero wind conditions, a speed of about 230 KIAS is about the most that you can use with a sustained 25 degree AoB.
I'm with you, keithl! If there's a "new" Pans Ops, then I haven't got it either!
I have flown arcs at 210 kts in small turboprops but the turn on to the Final Approach Track / Localiser really is a knife edge well over max AoB to make the turn in time, and is far too gung-ho.
Here's some figures, using Pans Ops calculations, to give you an idea of how it works out :-
Associated conditions :
Altitude : 4000 FT
Temp : ISA +15
AoB : 25 degrees
Wind : Assumed zero.
At 160 KIAS (174 KTAS) = 0.95 NM (rounded adversely)
At 180 KIAS (196 KTAS) = 1.21 NM (rounded adversely)
At 200 KIAS (218 KTAS) = 1.49 NM (rounded adversely)
At 220 KIAS (240 KTAS) = 1.80 NM (rounded adversely)
At 240 KIAS (261 KTAS) = 2.14 NM (rounded adversely)
Obviously some additional allowance might be wise, if you expect a tailwind during the turn, but the above figures should give you an idea of the base amount by which you need to lead the turn. As a matter of interest, the speed that comes closest to a 2NM turn radius in the above conditions is 232 KIAS (253 KTAS).
Thus, in zero wind conditions, a speed of about 230 KIAS is about the most that you can use with a sustained 25 degree AoB.
I'm with you, keithl! If there's a "new" Pans Ops, then I haven't got it either!
Only half a speed-brake
Is it me or the thread missing the part that says you should most importantly stay within the speed limits prescribed at the given stage of approach, lest you aim to loose much more than just the piloting skills? Mostly applicable at "B" limited approaches where modern turboprops could easily overshoot any arc by a great margin in initial stages.
Also funny are the visual maneuvering radii at Greece, surprisingly about half of what you'd expect (based on TERPS, are they not?)
FD.
Also funny are the visual maneuvering radii at Greece, surprisingly about half of what you'd expect (based on TERPS, are they not?)
FD.
There is a big leap in turn radii between Cat B and Cat C aircraft - some, like the Metro and B1900, seem to fall between two stools. PANS OPS is being amended to reflect that operators must specify under which approach category they want particular aircraft types to be flown, and stick with it.
PANS OPS was developed from TERPS. In the intervening years, the two sets of criteria remain similar, with three main exceptions:
a. the missed approach
b. just about anything involving a turn
c. circling areas
c. is probably the most contentious, and the one area where US procedure specialists would agree TERPS is drastically inadequate.
The radii are far too small, and were probably one of the causal factors of the crash at Inchon a few years ago
PANS OPS was developed from TERPS. In the intervening years, the two sets of criteria remain similar, with three main exceptions:
a. the missed approach
b. just about anything involving a turn
c. circling areas
c. is probably the most contentious, and the one area where US procedure specialists would agree TERPS is drastically inadequate.
The radii are far too small, and were probably one of the causal factors of the crash at Inchon a few years ago
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Ozexpat -
The arcs I used to fly had a specified VOR radial that one had to cross which signified when the turn on to Final Approach Track / Localiser could be initiated.
With this printed on the plate there was no (approved) opportunity to start the turn early or late at pilot's discretion, so one was at the mercy of whatever speed the arc and final approach turn was designed for (again not printed).
Does this differ from your experience?
The arcs I used to fly had a specified VOR radial that one had to cross which signified when the turn on to Final Approach Track / Localiser could be initiated.
With this printed on the plate there was no (approved) opportunity to start the turn early or late at pilot's discretion, so one was at the mercy of whatever speed the arc and final approach turn was designed for (again not printed).
Does this differ from your experience?
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Well now I'll try a second time to post my reply. The first time I tried to reply, the system accused me of not being logged in - and, of course, I then couldn't get back to what I'd written! 
Wonder if a ModBod can find out what happened there?
keithl... always a pleasure to help a colleague!
reynoldsno1... I've heard a suggestion that the small circling radii were considered to be a contributory factor in that nasty prang in Colorado some years ago. The way I heard it, the FAA made some slight changes to enlarge circling areas, as a result of that finding and that at least some folks in the FAA think the circling radii need to be the same as Pans Ops. Time will tell though, I guess.
Ojuka... your right about it being unwise to commence the turn prior to the lead radial. Pans Ops requires us to provide a lead radial/bearing that equates to a 2 NM turn radius and there is no requirement to protect an earlier turn. It seems to me that your only option is to select a speed that will keep your turn radius within the 2 NM provided by the procedure.
In PNG, we don't have a problem with turn radius for this manoeuvre because we impose an overall speed limit of 170 knots on Cat A/B for Initial Approach and 200 knots for Cat C/D. This invariably means that, in zero wind, the turn radius of every aircraft is comfortably within the turn radius limits.
I would've thought that, in other parts of the world, there would be a duty of care to make some sort of regulatory comment about speed in that turn, if there's no speed limit on the chart or in the rules.
Personally, I make the turn at 170 knots in the B200 and this almost always results in a turn radius of 1.5 NM. I do some simple maths to derive a lead radial that equates to 1.5 NM, instead of the 2 NM and this almost always works out spot on.
This might not be totally suitable in your area of operations, if you regularly experience strong winds. We don't usually have a major problem with that and, even if we do, it's more likely to be a headwind than a tailwind, so it's not as critical to the turn. However, it should give you a basis for experimentation - in good wx of course!
Wonder if a ModBod can find out what happened there?keithl... always a pleasure to help a colleague!
reynoldsno1... I've heard a suggestion that the small circling radii were considered to be a contributory factor in that nasty prang in Colorado some years ago. The way I heard it, the FAA made some slight changes to enlarge circling areas, as a result of that finding and that at least some folks in the FAA think the circling radii need to be the same as Pans Ops. Time will tell though, I guess.
Ojuka... your right about it being unwise to commence the turn prior to the lead radial. Pans Ops requires us to provide a lead radial/bearing that equates to a 2 NM turn radius and there is no requirement to protect an earlier turn. It seems to me that your only option is to select a speed that will keep your turn radius within the 2 NM provided by the procedure.
In PNG, we don't have a problem with turn radius for this manoeuvre because we impose an overall speed limit of 170 knots on Cat A/B for Initial Approach and 200 knots for Cat C/D. This invariably means that, in zero wind, the turn radius of every aircraft is comfortably within the turn radius limits.
I would've thought that, in other parts of the world, there would be a duty of care to make some sort of regulatory comment about speed in that turn, if there's no speed limit on the chart or in the rules.
Personally, I make the turn at 170 knots in the B200 and this almost always results in a turn radius of 1.5 NM. I do some simple maths to derive a lead radial that equates to 1.5 NM, instead of the 2 NM and this almost always works out spot on.
This might not be totally suitable in your area of operations, if you regularly experience strong winds. We don't usually have a major problem with that and, even if we do, it's more likely to be a headwind than a tailwind, so it's not as critical to the turn. However, it should give you a basis for experimentation - in good wx of course!
Following all this with interest, and I'd just like to pick up Ojuka's point here.
Earlier than the L/R, I agree - you're outside the procedure. But later is surely OK? You used the phrase "could be initiated", and that's the way I teach it. Our helicopters are obviously on the slow side of Cat A (no Cat H in UK) and turning at the L/R would be too soon, so I describe it as marking the point where "you are free to turn a/r for the Final Approach Track".
Any of you experts disagree with that?
With this printed on the plate there was no (approved) opportunity to start the turn early or late at pilot's discretion
Any of you experts disagree with that?
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keithl... It's certainly difficult to conceive of an Authority that would not permit a turn at some appropriate point after passing the published Lead Radial. From memory (coz it's been a while since I've needed to look at it), Pans Ops requires publication of the lead radial as a warning that the aircraft is within 2NM of the next required track. Thus, it's up to the pilot to decide whether or not that is an appropriate distance to commence the turn off the arc.
There is certainly very little actual scope to commence the turn prior to the L/R so a pilot must anticipate the need to slow the aircraft to a speed where it can make a 2NM radius turn. But I'd be horrified if the official publications that Ojuka is using do not allow slower aircraft to proceed beyond the L/R before starting the turn. It is certainly allowed here in PNG and, I'm pretty sure, also in Oz.
Top marks for picking up that point - dunno how I missed it when reading his (or her?) post.
There is certainly very little actual scope to commence the turn prior to the L/R so a pilot must anticipate the need to slow the aircraft to a speed where it can make a 2NM radius turn. But I'd be horrified if the official publications that Ojuka is using do not allow slower aircraft to proceed beyond the L/R before starting the turn. It is certainly allowed here in PNG and, I'm pretty sure, also in Oz.
Top marks for picking up that point - dunno how I missed it when reading his (or her?) post.
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Keithl and Ozexpat -
My point on the restriction of the lead-in radial was meant to emphasise that it is TOO LATE for arcs flown at high speed; I didn't mean that the turn in couldn't be left until AFTER for slower aircraft.I appreciate this of course. My misprint.
The whole jist of my input was that anything over 180kts is uncomfortable in my experience and doesn't give much time for error correction. In a nutshell!
My point on the restriction of the lead-in radial was meant to emphasise that it is TOO LATE for arcs flown at high speed; I didn't mean that the turn in couldn't be left until AFTER for slower aircraft.I appreciate this of course. My misprint.
The whole jist of my input was that anything over 180kts is uncomfortable in my experience and doesn't give much time for error correction. In a nutshell!