Parallel entries to the racetrack
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On the Albi L09 it's "Hippodrome : T = 1 min 30", which means a 1 min 30 racetrack outbound.
The holding pattern is a standard 1 minute pattern and this is where you have the protection for the sector entries. All that achieves is to allow you to get onto the inbound holding track at least by the time you reach the NDB or Locator or whatever it is. You are then obliged to fly the racetrack before achieving final approach alignment as this is the only way that you'll have enough time for descent.
This will be the basis on which the procedure was designed. Do not make the mistake of thinking that your sector 1, 2 or 3 entry is protected by the longer time provided by the racetrack. It needs to be remembered that a racetrack is not a holding pattern, it is merely a method by which to achieve reversal. It is often quite a useful too for a procedure designer whenever there is a need to limit the amount of airspace that the procedure will occupy.
One reason for such a limitation might be a closely adjacent FIR boundary, but it could be for any number of other reasons too, of course. A great deal of airspace must be protected to cater for all the available sector entries, but this will only be protected within the confines the standard one-minute pattern, unless you are above MSA and have approval from ATC.
I hope this explains the situation but I'll keep checking back to this thread in case further clarification is required.
Thread Starter
OzExpat
Thanks for that. Can I just ask for clarification of what you're saying? And I'm asking about PANS-OPS procedures here, I won't ask you to speak for the French!
I'm having trouble squaring what you say with PANS-OPS Vol 1 3.3.2.2
Are you saying that racetrack entries (as opposed to holding pattern entries), are not, by default, protected?
Thanks for that. Can I just ask for clarification of what you're saying? And I'm asking about PANS-OPS procedures here, I won't ask you to speak for the French!
I'm having trouble squaring what you say with PANS-OPS Vol 1 3.3.2.2
Normally a racetrack procedure is used when aircraft arrive overhead the fix from various directions. In these cases, aircraft are expected to enter the procedure in a manner comparable to that prescribed for holding procedure entry with the following considerations:
a) Offset entry from sector 2 shall limit the time on the 30" offset track to 1 min 30 s, after which the pilot is expected to turn to a heading parallel to the outbound track for the remainder of the outbound time. If the outbound time is only 1 min, the time on the 30" offset track shall be 1 min also.
b) Parallel entry shall not return to the facility without first intercepting the inbound track when proceeding to the final segment of the approach.
c) All manoeuvring shall be done as far as possible on the manoeuvring side of the inbound track.
a) Offset entry from sector 2 shall limit the time on the 30" offset track to 1 min 30 s, after which the pilot is expected to turn to a heading parallel to the outbound track for the remainder of the outbound time. If the outbound time is only 1 min, the time on the 30" offset track shall be 1 min also.
b) Parallel entry shall not return to the facility without first intercepting the inbound track when proceeding to the final segment of the approach.
c) All manoeuvring shall be done as far as possible on the manoeuvring side of the inbound track.
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Bookworm,
Get your hands on a copy of RANT or even flight sim and try the Calais procedures. They can be done!
As far as I am aware, you are correct to say that one can make a parallel entry to the racetrack. Here is your para. b);
b) Parallel entry shall not return to the facility without first intercepting the inbound track when proceeding to the final segment of the approach
For that I read that if you are making a parallel entry and going straight into the final approach i.e. next time at the beacon you will track outbound to the mapt then you must not return to the facility without intercepting the inbound track.
The reason for that is the size of the final approach area at and beyond the beacon and the effect approaching the beacon at an offset angle could have on positioning in the final approach.
If however, you intend to go round the racetrack, you can return directly back to the beacon because that would place you no worse off than a direct entry.
Regards,
DFC
Get your hands on a copy of RANT or even flight sim and try the Calais procedures. They can be done!
As far as I am aware, you are correct to say that one can make a parallel entry to the racetrack. Here is your para. b);
b) Parallel entry shall not return to the facility without first intercepting the inbound track when proceeding to the final segment of the approach
For that I read that if you are making a parallel entry and going straight into the final approach i.e. next time at the beacon you will track outbound to the mapt then you must not return to the facility without intercepting the inbound track.
The reason for that is the size of the final approach area at and beyond the beacon and the effect approaching the beacon at an offset angle could have on positioning in the final approach.
If however, you intend to go round the racetrack, you can return directly back to the beacon because that would place you no worse off than a direct entry.
Regards,
DFC
Thread Starter
DFC
I agree with you (and para b, obviously) that you have to intercept the inbound track before reaching the facility. The issue is that, in order to descend according to the charted profile, you have to intercept the inbound track not just before reaching the facility but before the point at which you need to leave the altitude of the inbound turn.
In the case of Calais, you need to leave the altitude of the inbound turn (2000 ft) at 6.1d, some 2.1d before the MK, so you have to be established by then. I don't believe that can be done reliably with a sensible intercept angle, given that the outbound is just 1'30", i.e. potentially less than 3.5 miles.
Trying the scenario on a sim proves only that it's possible to manhandle an aeroplane in such a way that it sometimes works, presumably with some extreme intercept angle. I thought IAPs were designed so that they always work.
I agree with you (and para b, obviously) that you have to intercept the inbound track before reaching the facility. The issue is that, in order to descend according to the charted profile, you have to intercept the inbound track not just before reaching the facility but before the point at which you need to leave the altitude of the inbound turn.
In the case of Calais, you need to leave the altitude of the inbound turn (2000 ft) at 6.1d, some 2.1d before the MK, so you have to be established by then. I don't believe that can be done reliably with a sensible intercept angle, given that the outbound is just 1'30", i.e. potentially less than 3.5 miles.
Trying the scenario on a sim proves only that it's possible to manhandle an aeroplane in such a way that it sometimes works, presumably with some extreme intercept angle. I thought IAPs were designed so that they always work.
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Bookworm,
There is no need to manhandle the aircraft or to hae exceptional intercept angles.
With regard to intercept angles think back to your IR training days - if there was a very strong wind from say 160deg at Calais, you may use a 90deg intercept in a relatively slow aircraft and not fel uncomfortable because of the relatively slow groundspeed towards the inbound track. That would apply to turning inbound in the hold, turning inbound in the racetrack or turning inbound following a parallel join into the racetrack (to be followed by final approach).
However, with experience you will have a few tricks up your sleve that help ensure a perfect result every time. Again remember the IR training days in all those holds- better to be a bit wide and a bit long (within limits) and give yourself time to make a good intercept of the inbound track for a decent period of time.
Calais only poses a problem for you because you are flying a slow aircraft and with a low ground speed, the procedure timing does not position the aircraft far enough out to make a simple intercept.
Hint 1 - once within 5deg of the inbound course on the ADF you can descend to 1310. So if you are tight to the FAP just before intercept, you can effectively descend at something up to 1000ft/min to 1310 as soon as the ADF puts you in the right place. That will enable you to level and intercept the GS from below at the LOM. The justification for this is the Lctr approach not the ILS approach!
Now looking at the race-track. Think of the worst case scenario in no wind. Aircraft TAS 60Kt. No matter which way one does it (parallel entry or full racetrack) the aircraft will only be at 6 miles when the inbound turn is commenced. This is an exagerated example of your problem.
Hint 2 - the racetrack procedure is designed for aircraft to fly at up to 160Kt. If you are flying it at 120Kt and there is no actual wind then you can say that in theory you are causing your own 40Kt (160-120) headwind. Of course, once turned inbound you will still have that theoretical headwind so if you correct for it to the full it will take you a long time to get back to the beacon! However, there is scope for sensible corrections to the timing that will put you further out but not outside the limits of the procedure.
Remember that the racetrack is based purely on timimg.
However again having said all that, I have not had any problem with the procedure using 130Kt for the parallel entry straight into final approach or using the restriction on the jepp chart of requiring a 120kt speed to do the full racetrack before final approach.
Regards,
DFC
There is no need to manhandle the aircraft or to hae exceptional intercept angles.
With regard to intercept angles think back to your IR training days - if there was a very strong wind from say 160deg at Calais, you may use a 90deg intercept in a relatively slow aircraft and not fel uncomfortable because of the relatively slow groundspeed towards the inbound track. That would apply to turning inbound in the hold, turning inbound in the racetrack or turning inbound following a parallel join into the racetrack (to be followed by final approach).
However, with experience you will have a few tricks up your sleve that help ensure a perfect result every time. Again remember the IR training days in all those holds- better to be a bit wide and a bit long (within limits) and give yourself time to make a good intercept of the inbound track for a decent period of time.
Calais only poses a problem for you because you are flying a slow aircraft and with a low ground speed, the procedure timing does not position the aircraft far enough out to make a simple intercept.
Hint 1 - once within 5deg of the inbound course on the ADF you can descend to 1310. So if you are tight to the FAP just before intercept, you can effectively descend at something up to 1000ft/min to 1310 as soon as the ADF puts you in the right place. That will enable you to level and intercept the GS from below at the LOM. The justification for this is the Lctr approach not the ILS approach!
Now looking at the race-track. Think of the worst case scenario in no wind. Aircraft TAS 60Kt. No matter which way one does it (parallel entry or full racetrack) the aircraft will only be at 6 miles when the inbound turn is commenced. This is an exagerated example of your problem.
Hint 2 - the racetrack procedure is designed for aircraft to fly at up to 160Kt. If you are flying it at 120Kt and there is no actual wind then you can say that in theory you are causing your own 40Kt (160-120) headwind. Of course, once turned inbound you will still have that theoretical headwind so if you correct for it to the full it will take you a long time to get back to the beacon! However, there is scope for sensible corrections to the timing that will put you further out but not outside the limits of the procedure.
Remember that the racetrack is based purely on timimg.
However again having said all that, I have not had any problem with the procedure using 130Kt for the parallel entry straight into final approach or using the restriction on the jepp chart of requiring a 120kt speed to do the full racetrack before final approach.
Regards,
DFC
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Good question bookworm, thanks. It's been a real long time since I've looked at racetrack criteria and have never had to use one, so I got into the habit of thinking about them purely as reversal procedures. You're right, of course, in that Pans Ops requires protection for the sector entries - I looked it up today to confirm that, so it would appear that all sector entries are protected up to 1 minute and 30 seconds.
Thus, you would not be obliged to fly the full racetrack after completing the sector entry. Of course, if you elect to fly the standard 1 minute sector entry, all you've achieved is an entry to the holding pattern. In that event, you'd definitely need to go around the racetrack to provide the full time (ie distance) for descent on the inbound leg.
Of course, even if you fly the sector entry for the full time allowed by the racetrack, you're likely to lose some valuable time on the inbound leg by virtue of having to intercept the track, so it's probably a good idea to fly the full racetrack anyway. I have to look back at the Albi procedure to check (and don't have the time right now) but I have an idea that the maximum ROD has been fiddled a bit in that procedure.
I say that because the maximum ROD that can be designed in a final segment for Category A and B aircraft is only 655 feet per minute. Cat C, D and E can have up to 1,000 feet per minute. I suspect that the procedure doesn't quite cater for Category A and B aircraft on that basis.
I will try to have another look at the procedure within the next day or so and do some maths to confirm one way or the other.
Thus, you would not be obliged to fly the full racetrack after completing the sector entry. Of course, if you elect to fly the standard 1 minute sector entry, all you've achieved is an entry to the holding pattern. In that event, you'd definitely need to go around the racetrack to provide the full time (ie distance) for descent on the inbound leg.
Of course, even if you fly the sector entry for the full time allowed by the racetrack, you're likely to lose some valuable time on the inbound leg by virtue of having to intercept the track, so it's probably a good idea to fly the full racetrack anyway. I have to look back at the Albi procedure to check (and don't have the time right now) but I have an idea that the maximum ROD has been fiddled a bit in that procedure.
I say that because the maximum ROD that can be designed in a final segment for Category A and B aircraft is only 655 feet per minute. Cat C, D and E can have up to 1,000 feet per minute. I suspect that the procedure doesn't quite cater for Category A and B aircraft on that basis.
I will try to have another look at the procedure within the next day or so and do some maths to confirm one way or the other.
Thread Starter
Now looking at the race-track. Think of the worst case scenario in no wind. Aircraft TAS 60Kt. No matter which way one does it (parallel entry or full racetrack) the aircraft will only be at 6 miles when the inbound turn is commenced. This is an exagerated example of your problem.
But I like the train of thought, because I think it brings out the issue nicely. You're suggesting that, if the descent point is outside the facility used to define the racetrack, it's always possible to choose a speed for which you cannot reach the inbound track before the descent point.
However, there's a minimum speed for initial approaches of 90 knots. Thus I would have thought that, if sector 1 entries to the racetrack are authorised, it should always be possible to fly them at 90 knots, but possibly not at less. And I would have expected a design criterion for the minimum length of the racetrack leg time, dependent on the top of descent for the final approach, to allow that.
For example, if the racetrack leg had to be at least 1 min beyond the top of descent point (which allows something like a 30 degree intercept to work), and that top of descent point were 2 miles from the facility, that would oblige a minimum leg length of (2 miles / 90 kt) + 1 min = 2 min 20 secs. For 120 kt that could be reduced to 2 min, and for 150 kt it comes down to 1 min 48 sec. If you can't protect those lengths, then sector 1 joins should be explicitly forbidden.
But perhaps no such criterion exists.
In the particular case of Calais, it's complicated by some doubt about whether sector 1/2 entries are authorised below 130 kt.
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Well now that I have the time, I tried to look at that Albi L09 procedure again. Unfortunately, I had trouble downloading it and suspect that the local gateway server is the culprit. 
But, I've had another look at the Calais ILS24 procedure.
I have no understanding of French at all but I suspect that the speed limits relate to racetrack timing. If this is correct, then for aircraft IAS between 130 and 160 knots, outbound time is 1 min and 30 secs. And, for aircraft below 130 KIAS, outbound timing is 2 mins. I further suspect that sector entries to the racetrack are limited to a maximum timing of 1 min 30 secs, but I might be wrong about that.
I don't see anything that looks like a speed restriction on the standard 1 min holding pattern. If this is the case, you can use a higher speed than 160 KIAS to enter the hold and slow down for the racetrack.
I see that the minima box only caters for categories A to C and, while cat. C aeroplanes can handle 160 KIAS, it's a bit slow for some of the bigger cat. C types.
All in all, not the sort of procedure to start reading about just before you start to do it!
This one needs quite a bit of advance planning, to get the aircraft configured early.
But, I've had another look at the Calais ILS24 procedure.I have no understanding of French at all but I suspect that the speed limits relate to racetrack timing. If this is correct, then for aircraft IAS between 130 and 160 knots, outbound time is 1 min and 30 secs. And, for aircraft below 130 KIAS, outbound timing is 2 mins. I further suspect that sector entries to the racetrack are limited to a maximum timing of 1 min 30 secs, but I might be wrong about that.
I don't see anything that looks like a speed restriction on the standard 1 min holding pattern. If this is the case, you can use a higher speed than 160 KIAS to enter the hold and slow down for the racetrack.
I see that the minima box only caters for categories A to C and, while cat. C aeroplanes can handle 160 KIAS, it's a bit slow for some of the bigger cat. C types.
All in all, not the sort of procedure to start reading about just before you start to do it!
This one needs quite a bit of advance planning, to get the aircraft configured early.
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The SIA Chart has the following statement - Les entrées dans l'hippodrome de 1 min 30 sont protégées
Using an online translator this translates into - Entries in the racecourse from 1 min 30 are protected
It seems to me that Jeppesen has interpreted this to mean that entries into the racetrack when the still air timing is more than 1 min 30 are not protected...................thus is places the warning on it's chart requiring aircraft below IAS 130 to enter the racetrack only via the holding.
If you think you are going to have problems with the racetrack where you are using 2 minutes, have a look at the Locator/DME approach where there is no racetrack and aircraft enter the final approach from the hold!................However again like I suggested previously remember that the hold is protected for airspeeds up to 170Kt IAS!!
Regards,
DFC
Using an online translator this translates into - Entries in the racecourse from 1 min 30 are protected
It seems to me that Jeppesen has interpreted this to mean that entries into the racetrack when the still air timing is more than 1 min 30 are not protected...................thus is places the warning on it's chart requiring aircraft below IAS 130 to enter the racetrack only via the holding.
If you think you are going to have problems with the racetrack where you are using 2 minutes, have a look at the Locator/DME approach where there is no racetrack and aircraft enter the final approach from the hold!................However again like I suggested previously remember that the hold is protected for airspeeds up to 170Kt IAS!!
Regards,
DFC
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Yes DFC, I was just looking at the Calais L/DME approach and came up with some interesting numbers. In the best possible case, without DME, you have 1 minute to descend from 2000 FT to 1310 FT, which equates to a ROD of 690 FPM. You better hope that there's no tailwind component to deal with, or you'll be blown toward the Locator in the inbound turn in the hold and then have less time to descend.
The designer can get away with requiring a high ROD in the initial approach segment but the problem is that, if you don't reach 1310 FT by MK Locator, you're above profile for the final segment and have to use a higher ROD than is particularly comfortable.
However, as you can initiate descent during the inbound turn in the hold, when within 5 degrees of the track, it probably works out pretty well. Most of the time. Much nicer if you can use the DME of course because you've got an on-going monitor on your descent profile.
I've finally been able to look at that Albi L09 approach again too. It looks like I must've had the wrong idea about the outbound timing in the racetrack. My calculations tell me that the nil-wind ROD is less than 655 FPM and, on the whole, this approach seems pretty reasonable to me.
The designer can get away with requiring a high ROD in the initial approach segment but the problem is that, if you don't reach 1310 FT by MK Locator, you're above profile for the final segment and have to use a higher ROD than is particularly comfortable.
However, as you can initiate descent during the inbound turn in the hold, when within 5 degrees of the track, it probably works out pretty well. Most of the time. Much nicer if you can use the DME of course because you've got an on-going monitor on your descent profile.
I've finally been able to look at that Albi L09 approach again too. It looks like I must've had the wrong idea about the outbound timing in the racetrack. My calculations tell me that the nil-wind ROD is less than 655 FPM and, on the whole, this approach seems pretty reasonable to me.
