NDB Tracking with wind
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Apparently, it's OK to adjust "heading and timing" to skew the outbound track of a hold, as we all do, but not to adjust "heading and timing" to skew the outbound track of a course reversal, despite the same words
A racetrack is not a reversal procedure - it is a racetrack procedure. If using a racetrack procedure then you make the appropriate adjustments similar to the hold but remember that when the outbound timing is greather than 1 minute, you will only use single drift i.e. you will try to acurately follow the required track after 1 minute outbound.
Ask yourself why you use tripple drift outbound in the hold - the answer is to correct for wind efect in 1 the outbound turn, 2 then outbound leg and 3 the inbound turn.
On a reversal procedure (which can be a 45/180 or 80/260 procedure turn or a base turn) where the base leg procedure is used, you do not have an outbound turn to allow for, you will have track guidance provided (which you don't have on a racetrack or hold outbound) and the track will have an appropriate splay for both the distance outbound and the category of aircraft and thus apply appropriate drift and the protected area of the inbound turn is such as to allow for the afore mentioned crosswind.
Here is the appropriate quote from 8168 (my emphasis);
Reversal Procedure
The reversal procedure may be in the form of a procedure or base turn. Entry is restricted to a specific direction or sector. In these cases, a particular pattern, normally a base turn or procedure turn is prescribed and to remain within the airspace provided requires strict adherence to the directions and timings specified.......
Finally when thinking about changing the track from the one specified even when there is no risk of hitting obstacles remember that ATC often use the fact that one is established on the prescribed track to provide lateral spearation and to keep aircraft with the appropriate controlled airspace.
Regards,
DFC
A racetrack is not a reversal procedure - it is a racetrack procedure. If using a racetrack procedure then you make the appropriate adjustments similar to the hold but remember that when the outbound timing is greather than 1 minute, you will only use single drift i.e. you will try to acurately follow the required track after 1 minute outbound.
Ask yourself why you use tripple drift outbound in the hold - the answer is to correct for wind efect in 1 the outbound turn, 2 then outbound leg and 3 the inbound turn.
On a reversal procedure (which can be a 45/180 or 80/260 procedure turn or a base turn) where the base leg procedure is used, you do not have an outbound turn to allow for, you will have track guidance provided (which you don't have on a racetrack or hold outbound) and the track will have an appropriate splay for both the distance outbound and the category of aircraft and thus apply appropriate drift and the protected area of the inbound turn is such as to allow for the afore mentioned crosswind.
Here is the appropriate quote from 8168 (my emphasis);
Reversal Procedure
The reversal procedure may be in the form of a procedure or base turn. Entry is restricted to a specific direction or sector. In these cases, a particular pattern, normally a base turn or procedure turn is prescribed and to remain within the airspace provided requires strict adherence to the directions and timings specified.......
Finally when thinking about changing the track from the one specified even when there is no risk of hitting obstacles remember that ATC often use the fact that one is established on the prescribed track to provide lateral spearation and to keep aircraft with the appropriate controlled airspace.
Regards,
DFC
A racetrack is not a reversal procedure - it is a racetrack procedure.
On a reversal procedure ... where the base leg procedure is used, you do not have an outbound turn to allow for
and to remain within the airspace provided requires strict adherence to the directions and timings specified
3.3.3.6 Wind effect. Due allowance should be made in both heading and timing to compensate for the effects of wind to regain the inbound track as accurately and expeditiously as possible to achieve a stabilized approach.
? Looks to me as it is reminding pilots of the need to adhere to the corrected distances and timings.
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3.3.3 deals with both Racetrack and Reversal procedures. Your quote is dealing purely with racetrack procedures. Next you will be telling us that a racetrack must be entered from +/- 30 deg of the outbound track (also found in that part you are quoting from).!
In any procedure if you are provided with a track and a navigation aid to use when following that track then it is simple - you follow the track you are given.
Imagine that the leg you are looking at on your chart was the first leg of a SID that required a turn back overhead the beacon - would you leave the SID track to the upwind side or would you follow the track allowing for the crosswind and then do your best to intercept the inbound asap using the standard rate1/25deg bank?
Regards,
DFC
In any procedure if you are provided with a track and a navigation aid to use when following that track then it is simple - you follow the track you are given.
Imagine that the leg you are looking at on your chart was the first leg of a SID that required a turn back overhead the beacon - would you leave the SID track to the upwind side or would you follow the track allowing for the crosswind and then do your best to intercept the inbound asap using the standard rate1/25deg bank?
Regards,
DFC
3.3.3 deals with both Racetrack and Reversal procedures. Your quote is dealing purely with racetrack procedures. Next you will be telling us that a racetrack must be entered from +/- 30 deg of the outbound track (also found in that part you are quoting from).!
3.3.3 is Flight Procedures for Racetrack and Reversal Procedures
3.3.3.1 Entry. Unless the procedure specifies particular entry restrictions, reversal procedures shall be entered from a track within +/- 30 deg of the outbound track of the reversal procedure. However, for base turns, where the +/- 30 deg direct entry sector does not include the reciprocal of the inbound track, the entry sector is expanded to include it. For racetrack procedures, entry shall be as 3.3.2.2, unless other restrictions are specified. See Figures III-3-3, III-3-4 and ID-3-5.
(My italics)
3.3.3.2 Speed Restrictions, 3.3.3.3 Bank Angle, 3.3.3.4 Descent clearly all apply to both racetrack and reversals.
3.3.3.5 is entitled Outbound timing - racetrack procedure and is therefore designed to apply only to racetrack procedures.
3.3.3.6 is Wind Effect and clearly applies to both racetrack and reversals.
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The one thing that racetracks have in common with base turn procedures is that both are normally regarded as initial approach segments. Therefore, the outbound timing can be - and in all of the charts I've seen around the world, invariably is - longer than 1 minute. Two and three minute outbound timings are fairly common.
Therefore, the concept of "triple drift", as is often applied in a standard holding pattern, is not a good idea in an initial approach segment. Clearly, it is necessary to apply a correction for drift and/or timing (when approrpiate), but using a "triple drift" concept in the o/b leg of a racetrack could mean that your actual ground track will explore the outer extremeties of the protection area.
While this could obviously have consequences in relation to obstacles, ATC also apply separation based on the size of the primary protection area, plus a mile (I think). Therefore, while you might not hit a mountain, you could be giving another pilot some anxious moments.
Therefore, the concept of "triple drift", as is often applied in a standard holding pattern, is not a good idea in an initial approach segment. Clearly, it is necessary to apply a correction for drift and/or timing (when approrpiate), but using a "triple drift" concept in the o/b leg of a racetrack could mean that your actual ground track will explore the outer extremeties of the protection area.
While this could obviously have consequences in relation to obstacles, ATC also apply separation based on the size of the primary protection area, plus a mile (I think). Therefore, while you might not hit a mountain, you could be giving another pilot some anxious moments.
Therefore, the concept of "triple drift", as is often applied in a standard holding pattern, is not a good idea in an initial approach segment.
Examples:
Standard 1 min hold: (1 min + 2 x 1 min turns) = 3 min total to 1 min o/b so 3x drift
3 min ractrack: (3 min + 2 x 1 min turns) = 5 min total to 3 min o/b so ~1.7x drift
3 min base turn: (3 min + ~1 min turn) = 4 min total to 3 min o/b/ so ~1.3x drift
Of course the last one is the contentious one.
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3 min base turn: (3 min + ~1 min turn) = 4 min total to 3 min o/b/ so ~1.3x drift
Rubbish.
If one takes the extreme case, one will be tracking 30deg from the outbound leg at the start of the procedure. Thus one will have to intercept the outbound leg somewhere into the outbound timing or 3 minutes. Also if you only spend 1 minute turning, you will only complete 180degrees at rate 1 and thus will not only be heading across the inbound track but with the crosswind component that started this debate, you will disappear into the unprotected zone at a startling rate.
The whole notion of 3 x drift is used because no track guidance is available on the outbound leg of a hold or a racetrack procedure.
In a racetrack procedure of more than 1 minute outbound, the standard method of operation is to apply 3 X drift for the 1st minute and then reduce that to 1X drift for the remainder of the outbound time.
How can I explain this simply so that you will undestand?........
Imagine you had GPS guidance on the outbound leg of a racetrack procedure that enabled;
a) you to track the outbound leg with a certain amount of accuracy; and
b) the protected area to be reduced in accordance with your ability to track accurately outbound.
Would you not think it a tad dangerous to blindly apply 3 X drift even when it is clear that the protected area may not contain such an allowance and also worry that in the CFIT accident report, the data download the investigator takes from the avionics shows you outside the published required track?
Purely used as an example of course!
Regards,
DFC
Rubbish.
If one takes the extreme case, one will be tracking 30deg from the outbound leg at the start of the procedure. Thus one will have to intercept the outbound leg somewhere into the outbound timing or 3 minutes. Also if you only spend 1 minute turning, you will only complete 180degrees at rate 1 and thus will not only be heading across the inbound track but with the crosswind component that started this debate, you will disappear into the unprotected zone at a startling rate.
The whole notion of 3 x drift is used because no track guidance is available on the outbound leg of a hold or a racetrack procedure.
In a racetrack procedure of more than 1 minute outbound, the standard method of operation is to apply 3 X drift for the 1st minute and then reduce that to 1X drift for the remainder of the outbound time.
How can I explain this simply so that you will undestand?........
Imagine you had GPS guidance on the outbound leg of a racetrack procedure that enabled;
a) you to track the outbound leg with a certain amount of accuracy; and
b) the protected area to be reduced in accordance with your ability to track accurately outbound.
Would you not think it a tad dangerous to blindly apply 3 X drift even when it is clear that the protected area may not contain such an allowance and also worry that in the CFIT accident report, the data download the investigator takes from the avionics shows you outside the published required track?
Purely used as an example of course!
Regards,
DFC
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I read what you wrote bookworm. I'm not exactly sure how we managed to meander into racetracks and holding patterns, when the topic clearly centred on NDB tracking. One is demonstrably NOT tracking anything except DR on the o/b leg of a holding pattern or racetrack. I'm not going to get any further into any of that myself.
However, I feel that I must still take issue with you about using anything in excess of the actual amount of correction for drift. To take any more than that, you will not be anywhere near where you're expected to be, by the end of the o/b timing. You might still be within the procedure protection area, but I stress the word "might". That's a helluva word to use when considering the safety of the flight and your responsibilitity towards the pax.
And you also MIGHT have eroded some of the separation that ATC provides, to keep other aircraft way from you. If this is applied, it'll be based on the dimensions of the primary protection area, plus about a mile.
All in all, I believe that your Check Captain will - quite rightly - want to see that you remain within your 5-degrees tracking tolerance on the o/b and i/b leg. If you happen to get a check on a day (or night
) with 50+ knots of wind across the o/b leg, the Checkie might take more than a passing interest in the way you handle the approach... 
However, I feel that I must still take issue with you about using anything in excess of the actual amount of correction for drift. To take any more than that, you will not be anywhere near where you're expected to be, by the end of the o/b timing. You might still be within the procedure protection area, but I stress the word "might". That's a helluva word to use when considering the safety of the flight and your responsibilitity towards the pax.
And you also MIGHT have eroded some of the separation that ATC provides, to keep other aircraft way from you. If this is applied, it'll be based on the dimensions of the primary protection area, plus about a mile.
All in all, I believe that your Check Captain will - quite rightly - want to see that you remain within your 5-degrees tracking tolerance on the o/b and i/b leg. If you happen to get a check on a day (or night
) with 50+ knots of wind across the o/b leg, the Checkie might take more than a passing interest in the way you handle the approach...
However, I feel that I must still take issue with you about using anything in excess of the actual amount of correction for drift. To take any more than that, you will not be anywhere near where you're expected to be, by the end of the o/b timing.
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Bookworm,
The size of the protected area at the end of the outbound leg is suficient to contain the aircraft allowing for any inadvertant difference between the ideal and actual position of the aircraft.
Even if the protected area was 50nm either side, you would still be required to follow the given outbound track as accurately as possible. Thus the actual size of the protected area should have no influence on how accurately you try to fly the procedure.
Regards,
DFC
The size of the protected area at the end of the outbound leg is suficient to contain the aircraft allowing for any inadvertant difference between the ideal and actual position of the aircraft.
Even if the protected area was 50nm either side, you would still be required to follow the given outbound track as accurately as possible. Thus the actual size of the protected area should have no influence on how accurately you try to fly the procedure.
Regards,
DFC
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DFC, you really are a bore. You have an opinion on almost any subject and try to tell professionals, real professionals, how it should be done. You will get nowhere doing that.
There are two people you have rubbished, one of which has more experience in NDB approaches and procedures than you will ever have. He set them up in PNG and he is man to be respected. He knows what he is talking about believe me. You on the other hand just try to tell everyone how clever you are.
You might be but you are impressing no-one.
Get of your high horse and stop going round PPRuNe telling good FD people how to do their job. More than you know they know.
I agree with bookworm by the way. WHO mentioned reacetracks?
Give us a rest from your 'teaching grandmother to suck eggs.'
There are two people you have rubbished, one of which has more experience in NDB approaches and procedures than you will ever have. He set them up in PNG and he is man to be respected. He knows what he is talking about believe me. You on the other hand just try to tell everyone how clever you are.
You might be but you are impressing no-one.
Get of your high horse and stop going round PPRuNe telling good FD people how to do their job. More than you know they know.
I agree with bookworm by the way. WHO mentioned reacetracks?
Give us a rest from your 'teaching grandmother to suck eggs.'
PPRuNeaholic
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I wish that I could say that there's a "one size fits all" type of answer to that, but there isn't. The best that I can tell you is that the primary protection area comprises an allowance for along-track accuracy, which is equivalent to the assumed accuracy of the navaid - there is a broader allowance for an NDB than for a VOR, which reflects the better accuracy of the latter. This is combined with an assumption as to where the aircraft is likely to be at the end of the o/b timing. This has both a positive and negative factor based on TAS for the highest and lowest speed aircraft within the speed range for the category (or categories) allowed to use that particular o/b leg.
There is also an allowance for errors in the timing used by the pilot, plus an additional allowance for delay in recognising the end of the o/b leg and initiating the turn. There is also an allowance for an omni-directional wind during the turn. The velocity of this wind might be a "statistical value", or the standard "2h+47" in Pans Ops.
The primary area also includes protection for entry on 30 degrees either side of the o/b track. This is joined to the rest of the protection to build the primary area. There is also protection for the situation where the omni-directional wind carries the aircraft beyond the i/b track.
Surrounding this whole area is a secondary area that extends 2.5 NM laterally. Within this area, MOC reduces linearly to zero at the outer edge.
If you can get hold of Vol 1 of Pans Ops, it will probably describe it better than that. Vol 2 will certainly describe it better, but it's heavy reading for those who haven't done a Pans Ops course. In fact, it was heavy reading for me when I first started designing procedures, so it might be too technical for many folks.
I hope this helps.
There is also an allowance for errors in the timing used by the pilot, plus an additional allowance for delay in recognising the end of the o/b leg and initiating the turn. There is also an allowance for an omni-directional wind during the turn. The velocity of this wind might be a "statistical value", or the standard "2h+47" in Pans Ops.
The primary area also includes protection for entry on 30 degrees either side of the o/b track. This is joined to the rest of the protection to build the primary area. There is also protection for the situation where the omni-directional wind carries the aircraft beyond the i/b track.
Surrounding this whole area is a secondary area that extends 2.5 NM laterally. Within this area, MOC reduces linearly to zero at the outer edge.
If you can get hold of Vol 1 of Pans Ops, it will probably describe it better than that. Vol 2 will certainly describe it better, but it's heavy reading for those who haven't done a Pans Ops course. In fact, it was heavy reading for me when I first started designing procedures, so it might be too technical for many folks.
I hope this helps.
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No-one has mentioned IAS yet - so I will!
PANS-OPS 8168 para 1.6 gives the range of speeds for calculation of various segments of the approach procedure. Base turn is part of the initial approach, and for a Category C aircraft the speed range is 160 - 240 knots. In still air you will stay within the procedure anywhere within that range. So if you have a "tightening" crosswind for the turn onto the inbound track, make sure you are at low speed. Simple and practical.
It is unsafe to adjust the outbound track. Also simple.
Cheers, TP
PANS-OPS 8168 para 1.6 gives the range of speeds for calculation of various segments of the approach procedure. Base turn is part of the initial approach, and for a Category C aircraft the speed range is 160 - 240 knots. In still air you will stay within the procedure anywhere within that range. So if you have a "tightening" crosswind for the turn onto the inbound track, make sure you are at low speed. Simple and practical.
It is unsafe to adjust the outbound track. Also simple.
Cheers, TP
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With due respect to TyroPicard, the actual speed range for the Categories is dependent on how each State has implemented Pans Ops. For instance, I have an idea that the UK uses a maximum IAS somewhere around 180 or 185 knots for initial approach. In PNG, categories A/B are restricted to 170 KIAS and categories C/D to 200 KIAS.
I think that Jeppesen documents spell out all the implementation differences, but I don't know other such organisations.
I think that Jeppesen documents spell out all the implementation differences, but I don't know other such organisations.
