Leaving a holding pattern
Originally Posted by Spendid Cruiser
You will have explain where I was inconsistent. Regardless, ICAO says stay within the limits of the pattern. To me that means stay within the pattern as much as possible.
Course reversals are defined in detail in the ICAO Flight Procedures doc. If it doesn't fall under that definition, as you have already identified, then it is just an Initial Approach Segment as also defined in the docs.
Guest
Join Date: Apr 2009
Location: On the Beach
Posts: 3,336
Likes: 0
Received 0 Likes
on
0 Posts
bookworm:
Indeed, if you arrive via the TGO 343 radial (without an instruction to hold) you turn left to intercept the 254 radial. And, in my circumstance of being in the hold then turning right to a heading of 300 degrees to intercept the TGO 254 radial, I would subsequently turn left from that 300 degree heading to intercept the 254 radial.
I'm sorry for labouring this one, but it does seem that there's still an ambiguity. If I'm inbound on track 343 to TGO on the REUTL4A arrival and cleared for the approach with no mention of the hold, surely I'm supposed to make a 90 degree left turn on to 254, and the procedure designer is supposed to check that I can do so safely, because it's part of the classic arrival-approach depicted in PANS-OPS fig I-4-1-1 "Segments of instrument approach". But because there's a hold depicted there turning left from the inbound leg is suddenly unprotected?!
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes
on
0 Posts
Bookworm,
Two distinct issues. One was a response from somebody stating they didn't know where the definition for a reversal was and the other is discussing the issue in hand - leaving a hold.
Blooper: I see that I have been writing "intermediate" when I meant to write "initial"
Perhaps that clears it up?
I'm advocating the green route.
Two distinct issues. One was a response from somebody stating they didn't know where the definition for a reversal was and the other is discussing the issue in hand - leaving a hold.
Blooper: I see that I have been writing "intermediate" when I meant to write "initial"
Perhaps that clears it up?I'm advocating the green route.
Useful diagram. The blue route you draw is an interesting one: you assume anticipation of the TGO (fly-by) for the REUTL4A arrival, but not for leaving the hold.
If you allow similar anticipation, and scale the size of the hold to reflect the radii you've drawn, then there are a number of other possibilities. One is to make a left turn from the beginning of the inbound leg, but then one starts to ask "why not simply roll out of the inbound turn on a heading of 300?" Which is not so dissimilar from the green route!
If you don't allow such anticipation, the blue route is not so far away from the red route.
If you draw the same diagrams for the LBU hold, I think you'd be hard pressed to reject that 52 degree right turn on to the initial approach 230 track. That's much less extreme than the turn from the BADSO1A arrival. But one can keep finding examples of such holds at different angles (take a look at EDDF), so where do you set the limit? Is it "30 degrees max or you must manoeuvre in the hold" as for a course reversal? But there's no mention of that in PANS-OPS.
You can see why RNAV/RNP is so popular...
If you allow similar anticipation, and scale the size of the hold to reflect the radii you've drawn, then there are a number of other possibilities. One is to make a left turn from the beginning of the inbound leg, but then one starts to ask "why not simply roll out of the inbound turn on a heading of 300?" Which is not so dissimilar from the green route!
If you don't allow such anticipation, the blue route is not so far away from the red route.
If you draw the same diagrams for the LBU hold, I think you'd be hard pressed to reject that 52 degree right turn on to the initial approach 230 track. That's much less extreme than the turn from the BADSO1A arrival. But one can keep finding examples of such holds at different angles (take a look at EDDF), so where do you set the limit? Is it "30 degrees max or you must manoeuvre in the hold" as for a course reversal? But there's no mention of that in PANS-OPS.
You can see why RNAV/RNP is so popular...
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes
on
0 Posts
Thanks, wobbly hand drawn so don't give too much weight to where the lines fall. Yes, I was thinking about that anticipation. I think the 737 FMC would anticipate the turn on the IAF, but would pass fly over the 11.4d point before turning. But if you don't anticipate then you fly through TGO and onto the other side which is what we have been saying one should avoid!
I think you may intercept 254º later than desirable (in reality, at 230kts the hold would be much bigger than drawn), IMHO best keep the right turn going until a suitable track for intercept of the initial has been attained.
One is to make a left turn from the beginning of the inbound leg
Join Date: Mar 2002
Location: Euroland
Posts: 2,814
Likes: 0
Received 0 Likes
on
0 Posts
Can I start this post with a plea - that might seem obvious - at a turn point always turn the shortest way to the next track (unless there is something specified to the contrary).
Seems that some people have forgotten this very important principle and the fact that the turn area only protects turns in this direction.
Turns are specified either at a fix or at an altitude.
In this case TGO is a fix where a turn is specified.
This is not a reversal procedure (Procedure turn or base turn). Therefore the requirement to enter +/- 30 does not apply.
The fact that there also happens to be a hold at this fix is simply a distraction.
If cleared to proceed beyond the IAF one must cross the IAF.
If one is in the hold then when cleared for the approach one must route via the IAF and at the IAF turn in the shortest manner to establish outbound from the IAF.
At 5000ft one is terrain safe for the turn shortest way round and since one can not descend to 4000ft until established outbound in terms of when one can descend to 4000ft there is no gain by doing some unnecessary long turn.
Turning the long way round can cause a number of problems. Imagine how far the aircraft is going to drift during all that time when there is a very strong tailwind on the inbound leg of the hold. It is possible that some aircraft turning the long way round could end up pointing at TGO from the northeast. They would then have to cross TGO again (possible from an unplanned direction) and after crossing the fix turn right to establish outbound. The aircraft in this case would be in a situation where it is turning through was was designed as the inside of the turn area and the posibility of going outside the protected airspace is high.
Furthermore, one has to remember that the turn to establish on the Initial Approach segment must be made at a fix. If one continues the hold i.e. turns right at TGO then from the moment TGO is passed the aircraft is no longer tracking any navaid and is operating on DR. One simply compounds the problem here by trying to establish on the Initial Approach leg somewhere west of TGO.
The size of the protected airspace to cope with (the worst case) situation where and aircraft turns the long way round and then DR's to some point west of TGO will be far bigger than the airspace required for a simple turn.
ICAO 8168 is very specific with regard to fix tolerance for the IAF. Turning the long way round can negate the fact that TGO and the Initial Approach Leg complies with those requirements.
So in this case, no matter where one is in the hold, when cleared to proceed beyond the IAF one must route to TGO and at TGO - the specified turn fix - turn the shortest way round to establish on the initial approach.
Remember that the altitudes charted are minimum altitudes. There is no rush to get down to 4000ft just to fly level for an age. While I don't know what the local plan is, Non-Radar, procedural I would not be holding an aircraft at TGO, 5000ft with another aircraft on approach because if there is a missed approach you have a conflict. There is plenty of room to hold 1000ft above the missed approach altitude and once established on the initial approach, just look at all the miles available to loose 2000ft.
If it is not procedural (non-radar) then hey you are going to be vectored!!
Seems that some people have forgotten this very important principle and the fact that the turn area only protects turns in this direction.
Turns are specified either at a fix or at an altitude.
In this case TGO is a fix where a turn is specified.
This is not a reversal procedure (Procedure turn or base turn). Therefore the requirement to enter +/- 30 does not apply.
The fact that there also happens to be a hold at this fix is simply a distraction.
If cleared to proceed beyond the IAF one must cross the IAF.
If one is in the hold then when cleared for the approach one must route via the IAF and at the IAF turn in the shortest manner to establish outbound from the IAF.
At 5000ft one is terrain safe for the turn shortest way round and since one can not descend to 4000ft until established outbound in terms of when one can descend to 4000ft there is no gain by doing some unnecessary long turn.
Turning the long way round can cause a number of problems. Imagine how far the aircraft is going to drift during all that time when there is a very strong tailwind on the inbound leg of the hold. It is possible that some aircraft turning the long way round could end up pointing at TGO from the northeast. They would then have to cross TGO again (possible from an unplanned direction) and after crossing the fix turn right to establish outbound. The aircraft in this case would be in a situation where it is turning through was was designed as the inside of the turn area and the posibility of going outside the protected airspace is high.
Furthermore, one has to remember that the turn to establish on the Initial Approach segment must be made at a fix. If one continues the hold i.e. turns right at TGO then from the moment TGO is passed the aircraft is no longer tracking any navaid and is operating on DR. One simply compounds the problem here by trying to establish on the Initial Approach leg somewhere west of TGO.
The size of the protected airspace to cope with (the worst case) situation where and aircraft turns the long way round and then DR's to some point west of TGO will be far bigger than the airspace required for a simple turn.
ICAO 8168 is very specific with regard to fix tolerance for the IAF. Turning the long way round can negate the fact that TGO and the Initial Approach Leg complies with those requirements.
So in this case, no matter where one is in the hold, when cleared to proceed beyond the IAF one must route to TGO and at TGO - the specified turn fix - turn the shortest way round to establish on the initial approach.
Remember that the altitudes charted are minimum altitudes. There is no rush to get down to 4000ft just to fly level for an age. While I don't know what the local plan is, Non-Radar, procedural I would not be holding an aircraft at TGO, 5000ft with another aircraft on approach because if there is a missed approach you have a conflict. There is plenty of room to hold 1000ft above the missed approach altitude and once established on the initial approach, just look at all the miles available to loose 2000ft.
If it is not procedural (non-radar) then hey you are going to be vectored!!
Last edited by DFC; 29th Dec 2010 at 10:16.
Guest
Join Date: Apr 2009
Location: On the Beach
Posts: 3,336
Likes: 0
Received 0 Likes
on
0 Posts
DFC:
In this hypothetical discussion we don't know what the local plan is, either. But, it is a fact that the TGO 228 radial holding pattern is shown on an ILS 07 arrival chart, as well as on the approach chart. So, it is presumably there to absorb arrival delays on occasion as well as provide a terminus for the missed approach. If arrivals are held there on occasion, perhaps they are held at 6,000, or higher. Or, perhaps if arrivals are held there then alternative missed approach instructions are issued to an aircraft on the approach. We don't know any of that.
If radar vectors are used, then perhaps the missed approach holding becomes moot; or perhaps the arrival holding becomes moot.
The point of the hypothetical is: what is the best manner in which to depart the hold for the ILS 07 approach whether an arrival or a missed approach airplane. Turning left at TGO is not the prudent option. Returning to TGO if outbound in the hold may not be the best option, either.
However, turning left in a fly-by maneuver southwest of TGO is the proper method on arrival from the south without the hold being assigned. The illustration above shows how a modern FMS would calculate and excute the course change from the TGO 163 radial to the 254 radial absent the holding pattern.
As to descent, modern FMSes don't descend any sooner than necessary. "TOD" (top of descent) along the 254 radial in the illustration on Post 46 is where an aircraft arriving at 5,000 from the south would leave 5,000 for 4,000--well after being established on the 254 radial.
Remember that the altitudes charted are minimum altitudes. There is no rush to get down to 4000ft just to fly level for an age. While I don't know what the local plan is, Non-Radar, procedural I would not be holding an aircraft at TGO, 5000ft with another aircraft on approach because if there is a missed approach you have a conflict. There is plenty of room to hold 1000ft above the missed approach altitude and once established on the initial approach, just look at all the miles available to loose 2000ft.
If radar vectors are used, then perhaps the missed approach holding becomes moot; or perhaps the arrival holding becomes moot.
The point of the hypothetical is: what is the best manner in which to depart the hold for the ILS 07 approach whether an arrival or a missed approach airplane. Turning left at TGO is not the prudent option. Returning to TGO if outbound in the hold may not be the best option, either.
However, turning left in a fly-by maneuver southwest of TGO is the proper method on arrival from the south without the hold being assigned. The illustration above shows how a modern FMS would calculate and excute the course change from the TGO 163 radial to the 254 radial absent the holding pattern.
As to descent, modern FMSes don't descend any sooner than necessary. "TOD" (top of descent) along the 254 radial in the illustration on Post 46 is where an aircraft arriving at 5,000 from the south would leave 5,000 for 4,000--well after being established on the 254 radial.
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes
on
0 Posts
Can I start this post with a plea - that might seem obvious - at a turn point always turn the shortest way to the next track (unless there is something specified to the contrary).
Seems that some people have forgotten this very important principle and the fact that the turn area only protects turns in this direction.
Seems that some people have forgotten this very important principle and the fact that the turn area only protects turns in this direction.
Also, by my reckoning, if a medium jet turned left out of the hold it would intercept the initial just in time to start the descent. If it turned right it would have a nm to spare.
Neither tailwinds or DR is relevant as a right turn would stay with the holding pattern until a track of 300º had been achieved to intercept the initial.
It doesn't matter what way you cut it, staying south of TGO for any manoeuvring is covered by the hold, the initial and the arrival buffer areas.
Join Date: Mar 2002
Location: Euroland
Posts: 2,814
Likes: 0
Received 0 Likes
on
0 Posts
Shortest by what measure?
Also, by my reckoning, if a medium jet turned left out of the hold it would intercept the initial just in time to start the descent. If it turned right it would have a nm to spare.
Neither tailwinds or DR is relevant as a right turn would stay with the holding pattern until a track of 300º had been achieved to intercept the initial.
The only time it is not relevant is when the aircraft is tracking inbound to or outbound from TGO. While turning the aircraft is being drifted downwind. From the completion of the turn until the aircraft has established on the outbound radial the aircraft is operating on DR. The amount the aircraft drifts during the turn depends on how long the aircraft spends turning. the amount the aircraft drifts on the DR leg to intercept depends on what wind info is available and how the pilot uses it.
The easiest way to look at this is to remember that you want to spend the minimum amount of time with no tracking information. You do not help yourself in this regard by increasing the time spent turning.
Finally, it is very possible that having turned the wrong way, when a track of 300 is acheived the aircraft will be positioned in such a place that a track of 300 will not intercept the outbound radial and will fail tom return to TGO. not a good place to be eh?
It doesn't matter what way you cut it, staying south of TGO for any manoeuvring is covered by the hold, the initial and the arrival buffer areas.
You fail to recognise that with a strong northerly wind, your aircraft will establish on the track of 300 some way south of the still air point for the start of the hold outbound leg. The aircraft will then track 300 which will cause it to miss TGO and leave the holding area. How do you know that where the aircraft leaves the holding area it will be within the middle half of the Initial Approach area (wher obstacle clearance is assured? Or that it will be within the turn area designed for a correct direction turn?
The turn fix is TGO. Treat it as such - a turn fix - a turn at the IAF. Forget the hold as soon as you are cleared beyond the IAF and route to TGO where you make an appropriate turn to establish outbound and not to fly tyhe hold again (unless you want ATC to repeat the clearance to proceed beyond the IAF because it looks to them that you are flying another hold) and they do not expect you to turn the wrong way.
Join Date: Dec 2007
Location: paradise
Posts: 559
Likes: 0
Received 0 Likes
on
0 Posts
I'll take a simplified look at that, being at 5000 ft is above MSA in all sectors (highest being 4700) thus it doesn't matter which way one turns as long as 5000 is maintained till established on 254 outbound. However I'd agree with the shortest way version simply coz the box would do it too. MVA in this sector is 4000 ft and then 3500 on downwind, so I presume that's what ATC will do as well. In this context 5000 ft holding over TGO is more suitable for MA.
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes
on
0 Posts
DFC,
Apart from TGO being a fix, I don't think I agree with anything you've written. I suspect in the absence of any clear an unambiguous guidance it is left to judgement. We've each made our points and we're not going to agree
Apart from TGO being a fix, I don't think I agree with anything you've written. I suspect in the absence of any clear an unambiguous guidance it is left to judgement. We've each made our points and we're not going to agree
Join Date: Mar 2002
Location: Euroland
Posts: 2,814
Likes: 0
Received 0 Likes
on
0 Posts
No problem.
I am using DOC8168 as a reference.
What are you using?
Can you provide some reference to DOC8168 or TERPS that shows a turn area constructed for a "long way round" turn?
As someone said earlier, will you turn in the direction of the hold at the other IAFs when given onward clearance?
I am using DOC8168 as a reference.
What are you using?
Can you provide some reference to DOC8168 or TERPS that shows a turn area constructed for a "long way round" turn?
As someone said earlier, will you turn in the direction of the hold at the other IAFs when given onward clearance?
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes
on
0 Posts
Using the same ICAO doc, standard fare in the Jepps on the flight deck.
Would I keep the turn as much as possible within the 1000' clearance buffer area in IMC? Yes I would
As someone said earlier, will you turn in the direction of the hold at the other IAFs when given onward clearance?
Guest
Join Date: Apr 2009
Location: On the Beach
Posts: 3,336
Likes: 0
Received 0 Likes
on
0 Posts
DFC:
In this hypothetical there is a holding pattern we are parked in and there is a straight initial approach segment. The holding pattern at this location mandates right turns, which may seem to be the long way around if viewed as a "turn area" rather than a holding pattern.
Another aspect is that the charting makes the pattern appear to not overlap the initial approach segment. If you construct either the TERPs or the PANS-OPs containment areas for both the holding pattern and the R-254 initial approach segment, you will see that the holding pattern containment area extends well beyond the centerline of the TGO 254 radial.
I'll construct both the pattern and the initial segment using TERPs and post it. PANS-OPS would have some differences but they would not be significant.
Can you provide some reference to DOC8168 or TERPS that shows a turn area constructed for a "long way round" turn?
Another aspect is that the charting makes the pattern appear to not overlap the initial approach segment. If you construct either the TERPs or the PANS-OPs containment areas for both the holding pattern and the R-254 initial approach segment, you will see that the holding pattern containment area extends well beyond the centerline of the TGO 254 radial.
I'll construct both the pattern and the initial segment using TERPs and post it. PANS-OPS would have some differences but they would not be significant.
Guest
Join Date: Apr 2009
Location: On the Beach
Posts: 3,336
Likes: 0
Received 0 Likes
on
0 Posts
This is a to-scale illustration of the TGO holding pattern (230 knots @ 6,000) primary containment area and the TGO 254 radial initial approach segment's primary containment area. (using U.S. TERPs).
Join Date: Mar 2002
Location: Euroland
Posts: 2,814
Likes: 0
Received 0 Likes
on
0 Posts
PANS OPS has some quite significant differences. However, let's stick with one standard even if it is not the applicable one.
Can you please construct a turn area based on an aircraft flying inbound to TGO on the same radial that is the inbound leg of the hold and making a left turn at the fix?
Can you also plot the primary and secondary areas of the various holding and initial approach sectors you have described.
Thank you
As I said, being in the hold is simply a distraction and there is absolutely no requirement to continue in the hold once given onward clearance.
Having designated TGO as a turn fix the procedure designer has to design the turn area - in the appropriate direction. They do not expect aircraft to turn in the wrong direction. The protected airspace for the turn will be different from the protected airspace for the hold and by turning the wrong way you can cause problems because once established inbound in the hold, if then cleared to proceed beyond TGO on the Initial Approach leg, ATC are entitled to assume that you will turn left and base separation on that.
You could find that for example an aircraft which is established inbound on the hold and cleared for the approach is deemed separated from an aircraft on a departure because the departure protected area and the turn area (to the left) do not intersect. If you turn right without clearance you can cause big problems.
So like I said - can anyone give me an example from PANS-OPS or TERPS of a turn at at fix which is initially away from the desired onward track?
Can you please construct a turn area based on an aircraft flying inbound to TGO on the same radial that is the inbound leg of the hold and making a left turn at the fix?
Can you also plot the primary and secondary areas of the various holding and initial approach sectors you have described.
Thank you
As I said, being in the hold is simply a distraction and there is absolutely no requirement to continue in the hold once given onward clearance.
Having designated TGO as a turn fix the procedure designer has to design the turn area - in the appropriate direction. They do not expect aircraft to turn in the wrong direction. The protected airspace for the turn will be different from the protected airspace for the hold and by turning the wrong way you can cause problems because once established inbound in the hold, if then cleared to proceed beyond TGO on the Initial Approach leg, ATC are entitled to assume that you will turn left and base separation on that.
You could find that for example an aircraft which is established inbound on the hold and cleared for the approach is deemed separated from an aircraft on a departure because the departure protected area and the turn area (to the left) do not intersect. If you turn right without clearance you can cause big problems.
So like I said - can anyone give me an example from PANS-OPS or TERPS of a turn at at fix which is initially away from the desired onward track?
Last edited by DFC; 30th Dec 2010 at 16:47.
Join Date: Mar 2002
Location: Euroland
Posts: 2,814
Likes: 0
Received 0 Likes
on
0 Posts
Would I keep the turn as much as possible within the 1000' clearance buffer area in IMC?
I asked - Would you turn the wrong way at any of the other IAF's?
The procedure designer will have contructed a turn area - why do you feel the need to make up your own procedure?
Can you give us an example of another situation where you will turn the wrong way simply because there is a hold (which you are not cleared to follow) at the turn fix?
Guest
Join Date: Apr 2009
Location: On the Beach
Posts: 3,336
Likes: 0
Received 0 Likes
on
0 Posts
DFC:
I don't think we are communicating. The immediately preceding illustration shows the primary areas for both sectors, as you call them. The secondaries are irrelevant to this discussion, but they are two miles wide around the holding pattern and on each side of the initial segment primaries. I chose to leave them off for clarity and to show the airspace that is protected for ATC purposes, assuming non-radar ops.
There are not significant differences between PANS-OPS and TERPs except for the visual circling areas. An airplane doesn't know whether it's inside a cloud in Germany or Colorado.
As to "turn areas" as you call them, there would not be any turn area construction for a turn at TGO absent being in the holding pattern.
This horse has been beat enough.
Can you also plot the primary and secondary areas of the various holding and initial approach sectors you have described.
There are not significant differences between PANS-OPS and TERPs except for the visual circling areas. An airplane doesn't know whether it's inside a cloud in Germany or Colorado.
As to "turn areas" as you call them, there would not be any turn area construction for a turn at TGO absent being in the holding pattern.
This horse has been beat enough.
