Distance based holds

[ClintonBaptiste]

Just a quick question about distance based holds. I apologise if this is the incorrect forum.


Having had a discussion among work colleagues, examiners and the legendary insomniac manual 8168, we came to an issue with the teardrop entry.

If for example we have a distance based hold on radial 108 between 10 and 15nm. and we enter in a teardrop. (inbound 288, outbound 108)

a) Do you fly the teardrop for 1 minute, then the outbound 288 until the 15nm.

b) Fly the teardrop for 1 minute, then turn inbound.

c) Fly the teardrop heading to the 15 nm.

According to 8168 it appears to be answer (c), but if somebody could clear this matter up it would be greatly appreciated. Many thanks

[mad_jock]

The 15Dme would be a limit not a you need to go out to this distance.

If in a 90knot hold speed aircraft I would just fly the normal tear drop and turn back when good and ready but before the 15dme.

The 15 DME is there just to keep you inside protected airspace its a not beyond not a must get to.

So I would say none of the given answers. The rosun hold at Manchester airport in the UK has a similar feature and was causing no end of CRM issues between crews and examiners. It was only solved after phone call to Manchester ATC about it. The limit was to keep you inside controlled airspace at the lower levels.

If you can give a link to a plate its easier to explain. Its probably and airspace issue or high ground nearby at the lowest level.

[HeliAviator]

Assuming your offset hold is 108R at 10D for a standard holding pattern, the 15D is the protected range for the proceedure. You would make your sector 2 join for the "teardrop", departing the 108R/10D tracking 078 for one minute, before turning right and taking up the 285 inbounbd QDM to take up the standard hold at 10D and turning right.

Hope this clarifies!

[frontlefthamster]

'protected range'???

[DFC]

The refernce is ICAO DOC 8168


1.4.8.5
Method of arrival at a VOR/DME holding and the corresponding entry procedures
Where the entry point is the holding fix:
a)

Arrival on the VOR radial for the inbound leg, on the same heading as the inbound track (see Figure I-6-1-3 A).
The arrival path (or its last segment) is aligned with the inbound track and follows the same heading. The entry
consists of following the holding pattern.
b)

Arrival on the VOR radial for the inbound leg, on a heading reciprocal to the inbound track (see
Figure I-6-1-3-B).
1) On arrival over the holding fix, the aircraft turns onto the holding side on a track making an angle of 30°
with the reciprocal of the inbound track, until reaching the DME outbound limiting distance.
2) At this point it turns to intercept the inbound track.
3) In the case of a VOR/DME holding entry away from the facility with a limiting radial, if the aircraft
encounters the radial ahead of the DME distance, it must turn and follow it until reaching the DME
outbound limiting distance, at which point it turns to join the inbound track.
c)

Arrival on the DME arc defining the holding fix, from the non-holding side (see Figure I-6-1-3 C).
1) On arrival over the holding fix, the aircraft turns and follows a track parallel to and on the same heading as
the outbound track.
2) When it reaches the DME outbound limiting distance, the aircraft turns to intercept the inbound track.
d)

Arrival on the DME arc defining the holding fix, from the holding side. An arrival track leading to this type of
entry should not be specified if possible, particularly in the case of a VOR/DME holding procedure away from
the facility. If an appropriate DME distance is chosen, this type of arrival can actually be replaced by one on a
DME arc terminating in the extension of the inbound track (see a) above and Figure I-6-1-3 D).
However, space problems may rule out this solution. Criteria are therefore provided for an arrival on the DME
arc defining the holding fix, coming from the holding side:
1) On arrival over the holding fix, the aircraft turns and follows a track parallel and reciprocal to the inbound
track, until reaching the DME limiting outbound distance. It then turns to intercept the inbound track (see
Figure I-6-1-3 E).
2) If the entry point is the fix at the end of the outbound leg, arrival (or last segment thereof) is effected along
the VOR radial passing through the outbound fix. On arrival over the fix at the end of the outbound leg, the
aircraft turns and follows the holding pattern (see Figure I-6-1-3 F and G).

[frontlefthamster]

DFC,

I'll humour you...

We're 2nm south (or north, your choice, as the OP didn't specify a direction of turn) of the VOR...

The FRD at the hold is called 'OBBAT' and we're told 'own navigation to OBBAT to hold...'.

You suggest that this clearance contradicts 8168, or that we must make our own interpretation of 8168 to suit.



but...



Neither is the case, in fact, and we may, in fact, fly any appropriate entry as if there were a beacon at OBBAT...

[DFC]

No that does not change the situation. using conventional nav, one would establish outbound on the defining radial in suficient time to ensure that the 8168 requirements for minimum leg length prior to entry are complied with.

If you are talking RNAV then there are a different set of rules.

To make it simple I have edited my previous post and simply pasted the appropriate part of 8168 so that there can not be any misunderstandings.

However, the actual answer to the original question is given in general by the following paragraph;

1.4.9 Time/distance outbound
The still air time for flying the outbound entry heading should not exceed:
a) one minute if at or below 4 250 m (14 000 ft); or
b) one and one-half minutes if above 4 250 m (14 000 ft).
Where DME is available, the length of the outbound leg may be specified in terms of distance instead of time.

----------

As Mad Jock says, the DME is a limit rather than a target.

However, one must remember that the idea of a hold is to delay the aircraft and therefore unless the required delay is less there is noting wrong with using up the time by flying outbound until the limiting DME and thus taking more than 4 minutes to fly the hold (in still air).

Passenger comfort dictates longer legs wings level if possible.

[frontlefthamster]

DFC, in non-RNAV it would be legitimate to route towards the holding fix via another intersecting radial, for example, or by establishing early on the holding radial, or via a dme arc.

Given that, as you say, Where DME is available, the length of the outbound leg may be specified in terms of distance instead of time.

----------

As Mad Jock says, the DME is a limit rather than a target.

Would you supply your reference which justifies the 'limit rather than target' statement? I think it's quite clear that the dme range is not a limit, but is a target.

[Big Pistons Forever]

I am not familiar with European rules, but in North America the only restraint that must be observed is the requirement to always remain within protected airspace. With respect to a hold, it means that you flight path to the point in space which defines the holding point and all subsequent manoevering is in airspace which has been protected from incursions by other aircraft and provides adequate clearance from the ground. After that all you get is style points and you can pretty much drive around the hold anyway you like. The beauty of DME holds is it cuts down on the endless turning and does away with all the nausea of having to time the legs which why, if asigned a hold I always ask for a DME distance. However the true mark of a wise aviator is not finessing the hold entry, it is avoiding holding in the first place, by anticipating a holding situation and reducing speed early.

[DFC]

but in North America the only restraint that must be observed is the requirement to always remain within protected airspace


Overall the same principle applies everywhere. However, 8168 does specify certain methods to be used. These ensure that in the worst case, the highest category aircraft at the maximum holding speed will remain protected. In a C172 (Cat A), it is difficult (but not impossible) to fly outside the protected airspace in a hold designed for B737s (Cat C).

In fact if the hold is designed for CAT C, one could probably hold in a C172 on the wrong side at the wrong end and still not fly outside the protected airspace!!!!. Not a good idea however. :}

I personally never had a problem with flying outbound along the inbound radial until the DME (or time) limit and then turning onto the holding side to establish inbound again until it was pointed out to me that 8168 requires one to follow the 30 degree leg and turn in the direction of the hold.

I could see no real difference until it was pointed out that doing it my way had a greather posibility of getting it wrong and failing to get back on the inbound radial before the fix.


The beauty of DME holds is it cuts down on the endless turning and does away with all the nausea of having to time the legs


One should always time the hold - it is both a crosscheck and a back-up. Same reason why one always starts the stopwatchwatch at the FAF even when there is DME.

Agree with the reduction in turning (which keeps the pax happy).


However the true mark of a wise aviator is not finessing the hold entry, it is avoiding holding in the first place, by anticipating a holding situation and reducing speed early.


If ATC agree in advance then it can be a good idea. However, it is often better to get to the hold and be in a position to take a gap in the traffic than still be 50 miles away crawling along.

This idea works in Americas where there is plenty of open space and not unusual for speed control to be applied at Newfoundland when inbound to Boston. However, in Europe, it is not unusual for a single traffic stream to be feeding several major airports and if there are delays at one, slowing down the traffic destined for one may delay traffic for the others.There is also the issue of slowing down causing the aircraft to be within a sector for longer and thus using some capacity for longer and the fact that somewhere like Heathrow acheives it's highest arrival rate when it has a good selection of aircraft in the holds ready to be sequenced.

[mad_jock]

The reference is in the UK AIP gen 2.3.

http://www.nats-uk.ead-it.com/aip/current/gen/EG_GEN_2_3_en.pdf

The reference is on page 5 under legend left hand side the hold using the Mayfield VOR as the beacon.

Quite clearly next to it states "Normal holding pattern DME distance where shown defines limits of pattern"

Your missing the point of holds all they are for is for keeping aircraft in a certain bit of space inside a certain region. I am sure someone if they could be bothered could go and find the pan-ops definition of what that geometry of airspace should be. The plate definition of a hold is really for a procedural environment. In a radar environment with the permission of the controller you can hold where ever, you and the controller agree. You can do 3, 5 or even 15min holds if the controller agrees, outbound DME legs, fill you boots ask and if its OK with them do it.

[Big Pistons Forever]

DFC you said

"One should always time the hold - it is both a crosscheck and a back-up. Same reason why one always starts the stopwatchwatch at the FAF even when there is DME."

I do not see the point in timing a DME hold since if you loose DME you no longer are able to continue with your hold clearance. As for approaches I am lucky enough to fly an aircraft with an approach approved GPS so if the the DME signal is lost I still have distance information and the MAP is identified in the overlay in the case of the NDB approach. In any case I have never timed the ILS and there are not that many non precision approaches that do not have distance information available.

[frontlefthamster]

Mad Jock mentioned:


"Normal holding pattern DME distance where shown defines limits of pattern"


...and the bold italics are his, not the AIP's... I would venture that, in the same way, where no dme distance is shown, timing defines limits of the pattern... A chart key is not regulation...

Then there is the matter of where and how we hold in a radar environment:

In a radar environment with the permission of the controller you can hold where ever, you and the controller agree.

True, but only when in a published hold (remember, ATC are not permitted to use radar separation against aircraft in the hold), will you be procedurally separated from adjacent tracks and other holds.

In a hold, you are procedurally separated from other holding aircraft, and from non-holding aircraft on adjacent tracks. This is why you may sometimes be put on a radar heading for part of the hold, to accommodate the use of radar separation (less than procedural, to a minimum of 3nm laterally in terminal airspace) against adjacent aircraft.

To recap, if the hold says FRD at 10 nm, outbound to 15nm, that is where you must turn; not at a time.

And yes, reducing speed early is a lovely idea but knocks the landing rate for six and is simply impractical in most of northern Europe.

[mad_jock]

Yes the time does define the limit if no dme limit is specified.

And the time limits are defined in the AIP.

All charts for the UK are defined in the AIP and are the legal base for all other charts eg Jepps and Airads. The chart key is part of the regulation defining those plates in the UK. And if the AIP isn't good enough for you I suggest you don't fly in UK airspace or in fact any country's airspace if you don't agree what's in their AIP.

And I agree the hold is procedural environment it is designed as a work saving tool for the ATCO. It has protected airspace as per the pan-ops design. If you get put onto vectors by definition you are not holding any more. But this only applys to published holds. If the ATCO has put you in an adhock hold due to possibly wx over the published its still up to them to keep you separated.

If you are a cat B aircraft in a hold designed for a cat D aircraft which has a protected airspace to match you have 3 or 4 times more area than you actually need. So unless you are holding at Cat D aircraft speeds the ATCO can grant you what ever you like as long as it stays inside the protected area.


But actually it really doesn't matter if you do want to fly out to 15dme because you will still be in the protected area so if you want to, crack on. Your not doing yourself any favours but its perfectly safe doing what your doing so nobody will give a toss.

And to restate unless we have a link to the legal base plate ie the one that's published in the country's AIP including access to its key chart instead of some interpretation by Jepps we are arguing over a concept which bares no relation to the real world.

[DFC]

I do not see the point in timing a DME hold since if you loose DME you no longer are able to continue with your hold clearance.


Would be nice to know how far you are from the VOR when you look over and see a blank DME display. If the hold is fixed on a navaid then it may be possible to continue with timing.

-----

Mad Jock,

The most important bit of the AIP is where is tells us about differences from the ICAO standards. In relation to 8168, this is in the appropriate part of the GEN section.

Please zoom in a little closer to the legend you speak of. You will see that what you quote as;

"Normal holding pattern DME distance where shown defines limits of pattern"


Is in fact;

"Normal holding pattern." - Note the full stop!!

(solid lines. alternative holding pattern shown below with dashed lines).

Second sentence;

"DME distance where shown defines limits of pattern"

This is simply a key to the charts. It simply shows how to tell the difference between the hold that is normally used and an alternative hold that may be published.

If it was anything else than one would see in the ICAO differences that the UK considers a left turns hold normal while ICAO considers a right hand one normal!!!!! :)

[Big Pistons Forever]

Would be nice to know how far you are from the VOR when you look over and see a blank DME display. If the hold is fixed on a navaid then it may be possible to continue with timing.

If you are given a DME hold than you have to have a working DME to fly it.
In the unlikely event " you look over and see a blank DME screen" than you have to get a new hold clearance....at which point you can worry about timing.

[frontlefthamster]

Yes the time does define the limit if no dme limit is specified.


...and conversely, the dme limit is definitive if specified.


All charts for the UK are defined in the AIP and are the legal base for all other charts eg Jepps and Airads.


...not so. The AIP does not contain all charts.


The chart key is part of the regulation


No, the AIP is information not regulation.


And if the AIP isn't good enough for you I suggest you don't fly in UK airspace or in fact any country's airspace if you don't agree what's in their AIP


I've been banging on on this topic for years, as it happens. How many folk flying into Swiss aerodromes are familiar with the 'maximum descent rates' quoted in ther AIP? Very few, but as I do read these documents, I'll keep going, thanks!


If you get put onto vectors by definition you are not holding any more

No, you may hold or fly a leg of the hold on radar headings. Let's say you're holding at FL120 at FIX, and there's an overflight at FL120 which wants to pass close by the hold. The ATCO may instruct you next time over FIX to take up a radar heading, so that the overflight can pass by also on a heading - to keep the overflight procedurally separated might mean a large deviation. Once the overflight has passed, you'll be released back to FIX to re-enter procedural holding.


If you are a cat B aircraft in a hold designed for a cat D aircraft which has a protected airspace to match you have 3 or 4 times more area than you actually need. So unless you are holding at Cat D aircraft speeds the ATCO can grant you what ever you like as long as it stays inside the protected area


I think you're getting a bit confused over approach speed categories and holding. In the ATC world, there is no practical difference between a PA-28 and a B747 in the same hold. Either the hold is deemed separated at that level, or it isn't. The MATS Part 2 or its equivalent will define deemed separations between holds and between holds and tracks, with conditions. The controller must keep to those conditions, and so does not have complete discretion. Maximum holding speeds are published by various authorities (principally ICAO and FAA). Approach categries are based on 1.3vs in landing configuration (for non-fbw aircraft, 1.25 for fbw in general), and do not necessarily reflect holding speeds which are for a clean aircraft.


But actually it really doesn't matter if you do want to fly out to 15dme because you will still be in the protected area so if you want to, crack on. Your not doing yourself any favours but its perfectly safe doing what your doing so nobody will give a toss.


..except that if I don't fly to 15dme on my LPC, I'll fail the check. If someone doing his check with me doesn't fly to 15dme, he'll fail his check. As DFC says, passenger comfort perhaps favours longer legs.

Rising to your bait, I'll give a toss, taking satisfaction from operating the aircraft correctly...

[mad_jock]

The protected areas are in pan-ops the area does change depending on the cat the hold is designed for.

And conversely it is obviously an opinion of the TRI/TRE because I wouldn't fail an LPC/OPC for treating it as a limit.

So if the AIP is only Information what does regulate the plates and procedures?

Again with these discussions the only way to find out is to put it on the ATC forum. Like the procedure after missed approach off a visual I suspect we will all be wrong.

I said before my opinion is I also operate correctly by treating it as a limit not a must cross. The people who really don't give a toss are ATC because both our methods keep us in the protected airspace so we don't infringe on the other traffic.

I have started a thread on the ATC forum so with any luck we can get some input from the people that actually design the bloody things.

[DFC]

I think you're getting a bit confused over approach speed categories and holding. In the ATC world, there is no practical difference between a PA-28 and a B747 in the same hold. Either the hold is deemed separated at that level, or it isn't. The MATS Part 2 or its equivalent will define deemed separations between holds and between holds and tracks, with conditions.


The hold will be designed to contain certain categories. The maximum holding speeds on which the protected airspace is based depend on the approach category i.e. CAT A/B holds are a max of 170Kt and trying to hold there in your B747 at 240Kt will put you outside the protected airspace.

The deemed separations used by ATC will be based on the size of the protected airspace and thus the largest aircraft that can use the hold.

Radar separation can not be used to separate aircraft holding. ie. you can not climb one aircraft in a hold through the level of another aircraft also in the hold even if you have the required distance. The rationalle behind this rule is the problem with establishing and maintaining identification when several aircraft are in a hold. Even SSR can have problems such as label swap etc. Not to mention that in general one has no real idea of when aircraft in the hold will turn.

Radar can be used to separate non-holding aircraft from others that are holding. If this was not the case, it would be very slow in the London TMA where for example the Heathrow outbounds to Dover pass both the Ockham and Biggin holds.

---------------

Let me repeat the quote that I provided to answer the original question;


Arrival on the VOR radial for the inbound leg, on a heading reciprocal to the inbound track (see
Figure I-6-1-3-B).
1) On arrival over the holding fix, the aircraft turns onto the holding side on a track making an angle of 30°
with the reciprocal of the inbound track, until reaching the DME outbound limiting distance.
2) At this point it turns to intercept the inbound track.
3) In the case of a VOR/DME holding entry away from the facility with a limiting radial, if the aircraft
encounters the radial ahead of the DME distance, it must turn and follow it until reaching the DME
outbound limiting distance, at which point it turns to join the inbound track.
c)



That seems very specific that the 30degree leg is flown until reaching the DME outbound limit. No mention of timing as an alternative provided the limit is not exceeded.
I have asked a few people about this and their answer was that turning inbound early could result in the aircraft going onto the non-holding side and outside the protected airspace. Of course the whole design is based on the higest category aircraft that can use the hold. The final answer was - the hold is designed to waste time....why rush it!

------

In the unlikely event " you look over and see a blank DME screen" than you have to get a new hold clearance....at which point you can worry about timing.


And (when based on a navaid) having received a clearance to continue the hold using time, you look at the watch saying 00:00:00 and think - "I wish I knew where I was on this leg" :eek:

We teach "Time, Turn, Talk" overhead the beacon / fix. Time being start the watch.

[Jumbo Driver]

..except that if I don't fly to 15dme on my LPC, I'll fail the check. If someone doing his check with me doesn't fly to 15dme, he'll fail his check.

With all appropriate respect, I think this is absolute rubbish. The outbound DME shown on the chart simply defines the outer limit of the hold. I would not fail anyone for turning "early" within this limit nor would I expect to be failed if I did so on check.

What authoritative basis could you possibly use for failing someone in such circumstances?


JD
:)

[DFC]

What authoritative basis could you possibly use for failing someone in such circumstances?


If one wanted to one could use DOC 8168 -Pans OPS


1.5 HOLDING
1.5.1 Still air condition

a) Having entered the holding pattern, on the second and subsequent arrivals over the fix, the aircraft turns to fly
an outbound track which will most appropriately position the aircraft for the turn onto the inbound track;
b) It continues outbound:
1) where timing is specified:
i) for one minute if at or below 4 250 m (14 000 ft); or
ii) for one and one-half minutes if above 4 250 m (14 000 ft);
or
2) where distance is specified until the appropriate limiting DME distance is reached; then
c) the aircraft turns so as to realign itself on the inbound track.


Failure to comply with 2) above.

However, in practice it would be cruel to do such if the aircraft was safely flown within the protected airspace and met the two mandatory requirements of;

1. Establishing on the published inbound track; and

2. maintaining that track for a "reasonable" amount of time before the beacon / fix.

If you want to go down the road of "I don't have to fly all the way out to the limiting DME" then you must also subscribe to the "I don't have to fly all the way out for a full minute (still air).

Think about the consequences of turning back to the beacon too soon.

the hold is there to delay. What's the rush

[Big Pistons Forever]

DFC

In the unlikely event of loosing the DME on a DME hold one is required to report this fact to ATC. If the hold was between two DME distances on an airway or radial than obviously ATC would have to come up with a new place for one to hold so the fact that you had been timing the legs has now become irrelevant. If the holding point is a VOR than on receipt of the hold clearance you do what you always do when you get a new hold clearance....the entry procedure...which is probably going to be turn to and intercept the inbound track and since you will probably allready be well passed the turn point to inbound for a timed hold, again the fact that you have been timing will not provide any practicable advantage

I realise this is a somewhat pedantic discussion but it is IMO part of the problem with IR instruction, at least in Canada, the mindless conduct of a procedure, In this case timing every leg of every hold, without any context or an understanding of "why" the practice of timing started. When you are saying "timing" is important what you are really saying is "maintaining situational awareness" is important. Under some circumstances (eg holding at an NDB) then yes timing the legs is the mechanism you use to maintain situational awareness. In a DME hold it is the DME that is providing
situational awareness and therefore it is important that the information it is giving is fully understood and used.

IR flight training IMO is far too full of "you had better be procedure X because failure Y could occur". Timing the FAF to DH leg of an ILS "because the GS might fail" a widespread practice in Canadian IFR training, is a another prefect example of such procedural silliness.

[Jumbo Driver]

However, in practice it would be cruel to do such if the aircraft was safely flown within the protected airspace and met the two mandatory requirements of;

1. Establishing on the published inbound track; and

2. maintaining that track for a "reasonable" amount of time before the beacon / fix.

Yes, DFC, it would indeed be cruel ... and pedantic ... and in my book extremely difficult to justify since, despite your quoted references, there is still nothing to say the pilot may not turn before reaching the limit of the hold as defined by the DME.

Safety must be the keyword and turning before reaching the hold limit is clearly neither unsafe nor prohibited.


JD
:)

[DFC]

despite your quoted references, there is still nothing to say the pilot may not turn before reaching the limit of the hold as defined by the DME


8168 - the applicable standard says;

It continues outbound where distance is specified until the appropriate limiting DME distance is reached then the aircraft turns so as to realign itself on the inbound track.

Seems quite specific to me as to when the turn is to be made. Don't see any options for turning back early when the hold is to be continued.

To give weight to your argument it would have to say something like;

"It continues outbound where distance is specified until not more than the limiting DME distance is reached then the aircraft turns so as to realign itself on the inbound track."

But that is not what it says!!

Don't forget that turning back early risks not establishing inbound and thus either missing the holding fix completely or crossing it on a heading that requires the aircraft to complete another (sector 1) entry procedure.

Some holds do not permit sector 1 entry procedures so what then?

The one case where 8168 permits the hold to be shortened (adjusted) is when one is cleared to leave the hold at a specific time. However, it is very specific in saying that the adjustment must be done within the limits of the hold i.e. don't do an orbit starting at the fix and end up crossing the fix at 90 degrees to the inbound track / track to leave the hold.

It may be pedantic but while I said failure would be cruel if the aircraft remained in the airspace and always tracked the inbound for a reasonable amount of time, it would have to be a debrief item because failure to comply with 8168 shows a lack of knowledge / training. (the first usually being as a result of a failing in the latter).

[Jumbo Driver]

We'll have to agree to differ then, DFC ...


JD
:bored: