Holding question

[Evo]

If i'm doing a direct entry into a hold on a bearing that means i've got to turn through much more than 180 degrees (i.e. it's almost an offset entry), how do I get the turn outbound correct?

If I start a rate one turn through ~250 degrees as soon as I cross the beacon then the outbound leg will be too close in and I'll shoot through the radial when I turn on the inbound leg. I guess I can turn through 'something like 180 degrees', 'wait for a bit' and then finish the turn outbound? Or turn through less than 250 degrees to the outbound and then more than 180 inbound? Or...? What's the easy way to do it... :confused: :confused:

Got every other option clear in my mind ... but this is the one i've got to do... :(

[Circuit Basher]

If you have a copy of Aerad, then hold entries for different sectors are in the Flight Information Supplement.

This question was asked here back in May 03 and this link (http://www.pilotlist.org/zahar/howto.htm) was offered to describe how to do it.

The original thread is here (http://www.pprune.org/forums/showthread.php?s=&threadid=91243).

Hope this answers the question.

[Evo]

CB - I posted that link in the first place :O but I don't think it answers my question...

[Circuit Basher]

DOH! (http://uk.msnusers.com/CircuitBasher/Documents/DOH.WAV) ! (this is an audio clip!) :D

Sorry - should have looked at who posted it!

I would have personally gone for a teardrop entry, but looking at the picture - if you say 'it's more than a 180 deg entry', then shirley if you turn the opposite direction, it's less than 180 deg?? :confused:

Have I lost the plot completely here??! :) := :oh: :uhoh: :\

[Evo]

Maybe I didn't explain it well. Say you've got a right-hand hold where you track (magnetic) north inbound and south outbound. No wind.

Arriving from between 110 and 290 degrees it is a direct entry, 290 to 000 is teardrop and 000 and 110 is offset/parallel. In my example, say you're tracking to the beacon on the 295 radial, so it's direct entry, and you have to turn through 180+65 = 245 degrees to the outbound leg. Do that all in one rate-1 turn and you'll be on the right track but too close in to the beacon to do another rate-1 turn to the inbound track... so how do you adjust it?

[IO540]

Perhaps the answer is that you don't need to get holds precisely right. A hold is designed to have enough room around it to accommodate a 747 doing rate 1 turns at say 200kt.

A reasonable way, probably wrong though, is to intercept the inbound 360 radial, then turn onto a track of 360 and fly that to the beacon, and then your 1st rate 1 turn is 180 deg.

In practice, often, one has little idea of what the wind is doing up there and that's a much bigger source of imperfect holds.

[Flyin'Dutch']

EVO,

Firstly: I am not a 'Hold King!'

But if they are NDB holds you can look for the 'gate' which should be 30 degrees on the outbound leg at 1 minute or

VOR holds look at the CDI which will give you an indication of your position with regards to the VOR.

Anyhow in the situation you describe your outbound leg will be inside the projected hold and therefore in the safe zone. The only perceivable problem would be when you come around to establish on the inbound leg and conceivably will fly through the inbound track.

Again the ADF needle and VOR CDI will give guidance to get you back on track pretty quick.

HTH

FD

[Evo]

Not too worried about wandering outside the safe zone, you really have to b*gger things up to do that in a PA-28. However,


The only perceivable problem would be when you come around to establish on the inbound leg and conceivably will fly through the inbound track.


That's what tends to happen - and this scenario is what happens routing direct to the SAM hold. I can fudge it by flying over the beacon, turning 180 degrees, waiting 'a bit', then turning outbound. Just wondered if there was a rule of thumb for what 'a bit' is, or if there's another way. Flying on instruments I quite like to know what i'm doing and why i'm doing it - and a decent hold entry would be nice for the IMC test too... :)

[MasterCaution]

I can fudge it by flying over the beacon, turning 180 degrees, waiting 'a bit', then turning outbound. Just wondered if there was a rule of thumb for what 'a bit' is, or if there's another way.

So assuming (a) I've got my trigonometry right and (b) mathematically exact turns, no wind, etc. then I reckon the 'bit' should be ((1-cos(a))/sin(a)).(60/pi) seconds, where 'a' is the angle between the hold inbound course and the course being followed when joining - for direct entry joins on the turn-greater-than-180-degrees side.

This gives 13 seconds for the extreme at 70 degrees. 30, 40, 50 and 60 degrees would be 5, 7, 9, 11 seconds respectively. So course difference divied by 10 (drop the rightmost digit), double, subtract 1.

This method also gets you on the outbound leg early by the same amount.

MC

[DFC]

Most people are correct when they say that the holding protected airspace is quite big compared to a PA28's holding speed. Even CAT A and B holds allow for a holding speed of 170Kt.

Thus when flying round the hold, try to be slightly wide on the outbound and slightly long. This provides you with the best chance of establishing on the inbound track and maintaining that track for a reasonable amount of time inbound.

As for entries;

Entering straight up the inbound track.....no problem and when considering the teardrop or parallel entry, you can intercept the inbound track during the entry procedure thus ensuring that your first turn into the outbound portion of the hold starts in the normal way i.e. from being established on the inbound track.

If however, you are on a direct entry or complete a parallel entry which returns directly back to the hold fix, you are in a situation where a still wind turn of more or less than 180 degrees is required.

Rate 1 turn = 3 degrees per second.

When the required turn is more than 180 degrees at the hold fix, stop the turn when on a heading 90 degrees from the inbound track flying towards the holding side. Maintain this heading for the number of seconds required to turn through the excess at erate 1. Then continue the turn onto the outbound heading.

Example.....Hold inbound 360, outbound 180 Turns right. Approach the hold from 110 radial (heading 290). Direct entry.......excess in turn is 70 degrees = 18 seconds.

At fix commence rate 1 turn onto heading 090. Stop turn for excess - 18 seconds - continue turn to 180 deg.

When the turn is less than 180 deg, calculate the amount of turn already completed and as above calculate a timing in seconds. Having passed the fix, do not commence the turn outbound until the appropriate timing has passed.

Example.........Same hold as above. Approaching the hold from 270 radial (heading 090). Direct entry......90 degrees of outbound turn already completed.

Having passed the fix, do not commence outbound turn until 30 seconds after the fix.

The above assume no wind and when wind is a factor then an allowance should be made.

Furthermore, the aircraft is only turning at rate 1 when the required angle of bank is acheived. Make allowance for the time takes to establish at Rate 1 and for the rate to decrease to zero.

Hope that helps.

Regards,

DFC

[Evo]

Thanks, folks. Very helpful :ok:

[drauk]

Evo, DFC has given you a neat mechanism for doing it right, but I have two other comments.

Firstly, and perhaps most importantly, I don't believe that doing a hold is a requirement of the IMC test. I certainly didn't do one when I took my test. Quite what happens if you had to do one because ATC needed you to, and you mess it up, I am not sure.

Secondly, in the example you gave you said you were tracking to the beacon on the 295deg radial. If this were the case you would be doing a teardrop entry. I am guessing you mean your course was 295deg, in which case you are actually tracking to the beacon on the 115deg radial. If tracking TO a beacon on a given radial your course is always the reciprocal of that radial.

[Evo]

drauk

I agree that holding is a bit of a grey area, but if you look at Southamptons VOR/DME Rwy 02 approach (which I have a 50/50 chance of getting on my IMC test) getting the hold right is an important part of getting the procedure right. Also, the test standards require you to "comply with ATC instructions" and when you book approach practice with Southampton you are told (quite reasonably) that they're always going to be busy with commercial traffic, training flights take second place and they will fit you in when they can - so be prepared to be asked to hold. Maybe a passing examiner can explain the situation better, but my understanding is that i've got to be able to hold when asked to (although not to IR standards) so i've been spending lots of time on RANT - and some in the air - getting things right :) I guess I could go somewhere quieter, but if the weather turns rubbish Southampton is where i'd go so I may as well learn there.

And you're quite right - I meant that I'd have 295 set on the OBI and would be flying a heading of 295, but i'd be on the 115 radial.

[BEXIL160]

EVO... this might be of interest / use to you.

For the next THREE weeks the Southampton Radar is NOT AVAILABLE. (Actually the SSR does work, it comes from Pease Pottage, but they aren't allowed to use it while their own Primary radar is on maint)..

...anyway, effectively there is no radar at EGHI and hence all IFR a/c will be handled by a procedural approach control. This is cumbersome and time consuming, albeit very safe. End result? Not much opportunity for IFR training flights.

I'd give them a ring and ask about possible "quiet" periods, but I doubt there will be very many.

rgds BEX

P.S. Bournemouth's Radar is still "on"... hint, hint.

[Evo]

I'd give them a ring and ask about possible "quiet" periods, but I doubt there will be very many.


Gave them a call this morning, come back in three weeks was the reply... looks like my IMC test is 'on hold'... :{ :{

[Keef]

It's a very good idea to "learn" holds for the IMC rating. Despite the theory that holds aren't in the syllabus, if there's a hold depicted on the procedure, you will be expected to be able to fly it.

I've done at least one hold, and sometimes three different ones, on my IMC renewal tests.

Why wouldn't you expect to have to do a basic part of a procedural approach?

[topunicyclist]

Snap! Has anyone had any success with booking a practice app at Southampton whilst the radar's u/s?

[jerseymilkman]

I doubt you'll have much luck at Southampton for now. Even in a bizjet we get held in a stack over SAM until we can get slotted into the approach.
Go to Bournemouth instead - all ILS and hassle free.
Luck
JM

[topunicyclist]

I guess even if you guys experience delays, I have no chance. Still, I undertand the radar should be back online within a week or so.

The thing is I am currently doing my IMC training and have done some practice of VOR/DME at Goodwood, but as there is no ATC (only AFIS), I have to go elsewhere to practice a VOR/DME approach. The other approach I'm learning is the NDB/DME, and I've done that a couple of times at Shoreham.

I wouldn't have thought there was that much traffic to cause people to have to enter the hold even with the radar u/s - how many acft would be in the hold at any one time, and how many holds would you have to fly, out of interest?

[FlyingForFun]

Topunicyclist,

Not sure how others do this (in fact, I'd be interested to hear) - but when I did my IMC training, we didn't need ATC to practice a VOR/DME approach. In fact, we didn't even need an airfield!

Just find an en-route VOR/DME, add 1000' to all the altitudes on your approach plate (or more, depending on the local terrain), and use the en-route navaids as if they were the ones on the airfield that you're pretending to approach. Worked for me :ok: but I don't know if all instructors do this. Certainly saved me a fortune on approach fees!

(Definitely worth doing at least one approach to a real airfield, though - if you have a fairly high MDA, as an IMC-holder will do, then you fly all the way to the MAPt before removing the foggles, you'll find yourself a lot higher than you want to be, which was a bit of a shock to me the first time I saw it!)

FFF
-----------------

[keithl]

I teach MEIR courses and our method is: after the o/h, turn until 90deg to inbound track, hold that for 5sec per 30deg off (i.e. arriving at 90deg to hold, fly at rt angles for 15sec) then continue turn outbound.
That's the short version - if it's not clear, do get back to me.

[Northern Highflyer]

I am just starting my IMC training so apologies if I am missing something obvious here but
excess in turn is 70 degrees = 18 seconds
If it's a rate one turn shouldn't this be 23 seconds ?