Holds

[E-Flyer]

Hi Boys,

Ok quick question for you.


I've been introduced to two different types of CORRECTION methods for holds when dealing with a tail/headwind.

The 2/3 method which I don't agree with, and the other method of adding/subtracting the seconds according to your outbound / inbound tracks.


If I fly outbound for 1 minute, and end up flying 30 seconds inbound, would I not add 30 seconds to my next outbound leg making it a 1minute30 second leg? Cause this way my inbound would be corrected to 1 minute.

That's what I remember from my training; so what is the theory behind 2/3's?

I've heard that the reason the 2/3's work is because of the turns; but even if we have a tailwind on the outbound, when we turn to fly inbound our track is extended downwind as well as when we come over the fix and turn for the outbound again. So the factor that the wind displaces us is equal for our outbound turn, and our inbound turn.

So what's the real reason behind the 2/3's working. Cause I thought the addition/subtraction of seconds was the proper method.



Thanks !

[Tim]

that's similar to the rule i've always used. if you're short on time IB, add the difference to your OB. if you're OVER time subtract HALF the difference from the OB time.

i.e. 1 min OB = 1:20 IB, subtract :10 sec from the OB and fly :50 sec total

[old_man]

subract 2/3 or add 3/2

In your example flying outbound 60 seconds only produced a 30 second inbound leg. For every 2 seconds of outbound time it gives you 1 second inbound time. So if you go out for 90 seconds (what you were suggesting) you would get an inbound time of 45 seconds, not a minute. What you would have to do is add 3/2 of your error. In this case 3/2 of your 30 second error which is 45 seconds to give you and outbound time of 105 seconds. Why not a full 2 minutes to give you 1 minutes inbound? Well, like you said, turns, you are still going to get blown out while you are turning. You then compute a new correct for every time you go around.

That's the theory. Try it out in flight sim with a strong wind and tell me what you think. Does it really matter all that much in real life? Probably not but it is nice to try to be as accurate as you can.

[FlaplessDork]

If I fly outbound for 1 minute, and end up flying 30 seconds inbound, would I not add 30 seconds to my next outbound leg making it a 1minute30 second leg? Cause this way my inbound would be corrected to 1 minute.

Think about your ground speed. Going from a headwind to a tailwind, your groundspeed changes by twice the windspeed. Therefore this doesn't work.

I've always done the difference from a minute /2 or *2 depending on the whether you have a headwind or a tailwind on the indbound.

2/3 method works well too.

In reality, I just guess until I get 1 min inbound.

With a crosswind don't expect perfect racetrack patterns too. Your holds should look egg shaped.

[boozy]

I'm no authority on the subject, and I imagine in "real life" no one cares too much. But, you can calculate the "exact values":

Ground Speed IN 1min
----------------- = ------
Ground Speed Out X


You can solve this in your head roughly if you're quick at math: trig & ratios.

Turns are excluded

[boozy]

What I just wrote didn't "print out" nicely. The equation reads: The ratio of the groundspeeds (Out to IN) equals the inverse ratios of the time (In to OUT).

The fastest way then, is to just just peg one of the times as 60 seconds and compare the ratios to get the outbound time.

[Leerboy]

I always ask for 10 dme legs to remove the time issue. Yes I am lazy. It always works though.

[canpilot]

Used the 2/3 rule...hated it


Used the approximation rule.. it yielded the same results.. was less complicated and worked for the TC examiner.

I second option 2

[SAR_YQQ]

We use the 2/3 and 3/2 rule out here in Southport.

Worked just fine today in 30 knot winds - one timing correction and my student had the hold at 1min01sec inbound.

[The Old Fogducker]

SAR .... I hope you explained during the debrief that he'd need to do a great deal better than that next time out, or he's receive a DNCO, you'd recommend a CT, and he'll end up as an oiler in the bowels of one of our DDE's.

After all, its all about building confidence isn't it?

OFD

[Big Pistons Forever]

Hmmm... 1 second late on the inbound..... I guess that is OK....... if he were on one engine and flying partial panel while battling a cockpit fire

[loopa]

So here's a question.

What if you're asked to hold 13.5 DME away on R180 inbound on 030 holding right?

How do you go about the wind correction angles when you're not flying inbound on a specific radial?

Because in this case we have been asked to hold 13.5 DME south (R180) of the VOR inbound on 030.


Thanks !

[C-GPFG]

So here's a question.

What if you're asked to hold 13.5 DME away on R180 inbound on 030 holding right?

Pretty crazy hold clearance, you'd probably never be issued.

But if for some strange reason you were required to, I'd create a GPS waypoint at that position and OBS the inbound track for the hold and correct for wind as usual.

[loopa]

So here's a question.

What if you're asked to hold 13.5 DME away on R180 inbound on 030 holding right?

Pretty crazy hold clearance, you'd probably never be issued.

But if for some strange reason you were required to, I'd create a GPS waypoint at that position and OBS the inbound track for the hold and correct for wind as usual.

Well I think there are a few published holds as part of missed approach procedures in the states that have holds like that.. pretty crazy.

[C-GPFG]

So here's a question.

What if you're asked to hold 13.5 DME away on R180 inbound on 030 holding right?

Pretty crazy hold clearance, you'd probably never be issued.

But if for some strange reason you were required to, I'd create a GPS waypoint at that position and OBS the inbound track for the hold and correct for wind as usual.

Well I think there are a few published holds as part of missed approach procedures in the states that have holds like that.. pretty crazy.

That's true. I fly in the US a lot, and have yet to actually fly a missed approach all the way to the hold point.