Why a 1-minute "inbound" leg on holding patterns?

RussR

RussR

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When training on VOR holding patterns, we go to all this effort and mental gymnastics to try to make a 1-minute inbound leg. But, historically, why?

The question is not "why" 1-minute. It's "why" the inbound leg.

It would work out about the same if we instead timed the outbound leg for a minute, and didn't worry at all about the inbound leg. Now, I know the outbound leg traditionally doesn't always have an easily-definable start point, but we could just use "wings level" and simplify everything. Yes, wind would affect the shape, but it does that now anyway.

As I type this, one situation occurred to me - that of a holding pattern at the FAF for an ILS or VOR approach. In these situations, it is very helpful to have a inbound leg of at least a minimum length to get everything configured and stabilized. However, also in these situations, the inbound course would generally be into the wind, so a 1-minute outbound leg would result in a longer-then-1-minute inbound leg and therefore more time to get stabilized.

So, is there a historical reason for the timing being done on the inbound leg?
 
Just a guess...

All the lost comm stuff has you leaving holding fixes at specific times. Knowing your inbound leg time fits that scenario better.

Behind the boat we were given a VERY specific time to leave our holding pattern. Would have been tougher if we tried for a one minute outbound leg and an arbitrary inbound leg.

That’s all I got...
 
The hold point is often defined by a single point in space. A vor for example, or a dme fix on a certain radial. If you timed the outbound leg and had a decent headwind, you might turn around and have only a few seconds to get re-established on the radial. I don't know about you, but getting established in one minute is often the hardest part for me.

Do the same thought experiment with inbound timing. Headwind on the outbound means flying the outbound leg longer, but you still have that minute to get established. Tailwind on the outbound can still make that leg very short, but since it's a guessed heading and not a radial it doesn't matter.

The change I would make is 2-3 minute legs. In fact the one time I was given an actual hold I asked for just that. Makes it a lot easier. Thankfully now with gps holds are easy to program and the plane will fly them for you.
 
The 1 minute hold was a pre radar procedure, when navigation was VORs and NDBs, and there were few radars and no transponders. Having aircraft in tight holding patterns occupied the least airspace and a one minute sweep of the second hand on the clock was easy to manage.

Having aircraft occupying less airspace holding today is still a big advantage.
 
So there i was...

Hehe, one minute legs are indeed RARE. Usually just 10 miles, whatever...

one day I had 99kts ground speed inbound, 350 outbound. Hmmm... keyed the mic, “approach this is me, about leg length...”

approach: ya, we know, do what ever you can/want!
 
Since the inbound leg is the only clearly-defined leg, it makes sense to me that it would be the leg with a target time. Additionally, as @Tools noted, continued navigation is predicated on crossing the fix that you’re establishing time towards.
Jim K said:
The change I would make is 2-3 minute legs. In fact the one time I was given an actual hold I asked for just that. Makes it a lot easier. Thankfully now with gps holds are easy to program and the plane will fly them for you.
Click to expand...
2-3 minute legs makes more sense in a radar environment, but when you’re trying to precisely sequence aircraft in a non-radar environment, shorter legs make more sense. You can always request nonstandard leg lengths, but since the fail-down is still sequencing by time, keeping the one minute standard is good.
 
Clip4 said:
The 1 minute hold was a pre radar procedure, when navigation was VORs and NDBs, and there were few radars and no transponders. Having aircraft in tight holding patterns occupied the least airspace and a one minute sweep of the second hand on the clock was easy to manage.

Having aircraft occupying less airspace holding today is still a big advantage.
Click to expand...
The present protected airspace for holding patterns was developed in 1963.

Attached.
 

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Last edited:
RussR said:
When training on VOR holding patterns, we go to all this effort and mental gymnastics to try to make a 1-minute inbound leg. But, historically, why?

The question is not "why" 1-minute. It's "why" the inbound leg.

It would work out about the same if we instead timed the outbound leg for a minute, and didn't worry at all about the inbound leg. Now, I know the outbound leg traditionally doesn't always have an easily-definable start point, but we could just use "wings level" and simplify everything. Yes, wind would affect the shape, but it does that now anyway.

As I type this, one situation occurred to me - that of a holding pattern at the FAF for an ILS or VOR approach. In these situations, it is very helpful to have a inbound leg of at least a minimum length to get everything configured and stabilized. However, also in these situations, the inbound course would generally be into the wind, so a 1-minute outbound leg would result in a longer-then-1-minute inbound leg and therefore more time to get stabilized.

So, is there a historical reason for the timing being done on the inbound leg?
Click to expand...
I'd figure it was to make sure you had reasonable time to get established on the inbound leg. There could be wind conditions that if you did one minute outbound, you may only get half a minute inbound, maybe less
 
aterpster said:
The present protected airspace for holding patterns was developed in 1963.

Attached.
Click to expand...

Wally - thank you very much. That was actually a very interesting read and you aren't kidding when you say the basic criteria hasn't changed since then.

Regarding my original question, that document at the end has what I assume are three revisions of what was published in what is now (I assume) the AIM, and it actually had the timing on the outbound leg for the first two revisions.

July 3, 1961 Airman's Guide:

upload_2021-12-28_8-39-47.png

July 7, 1961 Airman's Guide:

upload_2021-12-28_8-41-7.png

In the Nov 1963 Flight Information Manual it changed to the inbound leg being the controlling length:

upload_2021-12-28_8-42-56.png
 

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Anyone know why right hand turns became the standard, instead of left hand as in traffic patterns?

Mike
 
Mikey said:
Anyone know why right hand turns became the standard, instead of left hand as in traffic patterns?

Mike
Click to expand...


The guy with the pen to sign it wasn’t a NASCAR fan? Otherwise, I’d like to know too
 
It had to be some time one some leg. It could have been 2 minutes on the outbound, but then this thread would be asking "why 2 minutes on the outbound".
 
Mikey said:
Anyone know why right hand turns became the standard, instead of left hand as in traffic patterns?

Mike
Click to expand...
Because propellers turn clockwise, making it easier to roll out of the right turn. Saves fuel.
 
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