Rule of Thumb
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Rule of Thumb
Over the years, I've run across a few "rules of thumb" in ATC. For example: When intercepting the final from a 90 degree base leg, start the turn when at "Ground Speed divided by 100" miles from the final.
If anyone has valid ATC "rules of thumb", please let me know ... I'm collecting them for new trainees.
Thanks.
atcea.com
If anyone has valid ATC "rules of thumb", please let me know ... I'm collecting them for new trainees.
Thanks.
atcea.com
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Us dumb brits simply use skill and judgement..... and bucket fulls of luck... largely!!! 
On a serious note, surely the above is wind speed/direction dependant!?!
On a serious note, surely the above is wind speed/direction dependant!?!
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Having spent 31 years doing, among other things, the Final Director at Heathrow I never heard of that one. I don't know of any Heathrow controllers who employ that method, but there are plenty who can sit there for an hour and get inch-perfect spacing (not me, I hasten to add)!
Just looked at your formula - asuming 180 kts groundspeed you're suggesting a turn-on starting at 1.8 miles from the centreline. I don't think that would work! If you double the distance you might get close.
Just looked at your formula - asuming 180 kts groundspeed you're suggesting a turn-on starting at 1.8 miles from the centreline. I don't think that would work! If you double the distance you might get close.
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It isn't an ATC rule of thumb but the way I learned it.
GS (NM/min) divided by 3. This term is also needed for the AOL.
I hope it'll work. I haven't had a chance to use it since I finished flight training.
GS (NM/min) divided by 3. This term is also needed for the AOL.
I hope it'll work. I haven't had a chance to use it since I finished flight training.
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HD,
The GS/100 method does work. It is the same method us pilots use to intercept a DME arc.
However being a good approach radar controller you would always put us on a 30deg leg before we join the centerline.
Perhaps the rule of thumb should be- if you have a guy 1.8nm from the centerline at 180Kt then it is tooo late for the 30 degree leg..........or if that guy is 1.5nm from the centerline then give a turn onto a heading that will capture from the other side along with something like "err not forgetting you just taking you through the loc for spacing err your number 1 report established"
Regards,
DFC
The GS/100 method does work. It is the same method us pilots use to intercept a DME arc.
However being a good approach radar controller you would always put us on a 30deg leg before we join the centerline.
Perhaps the rule of thumb should be- if you have a guy 1.8nm from the centerline at 180Kt then it is tooo late for the 30 degree leg..........or if that guy is 1.5nm from the centerline then give a turn onto a heading that will capture from the other side along with something like "err not forgetting you just taking you through the loc for spacing err your number 1 report established"
Regards,
DFC
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DFC.. I hear what you're saying but there is the factor of anticipation to be taken into account. A pilot watching for a particular point at which to commence a turn is ready to turn at a precise instant. When he receives an ATC instruction he has to absorb the instruction and then take the necessary action, which may take several seconds. The controller automatically - through training and experience - takes into account the time it takes for him to transmit the instruction, for the pilot to react and for the turn to commence. Believe me, it would be an exceptional challenge to get a large aircraft doing 180 kts on a 90 degree base leg on to a centreline from 1.8 miles away. A clockwork mouse might be different, but not a 747-400.
On the rare occasions when we were able to let pilots do a DIY ILS it amazed us how close to the centreline you could get and still complete a succesful intercept. On more than one occasion I've commented that if I'd left the turn that late they'd have screamed through the localiser!
Any current controllers care to comment, given that I'm long out of practice and have to rely on a beaten up old memory box?
On the rare occasions when we were able to let pilots do a DIY ILS it amazed us how close to the centreline you could get and still complete a succesful intercept. On more than one occasion I've commented that if I'd left the turn that late they'd have screamed through the localiser!
Any current controllers care to comment, given that I'm long out of practice and have to rely on a beaten up old memory box?
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It doesn't matter if it is a 744 or a Dash-8 doing 180kts. They are both going to make the same turn radius.
The "rule of thumb" is pretty good for approach type speeds and a 90 degree int.
If you haven't heard from the controller by 2.5nm, you will shoot thru the loc. You also have to allow for a bit of time to initiate the turn, so 180kt 2nm from loc works ok.
As an aside, having seen controllers at work in Europe, Australasia, Asia, and Nth America...
Heathrow win hands down.
It is a real pleasure working with you lot.
The "rule of thumb" is pretty good for approach type speeds and a 90 degree int.
If you haven't heard from the controller by 2.5nm, you will shoot thru the loc. You also have to allow for a bit of time to initiate the turn, so 180kt 2nm from loc works ok.
As an aside, having seen controllers at work in Europe, Australasia, Asia, and Nth America...
Heathrow win hands down.
It is a real pleasure working with you lot.
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It doesn't matter if it is a 744 or a Dash-8 doing 180kts. They are both going to make the same turn radius.
Cheers
URC
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URC, I think I know where you are coming from, but to put some cred. to my statement...
Radius of turn = V(sqrd)/G x Tan theta
Where Theta = AoB
Removing constants from the equation shows that the only variables are V and AoB (in a balanced turn)
I will grant you that rate of bank change in a -8 will likely be quicker than a -400 (hence the 0.2nm fudge factor in my previous post) but the effect of this will be very limited.
AFA bank angle is concerned, you will get 25deg out of the -400, much the same as the -8 et al
Only explanation I can offer is that maybe the -8 crew is a touch more spring loaded than the -400 crew that have just done 12 hours.
(standing by for -8 crew to tell how they do 12 hour days with 5 sectors and no crew rest)
As a side note, first to admit the turbo-props are a lot more nimble with speed and altitude requests.
Radius of turn = V(sqrd)/G x Tan theta
Where Theta = AoB
Removing constants from the equation shows that the only variables are V and AoB (in a balanced turn)
I will grant you that rate of bank change in a -8 will likely be quicker than a -400 (hence the 0.2nm fudge factor in my previous post) but the effect of this will be very limited.
AFA bank angle is concerned, you will get 25deg out of the -400, much the same as the -8 et al
Only explanation I can offer is that maybe the -8 crew is a touch more spring loaded than the -400 crew that have just done 12 hours.
(standing by for -8 crew to tell how they do 12 hour days with 5 sectors and no crew rest)
As a side note, first to admit the turbo-props are a lot more nimble with speed and altitude requests.
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Hi jtr,
I don't doubt your theory at all. But, as soon as you chuck a homo sapien into that formula, it all falls apart...
hehe
Cheers
URC
[Edit: Where would that nasty thing called intertia fit into all this??]
I don't doubt your theory at all. But, as soon as you chuck a homo sapien into that formula, it all falls apart...
hehe
Cheers
URC
[Edit: Where would that nasty thing called intertia fit into all this??]
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Funny how my brain can do all that without having the first idea about V(sqrd)/G x Tan theta
As an ex colleague (known for his tact once said as the aircraft cocked up a turn on a centre fix) If I'D done that you would have complained!!
Quite right too.
The only rule of thumb I have is if a certain operator has more than one aircraft in the sky approaching the same point on an instrument approach they seem to use a random number generator to give them approach speeds!! (thanks Jo-jo)
As an ex colleague (known for his tact once said as the aircraft cocked up a turn on a centre fix) If I'D done that you would have complained!!
Quite right too.
The only rule of thumb I have is if a certain operator has more than one aircraft in the sky approaching the same point on an instrument approach they seem to use a random number generator to give them approach speeds!! (thanks Jo-jo)