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What Does High Key mean when in the circuit?

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What Does High Key mean when in the circuit?

Old 19th Feb 2018, 08:54
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Question What Does High Key mean when in the circuit?

Morning All

I have often heard the term High Key when an aircraft is in the Circuit. What does this mean.

Cheers

Glider 90
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Old 19th Feb 2018, 09:06
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High key

I realise the use of it may vary slightly from type to type but generally it is a term used when doing a PFL pattern. It is roughly equivalent to the downwind call (low key or final key may be used for the finals call). The orientation may differ between aircraft but it is designed to allow a constant glide angle to be maintained from overhead the runway until touchdown.

I’m sure others can provide more detail for specific aircraft types. I can only speak for the Hawk. Our High Key (for a circling PFL) is 90 degrees off at the upwind threshold.

BV
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Old 19th Feb 2018, 09:09
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RAAF Mirage IIIs called High Key entering the downwind leg at 14,000 ft ... quite stimulating to watch from the Tower, and I suspect even more so in the cockpit.
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Old 19th Feb 2018, 09:18
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Going back a few decades: for the Hunter we used 5-6000 ft agl as High Key, entering the downwind leg, 210 kt clean. Low Key, abeam touchdown, ideally 3000 ft.
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Old 19th Feb 2018, 09:25
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Heights

I should have added that HK is approx 4500’ and LK approx 2500’.

Always think wind of course!

BV
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Old 19th Feb 2018, 09:44
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Wot's a PFL ?

LFH (Glider 1961)

..........
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Old 19th Feb 2018, 09:47
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Wot's a PFL ?
Practice Forced Landing
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Old 19th Feb 2018, 10:04
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Different from an AFL, as gliders do that all the time.
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Old 19th Feb 2018, 11:10
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Recall having a ride in a Belgian 104 (which wasn't for the faint-hearted) and being told their High Key was 22,000ft!
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Old 19th Feb 2018, 11:15
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There is a long thread on this on a certain other place that concerns flying little planes with a mix of outrage from some GA pilots and enlightenment from others, that people should use such terms when flying in 'GA' and not 'Military' airspace. For some people, being an ex-mil pilot winds them up no end before you've even got past the 'hello how are you' stage... Maybe previous offerings of pomposity have wound them up or maybe its just resentment at not having made it into the RAF. Either way, an awareness of different ways of skinning a cat and that others may not understand the words you use may be the way forward...

Or just join for a break to land every time...
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Old 19th Feb 2018, 11:18
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Originally Posted by Chris Kebab View Post
Recall having a ride in a Belgian 104 (which wasn't for the faint-hearted) and being told their High Key was 22,000ft!
Just listened to Arnulf Hartl being interviewed about flying the F104 and there is an interesting bit about partial power/dead stick approaches!! For those who haven't listened, these are an excellent series of podcasts - normal blokes talking about the planes they have flown.
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Old 19th Feb 2018, 11:33
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Someone will correct me with the precise details but ISTR that in the mighty Bullfrog, High Key was about 800', with Low Key about 400-500' depending on the CSLA and how that was going ....
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Old 19th Feb 2018, 11:43
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Originally Posted by thunderbird7 View Post
a mix of outrage from some GA pilots and enlightenment from others, that people should use such terms when flying in 'GA' and not 'Military' airspace. .... Either way, an awareness of different ways of skinning a cat and that others may not understand the words you use may be the way forward...

Or just join for a break to land every time...
I'm sure it wound up the civvies no end (and probably rightly so) when we practised diversions into a nearby civilian airfield. You could almost hear the amusement in the controllers voice there as he interupted whatever they were doing and said to his assembled throng ..

"All stations, clear the circuit immediately, military aircraft inbound" and their 'pi$$ed-offness' when a Bulldog trundled into sight, did an approach, not even a TnGo, and then bogged off again..
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Old 19th Feb 2018, 12:37
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JP Mk3a and Mk5 Hkey @2500' agl, Lkey @ 1500' agl.
Lkey downwind abeam RW threshold.
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Old 19th Feb 2018, 12:48
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Remember early Microsoft Flight Simulator?
It had red boxes in the sky, you flew through them to achieve the result required ie approach to land.

High Key, Low Key etc are "Key" points (or "Gates").
Achieve each gate in sequence and you should achieve your objective ie PFL.
If you are not at the required height, speed and position, you may be able to continue your (now modified) pattern or have to abandon it - with all that implies.

It formalises a procedure and makes it more likely that you will be successful in your task, be it practice or real - it gives you an early warning too if things are not going "to plan".

lsh

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Old 19th Feb 2018, 13:03
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Cargosales wrote:
Someone will correct me with the precise details but ISTR that in the mighty Bullfrog, High Key was about 800', with Low Key about 400-500' depending on the CSLA and how that was going ....
For the Bulldog PFL, ideally you would approach the desired landing area at 80KIAS and 2-3000' agl before tracking to 'Point 1' or High Key when the initial aiming point 1/3 way into the field appeared immediately in front of the wing leading edge. Then decelerate to 75KIAS and keep gliding straight ahead until the touchdown point appeared just behind the trailing edge (Point 2). Then turn with 30° AoB to track crosswind, aiming at a selected feature and allowing for drift, until the touchdown point appeared immediately ahead of the tailplane (Point 3). That was 'Low Key', at around 1500' agl, when you started a continuous gliding turn at 20°AoB at 75KIAS with Inter flap aiming to run the touchdown point along an imaginary line from its location on the left side of the aircraft to directly in front of the windscreen. If you were getting below the line, you increased bank and held the picture until you regained the imaginary line, then ease off the bank and reassess. Once straight in to the field, provided you were certain of getting in and were not below 200' agl, you would lower full flap and use a touchdown aiming point closer to the downwind end of the landing area. We used to practise this down to 100' agl when dual or 250' agl for student solos.
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Old 19th Feb 2018, 13:29
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cargosales,


"All stations, clear the circuit immediately, military aircraft inbound"

In what world was that ever heard?
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Old 19th Feb 2018, 13:50
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Originally Posted by Chris Kebab View Post
Recall having a ride in a Belgian 104 (which wasn't for the faint-hearted) and being told their High Key was 22,000ft!
I think one of my gliding instructors had flown WGAF F-104s at some point in his career.
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Old 19th Feb 2018, 14:01
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Originally Posted by pr00ne View Post
cargosales,


"All stations, clear the circuit immediately, military aircraft inbound"

In what world was that ever heard?
This one. At a civvy airfield in the West Mids that we were approaching to be precise.. I remember it clearly because it was so dramatic and pointlessly OTT..
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Old 19th Feb 2018, 14:18
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Originally Posted by BEagle View Post
Cargosales wrote:

For the Bulldog PFL, ideally you would approach the desired landing area at 80KIAS and 2-3000' agl before tracking to 'Point 1' or High Key when the initial aiming point 1/3 way into the field appeared immediately in front of the wing leading edge. Then decelerate to 75KIAS and keep gliding straight ahead until the touchdown point appeared just behind the trailing edge (Point 2). Then turn with 30° AoB to track crosswind, aiming at a selected feature and allowing for drift, until the touchdown point appeared immediately ahead of the tailplane (Point 3). That was 'Low Key', at around 1500' agl, when you started a continuous gliding turn at 20°AoB at 75KIAS with Inter flap aiming to run the touchdown point along an imaginary line from its location on the left side of the aircraft to directly in front of the windscreen. If you were getting below the line, you increased bank and held the picture until you regained the imaginary line, then ease off the bank and reassess. Once straight in to the field, provided you were certain of getting in and were not below 200' agl, you would lower full flap and use a touchdown aiming point closer to the downwind end of the landing area. We used to practise this down to 100' agl when dual or 250' agl for student solos.
Thanks BEags .. that sounds more like it. Guess I was thinking of normal circuit height, not PFLs.

Cheers, CS
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