Circuits
Joined: Sep 2002
Posts: 29
Likes: 0
From: UK
The obvious problem with using landmarks for the circuit turning points is that you won't be able take them with you when you go to another airfield. I was tought to start the turn onto x wind at 500 ft (QFE), start the turn onto downwind when the runway is just under the tailplane and turn base when the threshold is about 45 degrees behind you over your shoulder. Wouldn't have thought there is anything wrong with using land marks as long as you remember the way you were tought initially.
Joined: Sep 2002
Posts: 1,650
Likes: 0
From: Chichester, UK
Not a good idea to fly around a set of landmarks IMHO (other than the active runway, of course 
). There isn't really a single 'ideal' circuit - it changes with the wind and aircraft configuration (flaps, flapless, glide...) - and, as pythag says, you cannot those landmarks with you. You just need to learn to work out the turning points yourself - Read Thom book 1 (or Pratt's equivalent), ex. 12 and 13. He explains it much more clearly than I could
). There isn't really a single 'ideal' circuit - it changes with the wind and aircraft configuration (flaps, flapless, glide...) - and, as pythag says, you cannot those landmarks with you. You just need to learn to work out the turning points yourself - Read Thom book 1 (or Pratt's equivalent), ex. 12 and 13. He explains it much more clearly than I could
Moderator
Joined: Feb 2000
Aviation Qualifications: CPL
Posts: 14,480
Likes: 178
From: UK
On a lot of airfields, use of landmarks is inevitable. This is not for flight safety or training reasons, but to ensure that the local sensitive noise areas are avoided. Old Sarum is a good example of this, which has a necessarily rather non-rectangular circuit, at least to the South.
Mostly however, a good rule of thumb is to turn crosswind when high enough to turn safely, and turn base when the threshold is 45° behind you. Downwind leg distance should ideally be as close to the runway as you feel comfortable, but mostly will simply be in line with the chap in front of you.
Also, it is never a bad thing to extend on climbout, or downwind (or exceptionally crosswind) if the circuit is crowded or you are faster than the other traffic, so as to give you safe separation from the traffic in front.
G
Mostly however, a good rule of thumb is to turn crosswind when high enough to turn safely, and turn base when the threshold is 45° behind you. Downwind leg distance should ideally be as close to the runway as you feel comfortable, but mostly will simply be in line with the chap in front of you.
Also, it is never a bad thing to extend on climbout, or downwind (or exceptionally crosswind) if the circuit is crowded or you are faster than the other traffic, so as to give you safe separation from the traffic in front.
G
Why do it if it's not fun?
Joined: Jul 2001
Posts: 4,782
Likes: 12
From: Bournemouth
Agree with Genghis
All 6 of the circuits at White Waltham are identified by landmarks to avoid noise-sensitive areas. Two of them are non-rectangular. All 6 of them are much bigger than I'd like them to be.
But it's also important to be abe to judge your position relative to the runway, since this is the "usual" way of flying a circuit at an unfamiliar airfield (or even at a familiar airfield, if noise abatement isn't an issue).
Flexibility is important when it comes to traffic considerations. Extending downwind is the most common technique, but upwind and crosswind can be extended too. If you have ATC you may be told to extend for traffic, otherwise you'll need to spot the traffic yourself and make a decision about how best to avoid it. Being flexible with your speed, at least until you turn final, can also help.
FFF
----------
All 6 of the circuits at White Waltham are identified by landmarks to avoid noise-sensitive areas. Two of them are non-rectangular. All 6 of them are much bigger than I'd like them to be.
But it's also important to be abe to judge your position relative to the runway, since this is the "usual" way of flying a circuit at an unfamiliar airfield (or even at a familiar airfield, if noise abatement isn't an issue).
Flexibility is important when it comes to traffic considerations. Extending downwind is the most common technique, but upwind and crosswind can be extended too. If you have ATC you may be told to extend for traffic, otherwise you'll need to spot the traffic yourself and make a decision about how best to avoid it. Being flexible with your speed, at least until you turn final, can also help.
FFF
----------
PPruNaholic!
Joined: Aug 2000
Posts: 1,615
Likes: 0
From: Buckinghamshire
Its true what's been said re- the fact that there are plenty of places with noise-sensitive circuits where landmarks are used, but you can usually get a crib-sheet for these, either from the club involved or on the Bottlang plate (e.g. Wycombe).
But I believe that its most important you also do learn how to judge a circuit when the only reference available is the airfield itself. This is the "normal" case, and will enable you to land anywhere you might come across. As has been said, this entails turning xwind on climb-out at about 500', downwind achieve proper spacing by positioning youself so that your wing-tip appears to be at the same place as the strip you're about to land on, then turn base with the threshold approx. 45 degrees behind your shoulder, and lastly aim to be at approriate height (I use 600~700') when turning final.
However, in a crowded real-world circuit, you also need to exercise airmanship, as has been said: extend downwind if necessary (if you are faster than the guy in front, or if he is a zob and just goes too far downwind himself...) Never cut in front of someone on final (Yak pilot I "met" at Shoreham weekend before last: you know who you are!), and always be ready to go around if spacing (or anything else!) is not right.
It all comes with practice mate, so don't worry. For now, do whatever your instructor tells you to do, and read (and re-read) Trevor Thom (or whichever text you are using).
As a footnote, I had a fun experience this Sunday: my first ever "military" circuit! I was lucky enough to be able to fly a civilian aircraft which is based at an RAF airfield. The military fly an oval circuit... instead of turning 90 degrees to base then another 90 degrees to final, you make one continuous curved approach from downwind to final, judging your descent as you do so. Was actually pretty easy, and fun to do something a bit different! They also have a variation on th overhead join, whereby they join at the "Initial Point" (aka "IP" or "Initials") which is 2NM short of runway threshold, just on the dead side, and 1000' above circuit height - then descend on deadside and the rest like a regular overhead join (i.e. you then join downwind at circuit height). Cool!
But I believe that its most important you also do learn how to judge a circuit when the only reference available is the airfield itself. This is the "normal" case, and will enable you to land anywhere you might come across. As has been said, this entails turning xwind on climb-out at about 500', downwind achieve proper spacing by positioning youself so that your wing-tip appears to be at the same place as the strip you're about to land on, then turn base with the threshold approx. 45 degrees behind your shoulder, and lastly aim to be at approriate height (I use 600~700') when turning final.
However, in a crowded real-world circuit, you also need to exercise airmanship, as has been said: extend downwind if necessary (if you are faster than the guy in front, or if he is a zob and just goes too far downwind himself...) Never cut in front of someone on final (Yak pilot I "met" at Shoreham weekend before last: you know who you are!), and always be ready to go around if spacing (or anything else!) is not right.
It all comes with practice mate, so don't worry. For now, do whatever your instructor tells you to do, and read (and re-read) Trevor Thom (or whichever text you are using).
As a footnote, I had a fun experience this Sunday: my first ever "military" circuit! I was lucky enough to be able to fly a civilian aircraft which is based at an RAF airfield. The military fly an oval circuit... instead of turning 90 degrees to base then another 90 degrees to final, you make one continuous curved approach from downwind to final, judging your descent as you do so. Was actually pretty easy, and fun to do something a bit different! They also have a variation on th overhead join, whereby they join at the "Initial Point" (aka "IP" or "Initials") which is 2NM short of runway threshold, just on the dead side, and 1000' above circuit height - then descend on deadside and the rest like a regular overhead join (i.e. you then join downwind at circuit height). Cool!
Why do it if it's not fun?
Joined: Jul 2001
Posts: 4,782
Likes: 12
From: Bournemouth
SZF,
Officially, no I don't think it is allowed at non-ATC airfields. Unofficially, if both of you are on the radio, and you know the other guy's call-sign (which you would do if you've been listening to his radio calls) it's not completely unheard of to ask him if he minds you going inside him. I've been passed like this several times, and have also passed other pilots like this several times. As long as there's good communication and everyone has everyone else in sight, it's not a problem. Generally tends to happen more often on the crosswind-to-downwind turn than anywhere else when a faster aircraft is behind a slower aircraft, in my experience.
FFF
--------------
Officially, no I don't think it is allowed at non-ATC airfields. Unofficially, if both of you are on the radio, and you know the other guy's call-sign (which you would do if you've been listening to his radio calls) it's not completely unheard of to ask him if he minds you going inside him. I've been passed like this several times, and have also passed other pilots like this several times. As long as there's good communication and everyone has everyone else in sight, it's not a problem. Generally tends to happen more often on the crosswind-to-downwind turn than anywhere else when a faster aircraft is behind a slower aircraft, in my experience.
FFF
--------------
Joined: Jun 2002
Posts: 1,795
Likes: 0
From: New South Wales
[QDM on one of his hobby horses]
I think the problem with circuits as they are taught is that they are too high and waaaay too big. Perspective-wise, it is much easier flying a 500 foot circuit close in to the airfield than these massive, airliner circuits at 1000 feet which we are all taught. Do some 'low level' practice circuits with your instructor and you'll find the picture much easier to visualise and this will then transfer back to when you have to fly circuits the size of the Isle of Wight again.
[/QDM off one of his hobby horses]
I think the problem with circuits as they are taught is that they are too high and waaaay too big. Perspective-wise, it is much easier flying a 500 foot circuit close in to the airfield than these massive, airliner circuits at 1000 feet which we are all taught. Do some 'low level' practice circuits with your instructor and you'll find the picture much easier to visualise and this will then transfer back to when you have to fly circuits the size of the Isle of Wight again.
[/QDM off one of his hobby horses]
