The Square Circuit

[whatunion]

im am interested to know if all flying schools still use the square circuit or are any using the RAF 800 feet oval.

my experience was that the 800ft oval produced a better handling pilot who re-acted more quickly in the circuit and could do better pfls.

also everbody seemed to stay within the atz and you knew were they were going to be. my experience with the square circuit was that a/c were all over the place, some appeared to be on cross countries!

[Foz2]

I would suggest that at busy training airfields a small oval circuit would cause problems simply because of the amount of inexperienced traffic coming in and out all the time.

A bigger circuit obviously means more trafffic can get into the air and there would be less go arounds due to people getting too close to each other. Sure an oval would probably increase your reaction speed, but it's not much use if you can't get into the circuit to practice due to the traffic!!

Foz

[Stephen Stark]

Where I am we still use the square circuit, and our aerodrome is located in a CTR, but I have a feeling that students have no concept of how far away they are from the runway. This is really noted when joining from a nav or something like that. Then again, eliptical circuits which we use at night are even worse. I have flown with students that almost fly over the RW on downwind. :sad: So what is the answer? I think students in the circuit are a danger anyway :} Have a good one with it!

[whatunion]

foz u said a bigger circuit means more people can get in but is that what u really want. 4 in a circuit is enough esp when you have solo students

i think we did 3 - 4 more circuits per detail with the ovals, so you ended up with more movements during a day. but the great thing was you knew were everyone was, same circuit points every time. when someone called final you knew where they were going to be. in a square circuit somone calling finals could still be finishing a cross country!

by the way there was no roll out on the raf oval circuitmain wheels down, full power, go.

the other great bonus was that you could even teach practice forced landings over the same pattern just higher!!! think about it.

the aim of a circuit originally was to stay in the atz, how many can say they are actually doing that with the monster square circuits they fly

[Foz2]

Yeah I do agree with you about knowing exactly where everyone is in the circuit keeping it neat and tidy, but if say 3 or 4 aircraft are in the circuit all doing touch and go's in a small circuit then it's quite hard for anyone else to either take off and leave the zone or arrive back from a nav as there is little room between aircraft in the circuit. This is obviously when you dont have ATC just A/G (all movements at pilots discretion).

Sure you could limit the circuit to no more than 2 aircraft doing touch and go's to allow room for others, but that isn't really possible at busy training fields.

A bigger circuit with the same number of aircraft doing touch and go's means that other aircraft can slot in between and take off and leave the zone without having to wait for too long at the hold and hence not wasting their money (if you are paying brakes on - brakes off time).

Just my thoughts!!

:p

Foz

[Stephen Stark]

Foz

Out of curiosity, where in the world are you based?

[Staller]

Students in the circuit are a danger hey?

Quite an inspirational comment from an instructor!

[fireflybob]

Funny but I have rarely come across a square circuit - plenty of oblong or rectangular shaped ones but not square!

Having worked for the military on contract (but not, I hasten to add, ex military myself) I have flown many racetrack circuits and I like the concept.

But, in the civvy world, lets imagine for a moment that we are going to standardise on racetrack circuits. How are we going to arrange for all pilots to be trained in racetrack circuits and on what date would this changeover occur?

As things stand at the moment it is perfectly legal to fly an racetrack circuit if the traffic conditions permit and you can obey the Rules of the Air with respect to conforming to the pattern, etc.

As has been said previously the big limitation with racetrack circuits is the number of aircraft which can safely be accomodated in the pattern. I believe the military limit this to 4 in, maybe 5 if one is to land.

Another factor is noise abatement considerations. Sadly, more and more circuits at GA airfields are being constrained by the NIMBY factor and we have to avoid flying over various hamlets or do split-a**e turns immediately after take off to keep the natives happy.

[BEagle]

One point - all military training aeroplanes are low wing. Thus it's relatively easy to look into the direction of the turn irrespective of bank angle.

But many civilian trainers are pieces of cr@p like the C150/152 with a high wing and a pretty dismal rate of climb. Fly one of those at 15 deg AoB through a continuous 180 deg at the upwind end of the circuit and you'll be blind in the direction of the turn for quite a while as you can't see through the wing! Certainly you'll be blind for much longer than you would in 2 x 90 deg turns at 30 deg AoB in a rectangular circuit.

Personally I'd prefer racetrack circuits with a downwind spacing such that the runway is always within gliding range. Realistically that's unlikely though. But those ludicrous Bomber Command circuits flown by many (e.g. as at White Waltham) have no place in light GA flying.

[Foz2]

Stephen Stark,

I am based just north of London, UK.

Foz

[FNG]

Alas, BEagle, the silly Waltham circuits are dictated by nimbyism, albeit accentuated by bad habits on the part of some pilots, but from the overhead join you can fly a proper circuit, tight in over green bits, and beat everyone else to the tea hut.

[Stephen Stark]

Staller

As far as I am aware, you have never sent a student solo in the circuit before, nor have you flown in a high performance aircraft when there are students solo in the circuit. I was not really trying to inspire you, and you obviously have not noted the satire in my comment:

Satire: A form of ridicule or mockery that exposes vice or folley.

Think about it hey?

[whatunion]

good point about high wing aircraft but the closest i had were these two, one that flew underneath me at around 300 feet on finals and landed ahead!!! another was the islander who flew underneath us downwind without seeing us. wouldnt have mattered if we been wingless we wouldnt have seen them!

they used to use a technique called ' looking out before turning' when i was an instructor! even used to lift the wing up. in my experience high wing pilots were more aware of the need to lookout. remember the ba hamble students that descended on one another, thats why all ex hamble cherokee's have windows in the roof!

[slim_slag]

fireflybob,

As things stand at the moment it is perfectly legal to fly an racetrack circuit if the traffic conditions permit and you can obey the Rules of the Air with respect to conforming to the pattern, etc.

Might depend on where you fly, in FAA-Land the AIM has pictures of traffic patterns and they have definite base and crosswind legs AIM 4-3-3 (http://www.faa.gov/ATpubs/AIM/Chap4/aim0403.html#4-3-3). I've heard a story about a plane in the pattern hitting somebody flying a straight in approach. As the person in the pattern who was having fun in a Pitts didn't fly a definite base leg the FAA blamed him. Also, if you don't fly a definite crosswind or base leg on your FAA checkride, the examiner is supposed to fail you.

[fireflybob]

slim_slag, thanks for that - I was referring to UK operation really - I guess when in Rome do as the Romans do!

[Sleeve Wing]

BEags.
As we have come to expect/respect, always sound counsel and well- considered ideas but, please, don't be too hard on Waltham !

Your argument regarding high-wing is so true but, as mentioned previously, what has happened to the "quick bank /look-see" school of sound instruction.
Having said that, I still agree that, for ab-initio students, the rectangular circuit is the safest.

WRT Waltham, as proffered by FNG, we suffer almost intolerably from "nimbyism".
Why people can't sue their solicitors for not warning them of the close proximity of an ex-ww2 airfield is beyond me !

When students are not in the circuit or the circuit is not too busy, many of the residents do oval circuits " over the green bits".
We don't like scenic tours anymore than anyone else.

Rgds, Sleeve.
:ok:

[whatunion]

Whether you do a square or oval circuit you still have to turn so its the same problem on a high wing a/c. whatever shape circuit you do you still have to do the same amount of turning to end up on finals!!!

Anyway, if square circuits are the only way, how come ATZs are all round?

[Another St Ivian]

Surely the counter to that is that on a square circuit you get the opportunity to get a good look along the next leg while flying along your current leg. So at base you can look to downwind, downwind you can look to crosswind, etc?

I too prefer oval circuits, I find them much easier to fly and they were easier to learn as a student.

ASI (an interested low hrs PPL)

[BEagle]

"Whether you do a square or oval circuit you still have to turn so its the same problem on a high wing a/c. whatever shape circuit you do you still have to do the same amount of turning to end up on finals!!!"

Hardly true,whatunion. It is the 'time spent blind' which matters. A slow turn to downwind in an 'oval' circuit means that the circuit direction will be obscured for far longer under a high wing than it would be for two quicker 90 deg turns in a 'square' circuit. Whereas in a low wing aeroplane it won't be. So a circuit which will accommodate both configurations will be 'safer' if it's rectangular.

But I far prefer a tight racetrack circuit (or 'oval' as it is wrongly termed)!

[whatunion]

pilots that fly ovals normaly turn at 30 degrees throughout while those who favour squares fly 15 degree banked turns in my experience.

Its not just the amount of time you spend blind that may be the deciding factor in getting close to another a/c in the circuit. its also your standard of lookout and ability to listen out and form a mental picture of what is going on. with four in an oval you should know where everyone is.

the square circuit non discipline i have seen means, get as many in the circuit that want to fit in and make any sort of pattern you feel happy with and turn final at any distance.

get three flying schools in a circuit and you will have 3 different patterns!

[Milt]

Buzz Circuit

Used to love the fighter buzz circuits in use in the 50s.

Procedure was to dive low and medium fast over the intended touch down point then pull up in a tight climbing turn with power back and RPM to max slowing to lower gear and flap in the turn at appropriate speeds and adjusting the manoeuvre and speed to be still turning over the end of the runway. One was able to readily keep the intended touch down point in easy view throughout.

After practice one could judge all of that accurately to roll out straight for a short flare to touch down.

It was a wartime procedure to get a fighter on the ground in the least time to reduce exposure to any enemy fighter attack.

Later Military adopted the entry to airfield traffic patterns via an Initial run at 1000 ft AGL down the active runway with breaks out of formations to result in a down wind spacing. This way all traffic becomes sorted for landing well away from the airfield.

Still used today for military.

[whatunion]

milt, it was still very much in use when i instructed 14 years ago and was called a run and break!

i gave it up when i hit stall buffet in an aztec over the airport cafe one morning!

[ACW 335]

i fly both oval and sqaure.

Where i fly at my VGS in the instructor role, we fly racetrack as we are in military machines. We find that the amount of traffic you can get in the circuit varies depending on the runway length; but 4 is no problem.

There is also the rule that on first solo's the circuit must be clear of all over traffic. There are also less places to join as there is no base.

When i fly civvy, i find that people under instruction fly bomber circuits, which aren't necessary (apparently its for spacing!?!), and everyone else flies a sort of normal rectangle size. The only problem is, that people join EVERYWHERE - over head, straight in, crosswind, left base/right base or downwind. And with bomber circuits going on as well you haven't a clue where everyone is as everyone percieves the circuit to be a different size.

However, low level circuits are oval :p

Racetrack in my opinion creates more accuarate more controlled circuit flying; it also holds a less ambiguity to where the rest of the circuit traffic is! You can also get far more circuits done in 20 mins than you can in a rectangle as there is far less *rsing around going on!

(Im a low hour PPL with high VGS hours) Like ASI i learnt the military way.

[whatunion]

acw 335
thank you for that, i had forgotten that phrase the 'bomber circuit'.

anyone who advocates square circuits should read you post, you are spot on.

the ridiculous circuit pattern flown by flying clubs is the one reason why i never want to fly light a/c again as an instructor.

how can you monitor and teach in such a n undisciplined enviroment?

[fireflybob]

With reference to "bomber circuits" the problem often seems to be that pilots will insist on extending downwind from the point where they would normally turn base leg instead of turning base leg and conducting a Go Around from base leg maintaining circuit height. The aircraft behind this aircraft also extends downwind so that at many GA airfields most if not all the aircraft in the circuit are on base leg or final!!

By turning base leg and conducting a GA this means the aircraft behind you can conduct a "normal" circuit and quite often you can make an early turn downwind from the go around.

That said, there are times when you might extend downwind for sound airmanship reasons but broadly speaking my point is that aircraft should not extend downwind for separation purposes. Finally, these comments are related to airfields without an ATCU where we presume the expertise of the controller avoids this situations also!

No doubt, whatunion, will have some argument to rubbish what I have said in this posting - that's got that one off before we start!

[whatunion]

wrong again
if you are advocating going around from base leg rather than extending downwind i agree.

[fireflybob]

whatunion - I should have guessed - LOL!!

[ACW 335]

acw 335
thank you for that, i had forgotten that phrase the 'bomber circuit'.

anyone who advocates square circuits should read you post, you are spot on.

the ridiculous circuit pattern flown by flying clubs is the one reason why i never want to fly light a/c again as an instructor.

how can you monitor and teach in such a n undisciplined enviroment?

I have to say, i agree whatunion, hats off to those GA instructors who go up day in day out to teach ex 12&13 - they are nuts! i wouldn't.

If clubs are going to continue with sq. ccts they need to seriously address the re-join/join procedure (limit to overhead join?). and also perhaps reiterate the spacing on downwind between the runway and the aircraft... i certainly bought up the bomber circuit issue at the last safety meeting at out airfield

[Vortex Thing]

Run and break from initials is still used as standard practice. It would be nice if occasionaly people realized that there is more than 1 armed service with pilots.

Military cct would probably cause less offence than RAF cct. However I do digress. Surely whatever type of cct you fly you need to be able to reach the runway should you suffer an engine failure (SEP obviously) and I believed that this was taught to be acheived by keeping at least the wingtip, but preferably the roundel (or where one would be) running along the rwy regardless of cct type.

If you are teaching flying further away than this could you please tell me why as I am confused as to why you would want to place yourself in an a/c near the ground with no sensible options in the case of FLWOP. Giving the student more time doesn't mitigate indoctrinating them at such an early stage something that could get them into trouble later on in life.

If you think the ccts at WW are big try ones you see at Elstree and Blackbush often 2.5d out!!!

[bpster]

Square CCTS are much easier for a low hour PPL or student to manage. People do have a tendancy to join from everywhere but the standard join in the civillian world is overhead, normally 2000'. you would usually do this to an airfield you dont know or when it is busy. Or if low hours, all the time. This gives you a chance to map out what is below, work out which way you are going and map out where all the other aircraft are from above. Anyone wishing to do a non standard join should take it upon them selves not to get in the way of anyone joining overhead, this would normally be resident ac or an experienced pilot. You can not compare civvy flying procedures to military ones. Remember they have 2 totaly different objectives. CCTS are only really ever flown for currancy or training. This should also be the case in civvy world but it isnt. Soome people do just enjoy doing ccts.

Oh and Vortex Thing, what have you against the RAF? I would like to know.

Also with reference to fireflybob, i do agree with what you say about civvy ccts and the unwillingness to go around but do remember most of the PPL world dont have a lot of money. I dont. If i am flying on my PPL i will adjust my cct to get out of it what i want. Rightly or wrongly, as long as it is safe. However if i am flying military, i will follow everything to the letter and if that means going around at cct height then so be it, i am not paying for it.

Maybe not quite tyhe right attitude and i know it but i bet everyone else who both gets paid to fly and pays to fly will say the same. Their flying disciplines will change depending on who is paying!

i would also likle to add that oval ccts are only at their most effective when the cct is full of similar or identical ac, hence why it is used in the military (with some exceptions). GA airfields tend to have 1 of every ac under the sun all flying at different speeds. The oval cct would be very difficult to manage both from a pilots and an air trafficers point of view. Unless you have different cct heights for different types which is what the military does to seperate types in the oval cct.

[JUMBO400]

I just wished that fixed wing pilots became aware of helicopters in the circuit, Had a C172 cut inside me today in the circuit at Cambridge, I was at 700 QFE tight in, where I should be and this Cessna was also at 700 feet apparently could'nt maintain circuit height of 1000 feet, so tight he must have had to to a steep turn to get onto final.

[Cambridge Aero Club]

Hi Jumbo,

Problem at Cambridge is two fold:

Firstly, as you are aware most of the fixed wing pilots have no idea where the helicopter circuits are, but be assured that I am trying to improve the situation!

Secondly, ATC will often respond to a request for a low level circuit from a fixed wing pilot undergoing training with a blanket 'approved' reply. They will usually then call the helicopter and advise them that there may be conflicting traffic at their circuit height... Good in theory but as you know a 'little' controlling from ATC is often worse than none at all thus leading to confusion. With credit to them however, they always try to accommodate all requests from all types, and with an ever increasing level of helicopter traffic at Cambridge doing circuits this situation is becoming more frequent.

In the mean time I suggest we try to improve communication between the two 'camps' and possibly liaise a little more with the ATC authority at Cambridge. I will raise the subject at the next Heads of Dept meeting.

It's probably worth mentioning that low level circuits are an often examined part of the PPL syllabus during skills tests so w have to make sure students can do it properly, including maintaining situational awareness, however, it often takes them a number of attempts before they feel confident doing it.

I will brief my instructors accordingly and please do the same in the whirly club!

Best wishes,

Aero Club.