The Square Circuit
 

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!

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

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!

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

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

Foz

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

Students in the circuit are a danger hey?

Quite an inspirational comment from an instructor!

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.

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.

Stephen Stark,

I am based just north of London, UK.

Foz

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.

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:

Think about it hey?

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!

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. 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.

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

The Square Circuit.
 

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:

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?

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)

"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)!

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!