Circuit flying
 

Yesterday, on a recency check flight I was told by the instructor that I must not extend flaps in a turn or use more than 15 degrees of bank in the circuit., all news to me.

Is this something new in flying training ?

I have 15,000 hours on a wide variety of jet and piston aircraft, ex CFS A cat standards QFI, etc. etc. and not encountered these issues before.

Comment ?

Perhaps the instructor has a point...if it's a A380!

I have always taught (and been taught) to limit the angle of bank in a climbing turn to 15° and to try to avoid extending the flaps in the turn, but sometimes it can't be helped, for example during a glide approach. Cessnas have a large nose up pitch change when flaps are extended which could get a low time student into trouble if they are not paying attention. I make sure turning in the base leg configuration is practised plenty of times at altitude before bringing the student into the circuit. I too am a believer in explaining the situation rather than saying "don't do that because it's dangerous".

What a load of bovine excrement! Where do these third rate instructors learn all this rubbish and how do they ever pass a PC? Are there really FIEs around who will accept nonsense like this?

I'm with Collieflyer One in regard to limiting climbing angles of bank as exceeding it degrades climb performance.
As for selecting flaps in a turn, I was told off by a highly respected and very experienced examiner whilst doing my 1179 in a Cessna 172 for my initial CPL issue. I was turning final and extending from 20 to 30 deg. He said in the debrief that if the flaps went asymmetric you'd never sort out the roll thus induced and 'don't ever do that again'. I think that he'd had an issue with the electric flaps in Cessnas.

TOO

Some years ago I got a new FO on "my" Citation. When I aked for "flaps up" after take off, he wouldn't raise them. I called again and he answered: "we are in a turn, can't raise them now!". (I know colleagues/former colleagues who would have landed straight back and dumped him on the apron). So obviously this s*** is taught in more than one place...

You really wouldn't believe the nonsense that a few of them accept, thereby releasing a numpty into the big wide world with no further checking for 6 years.

It's enough to make you weep! :{

How much roll rate will you get from asymetrically deployed flaps? 100 degrees per second, maybe more. So what difference will it make if you are already at 15 or 20 degrees of bank before moving the flaps? And the chance that your bank counters the flap asymmetry is 50 percent anyway, gving you one split second more to move them back...

No more than 15deg AoB! How does that work??

Before you know it they'll be getting people to rollout halfway through the upwind turn and final turn and fly straight for a bit to make the circuit even wider!!!

Some "instructors" need a bigger ATZ.

If an instructor or an examiner makes comments like that, ask them "Why?". If they cannot answer, ask them to find out! Many comments such as these may have an origin that is/was valid on some aircraft type for a good reason. However, it is usually unnecessary to apply such limitations to all types. My thoughts on reasons why these comments may have been made:

- Maximum 15 deg bank angle in the circuit. During the finals turn, some aircraft need a maximum bank angle limit in order to maintain an adequate margin from the stall at a sensible speed around the finals turn. If you fly faster you can use more bank but that then necessitates a large speed reduction after rolling out on finals. However, in a 15 deg bank turn the stall speed is only 3.5% greater than in 1g flight and so that appears to be an unrealistic bank angle limit for stall reasons. If an aircraft has a strong spiral mode, as bank angle increases the lateral control input to maintain constant bank angle increases. However, with elementary training aircraft it is highly unlikely that a strong spiral mode would exist and so that should not generate this limit. If an aircraft has low specific excess power then limiting the bank angle during climbing turns will result in a better overall climb rate, and in an 80 KIAS climb you will still have a turn rate of approximately rate 1. Therefore, I would concur with that but only for low powered aircraft; it is not necessary for all trainers and is not a reason to limit bank angle in a finals turn.
- If there is a strong pitch trim change when flaps are lowered and you lower them in a turn then you will have to re-trim in the turn, something which is not normal practice. Therefore, in that case I would recommend not lowering flaps in a turn. However, if there is no significant pitch trim change then there is, in my opinion, no reason not to lower them in a turn.

In the B747-200 there was a 15 deg bank limit if you suffered 'split flaps' (inboard and outboard sections at different angles to each other albeit the same for each section on both wings). I suspect that this was probably due to the change in spanwise lift distribution that resulted in a change in stall characteristics and in roll control power. At pattern and approach speeds the autopilot gave 27 deg of bank and so you had to hand fly the approaches in that case and I have had to fly one.

Teaching on the Bulldog was that the upwind turn should be flown at 15~20° AoB at 80KIAS, starting at 500' in an 800' height circuit.

But that was only because we flew 'racetrack' circuits rather then 'square' circuits, so the specified parameters achieved the normal downwind leg following the continuous turn.

'Inter' flap was selected downwind, with the speed decaying to 75KIAS. At the '45°' point at the end of the downwind leg, again a continuous 15~20° AoB turn was flown to final, rolling out at a height of 400'. Then it was full flap, 70KIAS and point/power to touchdown.

Hence although I can see the relevance of 15~20° AoB when flying a 'racetrack' circuit, it is nonsense for the usual civilian aerodrome 'square' circuit - where the only 15~20° AoB turn might be the initial turn to the crosswind leg, in order not to reduce the climb rate. But all other turns should be made with around 30° AoB, to limit the amount of time needed in the turn when, in high wing aeroplanes, your view of others in the circuit is reduced.

In HM's Gnats, around 60° AoB and pulling to the buffet nibble was often the way we turned from take-off to downwind - don't try this in a spamcan though!

Instructor course at On-Track 9 years ago . Using 'wot' appears to be a Grob Tutor syllabus adapted for a PA28 .
Climbing turns limit to 15*-20* AOB due reduction of climb rate with greater AOB .
Medium level turns in circuit , which is 30* AOB , else you'll be in the next county / country .
Descending turns up to 30* AOB [ preserves stall margins , as on base / final turn you'll have F25 {PA28} ].
Bad wx ccts , 500' QFE [ PA28 ] F25 , 75kts IAS climbing turn with up to 30*AOB , level and descending turns up to 30* AOB .
Don't remember any major differences from the Marshalls of Cambridge C150s of 46 years ago.
It's 8 years ago and beyond ; but over 6 civil jet families and 1 T/prop . I do not remember any restrictions on turning and retracting/extending , flaps/slats .
Although I do recommend to studes to have wings level , safe speed and 200'+ , for retracting flap AFTO. [ AOB may have 'G' pulled together with imbalanced flight and their effects on stall/spin . ]

Hope this helps ,

rgds condor.

If you are flying a military/FJ circuit, ie continuous turn from end of downwind leg until final, surely you HAVE to extend flaps in the turn? Well I did anyway.

BEagle...... Are you able to let us know why military circuits are a racetrack pattern, just wondered what the historical basis was?

IIRC it was posted/speculated on here some while ago that it stems from the high nose attitude required by tail wheel aircraft thus a continuous turn to short finals afforded better visibility of the landing area.

WRT to the OP, I teach low hours PPL students not to do it due to their capacity to cope with the trim change and possible asymmetric deployment. Quite happy to see more qualified/experienced pilots do it and I don't bollock them for it. Quite happy to do it myself as well!

Duchess Driver...... I was wondering whether racetrack paterns originated from say spitfire, mustang, and DH82 approaches, but is it still appropriate to military SEPs, fast jets and heavy transport these days?

Has anyone here actually experienced asymmetric flap deployment? I haven't seen it in 50 years of flying.

Yes, not personally but I know that about ten years ago a student flying solo circuits at a nearby airfield in a C152 had the cable that lowers the flap on the opposite side to the flap motor break. He did a really good job of landing with 20 degrees on one flap and the other retracted.

For the circuit ab initio I teach 15 deg AOB for the climbing turns and 30 for level and descending turns. As a general principal I think it is reasonable to limit bank angle in climbing turns.

30 deg's in the rest of the circuit allows for nice square corners.

Again as a general principal while I do not prohibit flap extension in a turn, I definitely discourage it.

The bigger issue IMO, is nor bank angle or flaps in turns it is teaching the judgement and anticipation so that the circuit works with the desired bank angle and the flight path is managed so that flaps don't have to deployed in a turn.

Sadly in lieu of emphasizing flight path management in flight training schools, we too often get one size fits all "rules" mindlessly passed down from one instructor to another.

Well, sort of! The flap system had been disassembled, lubricated then reassembled. When the splined drive shaft was refitted, the guys managed to insert a shaft locking bolt through the 'female' socket without ensuring the 'male' shaft was fully inserted. All functional Passed. Coincidentally on the first trip afterwards we were flying a few simulated circuits at height. During one selection, the splined shaft fell out of the drive unit. Fortunately it was in a fairly advanced aircraft that sensed flap shaft rotation at both outboard flap screw jacks. When one stopped turning it froze the flap system before any significant assymetry occurred.

Oh, the maintenance instructions did include a warning to ensure the splined shafts were fully inserted prior to fitting the locating bolt!!!

I have...twice.
Once in a Cessna 150 VFR and once in a Twin Comanche in night IMC.
Both in retraction though, one after a stall and the other going missed approach it rolled on us.

Maybe.
What he should have done was land with flaps up or both at 20 depending how it failed.
Undo what you did last.

I agree, he couldn't have landed with them both at 20 but he could have landed flapless. Twin comanches have a bit of a reputation for assymetric flap retraction if the nylon bushes are greased.

I've flown with several ex-CFS instructors/examiners over the years for both FI and FIC work and recall asymmetric flap effect mentioned a number of times with the recommendation to avoid configuring flap in turns in light aircraft. 15 to 20 degree bank angle limits in climbing turns was also recommended to preserve climb performance, lookout and speed but again, in light aircraft and for teaching inexperienced trainees. Up to 30 deg level and descending turns however would be usual in the circuit if I recall.

The 15 degrees angle of bank in a climbing turn goes back to the old days when for cross-country flights one always set course over the top of the aerodrome rather than just climbing on track.

In order to reach the set course height it was quicker to get there at 15 degrees angle of bank in terms of rate of climb than at (say) 45 degrees angle of bank where the rate of climb is significantly reduced. One problem of only using 15 degrees angle of bank in a climbing turn in to the circuit is that in high wing trainers like Cessna 172 the lowered wing blanks out the pilots view during the turn leading to possible traffic confliction.

Using 30 degrees angle of bank in the circuit makes stuff-all difference in rate of climb while the time in the blank spot is less.

I'd put it the other way around - why do civilians fly square circuits?

A circuit is surely intended to bundle a number of exercises (take off, climb, turn, level, speed changes, approach judgement and landing) in the vicinity of the airfield and as the engines of the early days were less than reliable one should never be out of gliding range of the field when in the circuit. That requirement, though often ignored today surely remains an important aspect of circuit flying.

The downwind leg ended with what is effectively a PFL - power off and adjusted with blips of engine (rotary). We now extend that a little to allow power assisted finals but the attitude judgement in that constant turn still replicates a PFL, good practice.

Square curcuits inevitably push the circuit too wide by the need to insert wings level sections on crosswind and base and you lose the safety of being in gliding range of the field and the all-important attitude judgement of adjusting your turn to achieve whatever gate is set for the finals point.

I can't see why civvies do these vast square circuits getting 6 - 8 circuits per hour instead of a dozen. Returning to racetrack circuits would solve the cross-country circuit syndrome at a stroke.

At Sleap in the 1960's, the CFI was a pragmatist who appreciated that what ab initio students need is as many landings as can be squeezed into the hour, and that flying text-book circuits was a waste of time and money. Accordingly, he and the other FIs would take control at 200ft after take-off, fly the shortest possible route to line up on final at 500ft, hand over to the student to do the next touch-and-go, and take over over again at 200ft.

We were the only operator at the airfield, which made that easier. But most regional airports don't have all that many commercial (ie priority) movements during much of the day.

At Sleap in the '60s I flew as often as I could manage with the great Adam Wojda, an ex-RAF Polish FI with little respect for authority. One of my sessions with him was learning how to fly a really square circuit (not needed at Sleap, but elsewhere there were stuffy controllers, eg Sywell) by doing a neat little modified stall turn at each end of the downwind leg. He also taught me to sideslip the Auster from side to side down the final approach; it gave you a better view of where you intended to touch down. Evidently this was common practice in WWII tail-wheel fighters, known as fish-tailing.

Much later in life, I would make my feelings known that the flying club at an airport I worked at was simply defrauding its students by flying ridiculous "Bomber Command" circuits that took anything up to 15 minutes. Their problem was that the FIs didn't know any better. My heart sank every time I saw their Cessna 150s being dragged down a 2-mile approach with flap all the way and lots of power. This still goes on today, and it's wrong.

All of my pre-solo circuits (Cessna 150) were power off abeam the numbers, first notch of flaps. Turn base (square corners), second notch of flaps. Turn final, full flaps. No additional power (but remember carb heat). Always made it to the runway.

Ab inito training in the circuit is a lot more than learning how to flare and then touchdown. A proper square circuit reinforces all of the foundation skills of climbing, climbing turns, transition to cruise, level turns, descending turns and descending at a stable pre selected airspeed.

Before you can consist learn to land well you need to be proficient at all the other essential skills.

Good instructors will emphasize accurate co-ordinated flying at every part of the circuit, not just the last 10 feet.

These poor guys did...

The Heathrow Airspeed Ambassador crash was caused when left flap actuating rod failed allowing the already deployed flap to retract, so it wasn't technically during flap deployment. Several horses on-board were killed in addition to the crew.

Of the 2 BEA Tridents that were damaged, G-ARPI was tragically lost 4 years later at Staines due to a configuration stall. The droops (slats) were inadvertently retracted somewhat below the minimum retraction speed!

Thank you for all your comments.

After a lifetime of flying many types, I think I will continue to do as before, using bank upto 30 degrees on the circuit, or less, but not more, to produce the radius of turn required dependant on x wind, circuit pattern, etc., It has served me well for 55 years.

Of course 15 degrees of bank is appropriate at times. On the VC10 it was a company requirement to roll off bank to 15 degrees before flap retraction and IIRC the bank angle on the Boeing 737 was only 15 degrees following engine failure requiring an emergency turn, optimising climb rate on one.

I was flying a Warrior which climbed perfectly well ( 2 up 2/3rds fuel, 22 deg, c. ) at 30 degrees of bank and I absolutely believe that any and all competent pilots should be able to easily manage flap operation in a turn., the risk of asymmetric flap being extremely remote. Perhaps I am wrong in believing that a light single will have enough roll authority to overcome asymmetric flap, just as the 757/767 could handle asymmetric leading edge extension.

Someone mentioned Bomber Command circuits, reckon I could have done a tighter visual circuit in a Canberra than some of the lumbering circuits I have seen on some single pistons !

I will discuss the issue with the CFI and try to get to the root of the issue.

Thank you , again, for your comments.

I think it was suggested following the Dan Air Tenerife accident, had the aircraft made a wings level climb rather than a climbing turn, the aircraft would have cleared the terrain.

Also, yes some civilian circuits flown are unusually large, especially if you have an engine failure downwind or on base.

In answer to your originak question, 15 degrees in the climbing turn and all other turns 30 degrees. Flaps in the turn like sideslips in the turn should be exercised with caution, likewise sideslipping.

Should anyone be interested in the possible outcome of excesive bank angle and possibly sidesliping onto finals, the fatal accident of Chipmunk G-BDID serves as a warning.

Does that differ from a proper racetrack circuit? Apart from having two more turns and the inevitable widening of the circuit which doesn't seem desireable under any circumstance?

noflynomore.

The important part of my statement was the "properly flown circuit " bit.

What ever the circuit configuration if should be flown accurately. However the pretty much universal default circuit at civilian aerodromes is a square circuit.

What the air force used to do at military aerodromes is irrelevant.

With respect to "bomber circuits" the operative word is again "properly flown". If you are number 1 in your Cessna then the base leg should be turned so that the runway can be made with out power. If like me yesterday you were No 5 behind 2 Cessna's a Dash 8, and a 737 then your circuit should be managed to ensure proper spacing behind the jet with a flight path above the jet flight path and a planned touchdown beyond it's touchdown. This entailed a fairly wide circuit with circuit height maintained well into the final leg before a descent was initiated with a planned touchdown 1500 feet down the runway. My circuit ended up much wider than I would have flown if I was number 1, but was IMHO "properly flown"

Originally a circuit involved an aerodrome and an aeroplane. A properly flown circuit would be different for each aeroplane if you wish to maintain the runway on the wingtip whist downwind. With an increasing sensitivity to noise, aerodromes publish local circuit patterns as a single line on a map and then expect all pilots to follow the line. The line itself has been drawn on the basis of where the complainers live and hence places to avoid, nothing to do with where an aircraft actually goes if flying a circuit properly.

Too many instructors rush their students into the circuit, their comfort zone for teaching, and the poor student needs thinking time, so the circuit grows to accommodate this. Instead of going around if the aircraft in front extends, the next pilot extends further until the circuit leaves the ATZ!

As for 15 degrees of bank in a turn, often this emanates from the CFI and the poor instructor is just doing what he has been told. I recall one school where nobody was allowed to use full flap in case they have to go around!

Sadly, this nonsense gets worse rather than better

Whopity, agreed. Some ought to take a local area chart when circuit flying - they need to plan their downwind navex and rejoin!

I was once teaching circuits in RAF Bulldogs at a civilian airfield where we were flying two circuits for every one flown by some other SEP pilots. Some aircraft were flying downwind outside the ATZ. We certainly weren't going to follow them out that far so we flew inside their circuits. ATC were in full approval.

ShyTorque.. not sure if I was SATCO I would allow such a novel approach, but it can not be easy with civil and military traffic.

I remember once in the Maritime Alps requesting right hand circuits over an issue of terrain clearance in the left hand circuit on a particular runway, so ATC put me into a right circuit and everyone else in a left hand pattern.

It was only a matter of time before two aircraft ended up flying towards each other on opposite base legs, and an exchange of words. But the matter was resolved in the end.

Homsap, The other SEPs in question were flying upwind to the ATZ boundary, then crosswind to a lateral spacing of about 2.5 miles, flying the downwind leg completely outside of the ATZ then flying something like a 4 mile final. Our downwind spacing was as per RAF teaching, with the RAF roundel (about 2/3 wing span) just "touching" the runway.

Years later, in a civilian aircraft, our chief pilot received an irate phone call from an instructor who complained that he (in person) hadn't given way to him. It turned out that the CP was flying an instrument approach through the overhead (via the NDB) and talking to ATC. He briefly saw the other aircraft and assumed it was making an overhead join without calling. This was the aircraft flown by the instructor. Not only had the instructor left his own ATZ (he was flying circuits at another airfield, 6 nm away) on an extremely long "downwind" leg but he had entered the ATZ of another airfield to the overhead at circuit height, where the alleged incident occurred!