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.