Re: Base to Final Turn [Archive]

Shaft109

25th Jul 2006, 16:42

Can someone explain why the civvy circuit pattern is square, with 2 tightish 90* turns close to the ground on finals and relatively slow?

After looking at recent accidents I thought about the way I learned in Motorgliders in the RAF VGS. This was a constant turn from downwind abeam the numbers until short finals, at about 15-20* AOB. The approach speed was selected before making the turn and maintained until touchdown - 65-75kts depending upon wind.

I found it quite hard to adjust to the PPL way because a constant easy turn seems easier than 2 tight turns. It may be down to Gliders having smaller turn radii (radiuss? not to good with spelling).

This is more out of interest and is not meant to be derogatory.

Thanks Shaft

tmmorris

25th Jul 2006, 16:49

Shaft109, what you were taught is the standard military circuit. I can see many advantages to it but not that many disadvantages, myself, though perhaps others will come up with ideas. Principal benefits:

a. it keeps the circuits small and within the ATZ;
b. as a result most of the circuit is within gliding range of the runway or at least the airfield if it all goes quiet;
c. more circuits per hour = cheaper training.

OTOH there are fewer 'slots' in the circuit at once, but then that hardly matters if you can do one every 4 minutes (my average at home base).

Tim

tonyhalsall

25th Jul 2006, 17:06

I have no Knowledge of military circuits but I can see a lot of benefits to what you suggest.

Sometimes I think that much of what we practise in GA is so steeped in tradition and 'the way it should be done' that we complacently blunder on doing the same old stuff.

Overhead re-joins are a perfect example of 'tradition' which was based on the poor climb performance of much older aircraft. I believe that the crossing of the numbers to downwind is now an accident waiting to happen with the much higher climb performance of modern kit and microlight type aircraft.

Fournicator

25th Jul 2006, 17:37

Big fan of military oval circuits.

Nominal angle of bank used in the climbing upwind turn varies from 20-60deg, depending on the performance of the aircraft, to achieve a standard downwind spacing that enables a landing on the airfield should the donk fail. Finals turn uses 15-45deg AoB, again dependant on aircraft performance, to achieve the required turn radius.

Angle of bank varied for crosswind - more bank when turning "with" the wind, eg upwind turn with a slackening wind, and less bank when turning into it.

Anyone actually got any good reasons for doing square circuits, generally out of gliding range of the airfield and outside even the ATZ?

dublinpilot

25th Jul 2006, 17:54

Anyone actually got any good reasons for doing square circuits, generally out of gliding range of the airfield and outside even the ATZ?

What ever about the square circuits bit, the out of gliding range and outside the ATZ bit will be hard to justify! Circuits should always be kept inside an ATZ in my view.

In a militiary circuit, is the downwind equilivant still straight? ie. curve on take off until downwind....straight downwind, and then curve to touch down? Or is is just one big curve?

How does one join a militiary circuit?

dp

soay

25th Jul 2006, 18:10

How does one join a militiary circuit?
Good question. At Blackpool, where I was flying today, most joins are to base leg, and I'm not sure if that would still work with the military circuit.

Fournicator

25th Jul 2006, 18:33

Standard Join:
Join via 'Initials' - on extended centreline of active runway, about 3nm back from threshold. Run in deadside (ie keeping clear of any cct traffic liveside) at cct height, adjusting position where you turn downwind to fit in with traffic in the cct.

Run and Break:
Much like the standard join, but running in lower and faster than standard join, then using the break up (often to cct height) to help bleed the speed off. Break position again adjusted to fit in with existing traffic.

Of course, one can also position at hi-key for the active runway for a PFL or join downwind. Downwind leg is indeed parallel to the runway.

nobby

25th Jul 2006, 19:23

The bank angle must also not exceed 20 degrees of bank (target 15 degrees) whilst turning at any point whilst in the circuit

Nobby

Fournicator

25th Jul 2006, 19:25

Will people please stop trying to bait me tonight.

Nobby, if you are for real, which I somehow doubt, then you're wrong. Far too many PPLs seem scared of bank, failing to realise it's a lack of airspeed that will kill them.

Pitts2112

25th Jul 2006, 19:59

The constant-turn descent is the way I fly all my circuits in the Pitts and Taylorcraft. Works a treat. It's especially common in taildraggers because keeping the runway off the nose allows you to actually see it during the descent - a straight in final approach masks the runway under the nose and you end up coming in blind. I hate straight in approaches with a taildragger. Doing it this way also encourages coming in with some slip in as well, increasing the visibility past the nose and giving you extremely good control of positioning and airspeed.

Pitts2112

Fournicator

25th Jul 2006, 20:04

Pitts2112

25th Jul 2006, 20:21

Pitts:
Not for one moment disagreeing with you, for your type of aircraft I'm sure that type of approach is ideal.
However, lest anyone gets confused, the oval circuit I described features a straight final approach after a descending 180 degree finals turn.

Fournicator,
Yep but still essentially the same thing, unless you're talking about an extended straight final. In the case above as with most high performance taildraggers (hence the technique often being called a Spitfire Curved Approach), you'll find the curve finishes more or less around the numbers or a bit short of them with the exact details a matter of specific conditions and pilot preference. I prefer to hold the slip in until almost touchdown but will straighten out the curve further back away from the numbers depending on how short I want to land and how short a landing roll I want to have.

In both cases, you're still only talking about a straight bit of less than a couple hundred meters. Is that what you mean or are you talking something else?

nobby

25th Jul 2006, 20:25

robin

25th Jul 2006, 20:33

Having had a few occasions on a straight in approach where not just the runway disappears, but sometimes the whole airfield did, I am addicted to the curving approach. Besides which, it feels so good!

Fournicator

25th Jul 2006, 20:35

Pitts:
A mil cct commonly has a final approach of just under a mile, probably a bit longer than you had in mind! Not that I'm not a fan of the appraoches you describe, especially for the aircraft we're talking about, but just to make clear the ccts I was originally describing.

Shaft109

25th Jul 2006, 20:39

The A/C in question is a Grob 109, it's a taildragger so a curved approach is appropriate really thinking about it.

www.military-airshows.co.uk/ abingdon2005/1750.jpg

To clarify what I learned i'll go through a basic circuit as is remember it, from 1998 ish as it might have changed, and my point is how it is simpler than a PPL style circuit.

All heights in QFE, and ignore the fact you actually "glide".

Take off and climb at 60kts straight out to 800ft (ROC 400fpm) "Pause" I was told a few times!

Level at 800ft, 60kts. Turn at about 15-20*AOB until downwind (also a constant turn). Maintain 60kts, 800ft until mid point downwind. Now A.P.T. reduce power to idle and maintain 60 kts in the glide, still on downwind.

As the piano keys meet the leading edge increase to approach speed 65-70kts in the glide, usually at 700' by this stage. Still on downwind.

As piano keys come out under trailing edge start turn at about 15-20* AOB.
Halfway round you should be at about 500' (Still air).

Roll out on finals at about 300' still having maintained approach speed. Land.

Joining was either 45* into downwind at cct height, or 90* to the upwind piano keys if you were engine off. (although at 900')

Basically the point I am trying to make is you are climbing, turning then descending steadily but not all at the same time. You have broken it down into little bits.
I can't help but think that the young lad down south in the Cessna 150 who died last week could have been trying to do more than one thing at once, forgot about airspeed then it got away from him. Maybe tightening the turn to stay square. Incidentally I was also 16 and had about 10 hours on my subsequent solos, which is what got me thinking about base final turns.:hmm:

As for EFATO's well turn back from 300', or fly a mini cct at 500'. (As you can tell i loved that plane:).

nobby

25th Jul 2006, 20:41

I use constant aspect on my turns for PFLs I find this straight forward and very precise and above took least time to master (well sort of). Thats how circuits could be flown.

Nobby

Pitts2112

25th Jul 2006, 20:41

Ah, right. Sure. Since the military no longer fly taildraggers, there's no reason to carry a slip or curve as deep into final approach.

In the curved approach, I find it much easier to estimate, right from the beginning of the descent, how the whole thing is going to go and what slight variations I'm going to need to make to hit my mark. I find that harder to do in an approach with two vectors 90*s appart. Maybe that's why the military do it that way? Also, one curve which is constantly updated is actually easier to fly and is less disruptive/discontinuous than two legs 90*s apart.

Would love to get an hour in an F-15E to see for myself!

Pitts2112

Shaft109

25th Jul 2006, 21:00

You made a good point about that old schoolmaster style "this is how it should be done!". It might look neat but is it the safest and most appropriate way now?

I have been boll**ed before by a civvy FI when I took off on the right parallel runway and turned 5* to the right to give a little bit more separation (at maybe 100') from the left runway. It was a very gentle bank BTW less than 5*.

"no turn below 500'!" I was told. Why? Apart from the fact I am used to doing full turnbacks from 300' I specifically did this because there was a fatal collision from just this sort of departure where the left guy drifted to the right, and the right guy drifted to the left. And seeing the attempts some students make........, that bit to the right might save your bacon.

I was just being a bit proactive and roasted for not following proceedure to the letter. This kind of attitude just doesn't make sense to me. :ugh:

dublinpilot

25th Jul 2006, 21:08

Am I correct in thinking that the Militiary circuit is more like image no 1 then, and less like image no 2?

Do I understand F correctly, in that the standard join in a militiary circuit is per the red line in image no 3?

dp

http://img282.imageshack.us/img282/3594/image2fj1.jpg

Fournicator

25th Jul 2006, 21:14

Shaft:
We tend to fly climbing upwind turns in things with more power, you do have to level off in the turn but it's no major drama.
As for the Grob 109 needing a curved final approach - it's hardly got a massive long nose to hide the runway, Spitfire stylee, so not sure I agree with you on that one. The straight approach from 300ft is as much of a help for the fast jet driver to sort everything out as it is for the 16 year old with limited experience on the Grob.

Pitts:
Mil tend to fly numbers, the advantage of flying higher performance aircraft is that they are less affected by the vagaries of the atmosphere and are more likely to work. From starting the finals turn at 1000ft, you pick a point on the ground in line with the runway and about a mile back, and do whatever you have to do in the turn to overfly that point, on speed, on height and wings level - flying from one known position to another. Some might argue that it's a bit of a robotic technique, compared to your techniques, but it bloody works!
Again, not for a moment decrying your techniques, have done such things plenty enough myself on my PPL, and you're right it is amazingly satiisfying as you realise it's all going to come together nicely!

Dublin:
Spot on mate, numbers one and three are indeed correct. You'd better watch out though, or RAF Central Flying School will be pinching your drawings for their publications! Hope you and me can continue to keep the hatchet well and truly buried!

Gertrude the Wombat

25th Jul 2006, 21:17

I believe that the crossing of the numbers to downwind is now an accident waiting to happen with the much higher climb performance of modern kit and microlight type aircraft.
Only if you do it with your eyes shut, surely? - I, at least, was taught that part of the point of the overhead join was to watch what was going on on the runway.

(It's not just modern GA aircraft that can take off through the crossing point - an empty Tristar (I think it was) can do it too, which is why ATC held one until I'd finished crossing overhead the runway. Probably my most expensive rejoin ever - for someone else :ok:.)

Shaft109

25th Jul 2006, 21:23

Yes, the 109 has a short nose but the downward vis is still a little poor. So it doesn't need to curve but the point about is being a more stable, steady approach is still valid.

Dublinpilot from my experience no 1 is what I described.

p.s. as you can tell from the pic, this last straight in bit to get everything sorted out is necessary as a taildragger with a near 60' wingspan will float quite a bit if your too fast.

dublinpilot

25th Jul 2006, 21:57

Hope you and me can continue to keep the hatchet well and truly buried!

I'm sure we can ;)

The only obvious disadvantage I can think of, would be in a high wing aircraft. I don't have a lot of time in high wing aircraft, but my overriding memory of them was hating the turns in the circuit, as I lost sight of the runway....ie where I was going.

Wouldn't a curved approach in a Cessna constantly hide the runway, and make judging your curve much more difficult?

Of course we could just ban all high wing aircraft :p

dp

Slow-Rider

25th Jul 2006, 22:00

Sorry Fournicator
Please accept my apology it's what my rubbish instructor taught me he quoted page 223 exercise 13a of book 1 flight training by Capt Peter Goodwin I didn't mention airspeed because that was not what I was leading to, I kind of thought that was commonly understood, once again please accept my apology. Should I write to Capt Goodwin:ugh:

Apologies to bring this up again Nobby but max AOB is not necessarily 15 to 20, infact on both my current ac and my previous ac my max AOB was 45 degrees whilst in the circuit.

The limiting factor on your angle of bank used in the circuit is speed at which you will stall. This speed increases as you increase AOB and therefore load as such different types of aircraft will have different approach speeds and stall speeds. I suspect therefore that your information is specific to your type of aircraft and similar.

A much clearer explanation of this relationship is given on one of the fatal accident threads from the weekend.

What's certainly true is that if your instructor tells you that you are not to exceed 20 degrees AOB in the circuit then don't.

As pointed out, diagrams 1 and 3 are correct for military circuits. I would add that the join in 3 could be made at any point along that deadside track to fit in with traffic and expedite recovery.

stiknruda

25th Jul 2006, 22:28

Pitts 2112 is my erstwhile display formation buddy, so no guesses that we fly similiarly!

One thing that was overlooked in all the previous posts was the "belly-check".

When I call turning final, from base - I always make it a practice to roll wings level once perpendicular to the runway and have a good bloody lok down the extended centre line in case someone is inbound!

The other thing is that if flying the circuit that 2112 mentions, I avoid a cone of danger displaced upwind and 30 degrees either side of centre line just in case I missed the guy on long final!

Stik

nobby

25th Jul 2006, 23:07

Thanks Slow-Rider for your time one last thing any one please, if my Vso 48kts and AOB is zero and my speed reduces to near 48kts and my AOB then increases slowly to 30* what condition of flight would I then be in. Am right in thinking that a stall or spin would ensue. So the two speed and
AOB go together, but we think more about speed than AOB. I know all aircraft are different but if we stay outside these conditoins then all is well.
The constant aspect during a PFLs works for me because I don't have to think too hard. 1000'agl line the wing tip up with target ie. piano keys and turn and line up at on the centre line
Thanks Nobby

Chesty Morgan

25th Jul 2006, 23:12

Nobby

Assuming you did NOTHING. You would end up in a spiral dive, with rapidly increasing airspeed and roll rate.

If however, you tried to maintain level flight, by increasing back pressure and therefore load factor, you would stall and potentially enter a spin.

tmmorris

26th Jul 2006, 07:25

Only thing to add DP to your third drawing is that the crosswind turn can be earlier if required to fit in with others in the circuit; the run and break is essentially the same thing but the crosswind turn starts immediately you are abeam the downwind numbers and might start at a height lower than circuit height (usually so that you can lose speed in the resulting climbing turn). Run and breaks have been discussed here before but essentially are a bad idea at an uncontrolled airfield...

Tim

High Wing Drifter

26th Jul 2006, 08:22

When I call turning final, from base - I always make it a practice to roll wings level once perpendicular to the runway and have a good bloody lok down the extended centre line in case someone is inbound!
I quite enjoyed M14P's method of looking for traffic when joining. Look up and what do I see? Trees!

Pitts2112

26th Jul 2006, 09:23

Run and breaks have been discussed here before but essentially are a bad idea at an uncontrolled airfield...
Tim
Oh, fer f*@k's sake, not again...:mad::ugh:
Another unqualified opinion with no basis in fact, reality or understanding...
Pitts2112

slim_slag

26th Jul 2006, 11:31

What's certainly true is that if your instructor tells you that you are not to exceed 20 degrees AOB in the circuit then don't.Well, I would ask why not.

I think there is some confusion on here between Angle of Bank and Angle of Attack. They are not the same thing.

That wings level "belly check" on base that Stik refers to is pretty important if you want to have a good look at what's happening on final. Also, the person who I think is one of the higest authorities on landing a Pitts doesn't actually teach a curving approach. He teaches a quick base leg where you check final, then to fly 'the line' to the numbers which actually tracks along the ground in a line. It might appear to be curved from the cockpit, but that's because he is constantly changing his side slip all the way down a final approach that is a few degress off the extended centreline. Well, that's what I think he is doing :)

What is most important is that everybody does the same thing. So mixing these "military" patterns up with a "civilian" pattern might not be the most sensible thing to do. If you are flying in the US at an uncontrolled civilian airfield and you fly a downwind then a final without a base leg in between, and you hit somebody and survive, the FAA will be more likely to violate you than the other guy. The AIM shows a base leg, and although it is advisory, you will get into trouble if you cause an accident by not following the advice.

NinjaBill

26th Jul 2006, 11:32

Normally, in an initial point join, you would turn in a little earlier than shown in DPs diagram part 3, crossing roughly the threshold of ‘09’. However its very easy to adjust this point, by extending or shortening the upwind leg, and slot into a place in a busy circuit.

There is no basis in fact for

Run and breaks have been discussed here before but essentially are a bad idea at an uncontrolled airfield...

that I can see, could you please substantiate this claim

Fournicator

26th Jul 2006, 11:34

Being violated by the FAA, sounds somewhat painful......

Can we please not go down the endless RIAB discussion road again please!?!

London Mil

26th Jul 2006, 11:44

I suspect it is easier to teach the 'base leg' cct than the constant aspect. That said, I find the military style cct far easier to fly.

RIABs, I echo the comments of previous posters. Let's just let that one lie for now.

Sedbergh

26th Jul 2006, 12:02

The BGA approved glider circuit has been 2 x 45 degree turns from downwind to crosswind followed by 90 degree final turn from crosswind for some time.

The 2 x 45's are so that you can still see the landing area rather than losing it under the wing going downwind. But it's a much tighter circuit than power

Vifferpilot

26th Jul 2006, 12:10

Isn't one of the factors against the military-style 1 x 180 finals turn that there is no belly check (awareness of what is outside the turn) whereas on a civil 2 x 90 the base leg provides an opportunity to check long finals or even a base leg join from the dead side (I've seen it done)? :confused:

It is however very easy to fly (and teach).

Mixing of the 2 types is difficult at best - we have both types where I work :ooh: and don't mention UHF vs VHF :oh:

tmmorris

26th Jul 2006, 15:37

Vifferpilot

26th Jul 2006, 21:56

Let me qualify.

A run and break manoeuvre is perfectly safe at an uncontrolled airfield if either (a) there is no circuit traffic, or (b) all the circuit traffic knows what a run and break means.

(a) is fine if you own the airfield, for example, or have amazing eyesight, or can guarantee that there is no NORDO traffic at the airfield. But it is hard to be 100% certain.

(b) is fine if the airfield is a military one (out of hours), or you know everybody who uses the airfield (e.g. you own it), but dodgy otherwise as it's not taught in the PPL syllabus.

There is nothing inherently dangerous about the manoeuvre, but it is not safe if there is other circuit traffic who do not know what to expect.

Tim

Don't quite follow yr reasoning there m8. Why should they have to expect anything? They should just continue on with their circuit procedures they are taught and everything will be fine, the RIAB is as you say a safe procedure. The same applies when civilian pilots visit military fields. They do what they are taught. As all pilots are taught to lookout and listen out and that 'flexibility is the key to air (power)' then there should be no problems at all. Unless this isn't the case where you are?

Fournicator

27th Jul 2006, 07:46

Viffer:

Sorry mate, but I disagree with pretty much everything you've said.

When visiting another airfield you should conform to their procedures and circuit patterns. When visiting civil airfields, even when flying HM's aircraft with my work hat on, I generally do what's expected at that airfield. Despite my feelings about them, I fly wide square circuits at civil airfields, because that's what everyone else is doing. In the same way I'd expect civil aircraft visiting mil airfields to fly oval circuits. In the same way, I tend to join civil circuits in the civil way. Exceptions made to this have been when taking a formation to the airfield in question, or when a RIAB has been requested by the airfield. Even in those cases, it has been thoroughly discussed on the phone before flying, and practised only at airfields used to the procedure and with the circuit clear.

Even if you can see other circuit traffic is well clear, your actions and unfamiliar RT will at the very least cause confusion. In addition, at an uncontrolled airfield you can never be entirely sure of the circuit traffic, so giving yourself the maximum time to locate it all by doing a standard join is surely advisable?

I'd also question your motives for wanting to perform a RIAB. RIABs are designed as the most expeditious way to recover one or more high performance aircraft, where the run-in speed is much faster than the normal circuit speed. There are very few civil aircraft for which that is the case, and the only real reason I can think of for it being required at civil airfields is as a convenient way to recover formations (although there are other options, as I've had to use on occasion when visiting civil airfields who've requested we don't RIAB).

I agree that a RIAB is not inherently dangerous, but prats who try to apply a procedure designed for high performance aircraft in a controlled circuit, to a low performance aircraft in an uncontrolled environment where other users are unfamiliar with it probably are pretty inconsiderate at least, if not dangerous.

London Mil

27th Jul 2006, 08:24

To quote Vic Reeves - "You wouldn't let it lie!" :ugh: :ugh: :ugh: :ugh:

Fournicator

27th Jul 2006, 08:30

I know, I was weak!

I did honestly try not to get caught up in the perennial discussion!

Pitts2112

27th Jul 2006, 09:02

I know, I was weak!
I did honestly try not to get caught up in the perennial discussion!

Must resist!!!

Must not look into the light!!!!

:):):):):)

Pitts2112

Vifferpilot

27th Jul 2006, 10:34

Viffer:

Sorry mate, but I disagree with pretty much everything you've said.

I'd also question your motives for wanting to perform a RIAB.

I agree that a RIAB is not inherently dangerous, but prats who try to apply a procedure designed for high performance aircraft in a controlled circuit, to a low performance aircraft in an uncontrolled environment where other users are unfamiliar with it probably are pretty inconsiderate at least, if not dangerous.

I don't want to perform one m8, I was replying to someone elses point that's all. I was just pointing out that it isn't inherently dangerous and as you rightly point out, light aircraft cannot achive the relative excess speeds of the aircraft type it was primarliy designed for, so there is still plenty of time to become aware of other aircraft in the circuit. If people wish to use it, they should of course check with the airfield beforehand and if busy, adopt a more standard civil join if they have been taught such. The chief reason for a RIAB is the minimal time disruption to other circuit traffic as it is (usually) a fairly rapid way of joining and landing. Circuit traffic need only carry on with their normal procedures as it is the joining traffic responsibility to avoid disruption to them.

.

I agree that a RIAB is not inherently dangerous, but prats who try to apply a procedure designed for high performance aircraft in a controlled circuit, to a low performance aircraft in an uncontrolled environment where other users are unfamiliar with it probably are pretty inconsiderate at least, if not dangerous.

Prats is a bit harsh m8.

When visiting another airfield you should conform to their procedures and circuit patterns.

And if the student in question (whether civil or miltary) has not been taught the others version of a circuit, then are you suggesting they should fly a procedure they have not been taught? We get civil aircraft joining here regularly, completing 'civil' circuits amidst a packed visual and instrument pattern of 'military' circuits, with little or no problem, because all pilots are taught to be flexible, lookout, listenout and minimise radio traffic (whilst similarly getting yr message across).

Fournicator

27th Jul 2006, 11:37

Pls cn we stp usg txt spk m8?

Vifferpilot

27th Jul 2006, 11:52

Pls cn we stp usg txt spk m8?

Apologies, a bad habit from another forum. :O

theresalwaysone

29th Jul 2006, 11:24

Didnt this thread start about circuit patterns not RIABs.

I have instructed civillian pilots in a 800ft military circuit pattern and although I was dubious at first my conclusion was that it produced a far better handling pilot. It also produced a pilot with better lookout and faster reactions and it was much easier to teach PFLs to these pilots. Also more circuits per hour meant earlier solos etc.

Noticably there were two other things unmentioned so far about oval patterns;

a touch and go was just that, a touch and go not a touch roll and go. The RAF teach go arounds from base leg. as well as final. In the particular circuit i am talking about there were Cessna 150s and Bulldogs, and Chipmunks at the weekend it all went very smoothly. On the otherhand at the other 12 flying schools i have worked at the circuit patterns were chaotic and dangerous but that is the main difference between civillain and military flying, discipline and standardisation. Get three different clubs and you would have three different patterns get three diffferent pilots and you would have another three different patterns even within schools you also have instructors teaching their own way rather than a standard agrred way. Out of all the 13 flying schools only 4 of them had agreed standardised patterns (I was CFI at those!) The thing about an oval is that it is much harder to deviate from a standard pattern. the problem with squares are that the crosswind leg becomes a cross country for some pilots who could never ever make a climbing turn downwind because its against the folk lore taught by some instructors

when i eventually owned my own school we taught both ovals and square circuits and each student elected to do an oval or a square in the pattern they were in at the time, allowing for other circuit traffic.

I got some criticism from the other schools on the airfield but interstingly when the cloud base got low they all still flew their students using 500 ft ovals. We always made a point of teaching both patterns but gave the student the choice of which to fly--no student ever preffered squares and why would they ovals are easier, quicker, safer and cheaper!

Teaching PFLs at the airfield was a doddle as all you did was join the oval circuit at 1500 ft downwind (the glide app oval circuit was 1500 ft agl)

the one argument you could use against ovals is that military student pilots are of a higher standard and ability that there civillian equivalents and therefore need more time and space. I beleived that till i started teaching ovals but I found that all the students i had over this 3 year period had no problems at all with ovals except when they were on dual land away cross country. they just couldnt belive that the aircraft on the horizon outside the ATZ was actually in the circuit!!!

Vifferpilot

29th Jul 2006, 15:12

The thread did get a little hijacked there, sorry!

...the one argument you could use against ovals is that military student pilots are of a higher standard and ability that there civillian equivalents and therefore need more time and space....

You could argue that the post-graduate Elementary Flying Training pilots are likely to be of a higher standard and ability, but you certainly could not use that argument for the University Air Squadron students or the Air Experience Flight cadet pilots and navigators. They arrive, more often than not without any previous flying experience and only need pass a rudimentary medical with no aptitude tests, yet they are all taught upwind climbing turns and racetrack military circuits with a constant turn from downwind to finals. They mostly seem to cope.

High Wing Drifter

29th Jul 2006, 18:40

...they are all taught upwind climbing turns and racetrack military circuits with a constant turn from downwind to finals.
Definately reads like more fun, but what is the real world advantage of ovals at civ airfields? Blackbushe often has 6 or more in the circuit, often a mixture of fast and slow. That lot compacted into a dense oval shape should a nightmare, there'd more go-arounds than you could shake a stick at.

theresalwaysone

30th Jul 2006, 01:19

Definately reads like more fun, but what is the real world advantage of ovals at civ airfields? Blackbushe often has 6 or more in the circuit, often a mixture of fast and slow. That lot compacted into a dense oval shape should a nightmare, there'd more go-arounds than you could shake a stick at.

well should there really be 6 aircraft in a circuit, unless their in formation i dont think so!

if airfield management established a rule you wouldnt get the problem but they dont thats my point, its free for all at airfields were civvy flying schools operate.

my last post i though explained the advantage of ovals in a civvy circuit but obviuosly its not always possible but dont forget you are teaching for life skills not just a skills test. If you were flying a £200 an hour a/c around the circuit and paying for it what shape would your circuits be!!??

Final 3 Greens

30th Jul 2006, 05:23

6 or more in the circuit is usually a function of a busy GA field and many airfields do limit the amount of circuit only traffic.

In my limited PPL experience, flying a ciruit is usually a precursor to making a landing and this is what most of the 6 (or more) will be looking to do. ;-)

Anyway, if the airfield is A/G or AFIS, how does a "maximum number of aircraft" policy get policed?

IMHO, it is not the shape of the circuit that is the blocker at busy GA fields, but the inability of many PPLs to fly a nice tight circuit.

The US PPL training, in this respect, tends to produce better results in my experience.

Personally, I'm a fan of the oval circuit, but would hesitate to use it in an environment where it was not standard since, like the RIAB, the dangers are not inherent in the manouevre, but rather in the gap in situational awareness that they may create for some other pilots.

IO540

30th Jul 2006, 06:54

The problem with six in the circuit is that unless they are flying at the same speed it won't work.

Either the faster one will end up doing a go-around, sometimes several times, before getting down, or he will have to extend the circuit downwind to create more distance before himself, and if he does that then it's pretty likely that some smartar*e behind him will cut him up on the inside.

That's what it is like at my two favourite examples of a free for all: Stapleford and Wellesbourne. The first one is particularly terrible and I have wondered whether some of the instructors even have a PPL.

I don't see that oval circuits will make a difference at these free for all locations, because few people bother to stick to the rule that you have to follow the previous traffic. They won't work, just like the rectangular ones don't work very well either. Would be OK on weekdays though.

Vifferpilot

30th Jul 2006, 09:56

I guess some airfield managers think it ok to have that many in the circuit, indeed, perhaps the situation almost demands it, but it does sound like an incident waiting to happen. We have a maximum of 4 in, plus 2 to land, and that can get tricky keeping a tab on others, especially when I'm trying to get someone up to their first solo and the AEF mass launch is on recovery! :eek:

theresalwaysone

30th Jul 2006, 11:28

10540 says--That's what it is like at my two favourite examples of a free for all: Stapleford and Wellesbourne. The first one is particularly terrible and I have wondered whether some of the instructors even have a PPL.

WELESBOURNE, NOW THERES A PLACE

Funny that because the circuit at Wellesbourne is why I stopped instucting in 1986. At that time the airfield manger was an ex-bankrupt second hand car dealer, a man with a mouth disproportionate to his brain. One of flyings greatest self appointed experts.

there are two incidents that finally lead me to refuse to send anyone solo in this circuit and to stick to airline flying.

1. a local twin owner requested a dead side direct left base join in a busy weekend circuit. (There never had been a Lh base on the southely runway due to the village) The spotty teenager in the tower,(A/g at that time) who probably didnt even have a RT licence gave him clearance to join directly onto the dead side base leg. I was with a student on the correct RH base leg-we were now head on but my student turned onto final well ahead of the twin. The pilot of the twin insisted that we go around but i took no notice and the twin had to go around. He later came into the flying school shouting his mouth off saying he was doing everyting correctly and he had 700 hours and a twin rating and he was right and i was wrong-I tried to explain to him that only an ATC unit with an ATCO can issue a clearance and that A/G is advisory I even showed him the section in the ANO but you see he had a twin and 700 hours!!!!--all quite funny really but awhile later the same pilot in the same twin flew back from Europe and cleared customs at Birmingham--he elected not to refuel even though both tanks were showing close to empty. On take off the one engine stopped due to fuel starvation and the aircraft rolled right over on its back and arrived on the grass inverted, fortunately the self appointed expert survived.lookout for him i think he is still at Wellesbourne, Derek is his name and I belive he still thinks he is an ace!

2. And this was the final one for me. The parachute Islander from Long Marston joined dead side and flew underneath us on downwind missing us by about 50 feet--he never even saw us and even though there was someone in the tower, another teenager, there was no traffic information or not even any comment by anyone.

I realised then that I could no longer send students solo in the circuit safely and gave up.

I could write a book about incidents at this airfield but I will leave you with a more pleasant thought
Why would you continue to call an airfield Wellesbourne when the most well know town in the world is a few miles away?

BEagle

30th Jul 2006, 11:47

Clearly you haven't been there recently - things have changed for the better over the last 20 years since you stopped instructing.

tmmorris

30th Jul 2006, 15:07

Agreed, Wellesbourne is much nicer now!

Why would you continue to call an airfield Wellesbourne when the most well know town in the world is a few miles away?

Perhaps in recognition of the part RAF Wellesbourne Mountford played in maintaining the freedom of this country from the Nazis?

Tim

Shaft109

30th Jul 2006, 22:16

To be honest I didn't realise that there was such disparity in circuits. I'm sure local factors at airfields mean they have to be tailored to suit but is there no CAA equivalent of a CFS - a standards unit that examines instructors?

p.s. I have also seen aircraft that fly circuits about 30miles wide! Especially one guy who flew downwind and did a 4 mile final, causing a knock on for everyone else behind him.

theresalwaysone

31st Jul 2006, 01:06

Agreed, Wellesbourne is much nicer now!

Perhaps in recognition of the part RAF Wellesbourne Mountford played in maintaining the freedom of this country from the Nazis?

Tim
Why not call it SMITHS FIELD then in recognition of Fred Smith who put and lost all his private money into Wellesbourne which also caused him to have a heart attack and die a broken and penniless man. Before Fred put his life savings into the airfield and it must be said, was used by a number of people, it was just another disused airfield.

20 years ago I found the the Smith Aviation stone plaque which was thrown up the back, outside the hangar which commemorated the Duke of Edinburgh re- opening the airfield so I dont suspect its present name remains due to any respect for anything or anybody, although its a nice thought not shared by Wolverhampton, Leicester, Nottingham, Northampton, Oxford, Birmingham etc . (possibly A better recognition would be a history of the airfields part in the war on display, if not already there, sadly missing from many ex WW2 airfields)

If it helps with the re-naming Fred was a Rolls Royce test development engineer during the war and said to have made a major contribution to the RR test programme.

Glad to here the airfield has changed but it was never the airfield that was the problem!

IO540

31st Jul 2006, 08:49

the airfield manger was an ex-bankrupt second hand car dealer

Astonishing..... he was thus perfectly qualified to run any business in general aviation.

I think a lot of people forget that any radio operator below the rank of ATC has no authority to "clear" anybody anywhere (much as some like to pretend otherwise) and the pilot can do what he likes.

So, if I am coming into some piece of grass, and the man on the radio is "ordering" me to fly an overhead join (another antiquated olde English tradition, designed originally to enable another wonderful olde tradition, the signals square, to be inspected) and I have already got it from him that he has no known traffic anywhere, I will just do a straight in, making the "final" call at various distances.

tmmorris

31st Jul 2006, 09:04

There are in fact nice photos of the wartime airfield in the cafe.

Tim

theresalwaysone

1st Aug 2006, 11:51

Photos are better than nothing but they do not give the history of the airfield.
Tim got me thinking there about these ex WW 2 airfields and there is a debt of repect owed to the part they all played in the war.
I wonder how many airfields actually have a history of their past somewhere where visitors can see it, I cannot remember ever flying into one that has. As this is off thread I will post a seperate thread in Private Flying.

I didnt start the Wellesbourne thing by the way it was 10540 who mentioned Stapleford and Wellesbourne as being a free for all in the circuit!

Kaptain Kremen

1st Aug 2006, 15:15

Back to the thread - we teach square circuits. although there are many advantages of oval, as discussed on this thread, for our high wing aircraft the view in the turn is poor/non existent for spotting aircraft and the runway and so we keep it to a minimum by making square circuits.
KK

Lister Noble

1st Aug 2006, 16:18

Old Buckenham has an excellent well kept exterior memorial to the missing US airmen and also some interesting WW2 photographs in the clubhouse.
Also do marvellous food,if you can manage the 16 oz 100% steak Mustang burger you are a better man than me!
Lister:)

Vifferpilot

11th Aug 2006, 11:19

Nardi Riviera

18th Aug 2006, 00:53

The original posted question was re "two tightish 90-degree turns".

I'd say that overshooting the turn to final is worse. At such point one tends to forget about stall-speed ratio vs bank angle, eyes away from the panel while banking too steeply at low speed.

Never do that in a Cub. :\

Sunfish

18th Aug 2006, 06:10

At the risk of getting flamed, are you considering the behavioural angle? A circuit with four legs at right angles neatly segments the workload and decision making into four phases with no overlap should you choose not to have any.

It also makes the traffic management (we do have six in the circuit on weekends, and since its parallel runways there are contra rotating circuits.) somewhat easier, especially with newer students.

I suggest that when the going gets slightly tough, like landing with a crosswind on an unfamiliar airstrip after a bumpy and long flight, the four phases of the circuit help to focus on the task at hand and hopefully not miss anything, especially for low time pilots like me.

I've made a few circular approaches ( gliding approaches) and while they are fun to do on a familiar field, I'm not so sure I'd like to try it in an unfamiliar location, like this one.

http://i8.photobucket.com/albums/a16/sunfish1/DSC02404.jpg