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Circuit/pattern spacing Q

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Circuit/pattern spacing Q

Old 13th Apr 2014, 12:25
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Circuit/pattern spacing Q

Got a quick question. So I have been taught to fly pretty tight circuits. WRT the 172 I am learning in, its about half strut downwind at 1000, turn base at 45 degrees. Today the weather was to shitty to do much, so my instructor sent me up to do some solo circuits. I got caught behind someone in the circuit, running out really wide on downwind, flying base out really wide. Each time, I turn downwind I fly as slow as I am game, about 70-75knots, and yet I still am turning base way after 45 degrees. I did 4 circuits then gave up in frustration because I was running out of time. I should have been able to do 6-7 circuits in the time I had the aircraft hired.

So the question is, why fly a wide circuit? I see plenty do it. I am being taught to fly tight in case of engine problems and so people know where to look for you in the circuit. When I flew in noumea, it was wide but that was because of noise abatement and the fact there is a big hill in your way. But at our aerodrome, there is no issue, so should you not adopt the normal close pattern?
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Old 13th Apr 2014, 13:09
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It's an ever present problem. Sounds like you were taught to fly properly. Unfortunately, others seem to be taught by those who fly a circuit more like a navex.

A colleague of mine was once phoned up by an irate instructor, complaining that he had "cut in front" of him and his student, as they were turning base leg in "his" circuit.

However, my colleague was on our company instrument approach, directly overhead the NDB, in the overhead of the adjacent airfield!

Not only was the instructor allowing his student to fly completely outside his own ATZ, he had gone five miles downwind, penetrated another ATZ and contravened someone else's circuit pattern without obtaining clearance. Idiot.
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Old 13th Apr 2014, 17:37
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1. Always 'look' with your ears.
2. Never extend downwind. I you do, that will cause heaps of trouble for others.
3. Extend upwind if necessary, but do tell ATC.
4. If someone is doing mega circuits, note their call sign and speak on the ground.
5. Go around at circuit height is the one ahead is flying an enormous circuit. Tell ATC.
6. Personally, I will cut in very tight, but not if the one ahead is on finals. He has priority.
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Old 13th Apr 2014, 17:46
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So the question is, why fly a wide circuit?
I have been asking that question for almost five decades. The best answer I have is...pilgrims. You encounter them everywhere, not just in the air. Nothing can be done.
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Old 13th Apr 2014, 18:26
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If someone is going wide out of the published circuit (not all fields have one):

"XY-ABC becoming number one, the plane before us has left the circuit".

Not the way to make friends, though.
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Old 13th Apr 2014, 18:30
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Flying from a mob airfield you get used to doing oval circuits, I've never understood why the 'standard' circuit is the way it is. Some folk fly downwind legs that are literally miles away from the runway. When I fly to a civ airfield I do a square as it's expected but it's not a very big square...

Well known vid but worth having another look at

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Old 13th Apr 2014, 18:35
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Personally I would never cut in front. If coming up too fast and under ATC follow the aircraft in front and/or request an orbit.... the aircraft behind is responsible for spacing.


A couple of months ago I was on base about to turn onto final when cut up by some prat a*sed idiot. If he was short of fuel he should have made a pan call; if he wasn't at circuit height he should have been and if he was in a hurry he shouldn't have been!!!!
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Old 13th Apr 2014, 19:36
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The vid that Thing has posted is a good laugh, but it's also spot on! Should be required viewing for every bomber pilot put there (and there are loooooootttss of them!).

So come on you 'bomber' pilots. You know who you are, I've frustratingly followed you around the circuit more times than not, so you're not a rare breed. Watch that vid, and then come on here and explain (please!) the rationale behind your ridiculous next-county-and-the-one after-that circuits!

But watch that vid first - and tell us why you think it's wrong. Please!
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Old 13th Apr 2014, 20:27
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I would much rather fly tight, racecourse circuits but noise abatement at my local field means you will get a right shoeing if you do. So X-country circuits it is.
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Old 13th Apr 2014, 20:30
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Yes of course, I realise that some fields have that consideration and one must comply. But the ones I have in mind do not.
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Old 13th Apr 2014, 22:30
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1. Always 'look' with your ears.
2. Never extend downwind. I you do, that will cause heaps of trouble for others.
3. Extend upwind if necessary, but do tell ATC.
4. If someone is doing mega circuits, note their call sign and speak on the ground.
5. Go around at circuit height is the one ahead is flying an enormous circuit. Tell ATC.
6. Personally, I will cut in very tight, but not if the one ahead is on finals. He has priority.
Number 3... This is what I should have done. The thought never occurred to me at the time. I fly out of a CTAF aerodrome, so no ATC to inform.

Number 4, well I am a bit uncertain about quizzing someone unless I am completely sure. Being an student, I don't want to jump to conclusions, I would rather ask first. The guy did a full stop after me, which was annoying because had I known I would have done a few more circuits. I overheard him and his passenger talking, and I think he might have been a flight instructor training the other guy, although I cant be certain.



Hey thing, I love the video BTW. I noticed the number of stripes increasing along the way!
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Old 13th Apr 2014, 22:37
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I seem to encounter this problem a lot as well. I don't think I fly overly tight circuits (unless I know I'm the only one using the field then I like to have some fun), but I do keep them reasonable and I seem to be forever running into people who love to take the really scenic route. It's even worse when it's a microlight doing <70kts.

I have become quite used to asking politely if I may overtake on the inside. I remember having to do this a couple of times as a student as well, although was more reluctant to then. I personally have never had anyone give me any bother about the request and they are normally happy to coordinate (non ATC field I should mention of course).

I did have it one time going into Biggin Hill when there was a twin (I was in a twin as well) doing massive circuits. After 2 requests from ATC to keep it inside the ATZ, he was asked to orbit at the end of his downwind leg and report ready to rejoin.
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Old 13th Apr 2014, 23:14
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I did have it one time going into Biggin Hill when there was a twin (I was in a twin as well) doing massive circuits. After 2 requests from ATC to keep it inside the ATZ, he was asked to orbit at the end of his downwind leg and report ready to rejoin.
That's the way!

Problem with someone flying too far downwind in a busy circuit is that the pattern gets longer and longer until it becomes ridiculous. It can become unsafe because pilots on the downwind leg don't realise some numpty is coming in from miles out like a stealth bomber and will turn onto finals ahead of him.
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Old 14th Apr 2014, 00:06
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Point about noise abatement taken, but I've been to several airfields where the noise sensitive areas would have been better avoided by flying the circuit inside rather than outside the avoids...
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Old 14th Apr 2014, 00:19
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I'm interested to know what people consider to be a 'normal' circuit.

Take a typical training aircraft, (C150/PA38) in calm conditions. Max rate of climb 500'/min (if you're lucky) at 60kt IAS.

Climb straight ahead to 500'= 1nm from the airfield. Turn left 90 degrees, continue climbimg to 1,000', level off, and trim,. Turn left another 90 degrees = 2nm from the airfield. Fly 'downwind' to a point about 45 degrees sight line to the touchdown point = 2nm from the airfield. Turn base, begin descent, set flap and start the final turn to be at 500' as you roll out of the turn =1nm from the airfield, with 500' to loose on the final approach.

Would most people agree that this is the smallest circuit that can be flown in such an aircraft, whilst at the same time, following the conventions of rectangular circuit patterns, climbing to at least 500' before turning, and being not less than 500' at the end of the final turn?


MJ

Last edited by Mach Jump; 14th Apr 2014 at 07:13.
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Old 14th Apr 2014, 01:24
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You seem to assume a zero length runway; and the distance from the takeoff point after 1nm, 90 deg turn, 1nm is 1.414nm not 2nm...

With a runway of nearly 1nm long, a takeoff run in the low 100s of metres or less, and a bit of headwind, the crosswind turn could well be barely beyond the end of the runway; the downwind turn moments before the downwind call abeam the upwind threshold. That's how it is where I fly, tight circuits at a military base.
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Old 14th Apr 2014, 04:33
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I'm interested to know what people consider to be a 'normal' circuit.
Here in BE, most a/d's publish the ideal circuit, for an example see the link below. Not that all pilots respect it...

http://www.fed-ulm.be/common/pdf/ulip/EBZH.nl.pdf
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Old 14th Apr 2014, 06:49
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You seem to assume a zero length runway; and the distance from the takeoff point after 1nm, 90 deg turn, 1nm is 1.414nm not 2nm...
I'm assuming that the runway is just adequate for the aircraft (Aircraft becomes airborne at about half way down the runway), that establishing level flight/trimming at 1,000' will take a few seconds before turning downwind, and allowing a bit for the radius of the turns.

That's how it is where I fly, tight circuits at a military base.
Yes, but assuming you are flying a rectangular circuit, not the conventional oval circuit there, and that you are in the same aircraft, your circuit will be much the same as mine.

The point I'm trying to make is that, in a low powered aircraft, the minimum size of the circuit is dictated not by choice, but by the performance of the aircraft.

I'm not going to argue over thousandths of a Nautical Mile.

Here in BE, most a/d's publish the ideal circuit...
Thanks Jan. Is the patern shown varied to account for local conditions, or a standard size fits all?


MJ

Last edited by Mach Jump; 14th Apr 2014 at 07:18.
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Old 14th Apr 2014, 07:44
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I'm interested to know what people consider to be a 'normal' circuit.

Take a typical training aircraft, (C150/PA38) in calm conditions. Max rate of climb 500'/min (if you're lucky) at 60kt IAS.

Climb straight ahead to 500'= 1nm from the airfield. Turn left 90 degrees, continue climbimg to 1,000', level off, and trim,. Turn left another 90 degrees = 2nm from the airfield. Fly 'downwind' to a point about 45 degrees sight line to the touchdown point = 2nm from the airfield. Turn base, begin descent, set flap and start the final turn to be at 500' as you roll out of the turn =1nm from the airfield, with 500' to loose on the final approach.

Would most people agree that this is the smallest circuit that can be flown in such an aircraft, whilst at the same time, following the conventions of rectangular circuit patterns, climbing to at least 500' before turning, and being not less than 500' at the end of the final turn?
My circuit, climb to 500, turn away from the houses over water (noise abatement) turn downwind for 1/2 strut on the 172, or about 3/4nm. Level off at 1000 (usually as you are turning downwind). Turn base at 45 degrees from threshold which is about 1nm away, if that., turn final to line up with runway. Doing that gets a really nice approach angle as well!

Of course that only works for aircraft of similar performance. Low performance aircraft fly a 500ft circuit, and high performance aircraft fly a 1500ft circuit according to CASA regulations here in Aus, so naturally the lower performance aircraft should fly an even tighter circuit, and the high performance aircraft will fly a wider circuit. At our aerodrome, we are restricted due to class C airspace above us, so the max circuit height is 1000, and we overfly at 1500. Above 2000 ATC get really cranky at us.
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Old 14th Apr 2014, 08:34
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The point I'm trying to make is that, in a low powered aircraft, the minimum size of the circuit is dictated not by choice, but by the performance of the aircraft.
Don't think anyone would disagree with that but there's no doubt that folk fly circuits that are far too big even taking into account a/c performance. IMO oval circuits (OK they're not really oval) are far more efficient. I did an experiment once at my own field in a 152. Three square touch and goes took me 15 minutes, three oval touch and goes took just over ten, bearing in mind my runway is 9,000'+ So if you were doing an hour's circuit training you would get an extra six circuits in. One of the other advantages of ovals is that you're a lot closer on the downwind leg so any donk problems are easily turned into a glide approach. The final turn takes a bit more judgement as you have to judge a 180 degree turn onto final rather than a 90 but hey, nothing wrong with developing good judgement.

Of course I fly whatever circuit is required at an away field.
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