Spotting other aircraft in the air......

[Andy_R]

If an aircraft is on a TRUE collision course then it isn't likely you will spot it. If it is head-on (recip track) then you are very unlikely to ever see it.

Correct me if I'm wrong BRL, but I think that may be why this thread emerged.

He was handling the controls in what was a choppy ride, so would have been fairly concentrated on the task in hand.
In the meantime I was busying myself with looking out the window admiring the view (there really were some spectacular cloud formations and the viz between showers was fantastic) but also monitoring the radio.
As an aircraft (which I knew from the transmissions was at the same height and on a reciprocal track) reported abeam a certain point it did raise my awareness tenfold as we were more or less in the exact same position. The time between seeing it and turning before it passed to our left was probably less than two seconds. Not dangerously close but not entirely comfortable seeing an aircraft appear in your screen coming at you!!!

I think what prompted the question was that he felt a little perturbed that he hadn't seen it.

In haze we probably wouldn't have and would never have seen it at all. Hence the benefit of at least lending one ear to a listening watch on the radio. And though we are all entitled to relax a little we should never let ourselves slip into the position of being unaware of what is occuring around us. And if you are up there always use your passengers to help keep a lookout.


Do I worry about a mid-air??

Not really. I drive 60 to 70,000 miles a year. I worry far more about some idiot hitting me in my car

[83 3708]

If an aircraft is on a TRUE collision course then it isn't likely you will spot it. If it is head-on (recip track) then you are very unlikely to ever see it.

to quote an old saying...

"Never fly straight and level in the combat zone for more than 30 seconds"

[MichaelJP59]

Here's a related question then.

Yesterday I was practising circuits doing touch and goes, along with 2 others and the occasional arriving/departing aircraft.

I kept track of it OK but I wondered what the correct procedure would be if I hadn't. Say for instance I am on downwind RH and someone calls to say they are on extended base leg (this is an A/G field BTW). Then say I cannot spot the traffic so am nervous about turning base.

Should I orbit on downwind? If I do that I could end up in conflict with the guy who is just turning onto downwind.

Thanks,
- Michael

[High Wing Drifter]

I would call out something like "Turning base and not visual with aircraft on extended base" Not sure if this is best or not. Like you, my worry with an orbit is what if the guy that you didn't know was behind you didn't see or understand what you were doing. I would probably put my landing light on at this point too (I always fly with strobes).

[FlyingForFun]

Michael,

First of all, it is illegal to orbit downwind in the scenario you describe. If it's a RH circuit, all turns must be to the right. I'll provide the relevant link to the AIP later if I can find it.

Secondly, you have right of way over the joining traffic. Traffic already in the circuit always has right of way over the joining traffic. So, technically, it's his problem, and not yours. If he's not certain he can avoid you, then he should break off his join, and join again (possibly from overhead, to give him a better chance of seeing and fitting in with the traffic).

Having said that, if you think you are in a situation where he hasn't seen you, isn't going to break off his join, and may end up conflicting with you, then obviously good airmanship requires you to do whatever you can to avoid the conflict. HWD's suggestion of an extra radio call is a good idea. Landing lights probably won't help (if he's behind you he can't see them, and if he's in front of you he probably can't see you at all, lights or not), but won't do any harm, but strobes would be a good idea.....

Remember, if you at all uncertain that it's safe to continue the approach, go around. You can do this from any point in the circuit.... if you are about to turn base but aren't sure it's safe to continue, then turn base, leave the power alone and stay at circuit height. Make a radio call ("G-CD going around from base leg"), and have another go when it's safer. Be aware of the traffic ahead of you - you might be able to (or even have to) turn an early crosswind in order to fit in with the traffic.

I think this is an excellent example of why the overhead join is so good, especially at an uncontrolled field. Plenty of time whilst in the overhead to spot all the circuit traffic, and plan the arrival to fit in with it. Admittedly it's not always possible, but it would nearly always be my choice of join at an uncontrolled field with more than one aircraft in the circuit.

FFF
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[MichaelJP59]

Thanks.

FlyingForFun, is it still illegal to orbit downwind in a RH circuit, even if you do a right-hand orbit?

I ask, because my instructor had me do it a couple of months ago, to get a bit of spacing as a Citation jet was lining up.

- Michael

[FlyingForFun]

Rule 17.5 of the ANO (which can be found on page 252 of the .pdf file):

(5) Flight in the vicinity of an aerodrome

Without prejudice to the provisions of rule 39, a flying machine, glider or airship while flying in the vicinity of what the commander of the aircraft knows or ought reasonably to know to be an aerodrome or moving on an aerdrome, shall unless, in the case of an aerodrome having an air traffic control unit that unit otherwise authorises:

.....

(b) make all turns to the left unless ground signals otherwise indicate

In other words, in there is not ATC, and a left hand circuit is in use, all turns must be to the left. If a right hand circuit is in use, and the signal square indicates that a right hand circuit is in use, it seems that turns may be made in either direction. But the spirit of the rule, if not the letter of the rule, seems to suggest to me that all turns must be made to the right in such a case. I wonder if the reason it is worded to allow turns to the left might be to allow for non-radio traffic to turn to the left whilst looking at the signal square, and then adjust and begin turning to the right once the circuit direction has been determined? In any case, I certainly wouldn't orbit on downwind, whichever the circuit direction, unless instructed to do so by ATC - and even then I would be looking out very carefully.

FFF
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[IO540]

FFF

There are as many people, with decades of flying experience, who think the OH join isn't safe at all. There was an article in last Flyer saying this.

It is OK if one aircraft is joining at a time. But if say four join concurrently (or are cleared to OH if it is an ATC field) and one is visual with just two of them (which would be good going unless one is in a baloon ) then one knows that the other two are at more or less exactly the same height as oneself - but one can't see them. Then one ends up doing the deadside descent, perhaps at the same time as somebody else. Last time this happened, and somebody undertook me at about 160kt about 100ft below me, I just departed the ATZ.

So, the OHJ is safe if there is nobody in the same place, and as unsafe as any other if there is conflicting traffic.

I don't think the OHJ would be invented today. It dates back to WW1 pre-radio days, and the signals square.

Re the original question, I would make regular radio calls reporting position and height while trying to spot the other traffic, and unless the other person is deaf they ought to watch out also. I don't think there is anything else one can do, in a non-ATC field.

[High Wing Drifter]

IO540,

My only thought regard the OHJ is that at least everybody knows what to expect and everybody can join overhead regardless of their join direction. All a/c should enter the overhead at the same point so it should be clear(ish) that a conflict is going to arise quite early in the proceedings. Without it a/c would be joining from base, OH, downwind, crosswind, blah!

Prehaps the reality is that people do that anyway...

Just my humble 120hrs worth of opinion

[Aussie Andy]

It's no good people suggesting the OHJ isn't safe unless the alternatives are considered and determined to be more, or less, safe.

The alternative often cited is the US-style join of 45-degrees to the mid-downwind leg. But is it safer? A recent experience in the US, at Petaluma to the north of San Francisco, has persuaded me that it may not necessarily be the case that 45-degree downwind joins are any safer. Picture this: at the airfield in question, there are some hills slightly higher than circuit height a couple of miles east of, and running roughly parallel to, the downwind leg of the circuit. The town of Petaluma is on the other side, hence all circuits are to the east for noise abatement.

So, to effect a 45-degree downwind join, everybody converges on a position in space about 2 miles east (but without hitting the hills!), so as to then track approx. 45 degrees to the mid downwind. Everyone is approaching from all directions at once, and no-one knows for sure where the others are coming from 'cause everyone just makes traffic calls "inbound", maybe giving a direction such as "from the N or S"... On the day in question there were 4 of us within a 1/4 mile all doing this at once, heads-swivelling, and trying to make it work out OK somehow, which of course it did...

This, to me, seems to represent exactly the same type of risk as when I joined in the overhead at White Waltham last Sunday - not better, not worse.

So, at busy yet uncontrolled fields I don't know of a safer alternative to the OHJ (other than the apparently equally safe / equally unsafe 45-deg mid-downwind join as practiced in the US). Can anyone suggest otherwise?

Maybe the situation in France is better? According to my copy of M. Casanova's "VFR Flight Rules France" (1998 edition), page 30 Non-Controlled aerodrome joining procedures "the pilot notes the position of any other aircraft in the circuit... and joins at the starting point of the downwind leg" (but it is also suggested it might be a good idea to first overfly the signal area and the circuit at 500' above the circuit height and then join after the starting point of the downwind leg...) So it sounds a bit like the OHJ again.

So I think its a bit of a point-less debate unless a viable superior alternative is put foward.

Andy

[FlyingForFun]

Andy,

A pretty good summary, I'd say. Whatever method one uses to join, if everyone uses it at the same time there will be a conflict.

The difference with the overhead join, IMHO, is that you can vary the size of your overhead bit and adjust where you fly the crosswind leg in order to fit in with other traffic. Compare this to the American 45-degree join - if you happen to be inbound at the same time as someone else, or your inbound leg happens to bring you onto downwind at the same time as some circuit traffic, or both, what can you do about it? The answer is not very much.

Just my personal opinion, of course. And it has been my experience (in many areas, not just this) that personal opinions are often based on the method which one was taught originally, especially when there is very little to differentiate between the methods. I think that, once someone has been brought up using any given method of joining, convincing them that any other method is better is very nearly impossible! Yes, I was brought up with the overhead join...

FFF
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[QNH 1013]

The US style 45degree downwind join is illegal in the UK because (see above) once you are in the ATZ, all turns must be made in the circuit direction. I suppose it could be used at the fields where the circuits flown are so large they go outside the ATZ, but then large circuits are another problem altogether.

I don't mind the overhead join (although its often not my first choice) but it is made more hazardous by poor RT. At one aerodrome I use, pilots flying circuits frequently call "downwind" as soon as they turn onto the downwind leg. If I am joining from overhead correctly, and I am flying cross-wind they should be ahead or to the left of me when they make this call, and therefore easy to spot. When "downwind" calls are made too early, time is wasted looking in the wrong part of the sky for the traffic.

At this aerodrome, final calls are often made by aircraft when they are still on base !!! This really puzzles me.

It happens so often that I can only assume the locals have been taught incorrectly.

[Aussie Andy]

final calls are often made by aircraft when they are still on base

Perhaps they are MIL trained pilots? at RAF Benson where I also fly, we have to confiorm to the MIL constant aspect circuits which entail a curved final approach, and the final call is made approx. where you'd normally call base. So maybe these guys learned in a MIL environment as cadets? Just a thought... your first guess at an explanation may be more likely though!

Andy

[MichaelJP59]

MIL constant aspect circuits

Not heard of a constant aspect circuit - what's one of these then?

- Michael

[FNG]

It is the circuit (oval in shape) flown by military aircraft. It can be regarded as one continuous turn from take off to landing. The term "constant aspect" refers to the picture you should have of the runway as you turn from downwind to land. If the runway aspect changes, you know that you are getting too high or too low, or are too tight/too far out. You may be taught this technique for forced landings, particularly if your instructor has any military connections or has read the Bulldog manual.

[YYZ]

Aside from all the relevant stuff being discussed, back to the pictures etc at the beginning of the post

The british.wmv is hilarious, my partner does allot of martial arts so it may have been funnier to me, who knows?

But good all the same

[MichaelJP59]

The term "constant aspect" refers to the picture you should have of the runway as you turn from downwind to land. If the runway aspect changes, you know that you are getting too high or too low, or are too tight/too far out.

But doesn't that apply to the final approach part of the normal rectangular circuit too?

- Michael

[FNG]

Similar: you are perhaps thinking of the "spot that does not move" approach technique used when aligned with the runway on final. The constant aspect technique involves flying by reference to your intended landing spot from earlier in the circuit.

[7gcbc]

"Constant Aspect" , I know these as Low Level circuits, where the turn to X-wind is made before the runway disappears, and not above 900 agl, and the base and final are merged into a descending/slipping turn.

Great for packing in the Touchs and go's, and you do so need the tower to be on your side, but in a 30 min jaunt, you can get around 6-7 in, it makes you work for it and makes it worth while.

you're only on downwind for a max of 20-25 seconds, so effectively you fly a doughnut !

Where I fly at Camden in NSW , you can get traffic IB on the tarmac, 06/24, and also on the glider strip which is parallell to the grass (which is where LL's are done) so , depending on whats going on, you also may get a go around instruction from the Tower, an extend on D/wind or an immediate turn as soon as lift off.

keeps you sharp! But man it;s fun!

Never did like the 45 deg join in the states, the brit method of overhead, or descending on the dead side is much safer, although with a Tower , anything goes.........

[Aussie Andy]

Never did like the 45 deg join in the states, the brit method of overhead, or descending on the dead side is much safer

Is there an equivalent "standard" join in Australia? I have an Australian "special license" for when I fly at home, but have only flown about 10 hours there and don't recall this.

Andy