CTAF Circuit Joining - Bushflight (con't)
 

G’day werbil et al,
.
Interesting one this. An answer (in part) to gadude’s Q below:-
.
werbilI Agree, as I suspect the answer to your hypothetical would in part answer gadude’s Q
.
gadudeThe ‘relative bearing’ of the aircraft that WILL hit you is perpendicular (high closing rate), and stationary in your field of vision (less obvious as no movement to trigger a focused look).
.
You will have varying degrees of ‘relative bearing’ issues no matter where you and the other targets are in the circuit, the difference with entering the circuit directly on BASE is that several other things are in play i.e. the descent, the need to look (assuming a left circuit) left (at the downwind leg) and right (at the final leg) for target traffic whilst slowing up, flaps, gear, checks (which would otherwise be partly or in whole completed on downwind where the chance of high speed convergence is least) …. BUT! the biggest difference of all is the inability to manoeuvre once on base i.e. can’t turn right to follow one on final, can’t extend downwind to space, so the only option once on base and you find out you are not spaced, is a left turn, climb and join upwind!
.
It is one thing to make a mental picture before reaching the circuit, it is entirely another to have a fully accurate picture joining base particularly if there are more than one or two in the circuit at the time!!!
.
My 2c :)

Giday Scurv!

Another well thought out and reasoned answer http://www.augk18.dsl.pipex.com/Smileys/howdy.gif

J:ok:

gadude said (in previous thread) Furthermore to the above post, what happens on arrival to an aerodrome with a few ultralight aircraft not equipped with radio putting around the circuit?

The extra time afforded in the circuit by joining downwind instead of base helps you to build a complete picture of all traffic in the circuit, not just that inferred from radio transmissions. Add to this some students I've encountered in the past flying an hour of circuits at a busy NSW aerodrome with the VHF switched off, and surely more time in the circuit for see-and-avoid starts to make sense?

toronto_flyer

Gidday Jaba,

Have the other bits arrived yet for the new toy? :8

G'Day....
 

G'Day 'Scurves'.........

Its just plain bloody obvious you are not busy enough..........!

(Rapunzel Rapunzel says....Let down............NOW!)

:)

Scurvy - G'day - great idea to separate this thread.:ok:

TF,

Increasing time in the circuit by requiring extra legs in the circuit creates the following problems which increase the collision risk.
(i) it increases the time in the highest traffic density areas substantially, and
(ii) it increases the density of traffic (aircraft per volume of airspace)
where there is a significant proportion of arriving / departing aircraft.

Being able to optimize scanning techniques increases the effectiveness of see and avoid, but my question is does the three legs of the circuit rule optimize it enough to reduce the overall collision risk per movement. Objective / scientific data is what I am suggesting should be considered and not just gut feelings of pilots such as me. Without a doubt mandatory use of use of radio optimizes traffic scanning far better than the three legs rule.

My closest call in the circuit was at night at YMMB (tower closed) about twenty years ago - the joining aircraft's strobes whited out my instrument panel as it joined crosswind - I was completing circuits at the time.

IMHO the downwind join with a turn opposite the circuit direction is probably one of the worst places to join the circuit - it is at this position in the circuit that distraction of setting up for landing and completing the pre landing checks is most likely to keep pilots from effectively scanning for traffic outside the cockpit.

Werbil,

You make some good points. We really do need quantitative research before we can ever hope to end this debate, as everyone has their own views from experience and training.

But making broadcasts on CTAF frequencies mandatory for all aircraft would be a plus for everyone :ok:

toronto_flyer

Some good, well reasoned posts. But the question I like is: With 60 years or more of accident & incident reporting, why does it seem that CASA can't make a real world analysis.

If you're wondering what the effect of everyone joining on base might be, have a think about operations at Hoxton Park where it is mandatory to fly 4 legs of the circuit before landing (unless I am mistaken).

I would have thought that everyone cramming into join crosswind would be like everyone joining base simultaneously?

At least they will all becoming from the same place doing the same thing. Someone calls "joining" and you would know where to look because they can only be in one place.

There has been many fatal accidents in circuits in the past regarding joining the circuit at the incorrect altitude also. I can not see anyone pointing it out yet.
The Hoxton Park mid-air comes to mind where the Tomahawk from Bankstown attempted to join crosswind flying straight into the other aircraft on downwind. If he was 500 feet higher as required the accident could have been avoided.
So it is not only important to fly the published number of legs it is just as important flying them at the correct altitude also.

Safe flying :ok:

Altitude segregation is key until positioned to mimimise the possibility of swapping of paint/fabric :ok:
.
Accurate alerting (in whatever form) is also key!

Hey Grif, howsit hangin :ok:
.
... yeh I know, canna help myself .... day off, missus and kids off doin' their thing :} :E .. cows and sheep on autopilot ... all is well :)
.
Might be over there in the next little while, we should catch up, will keep ya posted!

Do i seriusly have to go back to school?

Quote""The Hoxton Park mid-air comes to mind where the Tomahawk from Bankstown attempted to join crosswind flying straight into the other aircraft on downwind. If he was 500 feet higher as required the accident could have been avoided.""

If i were to join xwind I would have to be AT circuit hight don't I??

When you join overhead you should be 500 feet over the circuit, decent to circuit hight NON traffic site.

I stand to be corrected.

:ok:

Yes, yes you do.

ppppffff :} :ok: ... spelllin police alert :E

gadude
 

Yes, you are correct. I should have said" attempted to overfly at circuit height ". He should have been 500 feet above and let down on the dead side to join crosswind at the correct height. :(

Still no excuse for your spelling though :E

:ok:

The analysises that Scurvy quoted in this post http://www.pprune.org/d-g-general-av...ml#post4519960 are very relevant to this discussion. Interesting to note that final approach is the highest risk area of the circuit (logical - greatest concentration of traffic and great visual reference to enable accurate tracking).

Also interesting to note was that collisions generally occurred in excellent weather conditions.

Yr right 'griffo', doggy boy has far too much time on his hands down there:E
As for the cts joining? Well it's been the way it currently is for many moons, it works, it's safe & it's in place for good safety reasons. Scurvy summed it up well. One main reason I see it being needed is to allow time for everyone to space manage within the circuit. As others have said, you get say 3 A/C sorted out within the circuit after some R/T chatting then someone joins base & stuffs up the whole thing, like they say, get in line mate!
Joing straight in these days even though has in my mind added dangers (due non R/T traffic) works well enough providing everyone sticks to the rules, there in lies the real problem, there's always someone who 'thinks' they know better!




CW

SMS777 That makes more sence.

And I can breath I little relaxed. I was a little worried that I also had the cross wind joining wrong, like I had with the base leg joining not being allowed.
As for my spelling, wel I just didn't learn it when I grow up like most off you guys did.
Never been very good at it in my native lingo either.

At least gives some off the guys here someting to pick on.:O

cheers:ok: