G’day werbil et al,
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Interesting one this. An answer (in part) to gadude’s Q below:-
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werbil
I would be very interested to see an objective study on the actual risks of various circuit joining procedures. And I would suggest that if such a study was conducted the risks would be found to be very different in a circuit which has mainly arrivals / departures compared to one which has mainly circuit traffic.
I Agree, as I suspect the answer to your hypothetical would in part answer
gadude’s Q
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gadude
.... I still can't see why joining base is more dangerous than joining downwind. the point about having more situational awareness because you spent more time in the circuit is a little funny,
If you need to joing downwind and are flying down wind to make it safer because now you can sort your self and the rest off the circuit out, than what have you been doing on your aproach?
I can imagen that everyone else, just like me, makes a mental picture off whats going on way before you get to the circuit. You talk to others etc.
The ‘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).
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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!
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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!!!
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My 2c
