Originally Posted by
IFMU
True, I am burning away height when there is a possibility of sink, but I have height to burn. If you are low and hit sink, what do you do? Do you have height to burn, or is there just no sink that comes up low? We typically don't do a diagonal leg, but I have never lost sight of the runway. I mean, it's right there out my window.
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By flying a flatter (no airbrakes etc.) circuit and steeper final approach (2/3 airbrakes) there is more in reserve if you hit sudden nasty sink. Sink can happen very low at some sites, and if the airbrakes are only open a little shutting them may well not make the difference you need to avoid an undershoot. There is a 'cone' you can fly down to get to your desired touchdown point and flying down the top of it (steep approach) gives you a greater margin if sink comes along. It also tends to give a shorter ground run.
As to losing sight, if the reference point is near the threshold then you don't have to fly far downwind past it for seeing it and using it to judge your circuit to get harder than it need be.