Steering on the line for taxi
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Steering on the line for taxi
What's the usual way to steer a large aircraft on taxiways? Do you rigorously keep the nose wheel on the yellow centerline, or do you oversteer? (I understand oversteering to mean that you steer outside of the line on turns in order to keep the aircraft as a whole closer to the center of the taxiway.) I've heard conflicting things about this and I'm trying to figure out how it is really done.
On the one hand, I've heard that pilots routinely oversteer large aircraft to keep the main wheels from drifting off the taxiway and/or to make sure that the aircraft is centered and the wingtips clear obstacles. But on the other hand, I've also heard that centerlines and taxiways are designed so that all aircraft can steer properly by just following the centerline with the nose wheel.
Adding to the confusion is a remark for KSFO that says "airline pilots shall strictly follow the painted nose gear lines and no oversteering adjustment is permitted." Why does this airport mention this restriction?
In cockpit videos I've seen, pilots seem to be following the centerline carefully, but I've seen only a handful of cockpit videos.
On the one hand, I've heard that pilots routinely oversteer large aircraft to keep the main wheels from drifting off the taxiway and/or to make sure that the aircraft is centered and the wingtips clear obstacles. But on the other hand, I've also heard that centerlines and taxiways are designed so that all aircraft can steer properly by just following the centerline with the nose wheel.
Adding to the confusion is a remark for KSFO that says "airline pilots shall strictly follow the painted nose gear lines and no oversteering adjustment is permitted." Why does this airport mention this restriction?
In cockpit videos I've seen, pilots seem to be following the centerline carefully, but I've seen only a handful of cockpit videos.
Warning Toxic!
Disgusted of Tunbridge
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If the pilot follows the yellow line in a long aeroplane, the mainwheels will drag inside the turn by quite a distance. Therefore he should take the turn wide so the main body of the aeroplane more closely tracks the centreline. The less sharp the turn, the less care need be taken. But a widebody doing a 90 degree turn has to take great care.
At SFO, there are tight taxiway lines to parking gates and the problem may be that overshooting the turn could make you hit something. Such warnings are displayed prominently on charts.
I think you must be nearly qualified by now to a rather high degree!
At SFO, there are tight taxiway lines to parking gates and the problem may be that overshooting the turn could make you hit something. Such warnings are displayed prominently on charts.
I think you must be nearly qualified by now to a rather high degree!
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So is oversteering normally the rule for large aircraft, or the exception?
The KSFO restriction still puzzles me. The gates might be a tight fit, but surely the taxiways are not, and if you stay on the centerline, the rest of the aircraft is more likely to drift away from it than if you oversteer. Unless the taxiways are exceptionally wide, this would increase the chance of running off the pavement or squashing a taxiway light. I don't see what KSFO gains from the restriction. Maybe it's one of those California things.
I have the advantage of being able to watch my aircraft from above when taxiing in a simulator, and as you point out, the body of the aircraft as a whole stays centered considerably better with oversteering than without it. The same would be true of any vehicle, presumably—I notice that city buses do it all the time.
The KSFO restriction still puzzles me. The gates might be a tight fit, but surely the taxiways are not, and if you stay on the centerline, the rest of the aircraft is more likely to drift away from it than if you oversteer. Unless the taxiways are exceptionally wide, this would increase the chance of running off the pavement or squashing a taxiway light. I don't see what KSFO gains from the restriction. Maybe it's one of those California things.
I have the advantage of being able to watch my aircraft from above when taxiing in a simulator, and as you point out, the body of the aircraft as a whole stays centered considerably better with oversteering than without it. The same would be true of any vehicle, presumably—I notice that city buses do it all the time.
