I found a phrase that I don't understand while reading Jeppesen charts: "judgemental oversteering".

I found it in general information about taxi procedures. As I understand this procedure applies only to jumbo aircraft because it takes place only if the wingspan is more than 118ft (according to the chart which I read).

Can you explain to me what is it? What kind of conditions can require this procedure? Examples or images would be appreciated.

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    $\begingroup$ This would be a fun question for Terry to answer. $\endgroup$ – user9394 Jul 16 '17 at 1:59

"Judgmental oversteering" means to intentionally not follow the taxiway centerline when turning. It is a technique used on large aircraft to turn on tighter or smaller taxiways.

In a sense, it is like driving a long vehicle, such as a truck or a bus. Instead of following the lines on the road, the driver would deliberately overshoot the entry of turn, i.e. delay turning the steering wheel. This technique allows the rear wheels to stay on the road instead of going over the corner which may have fences, poles, pedestrians or other obstructions.

Here is a drawing from the 747x Quiet Longer Range Family Airport Compatibility document which illustrates the tracks of each gear for the "judgmental oversteering" and "cockpit centerline" methods:

enter image description here

This FAA document about airport design summarizes the pros and cons for each method (p.52 of PDF, p. 34 of document):

Cockpit Over Centerline. Taxiway intersections designed to accommodate cockpit over centerline steering require more pavement, but enable more rapid movement of traffic with minimal risk of aircraft excursions from the pavement surface. (...)

Judgmental Oversteering. Taxiway intersections designed to accommodate the judgmental oversteering method of maneuvering require the least pavement widening. However, judgmental oversteering requires complex maneuvering, increases the risk of aircraft excursions from the pavement surface, and slows the flow of traffic.

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    $\begingroup$ "pedestrians or other obstructions" - :) $\endgroup$ – Simon Jul 15 '17 at 20:39
  • $\begingroup$ @Simon Think LXGB :D $\endgroup$ – TomMcW Jul 17 '17 at 14:01

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