Hi folks one of most studied subjects I suppose. Here some extraction from Ozzie's regulations regarding the emergency turn radius.
6.1 Turn Radius Splay
The lateral obstacle containment area or splay in a turn can be significantly effected by temperature. The turn radius is a function of true airspeed (plus wind), which varies with temperature at the same indicated airspeed.
Also, the engine-out indicated airspeed (V2 or V2 plus an increment) varies considerably with weight, and limit weight is strongly affected by temperature. The temperature effect on both the maximum and minimum
turn radii must be taken into account. For turn radius consideration the following guidance can be applied:
Inner radius: Minimum dispatch weight at the coldest planned departure. This will give the tightest turn radius.
Outer radius: Maximum dispatch weight at the hottest planned departure. This will provide the largest turn radius.
However, it is acceptable to do a turn analysis based on a single critical temperature if that temperature produces results which are conservative for all other temperatures. In a turn, the specified lateral containment half-widths (i.e., one-half of the lateral containment maximum
width) should be applied to the inside of the minimum turn radius and the outside of the maximum turn radius. An average turn radius may be used to calculate distances along track.
However there are some places I can think of and as mentioned here like SZG or INN where its absolutely crucial to maintain a prescribed speed in order to stay within the turn radius which causes a weight penalties.
Cheers.