Many long-haul flights operate on re-dispatch, where the company has this procedure.
Have only had a problem at LHR one time....holding at LOGAN for 20 minutes, suspected a rat when told to hold for another twenty (ATIS all the while reporting 4000 metres), asked the F/E to monitor LHR ground and he reported that the airfield was going to low vis procedures and the RVR was now 800 metres....ATIS still reporting 4000.
Quick dash to LGW, first one in with others following close behind.
Three tons remaining at shutdown (TriStar), slim but workable.
ATC very accomodating that day...
