M.Mouse - Good point, but I don't think anyone is suggesting going mad - sensible corrections to fuel are required. It is sensible is to always plan a sensible contingency, applying professional judgement, above jet plan fuel. When performance allows it an extra 30 minutes is a sensible figure, I would say . I am not saying go silly - just be prepared, as situations like the one I had do happen. 30 spare minutes would have shown that I had excercised my professional discretion and had been prepared for unplanned possibles!
Yep! Quite agree that a fly by is a waste of time, generally. The technically untrained eye of Tower folk (no disrespect Heathrow Director)would be unwise to risk saying that it looked ok when it turned out not to be. To get an engineer to the tower with a good pair of binos is a better idea. It is still very unlikely to be of any real help, especially if the gear is down but not locked. It could be used as a last resort to help reassure one that the wheels are at least pointing roughly in the right direction though!
One small point! I have rarely seen LOFT exercises practicising such emergencies on min fuel!