As Marshall I have to say that when called upon to use the black flag it is  a lot easier to pick up a bike when you have some idea where in the field the bike might be coming.Under the new system unless you have logged all the changes in your programme you are never sure when they are due to arrive at your pull in point. I know ideally you should get a call from the previous two or three marshal points but experience shows this by no means always happens.When approaching you at up to 180mph you have little time to spot the rider.Black flagging is an important safety issue, ask Guy Martin when he was black flagged at Ramsey.