Plan A is used if all systems remain operational. It says that the train will continue to move at 60 +- 5 mph for the next 10 seconds, then slow gradually to 45 mph. The plan could consist of a section of "reserved" track for each second in the future, and the train is sticking to the plan if it remains within the reservation.

Plan B is used if service brake failure happens. It says the train will apply its emergency brake and slow to zero at a given rate.

Plan C is used if both the service brake and the emergency brake fail. It says the train will continue at 60 mph, and may speed up or slow down a little, before finally guaranteeing to stop within 30 miles.

All the plans would be written automatically by software, and each would be 'conservative' - ie. if there are any uncertainties, the plan must include them. Less advanced trains would have wider bigger plans, and must therefore keep wider separation distances.

Plan C is obviously very unlikely - and is therefore allowed to overlap with similar plans B and C of other trains - the reasoning being it is very unlikely for the service and emergency brakes of this train to fail, at the same exact time as the emergency and service brakes of another train.