05-03-2010, 02:05 PM
I may be wrong but surely "approach control" is an aspect condition which is based on a valid route being set. The signal will not clear from a red aspect due to the <<berth>> track not proven clear. Remeber, App Cont is usually berth OCC plus 't secs' [time].
Therefore, you are still fail-safe under "normal" failure conditions. There are credible but improbable conditions where the berth track was picked under specific circumstances that could allow the aspect to clear to a better aspect earlier than was designed. However, you have a further mitigation that the driver has route knowledge and should be preparing for the speed restriction [in the UK].
Jerry
Therefore, you are still fail-safe under "normal" failure conditions. There are credible but improbable conditions where the berth track was picked under specific circumstances that could allow the aspect to clear to a better aspect earlier than was designed. However, you have a further mitigation that the driver has route knowledge and should be preparing for the speed restriction [in the UK].
Jerry
Le coureur