Specifications

ST900 Family General Handbook
667/HB/32900/000 Issue 11 Page 171 of 265
Because every controller is introducing plans as though they have all been running
since the same base time, the actual time that a plan is requested to start is not
critical.
21.4.2 Base Time CLF Example
Consider a controller configured with a base time of 2am, a cycle time for the plan of
70 seconds, and a request to start at 7:30am.
When the CLF plan is requested to start, the controller determines that 5½ hours
have elapsed since the base time and the CLF plan would have effectively been
repeating every 70 seconds since starting at 2am.
Therefore, dividing 5½ hours, which is 19800 seconds (5½x60x60), by 70 seconds
gives 282 and a remainder of 60 seconds.
This means that the CLF plan would have completed 282 cycles and would be 60
seconds into the next cycle.
Therefore the CLF plan ‘resumes’ at time ‘60’ within its 70-second cycle time and
introduces the influences that would have been present if the plan had been running
since starting at 2am.
21.4.3 Entry and Exit Times
Base Time CLF Plans can also be configured with ‘entry’ and ‘exit’ times:
If the CLF plan requested to start has an ‘entry’ time configured, the plan will not
actually take effect until that point in its cycle time. The controller will continue to run
a lower priority mode, e.g. VA mode.
If the controller is requested to isolate, and the current CLF plan has an ‘exit’ time
configured, the plan will continue until it reaches that point in its cycle time. Only
then will the controller revert to a lower priority mode, e.g. VA mode.
If the controller is requested to start a new CLF plan while currently running a
different CLF plan, the controller checks to see if the current plan has an exit time
configured and if the new plan has an entry time configured:
If the current plan does not have an exit time configured and the new plan does not
have an entry time configured, the new plan is introduced immediately.
If the current plan has an exit time configured, the plan continues until that point in
the cycle has been reached. The new plan will then start unless it has an entry time
configured. In this case, the controller reverts to a lower priority mode, e.g. VA
mode, until the new plan reaches its configured entry time and takes control.