Walter Kennedy
As I understand it the IRA were not in the habit of ringing up and giving precise details of their next planned attack. The Security Forces had to be prepared to respond to incidents with the minimum of delay - thus there would have to be a minimum number of Air assets available each day to respond to attacks and other incidents. In this respect one Chinook could deploy a response team which would otherwise have required at least 2 Pumas.
The flying programme for the next day would be based on intentions given the current scenario at the time of programming. That programme would become redundant in the event of a incident.