I take it that the search planes can fly in the dark !......So why take off at first light. If it takes 2 hrs to get onsite couldn't they leave 2 hours earlier ??
The flight time from airbase to the search area is approximately 4 hours, not 2. The search planes are scheduled for take off at staggered times so as to keep at least one plane in the search area all or most of the daylight hours.