The Government border agency says departing flights for the Thanksgiving holiday required more screening than normal, partly due to passengers having more carry-on luggage to be screened which slowed processing down.
It says lanes were opened when rostered, additional lanes were opened when staff were available, with staff re-rostered from other tasks to help where they could.
But it says this wasn't enough to deal with the unusually high demand.
Avsec says it will continue to review what has happened over the last few days including the success or otherwise of any adjustments we have made.