Children prepare for the arrival of the emergency vehicles – and their sirens – during the Independence Day parade Wednesday in Freeport.

Officials at the Portland International Jetport are encouraging travelers who are flying out Tuesday to arrive at least two hours before their departure time to allow for increased wait times at Transportation Security Administration checkpoints caused by a malfunction in the screening equipment.

TSA engineers are working to resolve the issue, Assistant Airport Director Zachary Sundquist said, but until that occurs the malfunction is going to affect all lines, including those for passengers with TSA PreCheck.

Passengers also are encouraged to minimize carry-ons and to make sure that any prohibited liquids or gels are packed in their checked luggage to ensure quicker progress through security lines.

“We recognize that moving easily through our facility is what makes the PWM experience a good one,” said Paul Bradbury, airport director. “Unfortunately our partners at TSA are having technical issues which are impacting our ability to expeditiously process passengers.”