The second of two 12-hour strikes has begun at Glasgow and Aberdeen airports.
The move follows stalled talks between the AGS Airports group and the Unite union over pay and pensions.
Unite members at the two airports will walk out until 16:00 on Monday. The first strike took place on Friday.
Strikers include security staff, fire and operations teams – but not check-in or baggage handlers. During Friday’s strike, passengers experienced security and flight delays.
AGS said “robust contingency plans” would be put in place to try to ensure “business as usual” at both airports.
AGS Airports Limited owns Glasgow, Aberdeen and Southampton airports.
The union claims the company closed the consultation process on pensions on 24 May, as it attempted to close a defined benefit pension scheme.
This, they say, broke an Acas Agreement made in 2016 to keep the scheme open to existing members.