A four day strike by 500 security staff began at Manchester airport yesterday as 160,000 people were expected to travel over the Easter weekend.
But management said it would be business as usual.
The will continue until midnight on Monday over new contracts which unions say will lead to pay cuts and shift changes.
"Contingency plans are in place and extra security staff drafted in," said a spokeswoman for the airport.
"Security at the airport will not be compromised."
The Transport and General Workers' Union said that last weekend's industrial action at the airport had caused hundreds of delays.
But officials said the delays were caused by air traffic control.
The union's regional secretary Dave McCall said: "We apologise in advance for the inevitable delays that the travelling public will experience.
"However, the future of an effective, properly trained, valued and rewarded security service remains the main issue. We reject - and continue to reject - attempts by Manchester airport to have a cut-priced service based on burger bar rates of pay."
