Qantas, Jetstar engineers 'overworked'

'Tis the season to strike, with industrial action threatening to mess up festive holiday flight plans across the country.

Anyone with January flights booked with Qantas and Jetstar has been warned of delays as engineers continue a campaign of strike action over pay and conditions into the New Year.

More than 100 Qantas and Jetstar engineers walked off the job in Sydney, Brisbane and Avalon in Victoria on Thursday, on the first day of a possible five-day strike.

The heavy maintenance engineers have more strike action planned for December and into next year.

Alison Rose, from the Association of Professional Engineers, Scientists and Managers Australia (APESMA), said the action had been carefully planned not to impact Christmas flights but the same assurance cannot be given for January.

"We have called on Qantas to come back and talk to us to resolve our key issues of fatigue and professional recognition and development," Ms Rose told AAP.

"Qantas hasn't done that so the industrial action has commenced this morning."

Qantas group executive of government and corporate affairs David Epstein said the industrial action wouldn't impact flights.

"The announcement by union officials refers to sporadic action that has been going on for some time but has not disrupted Qantas operations and will not do so in the future," he said on Thursday.

"We have continued to negotiate in good faith and remain absolutely committed to finding common ground."

He said APESMA was seeking a pay rise of 26 per cent over three years, which was unreasonable.

Ms Rose said APESMA's members were seeking a pay rise in the vicinity of between 4.5 to five per cent a year over the life of the agreement.

She said the main issue driving the strike action was fatigue.

"It is not uncommon for them to have less than four hours' sleep between work periods," she said.

"We just need to work out how we can actually put proper rest breaks into this work pattern."

But, in some relief from more potential disruption, security screeners for Qantas and Jetstar domestic terminals at Melbourne and Avalon airports have reached an agreement with security contractor MSS and have cancelled their planned industrial action.

MSS agreed on Thursday afternoon to withdraw its proposal to create part-time casuals at Melbourne and Avalon airports.

The LHMU is claiming a victory in the deal which also includes a pay increase of 13.5 per cent over three years.