Health and safety concerns at Jetstar are part of strike action when staff at airports across Australia walked off the job on Friday, disrupting the travel plans of thousands of customers.

Despite Jetstar defending it’s “robust safety management systems”, SafeWork NSW slapped Jetstar with an improvement notice on Thursday night as crew prepared to walk off the job on Friday morning in a pay and safety dispute.

“Ground crews are at risk to health and safety from serious injury such as being crushed, ingested or other, when working around operational aircraft,” the notice seen by AAP states.

At least 250 staff in Sydney, Melbourne, Brisbane, Avalon, Cairns and Adelaide are involved in rolling two-hour strikes as part of a pay and safety dispute.

Passengers were warned to expect disruptions on Friday, with 10 flights already cancelled in Sydney, five in Melbourne, three in Brisbane and two in Adelaide before 9am (AEDT) Friday.

The ABC reported Sydney staff will strike from 5.30pm to 7.30pm, while Melbourne staff walked off the job from 9.30am to 11.30am, and will do so again from 4pm to 6pm.

Brisbane and Adelaide’s strikes occurred from 6am to 8am, and will recommence on Friday night from 6pm to 8pm.

Sydney’s near-empty Jetstar terminal on Friday morning. Photo: AAP

“The airline has cut its staffing levels right back to the bone, meaning workers are constantly under pressure,” Transport Workers Union national secretary Michael Kaine said in a statement.

Jetstar said it would never put staff at risk and has “robust safety management systems in place”.

“The TWU has a history of playing the safety card when it suits them, and this is another example of that,” Jetstar said in a statement.

“(The safety systems) are regularly reviewed and audited by a range of regulators, including the Civil Aviation Safety Authority.”

Jetstar also faces weekend strike action from its pilots – and has said it will cancel 44 services on Saturday and 46 services on Sunday as a result. There are reports the three days industrial action will lead to 120 cancellations in all.

On Friday, ground crew and baggage handlers were striking at different times in the various cities. Their action – less than a fortnight from Christmas – comes after the budget airline rejected workers’ demands for pay increases, minimum hours on the job and safety improvements.

“The airline has cut its staffing levels right back to the bone meaning workers are constantly under pressure,” Transport Workers Union national secretary Michael Kaine said.

The union claims Jetstar makes $4 billion in revenue, while workers are forced onto insecure low-paid work.

Negotiations broke down after the company rejected demands including for more rest breaks, a guaranteed 12-hour break between shifts and a guaranteed 30 hours a week.

The TWU strikes will be followed by four-hour stopworks from pilots on Saturday and Sunday. The pilots’ industrial action will continue throughout the week, with a range of lower level bans likely to cause delays.

Pay negotiations broke down after nearly a year, with Jetstar warning it wasn’t prepared to alter its position.

“The union’s demands would put significant pressure on the low fares our customers rely on and force us to review our investments,” Jetstar Group CEO Gareth Evans said.

“If we accept an effective 15 per cent net increase in pay that the union is demanding, there will be significant upward pressure on the low fares our customers rely on.”

Passengers are being told they will be notified if their flight is disrupted.

Those affected will be able to change their flights or get a refund, the airline said.

-with AAP