Jetstar Airlines is facing further allegations it is exploiting staff and compromising the safety of passengers.

A former flight attendant has told ABC's Lateline he quit his job at Jetstar because of safety concerns over long shifts for cabin crew and staff not being able to answer safety questions.

The budget airline maintains it has rigorous safety standards.

But a clause in the the contract for Singapore-based Jetstar crew states they could be forced to work shifts longer than 20 hours.

Former Jetstar flight attendant Dallas Finn joined the airline in June and quit two months later.

Two weeks before quitting, Mr Finn filed an incident report about fatigue after flying five return international flights in five days.

"The majority of these flights were quite busy, I found that my sleeping patterns were drastically effected to the point of fatigue," he wrote in the report.

"Clearly there are safety issues here pertaining to cabin crew if an emergency situation arises on the return flight from SGN OR MNL (Saigon and Manila), where the duty is 12/13hrs return."

Mr Finn told Lateline cabin crew were forced to work long hours.

"The majority of flights out of Darwin are back of clock, so you're leaving early evening and you're not getting back to the next morning," he said.

"The Ho Chi Minh flight is between a 12 and 13-hour day. They would actually change the pilots over in Ho Chi Minh but the cabin crew would have to fly back."

But Mr Finn says it was a flight he shared with Singapore-based staff that gave him more cause for concern.

"Before we actually get on a flight we have to go through a briefing and the questions are on an emergency procedure, an occupational health and safety procedure and a medical question," he said.

"I went to answer the emergency and the medical question when the cabin manager stopped me to get the Singapore crew to actually answer and, basically, they couldn't answer the emergency procedure and they couldn't answer the medical question.

"It was the first time I've actually been scared of flying because if something went down I didn't actually know if that crew would be able to back me up."

No-one from Jetstar was available to be interviewed on Lateline, but in a statement the airline said all crew are required to complete rigorous training.

"We're aware of a concern about the perceived proficiency of a crew member on a Melbourne to Darwin flight on 17 July 2011. These concerns were investigated and it was determined that the crew member satisfied proficiency requirements," the statement said.

Double standards

There are also concerns Jetstar's Singapore-based crew do not have the same protections as Australian crew.

Lateline has obtained a copy of the contract for Jetstar's Singapore-based flight attendants that states crew can be called on to work shifts up to 20 hours long.

But a clause in the contract also shows staff can be forced to work even longer than the 20-hour limit without consultation.

"The Planned Limit and Operational Extensions may be extended by agreement between Jetstar and the Supplier," the contract reads.

The supplier, Valuair, supplies cabin crew for Jetstar out of Singapore.

Valuair is unlikely to disagree with Jetstar on any crewing extensions as Qantas, though Jetstar Asia, has a 49 per cent share in the company.

A Singapore-based crew member told Lateline that Jetstar management points to the contract if staff complain about fatigue.

"If we complain about fatigue, or long hours or bad flight rosters, the management's reply is - 'you signed a legal contract, so you have to do whatever that is'," the crew member said.

While the contract states shifts can go beyond 20 hours, Jetstar said in a statement it does not roster 20-hour shifts.

"The longest rostered shift is 15 hours and 20 minutes. The average rostered international cabin crew shift is approximately 10-11 hours," the statement said.

In July, Lateline revealed Jetstar's Thai-based crew signed bonded contracts that required staff who quit or were sacked to pay back up to four-and-a-half months of their base wage.

The contract for Singapore crew similarly states they can be forced to pay back nearly three months of their base wage if they resign or are dismissed.

Mr Finn says Jetstar are exploiting foreign-based workers.

"I think they are abusing the situation with the working rights. They are going under Singaporean law and under Thai law but they are flying above our skies," he said.

Flight Attendants Association of Australia's Jo-Ann Davidson says the practices are "appalling".

"We would never allow under an enterprise agreement in Australia to have bonding for cabin crew, but they're allowed to do that overseas and we think that is unacceptable," she said.

Jetstar says overseas contracts reflects local market conditions.