BUDGET airline Jetstar pulled a woman with cerebral palsy from a flight because it believed she could not understand instructions.

Ashley Papworth, 21, was travelling from Brisbane to Newcastle to visit her family, but was barred from the flight because cabin crew thought she was unable to understand what they were saying.

Ms Papworth uses a wheelchair and hearing aid, but has travelled extensively without discrimination. Her grandfather, Michael Folbigg, said he was horrified by her treatment by the airline.

"There were family members available to help Ashley on to the flight and also to help with her on arrival at Newcastle," Mr Folbigg said. "(The airline) cited difficulties in communication as their reason for their refusal. Ashley is (diagnosed with) cerebral palsy, not an imbecile."

Disability Discrimination Commissioner Graeme Innes was saddened, but not surprised, by Ashley's treatment.

Mr Innes said people with disabilities were regularly discriminated against by airlines, but he said the problem was particularly bad with low-cost and budget carriers.

"Airlines are continuing with a policy that treats people with disability like second-class citizens," he said.

Disability service provider Northcott was contacted by Ms Papworth's family about the incident. Northcott CEO Kerry Stubbs said airlines had a responsibility to train staff better to stop discrimination.

"Get some training for your staff to help them see the person, not the disability," she said. "Too often we hear of companies that see people with a disability as a problem, rather than as a customer."

A Jetstar spokesman said Ms Papworth had travelled with family on previous occasions and the airline apologised for the inconvenience she suffered.

"One of our key independent traveller requirements is that a passenger must be able to communicate that they have understood our crew's safety and emergency instructions," the spokesman said.

"In this case, based on interactions with the passenger and her parents, our team was not satisfied that Ms Papworth could travel on this flight without an accompanying passenger."

Disability Services Minister Andrew Constance warned businesses that they need to abide by laws.