Passengers were horrified to see the pilot leave the cockpit to help out due to cabin crew shortage.

A safety demonstration aboard a flight didn't exactly have the desired effect when a pilot left the cockpit to help out because of a shortage of cabin crew.

Jo Osborn, a passenger on the 10-hour British Airways flight from Texas in the US to London, England, claimed that the pilot was "helping with the safety demo", which typically took place as the plane taxis to the runway, the Sunday Express reported.

"Want me to do it @British_Airways so he can fly the plane?" she asked on social media.

Getty Images A BA spokesperson said there were three pilots and 13 cabin crew aboard the Houston-bound flight.

Airline staff member Lolly replied that there are "normally" two pilots on each flight, adding "Hope this clarifies matters".

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Osborn thanked her for her response but noted that seeing a pilot perform a safety demo was "a first" although "he did a great job pointing out the exits".

The UK airline is investigating the matter but is adamant that there were enough pilots and cabin crew on board.

According to an airline spokesperson, there were three pilots and 13 crew members.

"Our cabin crew and pilots always work as a team to ensure the safety of our customers," the spokesperson said.

Osborne's claim came amid a week-long strike by BA Mixed Fleet cabin crew over wages, which followed months of union strike action.

The Unite union has claimed that cabin crew earn "poverty pay" - an average £16,000 (NZ$28,000) a year, including allowances - while BA has said that none of its staff earn less than £21,000 (N$37,000).