Please turn off all cell phones before takeoff

The study described how ‘a clock spun backwards and a GPS in cabin read incorrectly while two laptops were being used nearby.

‘During another flight, the altitude control readings changed rapidly until a crew member asked passengers to turn off their electronic devices.’

Older planes are most at risk to mobiles, Blackberrys and iPads, according to the study from the International Air Transport Association which ABC News has obtained.