It occurs when blood clots form during long periods of immobility. These can be fatal if they enter the heart or lungs, with several reports of deaths among airline passengers. She collapsed in the arrival hall of London's Heathrow airport after returning from Australia following the Olympic Games. Airlines have rejected any link between cramped air travel and DVT, but have begun giving passenger advice through inflight videos and magazines and on their websites.
Airlines advise that mild exercise can help prevent blood clots.
The debate as to whether there is any link between air travel and blood clots ensues.