Figures from the Civil Aviation Authority show that the frequency of pilots putting on oxygen masks to protect themselves from toxic vapours on UK registered planes rose from 16 in 2012 to 33 in 2013 to 40 last year.
Often passengers may be unaware of the flight crew’s concerns as the plane will fly on with just the captain and first offi cer hooked up to the “clean” air.
The dossier of cases also shows that last year there were two “Mayday” calls linked to fumes and another 14 classified at the lower level PAN alert or Possible Assistance Needed.