Letters: In Brief

Sir: I am intrigued by the current furore over mobile telephones and aeroplanes. If the radio signal emitted by mobile 'phones is so dangerous, might someone travelling near a runway inadvertently disable an airliner's vital systems when it is at low altitude and at its most vulnerable, taking off or landing? If this isn't the case, can the airlines explain why mobiles become so much more dangerous at 35,000 feet?

DAVID WILLIAMS

London N8