Airlines need tough policy on mobile phones

PUBLISHED : Tuesday, 24 March, 1998, 12:00am
UPDATED : Tuesday, 24 March, 1998, 12:00am

After the outbursts over the near destruction of recent performances in Hong Kong of Othello by pagers and cellphones, I draw attention to a more serious scenario.

Before the departure of each flight from Kai Tak, flight attendants explain the safety features of the aircraft, action in possible emergencies, point out exit doors, repeat the strict no-smoking rules and, finally, almost as an afterthought, request passengers not to use cellphones during the flight as this might interfere with the aircraft's navigation equipment.

This is not good enough. Human nature being what it is, there is no assurance whatsoever that someone will not fire up their cellphone or pager during the flight. Many on board may claim they did not hear the announcement and some may openly ignore it. Whether we like it or not, all cellphones and pagers should be handed over to the crew for the duration of a flight, before the owner is allowed on board.

How can these tiny devices interfere with the electronics on the plane? Aircraft all over the world are guided by high- and low-frequency radio signals so minute it is hard to believe they could be utilised to guide a huge aircraft to a safe and happy landing. Give these little signals a fighting chance and they will come through thick and thin, through rain, sleet, fog, and snow with flying colours.

Just take a look at GPS (Global Positioning System), which gives pilots precise latitude, longitude, altitude and time co-ordinates anywhere in the world. Imagine how weak the triggering pulses and signals must be after travelling thousands of miles through space from the controlled orbiting navigational satellites. Hardly a match for the strong local signals emitting from a cellphone inside the cabin of an aircraft.

The cellphone's signal can jam and create confusing oscillations and harmonics that can wipe out the very important navigational signals.

GPS is only one of many wonderful navigational systems depending on minute radio signals. Could cellphone users just stop and consider the network of vital radio signals emanating from transmitters throughout the region, there to guide planes safely to their destinations? Activating a cellphone on board an aircraft could interfere with any of these signals: crucial voice communication between pilot and air-traffic control; search and reflecting radar signals; VOR (very high-frequency omnirange) systems usually integrated with Tacan (Tactical air navigation) which then becomes Vortac, giving pilots precise range and direction; ADF (Automatic Direction Finding) which can be used as a back-up; and ILS (Instrument Landing systems), a device which guides each arriving aircraft to within a few metres of the threshold of a runway.

Considering all this, who has the right to risk carrying with them aboard a flight their pager or cellphone? WARREN and MARGARET EDGAR New Territories