Switch off, fly safe

Every time I fly, I see people put their phones under their thighs, look in the other direction and try to act deaf, all because the cabin crew has announced that all electronic devices, including their precious cellphones, have to be switched off for the duration of the flight. Recently, a man sitting next to me refused to do so. The flight was delayed and he was still on the phone.

Reprimanded a couple of times by the airhostess, the man decided to put the phone on airplane mode. The crew explained that he would have to switch it off completely. But the man countered that his calls were important, especially as the flight was late. As the debate turned into a heated argument, I tried to explain why it is important to switch off the phone in an airplane. But our friend was not convinced.

That episode made me decide that it was time I explained how a small mobile phone can cause havoc in an airplane. Though electronic equipment on airplanes is designed to ignore interference, there have been several instances when their navigational equipment showed errors. This was linked to a cell phone being used on board, though scientifically there are difficulties in proving that the gadget alone was the cause of the errors. But, I guess, it is better to be safe than sorry.

All electronic equipment, especially our phones, laptop computers and BlackBerrys, have a communication engine that not only listens for radio frequency signals, but also transmits them. Similarly, our iPods have Wi-Fi, while many other gadgets have Bluetooth. The airplane mode switches off the radio, but there are still chances that the device may send out signals, and that’s why we have to be cautious.

The aircraft uses sensitive navigational equipment, similar to a GPS in the car. The equipment depends on communication from the airfield below as well as satellites above to know where it is going. As all this communication is on radio frequencies, disruption or disturbance can make the plane deviate from its track. This can have disastrous effects, especially during poor visibility when the pilots are almost completely dependent on electronic navigation. Things can become even more complicated if the interference happens during take-off or landing.

The Government of India’s Civil Aviation Department circular dated September 12, 2003, categorically says that passengers can only use mobile phones as long as the aircraft is on the ground with its doors open. But, the phone cannot be used when the aircraft is refueling, when pre-flight functions are on, or when aircraft communication is happening. In no condition should the phones be used after the doors are closed, and this is a legal requirement, not a request.

But, why switch off an old Walkman or CD player which have no transmitters? These devices emit electro-magnetic radiation, which at times can exceed the prescribed limits and interfere with the onboard equipment like the auto-pilot.

The latest planes have a shield to protect their navigation equipment and some carriers have started allowing passengers to use cell phones mid-air. But till those planes come to India, it better to just switch off your phone and relax, maybe even chat up your fellow passengers and make some friends.

The Above article appeared in the Indian Express, on Sunday August 01, 2010


  1. Hey,
    This is Amol Sethi, pardon my informal way to address this email to you, I haven’t really ever written to any columnist! I’ve been a great fan of your column ever since I started actively reading the news paper. It’s very informative, simple to understand and very very interesting too. Recently I travelled to Leh, and back, and have had more than a couple flights to change. All while I quizzed myself to understand what could go wrong with a plane by a simple phone! But thanks to you, I’ve had all my queries answered, and that to when I was racking my brains on it. Though I wonder why don’t planes have cell phone jammers? Or make it mandatory for all tickets to have this message on it!
    Anyways, thanks for updating our knowledge on weekly basis. It’s a pleasure reading your articles.
    Amol Sethi