What really happens when you don't switch to flight mode

2016-04-08 21:14 - Louzel Lombard
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Cape Town - Have you ever thought what would really happen if you don't switch to flight mode? We all have. 

And to put your mind at ease - no... your little smartphone has not got the power to bring down a Boeing 737. Big surprise there. 

What it is able to do, is annoy the living hell of your pilot and that might cause your flight experience to go south.

Mobile phones create an unpleasant noise due to parasitic demodulation 33 000ft up. The noise sounds like when you place your phone next to an audio system, and screeching noises come through the speakers. For pilots, this is even worse, as the screeching sounds come through their headphones. 

According to a blog post for AirlineUpdates, an operating pilot writes that transmitting mobiles can and do cause audible interference on an aircraft’s radios. Passengers will easily recognised the sound, he says.

"‘You’ve probably heard this interference yourself when a phone is set near a speaker. It sounds like a “dit-dit-dit-dit”. It is not safety critical, but is annoying for sure."

Although this is fairly rare, the pilot says if they fly 50 times a month, they can hear the sounds through their headphones once or twice over that period.

Most commercial flights don’t allow passengers to use their mobile phones to make calls or send text messages in mid-air out of concerns over safety or the comfort of everyone on board. 

The ban was originally brought in over fears the radio frequency emitted by mobiles belonging to passengers or crew could malfunction a plane’s electronic systems. This, however, is not a problem with new phones and on-board systems. 

The ban remains in place just for the sake of the pilots. Because there is plenty of attenuation between phones in the cabin and the pilots’ radio, there can be radio pollution on board. If one person leaves on their phone, screeching sounds will occur. However, if say 50 people on board are inconsiderate enough who can’t be bothered to switch their cellphones off, there will be 50 phones constantly looking for cell towers at maximum power, screening through the headphones of the pilots in the cabin.

"That is a lot of radio pollution," writes the AirlineUpdate pilot blogger. 

"It is common courtesy. By switching your phone to airplane mode you show your appreciation to the people doing their job to get you where you want to be. I am not an electrical engineer, but I am an airline pilot," the pilot says. 

So how come some airlines are introducing WiFi on board, you might ask. 

When inflight cellular service is provided, there is a cell station right beside those phones.  They communicate at very low power without causing any disturbance.

Wi-Fi signal is much weaker than GSM frequency bands, and even at their peak, they won't cause any problems.

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