Wednesday, 17 October 2007 08:24
Hi Captain Lim,
I*ve been reading your web site with great interest.
I wonder if you could answer a question that*s been nagging at me for ages. When boarding a flight there is invariably an announcement that passengers must switch off their mobile phones.
Is the fly-by-wire really so sensitive that micro signals from mobile phones are going to affect it? I only ask as I live in Saudi Arabia and on every flight on the airlines here, some of the locals use their mobiles non stop ... and we haven*t crashed yet!
As always, your comments would be read with great interest.
I have answered this kind of questions a few times in the past. See some of them below (Please use Search):-
1. Can a US$20.00 CD player actually bring down a US$270 million aircraft?
2. Why can't I use my digital video camera aboard the plane?
3. What will happen if I fall asleep with my iPod on during the landing?
Signals emitted by the use of CD player, digital video camera and the iPod are not as critical as those emitted by mobile phones. Cellular phones are totally prohibited.
The FAA bars cell phone use in flight as well as other electronic devices during takeoff and landing to avoid disrupting plane electronics. The FCC bans its use because of ground concerns. Cell phones often don't work at 30,000 feet, but when they do, signals can reach hundreds of towers at once, clogging networks.
However, OnAir, a European company has found a way to make dialing safe and link up people from above the clouds soon. The company has been approved by the European Aviation Safety Agency to begin fitting such equipment to commercial jets, hopefully before the end of 2007. UK's Ryanair and Malaysia's AirAsia would be some of their biggest clients.
Some companies in Southeast Asia and the Middle East are expected to begin installing the equipment in 2008, but the more complicated markets of Japan and the US will have to wait until 2009.
To prevent the phones from interfering with the ground network, the system will only be available above 3000 meters (9000 feet). This is achieved four minutes after take-off and maintained until 10 minutes before landing.
Meanwhile, it is an offence for recalcitrant passengers to use cell phones in the air. Yes, planes have not crashed yet because pilots' skills and back up equipment have so far been very effective in saving some dangerous moments in the air.
We don't want to wait for the unlucky day when its indiscriminate use would lead to a crash!