Everytime I take a plane I hear the captain says: Please switch off your phone or I'll throw you out of this plane.
Everytime I go refueling I would see the no cell phone sign on the wall.
Why the hell la people... It's not even harmful to use mobile phone on the plane or at the petrol kiosks...(call me lanxi)
Urban legend says that your plane would fall if you fail to oblige the no-cell-phone rule on the plane. That's a busted myth my friend... and the reason why cell phones are banned is because they interfere with the navigation system onboard, i.e the captain might have trouble listening to his wife over the radio and thus he bans all other phones so that he could listen properly without the "didididi" sound.
On the airplane
Actually cell phone emits radio wave.
Exactly the same wave used by planes and the control tower(bingo!) and thus it could cause confusion to the navigation system; the system relies on waves emitted from the control tower and also other planes to move around, so if your cell phone is active, the plane probably won't crash but you'll get a rocky ride.
At the petrol station
How about the petrol kiosk? Well the MYTHBUSTER TEAM; Adam Savage and Jamie Hyneman did the experiment to test the myth and it's busted too.
Wave transmitted from cell phone is unable to ignite a fire, even when surrounded by gasoline vapor with the optimum fuel-air mix for ignition.
Imagine la... how can an EM wave start a fire~?! Light wave only have limited penetration in liquid la... Just think why is the ocean floor dark? Simply because the nature of the non-ionizing wave (in this case, visible light) doesn't allow it to penetrate far into liquid, the same goes for UV wave, Infrared, radio wave, etc.. but it is different for waves with shorter wavelength/ionizing wave i.e. Gamma ray and X-ray. Gamma ray could penetrate concrete wall @@
That's why when a submarine submerges it loses all contact with the outside world, and when it wants to make a call, it has to go to the surface or sends out an antenna long enough to resurface.
Moreover, a submarine cuts off all radio wave once underwater to avoid detection (unless it is built as target practice for the enemy =P)
Moreover, radio wave doesn't ionize anything~ (I heard that explanation from some random dudesssss, perhaps he did get ionized by his cell phone). So how could it ionize the surface of the petrol and get it ignited?!! (Do you get ionized when exposed to light?).
Only waves like X-ray and gamma ray are potentially dangerous to our health. So how can someone claim that wave from cell phone are dangerous (except for very high dose, like you speak on the phone for 3 damn hours, or speaking on 5 phones simultaneously), when it is much weaker than visible light?
So why are there cases where people caught fire when making calls at petrol station?
Well we get charged up when we're driving; the constant wind that brushes around our car charges us up, and you could sense yourself discharged once you get down from the car, at least I do, and often with a spark!(I ain't joking.. ask my frens)
So this spark is how the fire get started~ =)
When surrounded by petrol vapor(petrol is volatile) and oxygen (we have 21% of that in our atmosphere) and spark from your body, BINGO~~ it's a perfect ingredient for a fire~~~
Otherwise, it could be the battery~
Some devices do have electric-leaking problem, for example my laptop.. and obviously someone did own a leaky cellphone and that ignited a fire =P
So don't get fooled by those people who tell you that making calls at petrol station and you'd end up barbequed =P
But please don't ignore the cell-phone ban on plane, unless you want to make a nuisance of yourself and decide to have a rocky ride with all those folks with heart problem =)