Monday, April 07, 2008

On landing and take off

I don't fly often, but I can clearly spot a difference between the practice of the airlines (cabin crews) in the U.S. and Malaysia (and other Asian airlines?) towards turning on mobile phones on (after) landing.

In the U.S., as I observed until 3 years ago, pretty much everyone turns on her cell phones once the airplane touches the ground. And the crew seems to be OK with it. Always.

Here (mostly with Malaysia Airlines and Air Asia), they make it clear that passengers cannot turn their phones on until the engine is turned off. I've seen a cute flight attendant rudely reminded a passenger in one of my Air Asia flights. (She could've done it nicer, but it's an attitude problem, I guess.)

We know that mobile phones can cause electromagnetic interference to airplane devices. I copied a quite comprehensive explanations below from Jamie. She also provides the explanation why we are required to raise the shade and put the seat on vertical position - which is a real pain with Air Asia. (I wonder whether some flight attendants can clearly explain the reasons behind these requirements.)

But the question remains: if we use our phones after the airplane touches the ground, what would be the risk? Will the pilot gets lost and not be able to find the terminal?

Well, on a more serious note, we should comply to the regulation. It's always too late to say "I wish I did that" after an accident happens.

Why do you have to turn of all electronics during take off and landing?

People must not be preoccupied during take-off and landing so that in the event of an emergency, they can clearly hear instructions given by the Flight Attendants.

You are asked not to use any electronic devices, although some may be used after cruising altitude has been reached. Cell phones, wireless computer mouses, etc are banned for the duration of the flight. This is because they pose a risk called electromagnetic interference.

Electromagnetic interference is experienced by all of us on a regular basis. An example of this is if you put a cell phone near the computer, you can hear loud static in the computers speakers every time the phone rings, and the screen may start to shake. This technically should never happen, but the wire to each speaker is acting like an antenna, and it picks up side bands in the audible range. This is not a dire problem -- just a nuisance. But notice how common it is. In an airplane, the same phenomena can cause big trouble.

An airplane contains a number of radios for a variety of tasks. There is a radio that the pilots use to talk to ground control and air traffic control (ATC), a radio that the plane uses to disclose its position to ATC computers, there are radar units used for guidance and weather detection, and so on. All of these radios are transmitting and receiving information at specific frequencies. If someone were to turn on a cell phone, the cell phone would transmit with a great deal of power (up to 3 watts for a single phone). If it happens to create interference that overlaps with radio frequencies the plane is using, then messages between people or computers may be garbled. If one of the wires in the plane has damaged shielding, there is some possibility of the wire picking up the phone's signals just like a computers speakers do. That could create faulty messages between pieces of equipment within the plane. Now imagine what would happen if everyone on the plane were to use electronic devices, and you should be able to fully understand the ban on such devices.

Why on planes take offs and landings you must: open the windows and put the seat on vertical position?

You are asked to raise your shade so that in the event of an accident you can see through the window to help you remain oriented (which way is up, etc.). Because of this, it lets you see what hazards there are outside the plane (fires, debris and such), which would be important during an evacuation. It also serves as a way to let light into the cabin and make it easier for rescuers to see inside.

Upon descent (and also if you are taking off at night) they dim the lights to help your eyes adjust to the darkness, so if anything happens and it goes dark, you're not suddenly blinded while dashing for the exits. It makes the emergency path/exit lights more visible, as these might be the only lights you see in an emergency. As with the shades, it allows you to see outside for orientation, because with the cabin lights burning brightly, the glare would make it impossible.

The seats have to be in upright position for safety reasons. In case of an accident:
*it makes it easier for passengers to exit their seats
*passengers must have easy access to emergency exits (something they wouldn't have if seats are reclined)
*it allows passengers to assume the "crash" position if need be
*reclined seat backs could kill or seriously injure the passenger behind if it should come unbolted, or if the passenger behind it is thrown forward.