Mobiles on aeroplanes
QUESTION: Can we receive a mobile signal while travelling in an aeroplane?
ANSWER : Mobile phones can receive signals while travelling in an aircraft, provided the base station range allows. Territory covered with GSM network is divided into hexagonal cells. The covering diameter of each hexagonal cell may be from 400 m up to 50 km, which consists of base station that provides communication-receive and transmission, and antennae.
All GSM cellular communication telephone cells are performed via these antennae and stations, which are regulated by switching centre. Switching centre provides communication between city telephone network, base stations and other cellular communication operators. Every time you switch on your cell phone, the communication is performed with the nearest base station. Hence it is possible to receive signals on cell phone while travelling in an aeroplane, provided the base station range allows.
Cell phone use during flights is still banned by regulations because it disrupts cell service on the ground and have the potential to interfere with an airplane's navigation and communication instruments.
In theory, any device that emits electronic waves — including cell phones, laptops, electronic games, pacemakers and hearing aids — has the potential to cause interference to an aeroplane.
To be safe, it is recommended banning all electronics during critical phases of a flight, which are generally considered to be during takeoff and landing, when a plane is below 10, 000 feet.
From high in the sky, a cell phone acts like a sponge, sucking capacity out of the cellular sites that carry calls. For ground users, cell phones communicate by connecting to one cell site at a time, from the air, because of the height and speed of an aircraft, the phones often make contact with several sites at once.
If allowed this would limit call capacity, which could mean less revenue. The cellular signal from the air is also especially strong, since it is unimpeded by buildings or other ground clutter. That often means it can jump on a frequency already in use on the ground, causing interruptions or hang-ups.
And airborne cellular calls are sometimes free because the signal is moving so fast between the cells that the software on the ground has difficulty, recording the call made, put the plane at risk because cellular phones can disrupt the aeroplane's automatic pilot, cabin-pressure controls.
Modern aircrafts are installed with in-flight telephones mounted on passenger seats. The carriers receive a cut of the revenue from the telephones installed onboard.
They charge about about $6 for a one minute call, more than 20 times typical cell-phone rates. Thus the airlines and telecommunications companies also have an economic incentive to keep cell phones turned off in the air.
These in-flight telephones also operate on the cellular technology — using a single airplane antenna to which the onboard phones are typically wired.
The outside aircraft antenna that carries the air-phone calls also connects to a ground-based cellular network — but with cells that are spaced much farther apart to avoid multiple phone-ground links.
K. Kamalakannan, Doha, Qatar.
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