Why are we asked to switch off our mobile or keep in flight mode when we are travelling in a flight?
K.V. Sandeep
Rajahmundry, Andhra Pradesh
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Airplanes, soon after takeoff and much before landing, fly at an altitude of higher than a kilometre during their flight. They have to ascend to these high altitudes for the aerial flight to avoid turbulence due to clouds and the clear air turbulence (CAT) present at low and normal altitudes.
At such high altitudes, the pilots have to largely depend on the avionics and computer-assisted coded signal communications.
The pilots know the flight location and destination besides other geographical details by guided commands from the Global Positioning System (GPS) which links the control tower, airplane cockpit and geostationary satellites.
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Further, they can know the weather and other meteorological conditions and directions of landing and takeoff at the airports, only through wireless communications from the control towers at the airports.
In poor weather, the pilots use instrument landing system (ILS) to find the runway. Most of these avionics are remote operations and all the communications are in wireless radio and microwave semionics.
All the wireless signal trafficking is accomplished by modulated radio and microwave transmissions which type the cell phones also owe their functioning to.
If there are any mobile phones on board in the cabin of the flight in ‘ on' mode during takeoff, flight and landing, the microwave transmission between the mobile phone towers and the mobile phones might interfere with the communications the flights are busily engaged in (between the cockpit and the control towers).
It is mainly on this risk of interference of the mobile phone microwave signals with the crucial and vital avionics and semionics of the flight operations, that the air passengers are instructed to keep their cell phones switched off or in flight mode.
In the flight mode (also known as Airplane mode), all wireless radio and microwave communication features are disabled leaving only the entertainment functions such as music player, organizer, games, camera and other aspects that do not require the radio transceiver hardware activity.
Some airline operators do not permit even the flight mode and the use of any kind of electronic devices on board.
Anyway, the cell phones cannot serve as phones on board the flights because the cell phone towers on the ground cannot connect themselves to the phones at such high altitudes and such high flight speeds.
Prof. A. Ramachandraiah
Editor, Vidyarthi Chekumuki
Jana Vignana Vedika, Andhra Pradesh