Why turn off the phone in airplane

Navigation equipment was not sufficiently protected from external interference. 

Working phones interfered during the pilot's communication with the dispatcher, made it difficult to track aircraft in flight time, radio frequency radiation distorted readings of navigation devices.

Since then phones and devices have become more sophisticated. Most studies have shown that inclusion of electronic devices do not affect the modern navigational instruments. Therefore, in 2014 the European Aviation Safety Agency formally abolished the outdated prescription.

Some airlines still retains the ban due to inertia, but its widespread cancellation - is only a matter of time. Other abolished outdated rule on the condition that during take-off and landing is possible to use electronic devices for reading or playing games, but you can not use headphones to hear the flight attendants ads.

Often air carriers are not allowed to use the phone as usual, preferring to play it safe for the safety of passengers. Takeoff and landing - the most difficult phase of the flight, and it is important to avoid any noise, even minimal. However, it is possible that after further research and they will remove this restriction.

In Europe the use of gadgets at any time of the flight. In the US the restrictions apply takeoff and landing: during level flight no use communication does not prohibit. Russian airlines until stick to the old rules on the principle of what if something happened. Scientific or practical justification that prohibition is not, but the question remains debatable.In recent NASA study conducted in 2016, also states that electronic devices may interfere with GPS operation.

It is believed that mobile phones can cause interference with aircraft navigation and radio systems, especially for precision approach systems and UHF stations. So accustomed to think of the time when all the equipment was still working on some frequencies, both in the sky and the sea, and phones, and microwave ovens. Now radio-frequency grid is strictly divided. 

Nevertheless, even the instruction for pilots provides off mobile phones before taxiing. airline security departments to explain the requirement that at the time of takeoff and landing, passengers must be aware of what is happening and to react to emergencies.

Therefore, in the airplane asked to fasten your seat belt, remove things, open the shutter window to see what was going on outside the window. The phone is considered as an additional distraction.