Turn off your cell phone before you Board the Plane

It's very important to turn off your cell phone before you board the plane because modern aircraft depend greatly on radio waves to perform numerous functions, such as communication with the control tower, navigation, and regulation of cabin atmosphere. Radio wave interference from a cell phone seriously disturb these function.
You may not be aware that even when your cell phone is on standby it still sends out an electromagnetic signal that notifies the cellular network’s computer that the phone is active and can be contacted. The signal becomes stronger when the transmitter at the base terminal station (BTS) communicates with the cell phone to send a voice call or short message (SMS).
Actually, once the aircraft has taken off and approaches its cruising altitude, your cell phone will not work anyway, because the plane is too far from the BTS. Furthermore, the plane move so fast that once the phone’s presence has been detected and registered by a cell in the cellular network, the phone is no longer within that’s cell range. Yet if your cell phone is active, it is continually emitting electromagnetic signals that could seriously disrupt the aviation equipment.
Law No. 1/2009 regulates the use of handphones as stipulated in Article XXII Section 412 paragraph 5-7, which states that every person in an aircraft during flight who operates electronic equipment that interfere with aviation navigation, as referred to in Article 54 letter f, shall be punished with imprisonment of 2 (two) years or a fine of Rp. 200.000.000,- (two hundred million rupiahs).
The next paragraph states that if the accident resulted in damage or loss of aircraft and property, he or she shall be punished with imprisonment of 5 (five) years and maximum fine of Rp. 2.500.000.000 (two billion five hundred million rupiah). If his or her action resulted in permanent disability of death of person, he or she is liable to imprisonment of 15 (fifteen) years.

Article 431 paragraph 1-2 states that every person using a radio frequency, apart for flight activity purposes, that directly or indirectly interferes with aviation safety referred to an Article 306 shall be punished with imprisonment of 5 (five) years and a maximum of fine of Rp. 100.000.000,- (one hundred million rupiah), while paragraph 2 states that a criminal act as referred to in paragraph (1) that results in the death of person(s) shall be imprisoned 15 (fifteen) year and fined a maximum amount of Rp. 100.000.000,-.
So for your own safety and that of your fellow passengers, you must turn off your cell phone as soon as you enter the plane. If you have a phone in your carry-on luggage, check to make sure that it is turned completely off. The regulation has become the main agenda for Garuda Indonesia Airways.