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It's got nothing to do with avionics. It's to stop interference with base stations on the ground.

by throwaway7474 10y ago

ClassyJacket 10y ago
But you're allowed to have phones on the ground.
- LoSboccacc 10y ago
  Within the airport you are nowhere close enough to an antenna for it to matter. You know how old gsm phones made a d-d-d d-d-d ddZzz-d now and then when near a playing radio? That is long enough to completely mangle a control tower message. They let phone on grounded plane because a parked plane is not in critical contact with the tower. Now, having them off by age/model/features would be extremely complicate, most people won't genuinely know if their model is affected etc. So it's all electronic should be switched off or in airplane mode.
  - jrockway 10y ago
    Nice theory, but not true. You're allowed to use your GSM phone the second you land, but there is still plenty of critical communication to be done, like negotiating crossing other active runways while taxiing. 100% of runway incursions happen on the ground!
    - jcrawfordor 10y ago
      My understanding is that the concern is not interference with voice radio but interference with the more sensitive analog radionavigation equipment, e.g. VOR and ILS. These both aren't used on the ground and don't work on the ground anyway because of antenna orientation and other issues. VOR and ILS are very old and very simple technologies (at least as radio goes), making it fairly plausible that radio interference in particular bands could skew the ILS needle and cause a badly failed landing approach.
      - jrockway 10y ago
        But remember that both GSM and ILS/VOR/DME are licensed radio services, and thus shouldn't interfere. The speakers you hear the TDMA modulation in have a sticker on them that says "This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation." Indeed, it does accept the interference that causes undesired operation.
        jcrawfordor 10y ago
        This is a bit of a misinterpretation of Part 15. Part 15 devices bear the "must accept" language to indicate that they enjoy no particular regulatory protection from interference - the operator of a part 15 device may not compel action on the part of another person because that person's lawful operation is interfering with the part 15 device. Licensed services do enjoy regulatory protection, but that protection doesn't change anything physically - it just means that there is a regulatory remedy when interference is a problem. And one of those remedies is FCC regulations about where other devices can and cannot be used. While radionavigation equipment should be built to high standards for interference rejection, their being a licensed service is in no way a guarantee that other devices won't cause problematic interference. It just means that when other devices do cause interference, FCC enforcement is a possibility.
    - LoSboccacc 10y ago
      around here it is said to keep them off until the plane stops. almost noone does and the pilot aren't screaming at them, so there's that.
btgeekboy 10y ago
https://www.law.cornell.edu/cfr/text/14/121.306 https://www.law.cornell.edu/cfr/text/14/121.306 No, it's not. All electronic devices are banned by default, "[unless] the part 119 certificate holder [the air carrier] has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used."
- danaliv 10y ago
  The throwaway is probably thinking of the ban on cell phones, which is an FCC restriction, not an FAA one.
  - throwaway7474 10y ago
    This is correct as this article was concerned around the Samsung phone.

It's got nothing to do with avionics. It's to stop interference with base stations on the ground.

ClassyJacket 10y ago

But you're allowed to have phones on the ground.

LoSboccacc 10y ago
Within the airport you are nowhere close enough to an antenna for it to matter. You know how old gsm phones made a d-d-d d-d-d ddZzz-d now and then when near a playing radio? That is long enough to completely mangle a control tower message. They let phone on grounded plane because a parked plane is not in critical contact with the tower. Now, having them off by age/model/features would be extremely complicate, most people won't genuinely know if their model is affected etc. So it's all electronic should be switched off or in airplane mode.
- jrockway 10y ago
  Nice theory, but not true. You're allowed to use your GSM phone the second you land, but there is still plenty of critical communication to be done, like negotiating crossing other active runways while taxiing. 100% of runway incursions happen on the ground!
  - jcrawfordor 10y ago
    My understanding is that the concern is not interference with voice radio but interference with the more sensitive analog radionavigation equipment, e.g. VOR and ILS. These both aren't used on the ground and don't work on the ground anyway because of antenna orientation and other issues. VOR and ILS are very old and very simple technologies (at least as radio goes), making it fairly plausible that radio interference in particular bands could skew the ILS needle and cause a badly failed landing approach.
    - jrockway 10y ago
      But remember that both GSM and ILS/VOR/DME are licensed radio services, and thus shouldn't interfere. The speakers you hear the TDMA modulation in have a sticker on them that says "This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation." Indeed, it does accept the interference that causes undesired operation.
      - jcrawfordor 10y ago
        This is a bit of a misinterpretation of Part 15. Part 15 devices bear the "must accept" language to indicate that they enjoy no particular regulatory protection from interference - the operator of a part 15 device may not compel action on the part of another person because that person's lawful operation is interfering with the part 15 device. Licensed services do enjoy regulatory protection, but that protection doesn't change anything physically - it just means that there is a regulatory remedy when interference is a problem. And one of those remedies is FCC regulations about where other devices can and cannot be used. While radionavigation equipment should be built to high standards for interference rejection, their being a licensed service is in no way a guarantee that other devices won't cause problematic interference. It just means that when other devices do cause interference, FCC enforcement is a possibility.
  - LoSboccacc 10y ago
    around here it is said to keep them off until the plane stops. almost noone does and the pilot aren't screaming at them, so there's that.

btgeekboy 10y ago

https://www.law.cornell.edu/cfr/text/14/121.306 https://www.law.cornell.edu/cfr/text/14/121.306 No, it's not. All electronic devices are banned by default, "[unless] the part 119 certificate holder [the air carrier] has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used."

danaliv 10y ago
The throwaway is probably thinking of the ban on cell phones, which is an FCC restriction, not an FAA one.
- throwaway7474 10y ago
  This is correct as this article was concerned around the Samsung phone.