Benm
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- Aug 16, 2007
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Although I should point out - just because cell phones and most of the on board radios (Not just AM voice on VHF and whatever mode they use on HF, ADS-B is much closer to cell frequencies at 1090MHz) operate on entirely different bands doesn't mean they can't interfere with each other.
That said, isn't it more of a blanket ban on electronics with transmitters in them anyway? That makes sense - rather than restricting certain transmitters that might cause issues, just restrict them all. Way easier to manage.
It's easier to blanket ban, but often also nonsensical.
If there actually IS a problem it is easy to explain to people why they should not use devices on planes. It seems to vary between airlines, some ban the use of electronics that cannot transmit at all (like mp3 players without any wifi/network ability) during take-off and landing. Other airlines don't give a darn and only tell you to put cellphones in airplane mode as a formality.
Airplanes do use several systems in various frequency ranges that could be interfered with, but none of them are both critical to flight operations and sensitive to cellphone interference.
VHF voice communications, beacons and ILS localizers work at low frequencies, typically in the 108-200 MHz range, and are immunte to any cellphone transmissions.
ADS-B transponders and TCAS work at 1080 MHz which is not in any cell band, but could be affected by cellphones that aren't really in spec either - probably not brand name ones, but perhaps some chinese clones.
Radar and radio-altimeters usually work in higher frequency bands (over 2 GHz) which would not be directly affected by cellphone signals, but could get interference from harmonics from the cell base frequency in badly designed handsets.
In short: If both the aircraft systems and the cellphone comply with regulations, there is no problem. If either or both are defective, there could be, but it would be unlikely it would pose more than a nuisance.