Ask yourself why personal electronic devices are discouraged from being used on commercial flights during takeoffs and landings. The answer is simple. In the USA, if the device has an FCC certification, under Part 15 it qualifies as an "unintentional radiator". And if it has Wi-Fi or mobile telephone capabilities, it becomes an "intentional radiator" This crerates the opportunity for spurious emissions. The emissions, spurious or not, are just milliwatts. Aircraft scatter elevates the possible concequences by directing signals with orders of magnitude more power directly at aircraft and its antennas. Do the math and see the mixes and images that result.
And what sorts of RF equipment are commonly installed in the typical commercial aircraft?
(Courtesy of Robert Sudock, WB6FDF)