Originally Posted by
ContinentalFan
They don’t enforce airplane mode on cell phones; the WiFi is often on during initial taxi and is almost always still on during landing.
WiFi is a much lower power signal than a cell phone that’s pinging a tower.
While it is true that the primary reason cell phones are not allowed in flight is that it’s disruptive to the ground-based systems — they’re not designed to have someone change cells at 600 mph — it is also true that a cell phone will boost its gain substantially when it gets a weak signal. One phone won’t cause much interference, but a planeful certainly could.