Doing something because you're told to, without an explanation, can be annoying can't it? That's why we've often put our phones in flight mode on a plane with reticence. But now we know why it's worth doing.
According to a report by the Mail Online, mobile phones can affect the plane's comms. But don't worry, leaving your phone on isn't going to endanger anyone as it won't affect the plane's flight systems themselves.
The worst thing a connected smartphone can do is create annoying feedback in the headsets of the pilots. You know that noise speakers can sometimes make when you hold a phone near to them? That's what a pilot's communications radio can kick out if phones are left on.
So leaving your phone on during a flight might not cause anyone harm but it certainly is annoying. That "dat-dat-dat-dat" noise in your ear is distracting and the last person you want to distract or annoy, when taking off or landing, is your pilot.
One passenger, texting, did interrupt a radio call from traffic control - which could have potentially been dangerous.
That said, pilots have said that in about 50 flights they've only heard the interference once or twice. That could be thanks to dutiful passengers or simply that the odd phone left on doesn't cause that much interference.
Now you're informed you can choose to turn your phone off in-flight, knowing you're at least trying to save someone at work a great deal of annoyance and hassle.