If you fly commercially, you're familiar with the drill. Turn off your cell phones, I-Pods, and computers - anything with an on and off switch - until the plane gets above 10,000 feet.
The FAA says it's for your safety, but what exactly are they concerned about?
According to two San Diego State University electrical engineering professors, the rule is based largely on unknowns rather than scientific data.
When a plane is coming in for a landing or taking off, the flight crew informs passengers to turn off everything.
Most passengers have a vague idea of why the rule is in place.
Few truly understand whether it makes a difference, especially when they forget from time to time without problems or complaints.
Professors Fred Harris, Ph.D. and Madhu Gupta, Ph.D. say there is no technical merit for the rule.
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"Normally carried equipment just does not have the right kind of signal strength nor for that matter frequencies that would actually cause harm," said Gupta.
"If everyone turns on their cell phone it's like everyone is speaking at a party, the volume goes up, there's more noise, more interference. But, still it's an incredibly small amount of power," Harris said.
The FAA says there are still unanswered questions about what could happen.
"They're making and receiving a lot of communications from air traffic controllers, they're speeding up, they're slowing down, they're descending, making turns, so that's a critical phase of flight," said Ian Gregor with the FAA.
In an effort to avoid the unknown consequences of radio interference between the pilots and controllers on the ground all portable electronic devices or “peds” must be turned off below 10,000 feet.
The FAA isn't aware of any specific instances where electronic equipment has actually created interference.
Studies, the most recent between 2003 and 2006, have shown insufficient results.
"The results are negative so therefore they say they're non-conclusive because they don't support the position the FAA takes," said Harris.
"FAA is trying to error on the side of safety, even though no one has ever demonstrated there is a risk," Gupta said.
"I think it's really more of an unknown, anytime there is an issue of safety were going to be extremely conservative," said Gregor.
Something most passengers don't disagree with. Even if the rule is based on never-before-seen possibilities.
The FAA says the ban also helps to remove distractions during takeoff so that passengers can focus on the flight attendant's instructions, however that's not the main reason for the ban.
