When Kenneth Kirchoff notices that an airline passenger has failed to power off his gadget as instructed, he'll politely point out the oversight.
He might use a non-confrontational line such as this: "Excuse me, did you realise that you didn't turn off your device?"
What he doesn't mention during this brief interaction is who he is, what he knows and why you should listen to him.
If he won't share, I will.
Kirchoff is a research and development engineer with Boeing.
Since 2003, he has been testing aircrafts to ensure the safe usage of portable electronic devices (PEDs) onboard, focusing on how signals emitted from passengers' gadgets can muddle pilots' communications, navigation or surveillance systems.
His conclusion: "Interference is possible."
The debate over PED use on planes has turned into a seething nest of Angry Birds.
On one side are passengers, legislators such as Sen. Claire McCaskill, D-Mo., and electronics manufacturers and suppliers.
These folks question the science, and sense unfairness in the rule requiring travellers to unplug all devices during takeoff and landing.
This contingent wants its e-readers, its tablets, its DVD players, its video games, its Words With Friends (that one's for you, Alec Baldwin) and other techy diversions for the entire span of the journey, not just the middle portion.
Our customers "not only want to use PEDs in all phases of flight, they observe that many passengers already do, unintentionally or not," Paul Misener, vice president of global public policy at Amazon, told the Federal Aviation Administration during a comment period on the topic.
"They also know that pilots use PEDs in the cockpit; they see many other in-flight distractions besides PEDs; and they logically ask why PEDs are permitted on board aircraft if they actually are unsafe."
In the other corner are airline industry experts, including aviation engineers, professors and flight crew members, who support the regulation based on a variety of findings and rationales.
This group, however, is receptive to the possibility of new evidence and innovations that could spark an overhaul of the current rule, as long as the adjustments don't jeopardise passenger safety.
"The science needs to be looked at again," said Corey Caldwell, a spokeswoman for the Association of Flight Attendants. "We want to know beyond a shadow of a doubt that it does not cause interference."
The FAA sits in the middle of a fray of its own creation. It established the rule and relies on airline personnel to uphold it. But the regulation isn't inscribed in stone, and the agency could grab a chisel and start chipping away at any time.
Listen closely, because you may one day hear the sound of a regulation disassembling.
In January, the agency created the Portable Electronic Devices-Aviation Rulemaking Committee (PED-ARC) and invited a broad cross-section of industry experts to participate.
Members include Amazon, Boeing, the Consumer Electronics Association, JetBlue and the Association of Flight Attendants, among others.
The group will submit its recommendations by the end of July.
The FAA will then review the material and decide whether to change the current rule or keep it as it is.
Of course, bureaucracy often moves as slowly as a snail stuck in gum, so we've got some time to kill.
Let's spend some of it discussing what we know about PEDs on planes.
All electronic devices give off electromagnetic radiation and fit squarely into one of two categories: intentional emitters, which are designed to send and receive signals (smartphones, laptops, tablets) and unintentional emitters (DVD players, Nintendo games, calculators).
The signal strength varies according to gadget type.
Cellphones, for example, send strong signals, especially when they are struggling to stay connected to a tower.
Electric razors, by comparison, have the power of a sneezing flea.
Even gadgets in sleep mode emit a signal; hence flight attendants' insistence that passengers completely power off all devices.
The government bans a few PED uses on planes outright, such as making calls on a cellphone. (The Federal Communications Commission oversees this segment of the industry but leaves the rest to the FAA.)
Walkie-talkies, pagers and radios also appear on the short blacklist.
"Hundreds of phones moving at that speed would introduce a lot of signalling within the network," said Philip Levis, associate professor of computer science and electrical engineering at Stanford University, "as they jump from cell tower to cell tower."
Unsanctioned WiFi service is also forbidden.
The concern: A device's dogged quest for a connection could tread on the avionic system's primary bandwidth.
"Emissions into these bands can degrade the accuracy and performance of the systems," said Kirchoff.
The blocks of time that bookend every flight are crucial moments, with heightened risk for accidents and mishaps.
For this reason, the flight crew needs to weed out meddlesome distractions. In the cabin, flight attendants require passengers' undivided attention while they explain the safety procedures and prepare travellers for landing.
Up in the cockpit, pilots demand ninja-like focus to perform multi-step manoeuvres.
A signal from an e-reader probably won't ice their systems, but it could create a distracting noise.
"You can upset certain equipment with high enough power," said Kirchoff. "This is added workload for the pilot who needs a high level of concentration."
For a loose analogy of PED interference, Levis draws on a casual conversation: "When someone is speaking to you softly in a silent room, you can hear them fine. But if someone else starts talking at the same time, you can't understand them."
A handful of personal gadgets left on may have limited or unnoticed impact on avionics, a fact probably proven on every flight.
Yet multiply that number by 75 or 100 or 800, and you're talking about a loud cocktail party of chatter. "It can have a cumulative effect," said Kirchoff, "and can increase the level of noise and electronic signals."
To date, PEDs haven't caused any crashes, but pilots have noted incidents.
In an October 2012 survey by the Association of Flight Attendants, nearly 12 percent of crew members said that they'd received a cockpit request for passengers to turn off their devices because of "suspected electromagnetic interference."
NASA safety reports have also documented several situations involving PEDs.
For instance, a few years ago, a Canadair pilot noted a compass system malfunction after takeoff. The issue cleared up after a passenger switched off his iPhone.
Kirchoff has heard of similar anecdotes, although the Boeing scientist and his colleagues have never corroborated these reports. But he still supports the FAA rule.
Of course, we - a royal pronoun that includes Kirchoff - are only human.
People can be forgetful or lazy and neglect to turn off their gadgets.
According to the flight attendants' study, nearly 75 percent of surveyed crew members have witnessed passengers disobeying the PED policy on every flight.
Almost 83 percent of respondents said that the violation involved a refusal to turn off a cellphone.
In a separate study, the Consumer Electronics Association conducted a survey of in-flight habits in 2003 and again in 2013.
A key discovery: "Airline passengers are less concerned about the potential for interference with aircraft systems caused by PEDs than they were a decade ago."
Between takeoff and landing, the rules do loosen up.
Some international carriers, such as Qatar Airways, Ryanair and Lufthansa, provide in-flight cellphone service.
Passengers use their own phones inside a telecom bubble designed and certified specifically for the aircraft.
"Some airlines have installed systems to make this possible without interfering with airline systems or ground-based cellphone systems," said Perry Flint, a spokesman for the International Air Transport Association.
In addition, a growing number of airlines (United, Southwest, American, JetBlue, etc.) are offering Internet through a special WiFi plan. The low-fare bus model has sprouted wings. And of course, passengers are free to switch on their e-whatevers - in airplane mode only - once the plane reaches a cruising altitude of 10,000 feet.
They can noodle around with their gadgets until the final descent.
"It's what, 20 minutes, maybe less than that?" said Caldwell, referring to the no-PED time frame.
One of Boeing's projects is to design and build an aircraft tolerant of PEDs.
Kirchoff said that the models are in "testing phase." But the experts will need to put on their running shoes to keep up with technology.
"Wireless and electronic technologies change so quickly," said Levis, "and planes are intended to last for decades."
Levis is an advocate of the current FAA rule. "I'd be very uncomfortable if people had many kinds of electronic devices communicating wirelessly during flight," he said, "in part because some might be rare or do strange things that nobody has tested for safety in a plane."
Flight attendants, who already fight for passengers' attention, are also partial to the regulation. "We are first responders, not the PED Brigade," said Caldwell.
Kirchoff also sits on the turn-them-off side of the fence.
"There are a lot of layers of safety," he said. "If you remove [one] layer, you increase the probability of something happening."
He also brings up a related hazard that you don't need a PhD to understand: "You don't want to have laptops flying around."
- The Washington Post