Thanks Glenn. I'll add my 2 cents from my perspective as an airline pilot. It gets annoying when people turn on or leave on all their devices. The first clue is the buzzing in my headset from the interference with the cellular networks. (Edge networks are the most annoying.) Then the localizer needle starts bouncing back and forth. In decent weather, not a big deal, but try shooting an ILS approach in bad weather with the needles bouncing back and forth and buzzing in your headset, and you understand why people are asked to turn their devices off during critcal phases of flight.
Still...bottom line with this shuttle picture, the flight wasn't below 10,000' feet and not in a critcal phase of flight, so I'm glad the passenger took the photo so we can all enjoy the beauty of the launch.
Brandon K7BBR
Glenn Little WB4UIV glennmaillist@bellsouth.net wrote:
The rules are in effect to prevent possible interference to the aircraft navigation aids and communications equipment. The potential for mix produces from numerous consumer grade electronic devices emitting part 15 compliant RF is just to unpredictable for the FAA to allow these possible RF sources to be energized during the landing and take off phase of flight. If the interference were to occur at a higher flight level, the pilot has longer to respond and get the interfering emitter shut down. During landing and take off the reaction time is just too long to allow the devices to be turned on.
It is not a matter of general EMI. It is a matter of mix products from unknown emitters causing on channel interference to sensitive receivers.
73 Glenn WB4UIV ARRL Technical Specialist