the iPhone and the significance of 101.4

Again, I worked on this stuff in the past. As the previous poster mentioned if you fire up a cell phone 2 inches from a glass plate display sure you'll freak it slightly. It might even be unusable. But from the cabin... no... Chances are not high.

Did you ever wonder why airlines want your ipod turned off the first 10 and last 10 of every flight? No it's not "radio soup" as was posted in another thread... Sure the airplane is in a more radio intense environment but the ipod is almost unmeasureable... how could it interfere? It can't. Simply put the airline wants your COMPLETE attention in the event of an emergency which is 15 times more likely to happen in the first and last 10 minutes of every flight.

My point, simply from experience is that all aircraft radio gear, digital and analog have to go through many tests to be certified for use in an aircraft. Heat, vibration, etc. Our shop extended these tests to include RF interference. In my experience the likely hood of a cell phone, from the cabin, causing difficulties with the comm/nav equipment of the A/C is low.

Perhaps if someone had one of the really old 10 watt mobile phone packs they might success, but then you have numerous types of nav on board: INS, rNAV, GPS, VOR, TACAN, the list goes on. The chance of all of these being "swamped" is simply not there.

But frankly this conversation is moot because they are not allowed. The reasons are many. I'm just pointing out that what the flight attendant says "because they may interfere with the navigation systems of this aircraft" is what the airlines/FAA decided to say so that people would really take this request seriously.

I hold an ATP, ME, SEL, SES, rotorcraft, CFI, CFII, CFIME. I've been around airplanes as a pilot and worked on the radio gear as well. I've even turned on my cell phone in the cockpit of a Lear at 35,000. No problems. My buddy flies for a private jet charter company. Recently one of their aircraft experienced a very rare dual bus failure which left them with minutes of A/C power. Radios went down, luckily in VFR weather. What did they do? Pilot got out his cell-phone, call ATC on one of the numbers published in the Jepp and they landed VFR.

True his radios were dying but still alive. When they tried to transmit one radio would power down. So they could listen but not transmit. His cell phone didn't kill anything. The GPS still worked, and the hand held backup GPS was just fine as well.

Anyway enough of this... we've gotten off topic.

I should mention that when I say "radio gear" that generally means, comm, nav, flight director, autopilot, GPS, INS, FMS etc.

Generally all that stuff is lumped into the term "radio gear".

Sweet Jesus, that's awesome, awesome to the max!

WOW! That is the strangest thing! Does your alarm still go off at the right time?

markdr wrote:
Heres the video. I promised it tonight but couldnt turn on the light cause id wake my fiance. But at least you get an idea what happens to the clock. if you have your sound on you can hear what it does to the clock.

Okay, just out of interest, go to your Field Test screen by pressing:

star 3001 hash 12345 hash star in your phone keypad and press Call; you'll get the main Field Test screen.

Have a look at Network Information: what is the value for AR FCN?

It should vary somewhere between 0 to 124; this tells you that the phone is receiving a 850-900 MHz frequency. I'm guessing that the tower you are locked on to might give you an ARFCN number of 101?

Worth a try. It may be that your clock's antenna is locking on to the tower signal?

The sound you hear is the phone communicating with the tower and vice versa; perfectly normal in GSM/TDMA phones, such as the iPhone, and happens when your speakers are not shielded from RF interference. Seems the iPhone is worse in this respect than other phones, but it happens to all of them to some extent.

Message was edited by: jia10

I should add that this would only be possible if the clock has a radio on it as well?
Also, when testing, make sure you're in the same location, as the ARFCN number will vary depending on your location, and hence tower id. as well.

Message was edited by: jia10

jia10 wrote:

Worth a try. It may be that your clock's antenna is locking on to the tower signal?

Then it would do it even without the iPhone nearby. Perhaps you meant the clock was locking on to the iPhone signal? I wonder what would happen if the iPhone was put into airplane mode?

romad wrote:
Then it would do it even without the iPhone nearby. Perhaps you meant the clock was locking on to the iPhone signal?

Not sure how the clock part would lock onto anything, without a receiver of some sort. If it also has an FM radio built in, then it might do it via this route.

I wonder what would happen if the iPhone was put into airplane mode?

I expect that it wouldn't happen then. Recall that in the video, we heard the RF interference from the iPhone coming from the clock speakers, whilst the clock display was updating to 101.4. The speakers may have been from the radio, or just the alarm bit.

Message was edited by: jia10