use of electronic devices during Flight

[304065]

As any beginner pilot knows, VHF and UHF are line of sight. From an elevation of 1000 feet you can see many, many towers. This is the reason-- from FL 350 cruise you could lock up many towers on the same frequency.

Also, every radio uses a "local oscillator" to compare the received signal to- these cause RF emissions. Do you really want to see what happens if the pilots happen to be shooting an ILS Cat III into the fog?

The REAL reason is safety related but not in the way you might think. Standards of etiquette being what they are, the cellphone ban avoids the hundreds of potential episodes of choking the living beejaysus out of your fellow passenger who jabbers on a cellphone ALL THE WAY FROM NEW YORK TO LOS ANGELES

[spuggy]

Originally Posted by john_cramer

As any beginner pilot knows, VHF and UHF are line of sight. From an elevation of 1000 feet you can see many, many towers. This is the reason-- from FL 350 cruise you could lock up many towers on the same frequency.

Way it was explained to me (when I was working at a wireless phone company) was that all the towers that can "see" the phone arbitrate to decide who has the best signal, and when to hand off.

Not such a big deal when you're driving up the freeway @ 55 MPH and two or maybe three towers are involved, but significant when you can "see" a 100 towers or more, and are moving @ 600 knots to boot, and then multiply that by 50+ phones on the aircraft...

If there's effectively a tower on the aircraft, it's a slam dunk for the phone, it only talks to that...

The REAL reason is safety related but not in the way you might think. Standards of etiquette being what they are, the cellphone ban avoids the hundreds of potential episodes of choking the living beejaysus out of your fellow passenger who jabbers on a cellphone ALL THE WAY FROM NEW YORK TO LOS ANGELES

Heck yes. It's bad enough that no airline provides a "no children" area, much less service. Yet.

I love children, but I couldn't eat a whole one...

[cgarr]

W.C. Fields, Excellent!

[scottmandue]

Originally Posted by imcarthur

The day is coming & the joy of plane travel will suffer because of it.

Ian

Your kidding right?

I used to love flying, but between the pointless airport NAZI security and the seats shrinking every year as if we wouldn't notice our knees pressed to the seat in front and elbows jabbing me in the side all the way across the country and the new lack of in flight service I would hardly call it a "joy" anymore.

[imcarthur]

Originally Posted by scottmandue

Your kidding right? . . . . I would hardly call it a "joy" anymore.

Yeah. I'm kidding. Last year was a record for me . . . over 50 hours of flight delays . . .

Ian

[FOG]

A few points. The newer cell phones have far less power and have a tougher time reaching the ground (range issues),

About 20 years ago I have friend who worked installing the in-flight phones. Had a conversation with one of the company bosses. He essentially stated that they were going to lobby to get cell phones banned from commercial flights as it would cut into their profits.

I honestly can’t see how they are a safety issue. I have seen lots of -130 flights with multiple devices going and no safety related problems.

S/F, FOG

[LakeCleElum]

If cell phones worked and were allowed, I'd really be ticked to be sitting next to someone for hours on end while they yak'ed on the phone the whole time!

[BlueSideUp]

I actually have had a cell phone cause an issue on a flight. Up front we wear headsets and much like the radio in your car they can occasionally pick up a loud clipping sound from the cell phone. It tends to happen when the phone is sending/receiving (calls or texts) or when it is searching for a tower.

Let me tell you if you think it's irritating in the car try it with the speaker half an inch from your ear. I have actually asked passengers in flight to check their cell phones because the noise was interfering with our communication. Other than that, no cell phones don't cause the wings to fall off. No I don't want to sit next to someone on their phone telling a buddy all about their last colonoscopy.

[rudderboost]

I actually have had a cell phone cause an issue on a flight. Up front we wear headsets and much like the radio in your car they can occasionally pick up a loud clipping sound from the cell phone.

We can often hear when one of the pilots have forgotten to shut off their cell phone. When they transmit on the radio you can hear the clipping in the background.

[BlueSideUp]

Not that it's ever happened to me but that is the first thing I check.

[Jeff Alton]

Originally Posted by rudderboost

We can often hear when one of the pilots have forgotten to shut off their cell phone. When they transmit on the radio you can hear the clipping in the background.

We have instances of ground based cel phone use causing interference too!
We had a couple of towers moved to eliminate the problem.......

Rudderboost, you a controller?

Cheers

[Sonic dB]

this thead turned out to be an interesting read...thanx to every one of you guys with true experience in the aviation industry that shed some light on this.

[ZOA NOM]

The frequency spectrum for cellular phone use is way up in the UHF band, above 800 Mhz. The spectrum assigned to ATC is in the VHF range between 108 - 132 Mhz. Because of the selectivity requirements in the communication equipment, there is very little chance for a cell phone to interfere with ATC communication. There can be harmonic affects, however, that might explain some of the clicking described by a pilot earlier.

[Jeff Alton]

Well Industry Canada are the ones that determined that to be one of the causes, we have also had instance where we could here the actuall call. Not sure what may cause that too happen or cause the interference but it could be because some of our VHF is paired with UHF but now where near 800......

[rudderboost]

Rudderboost, you a controller?

No, I'm on the other side of the radio in the air. If your a controller in the B.C. area I bet I've talked to you a couple of times!

[Jeff Alton]

Upon further thought, that may not have been the interference they found, it may have been a tv station.

[Jeff Alton]

Rudderboost, I am a Vancouver Terminal controller, who do you fly for?

Cheers

[Joeaksa]

Originally Posted by BlueSideUp

I actually have had a cell phone cause an issue on a flight. Up front we wear headsets and much like the radio in your car they can occasionally pick up a loud clipping sound from the cell phone. It tends to happen when the phone is sending/receiving (calls or texts) or when it is searching for a tower.

Let me tell you if you think it's irritating in the car try it with the speaker half an inch from your ear. I have actually asked passengers in flight to check their cell phones because the noise was interfering with our communication. Other than that, no cell phones don't cause the wings to fall off. No I don't want to sit next to someone on their phone telling a buddy all about their last colonoscopy.

Same here. We can tell up front when someone in the back has a phone left on. To tell the truth its not much of a bother other that this damm chirping.

Rudderboost,

We would never forget to turn our cell phones off up front. Never... well that is after we did once and it ran the battery down all the way searching for a signal from Boston over the Atlantic to Istanbul...

[Sonic dB]

man you pilots fascinate me with what you do... flying rockets really. If i could do it all over again, i would have taken the advice of that Navy recruiter back in 87 who promised me that based on my perfect test score...he would "make me Top Gun"... I guess the pull of the blonde on the back of Cruise's motorcycle wasnt enough to sway me though. In another life perhaps.

Regarding control to plane communications, I remember being on a flight about 5 years ago during a major winter storm, where we couldnt land in Detroit so they were trying to figure out where to put all the planes and they directed us towards Minnesota... the communication was on the stereo system on the seats and I happened to tune in to hear the controllers talking to all of the pilots...at one point it got heated up with frustrated pilots demanding their instructions, people talking over each other etc...so the controller shut everyone up by saying 'listen, no one will speak unless we address them specifically...understand??" so everyone shut up and they were able to get things organized...that was a frank and fantastic listening experience for a person on that plane that night.

[304065]

Just because comm is VHF doesn't mean it can't hurt. What about DME?

An internationally standardized navigation system which allows an aircraft to measure its distance from a selected ground-based beacon. Such beacons are used throughout the world by all airliners, most of the military aircraft of the West, and a large number of general-aviation aircraft. The range of service is line-of-sight up to 300 mi (480 km) and system accuracy is usually 0.1 mi (0.16 km) but precision equipment, intended for use during landing, has accuracy of 100 ft (30 m).

The airborne equipment, called an interrrogator, transmits pulses of 1 kW peak power on 1 of 126 frequencies. These are in the 1025–1150-MHz band and are spaced 1 MHz apart. Each pulse is of 3.5 microseconds duration and is paired with another, spaced 12 or 36 microseconds later. The combination of frequencies and pulse spacings therefore provides 252 operating channels.

The beacon on the ground, called a transponder, receives these pulses, delays them by 50 μs, and then retransmits them, usually with a power of 1 kW, on 252 frequencies lying between 962 and 1213 MHz. The pulse-pair spacing is 12 μs on those frequencies not used by the interrogator, and 30 μs on those frequencies shared with the interrogator. The transponder transmission is called the reply. The frequency difference between interrogation and reply is always 63 MHz. This arrangement allows each transmitter frequency to act as the local oscillator for its associated superheterodyne receiver, the intermediate frequency of which is 63 MHz. For landing purposes, some transponders have powers as low as 100 W.

In the aircraft the replies to its own interrogations are recognized by their phase coherence with their own transmissions, and by the elapsed time measured between transmissions and reception (minus the 50-μs transponder delay), usually by means of a crystal clock. This elapsed time is about 12 μs for each nautical mile (7 μs for each kilometer), and is displayed in the cockpit on a digital meter, which is usually calibrated in miles and tenths of miles. See also Electronic navigation systems; Instrument landing system (ILS).

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