Why not use cell towers for ATC communication?

Discussion in 'Instruments / Avionics / Electrical System' started by StarJar, Mar 1, 2015.

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  1. Mar 1, 2015 #1

    StarJar

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    All across the USA we have cell towers, that handle millions of calls. It seems that it would be a small additional load to use them for general aviation.
    A way to do it would be that the towers, and flight facilities, would have a dual system that can recieve and transmit calls through existing air frequencies, or through cell towers.
    If a GA plane is only flown domestically, then maybe it could have only a 'cell' transmitter/reciever.
    I may have easily not considered something so, would like to hear ideas or info, that would take either side of the argument.
    I'm hoping for kind a brainstorming thread, so crazy ideas and observations would be acceptable, (untill shot down hard).
     
    Last edited: Mar 1, 2015
  2. Mar 1, 2015 #2

    Pops

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    We don't have cell towers all over the USA. There is a lot of area in my state that does not have cell phone service. I live in a county of 5000+ people and not one stop light in the county. I also live at the edge of 22K acres of woods. Over 25 down aircraft that has never been found.

    Dan
     
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  3. Mar 1, 2015 #3

    JamesG

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    Aviation already has its own reserved frequencies and an established install base of radio sets that are "certified" for use by aviation (all the Is dotted and Ts crossed). Getting equipment that rides on the cellular phone networks to that same level would take a lot of time and expense that I don't think anyone can afford, least of all the FAA.

    That said, on more than one occasion it has been necessary to place an airborne call to an airfield manager's cell phone to remind him (wake him up) that he had arriving traffic that day.
     
  4. Mar 1, 2015 #4

    StarJar

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    That's one of the things I was wondering about. But looking at AT&T coverage area, it looks like over 90% of the land mass is covered, and that doesn't include the better reception you might get with a little altitude.
    The uncovered areas are in very remote areas, and could be easily avoided, if desired.
     
  5. Mar 1, 2015 #5

    Matt G.

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    By your logic, most of Kansas, where I fly, would be considered a "remote area" by AT&T. I have Verizon for my cell phone because I want it to work if I land my glider out in the middle of nowhere. Even then, my phone does not work 100% of the time.

    What's wrong with the current system? This would be one of those, "it isn't broke, so let's keep trying" things, in my opinion...
     
  6. Mar 1, 2015 #6

    StarJar

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    Cheaper radios, for one thing. A modified cell is all the plane would need.

    All the FAA tower would need is a modified phone, and a phone line for each function: Tower, Ground, Atis. Could be made for less than $100 per tower.

    This what their coverage looks like: ATT.jpg
     
  7. Mar 1, 2015 #7

    fredoyster

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    The reason we don't use cell towers for ATC, and the reason in-flight use of cell phone networks is prohibited by the FCC (47 CFR 22.925) is that the whole concept of cellular telephony depends on a ground based user profile. Terrestrial users mostly move from cell to cell relatively slowly, allowing for handoffs from one to the next within the timing that is expected. The more important piece of the profile is that an airborne user will occupy a frequency across many cell sites at once (which otherwise re-use the frequency because a ground user can typically only reach one at a time) taking that frequency out of service or interfering with ground based users over a wide area. Yes, it sometimes works in an emergency and I would have no qualms about trying to call ATC on the cell phone if I had an electrical failure. But on a regular basis it would be a train wreck. Most cell phone networks are set up to reject calls that appear on multiple sites at once -- typical experience if you're on a mountain somewhere is that you get full signal strength but can't make or receive calls, because the cell network expects you to be associated with one or two cell sites at one time, not dozens as you are able to reach from higher elevation.

    FAA and FCC have been having a hot potato fest for the past few years on this topic. FCC is still considering a proposed rulemaking that would permit airlines to offer inflight cell phone service, requiring the airline to keep the signal on the plane and transmit it to the ground some other way than the terrestrial network. While the airlines might see this ultimately as another revenue stream, it's not going to happen tomorrow and the NPRM does not apply to general aviation as it requires that the aircraft be specifically licensed to act as a cell site for its occupants and connect to the phone network some other way than through the existing cell towers.
     
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  8. Mar 1, 2015 #8

    SVSUSteve

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    Yeah, those marketing "coverage maps" are questionable at best. You get more than a couple of miles off the interstate in most rural areas and your signal drops to the point where even making a 911 call is difficult.

    Plus, if the system works don't screw with it. Also, given then number of pilots on here who don't seem to like to use ATC unless absolutely necessary, I doubt you'll find much support for your idea even if it were technically practicable (which it isn't so far as I am aware)
     
  9. Mar 1, 2015 #9

    TFF

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    Phones that are TSOed would be expensive and very short range. The antenna is pointed pretty much down on cell towers. Also signals from cell towers have their antennas pointed into the state you are in; some kind of interstate law. I live where 3 states meet; if I cross state lines 50/50 I will loose the signal. I get to do a bunch of helicopter flying; below 2000 ft phone works OK; go much higher and it starts to go. A buddy has been 5-6000 but nothing high like IFR flying. AM radios in the 5W range have about a 50 mile range at about 2000 ft, better if higher. How do you prioritize airplanes over regular users?
     
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  10. Mar 1, 2015 #10

    StarJar

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    I appreciate that you know what you are talking about. The above is not commonly known.

    If they can detect the phone on several towers, it seems like they could also make a devise to detect which has the strongest signal, and switch when it gets stronger on another tower. Not needed for cars, as you say. Hmmm. maybe we are out of luck, at the present.

    Thanks for the info.
     
  11. Mar 1, 2015 #11

    StarJar

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    Yeah, it presently 'works' with expensive radios, so it must be a real burn for the ATC dislikers to have to fly around with these expensive radios. That you could say, is what I'm trying to 'fix'.
     
  12. Mar 1, 2015 #12

    SVSUSteve

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    Yeah, good luck with that. Given that you can get a handheld ICOM NAV/COM radio for $250 or less (less than what you would pay for a new iPhone), I doubt your multi-billion dollar infrastructure project and the technology on the pilot end is going to- pardon the pun- get off the ground.
     
  13. Mar 1, 2015 #13

    StarJar

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    Been a long time since I priced a radio. You make a good point, there.

    How about if I lower my price to $50 non tso'd, $100 tso'd.:nervous:
     
  14. Mar 1, 2015 #14

    TinBender

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    Cell tower antennas are basically designed to radiate in a horizontal doughnut to increase range. Nothing is going to change with that. It's not efficient to shoot radio waves up into the sky for a few people that could just use the radio frequencies already designated just for them. An aircraft radio costs less than a smartphone contract.

    But to me, phones on airplanes are kinda like the music input on an intercom. No.
     
  15. Mar 4, 2015 #15

    fredoyster

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    Yes, they detect which is the strongest signal and use that tower, that's how they pass calls from one tower to the next while you're driving down the highway. But they still have to mark that channel as busy so it isn't assigned to a ground-based mobile which would be interfered with by the much stronger line-of-sight signal from the aircraft.

    I may not know everything about this, but in 1979 I did call ATC on the phone for a landing clearance through an amateur radio autopatch system I had built, when I was getting my pilot's license and the comm in the rented plane failed.
     
  16. Mar 4, 2015 #16

    fredoyster

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    That's still possible, just not new. I have a few Collins VHF-250 radios, TSO'd and in good shape, that cost less than $100 each on ebay.
     

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