U.S. ATC Radio Spectrum Almost Full

[Airbubba]

U.S. air travel growth faces radio crunch

November 13, 2000
Web posted at: 2:49 PM EST (1949 GMT)

WASHINGTON (Reuters) -- The radio
channels critical for U.S. air traffic
control may be filled to the brim in five
years, threatening prospects for meeting
the growing demand for air travel, the
Federal Aviation Administration said on
Monday.

Officials said the crunch point -- when all frequencies are being used to the
maximum extent consistent with safety -- might come as early as 2005.

"We can keep going for three to five years, but after five years, it begins to get
really dicey," Steve Zaidman, the FAA's associate administrator for research and
acquisitions, said in a comment relayed by the FAA.

Moreover, the FAA and the aviation industry are not able to do anything to solve
the problem in under five years pending a decision on which of two rival
solutions to pursue, Zaidman told the Washington Post, which carried a detailed
account of the problem in Monday's editions.

Radio is the heart of aviation control, with a major airport requiring dozens of
frequencies. Air traffic controllers must have separate channels to talk to pilots
while they are taking off and landing. Dozens of separate frequencies are needed
for the radar controllers in the surrounding area.

FAA explores options

Twenty major centers need dozens more channels to guide planes at higher
altitudes and automated weather reporting stations consume dozens, as do
navigation aids and fire and rescue personnel.

"The radio spectrum is under pressure," said FAA spokesman Eliot Brenner. "In
the future, perhaps five years or so, it will become increasingly difficult to find
additional frequencies."

Brenner said Jane Garvey, the FAA administrator, was setting up a special panel
made up of government and industry experts to look at the possible solutions.

The airlines argue that time is running out and are pushing for a system now
being used in Europe, which could be in place in five years but would probably
be outdated in less than 20 years, the Post reported.

The FAA and some other aviation groups prefer a long-term digital solution that
could solve the problem for generations but would take nine to 12 years to
implement, the paper said.

Brenner said the FAA had frequencies it was holding in reserve to avoid an early
crunch. On top of that, he said there was a "buffer zone" around the distress
frequency that could free up more channels.

"We're going to do whatever it takes to resolve the problem," he said.

[ATC Watcher]

Very interesting development . About 14 months ago, Adminstrator Garvey was critising Europe for introducing 8,33, arguing that they were putting a financial burden to all (US) airlines operating in Europe because the Europeans could not manage properly their spectrum .
She said the US did not need 8,33 and were going digital directly.
If, as you report, the FAA planners with their usual insight, are predicting that Digital radios will take 9 to 15 years to implement, one can safely asume it will take considerably more time. Also counting the numbers of sectors you currently have , add a factor for the annual traffic growth, add 50% for contingency and you roughly have the number of frequencies you need FOR ATC in a given area at a given time.As the spectrum is fixed, the only variable is the date at which you run out of frequencies.
But adding numbers seems to be a problem with US officials at the moment. :)

[Konkordski]

10-1 on they plump for 8.33 in the very near future...

[Self Loading Freight]

I posted a couple of links to articles on this subject over in the dusty corridors of Tech Log,
http://www.pprune.org/ubb/NonCGI/Forum3/HTML/001461.html

R, anorakticus magnus

[Check 6]

Here are my two cents worth. I have my doubts that the U.S. ATC frequencies are almost depleted. This sounds a little bit like the typical "the sky is falling" syndrome. I.E. get the uninformed public concerned about a non-issue. I could be wrong, but I am a little skeptical about this one.

Check 6

------------------
Kick the tires, light the fires, first off is lead, brief on guard.

[forget]

This whole thing has baffled me for years. With 25kHz spacing the VHF Aeronautical Band provides 760 channels. Even with high altitude airways, where an aircraft’s radio footprint is at maximum, I cannot believe that 760 ‘Line of Sight’ frequencies are not enough. In my opinion this is either very bad management by the allocators of frequencies - or jobs for the boys. Who’s out there to explain, logically, why a three way split is/was needed. I’ll bet a privatised ATC would find an option - much more efficient, cost effective, and safe.

[Diesel8]

F.A.N.S ( Future Air Navigation System!!??)
should be approaching soon, with digital transmissions by either land based or space based communication.

[Londoner]

Interesting article in the current AOPA Pilot magazine (part of their Future Flight series) that deals with this topic. I've cut and pasted the relevant extract below.

Frequency congestion and 8.33 kilohertz spacing
With the across-the-board increase in air traffic we've seen in recent years, our existing pool of allocated VHF communications frequencies is rapidly loading up. On some ATC frequencies it often seems that you can hardly get a word in edgewise. The growth in air traffic has already prompted two jumps in the communications frequency spectrum—from 180 to 360 channels, and from 360- to 720-channel frequency spacing—and now we can expect more splitting of the aviation communications band.

The VHF spectrum currently allocated to aviation communications runs from 118.000 to 135.975 megahertz. Notice that there are three numerals after the decimal point. A new initiative would give us four numerals after the decimal point, and 2,280 more badly needed channels. These additional channels would come about by dicing up the comm spectrum into 8.33-kilohertz slices. It's a proven technique that's already being used to reduce delays in Europe, where airline traffic has exploded in volume over the past 10 years.

Now the United States must deal with the same problem, using the same method. This means a vast overhaul of ATC and aircraft hardware in the next few years. Translation: Unless you already have a brand-new comm radio (the newest radios are already equipped with this feature, to make them competitive in the European market), you'll have to buy one with 8.33-kHz spacing in about six years or so. Of course, so will ATC. The inevitable delays in implementing a project of this magnitude suggest that the timetable for making the switch to the new spacing probably won't happen until sometime after 2005.

To ease the transition, it's very likely that the new frequencies will be phased in gradually, say, with usage initially limited to the high-altitude airspace structure. But there'll be nothing to ease the economic burden of gearing up your panel to play the expanding-decimal game of the future.

VDLs 3 and 4
There's an alternative to the 8.33-kHz expansion. Some advocate the use of digital communications, using VHF datalink (VDL) frequencies 3 and 4, saying the demand for additional communications and other uplinked functionality can't be served any other way. By 2009, proponents say, we may well be using VDL 3 and 4 for voice, uplinked weather information, and ADS-B (automatic dependent surveillance-broadcast) and other traffic advisories. These VDL frequencies would be squeezed into the one-kHz segment between 136.00 and 137.00 MHz.

VDL uses what experts call time differential multiple access (TDMA) technology. Under this scheme, the pilot with a VDL 3 radio makes a radio call—or gets a textual clearance change from ATC—from a ground-based transceiver. The radio traffic works both ways in a request-reply arrangement. VDL 4 adds ADS-B or TIS traffic information, weather graphics, and other information in its uplink capabilities; it was mentioned briefly in an earlier installment of "Future Flight" (see "Links to Tomorrow," February Pilot). The difference between VDL 3 and VDL 4 is that VDL 3 "listens" for one of four time slots to open within each of 20 channels spaced 20 kHz apart, then sends or receives its transmissions when an opportunity avails itself. It doesn't take long, however, with transmissions able to come and go at almost instantaneous speed. VDL 4 doesn't need to operate under this scheduling scheme—its messaging is self-organizing, depends on airborne equipment to process messages, and can operate independently of ground-based equipment.

Though its implementation could take more than a decade, those in the know say that a VDL-capable radio ought to cost the approximate equivalent of $5,000 in today's dollars. The good news about VDL 3 and 4? They should serve aviation's communications needs for a 30-year period, and their use will probably be limited to the high-altitude airspace structure, where it would primarily serve airliners.

What about VDL 2?
It's understandable if you've gone acronym-happy by now. The happiest of you are probably wondering: Hey, he mentioned VDL 3 and 4. What happened to VDL 1 and 2?

VDL 1 and VDL 2 are alive and well these days, serving as the vehicle for transmitting digital ACARS (airborne communications addressing and reporting system) messages. ACARS is used by the airlines and larger corporate jets to forward messages. The airlines, for example, use ACARS to learn of gate changes, and transmit passenger, maintenance, and other information between their dispatchers and aircraft. VDL 2 is also being used in an experimental program aimed at streamlining ATC workload. Known as CPDLC (controller-pilot datalink communications), the idea is to free controllers to use their time focusing on sequencing and separation of traffic.

One study found that 40 percent of a controller's workload consisted of such routine—yet time-consuming—tasks as establishing initial radio contact with air traffic or handing traffic off to another frequency. With CPDLC these contacts are uplinked to the cockpit in text format using VDL 2.

In spite of the glitz surrounding VDL, so much progress has been made in the 8.33-kHz area that it will likely become the method of choice. The 8.33-kHz option promises more frequencies, much sooner than VDL. And with the threat of imminent "frequency gridlock," 8.33-kHz spacing appears a simpler, more attractive choice.

[411A]

Would suggest that all "company" ATC communications be relegated to another frequency spectrum. This would free up necessary frequencies for ATC use. No need to switch to 8.33 spacing. Let the airline companies with their big bucks pay the bill.