"FAA Administrator Marion Blakey said the crash of Comair Flight 5191
might have been avoided if the CRJ-100 had been equipped with Automatic
Dependent Surveillance-Broadcast (ADS-B). Blakey told reporters at a
news conference at UPS's headquarters in Louisville that ADS-B's LCD
screen (not unlike a host of vastly more affordable products currently
available to the private pilot) tells pilots which runway they're on and
that might have alerted the crew in time to avert the disaster. Blakey
was in Louisville to tout ADS-B as the next-generation air navigation
system, something UPS has already committed to. The cargo carrier has
spent $100 million of its own money developing ADS-B technology for its
fleet and it uses the gear in Louisville. The federal government has
earmarked $80 million to expand ADS-B service, which is mainly
concentrated on the east coast. It's also been deployed in Alaska and is
under development in the Gulf of Mexico. The first of that new $80
million will be spent installing ground equipment at UPS hubs in
Ontario, Calif., Juneau, Alaska and Philadelphia."

Read that article once, twice, and realize how screwed up we are
over ADS-B now. Its all about the "ground equipment" is it?

ADS-B was supposed to prevent TWO airplanes from COLLIDING. WHAT DAMM
PART OF ADS-B DOES IT SAY THAT IT SHOULD ONLY WORK IN THE PRESENCE OF,
AND WITHIN THE LINE OF SIGHT OF, "GROUND EQUIPMENT"?

The answer is that ADS-B is SUPPOSED to work between two aircraft.
The same aircraft that are, DUH, colliding. The same two aircraft who,
by simple physics, are getting an increasingly accurate fix on each
other because they are, again by simple physics, getting more and more
of an exact match in their GPS fix due to collocation. The same aircraft
that are getting the best signal exchange with each other and the lowest
signal latency.

OK, the short (and official) answer is that ADS-B isn't "supposed" to
prevent two aircraft, out of range of ground stations, from knowing
about each other. This is true, however, that does not take into
account the governments ability to screw up even good technology.

The fact is, the FAA is very uncomfortable with the idea of you actually
getting raw, unfiltered information about aircraft coming at you. You
might panic and do the wrong thing, like sue the daylights out of
the controller who sat eating dough nuts while it happened.

What the FAA has done, and the reason why "ground equipment" is required
with ADS-B, is that they are appointing themselves the intermediary for
all ADS-B traffic data. That is, whenever you are within range of FAA
line of sight facilities, they broadcast the data back to you. Even
though you have better, and more real time information on that aircraft
closing in on you, because, duh, speed of light and all that, the FAA
has the ability to intervene in the transaction. That's STRIKE #1.

The second issue is that the FAA has mandated that heavy aircraft, and
YOU, should use completely different and INCOMPATIBLE systems. They,
the heavies, will use mode-s transmission. You will use UATs. That means
that the heavy aircraft coming at you, and you with your overpriced
new ADS-B set, won't even be talking to each other. In fact, you will
be completely and utterly bound to the FAA ground station, perhaps
miles away, you tell you about the heavy aircraft that is bearing down
on you RIGHT NOW. That's STRIKE #2.

Why is that? Well, the official excuse is that the airlines are already
equipped with mode-s, so its "cheaper" for them. BULL. When was the last
time you heard about the airlines cutting costs on avionics? The true
reason is that the FAA considers heavy aircraft to be "their baby", and
their goal is to keep all those precious tax dollar generators separated
from us bad, insect like aircraft. The thinking goes like this: airlines
always go under positive radar control near the ground, and rapidly
climb to the higher, controlled and marvelously gnat free zones in the
levels. The short answer is that when a heavy and a gnat encounter
each other, the FAA wants to be there, electronically. Including the
ability to decide what avoidance will occur, and whether or not the data
will get recorded and used to absolve a controller of guilt in a later
trial.

The FAA SHOULD be trying to relax the onerous regulations for a change,
just for ADS-B, so that it has a chance of being cheap enough for light
aircraft to consider. ADS-B DOES NOT WORK UNLESS BOTH AIRCRAFT HAVE IT.
And FORCING a degraded link between light and heavy aircraft that
results in longer round trip delays for the signal, and possible
degradation from obstacles, and even atmospheric conditions is simply
placing politics over technological common sense.

Scott Moore

(who is an engineer in Silicon Valley, and an early avocate of ADS-B)