Mode S Technology
Interview with Robert Everett - 12/8/00
Summary: ATCAC came up with the idea for DABS. ATCAC talked to all
parties involved: GA, AOPA, LL, MITRE, commercial airlines, FAA,
etc. to assess needs. Crashes invoke action and reform. The problem
is ATC is slow to change.
We asked him about ATCAC. He said, he was asked to serve on ATCAC. He
remembers that it was a good group and everyone worked hard, tried to
look at the whole business, came up with the DABS idea. There were
people who felt the whole thing could be done with satellites but the
rest of us felt that it was premature at the time. The chairman - Ben
Alexander - asked him to serve, he remembers him being a very good guy.
Everyone understood that the ATC system had a lot of weaknesses. They
basically had been charged with a fresh piece of paper to look at air
traffic control, where it was going, etc (missed half this quote). "ATC
had always been quite safe, but not always efficient". Every once in a
while there were safety problems. You can't really separate efficiency
from safety - "it has to be safe but on top of that it has to be
efficient or it won't work".
[asked about satellites:] it was pretty clear that you could use
satellites for certain communications and for navigation but it was
premature. After all there are still problems/is still attention??
(couldn't hear) with much heavier use of satellites in ATC today, lots
of attention on using GPS in ATC, and will continue to be in the
future. There were no serious considerations for using satellites, it
was just one of the things that were brought up at the time. At that
time. ATC was mainly radars and beacon systems. Ground had to know
where airplanes were, planes had to know where they were... needed
location, communications, and monitoring, and "DABS seemed like a good
idea because it combined a more accurate beacon system with a
communications system". He said the fundamental thing was to measure
where the aircraft was and to communicate with them, which were
fundamental issues for ATC, and DABS did that.
he said the existing system allowed people on the ground to be able to
measure where airplanes were in 3D space, where they wre going, how
fast, and use this information to keep them apart. It wasn't all that
accurate, which led to very wide spacings between airplanes to make up
for inaccuracies in the beacon system. What was inadequate? the beam
width of the ground system of radars was wide, not very accurate, would
like to be able to do better. Like to have more communications with the
airplane, want system to be better built, easier to make work together.
"fundamentally you have a couple reasons to want to reduce
workload...as density increases, one way to handle it is to break the
space into smaller pieces. However, handoff problems get worse".
need cross-capacity to improve efficiency of the system. what you
would really like would be just to give a course at the airport in
advance, the airplane follows the course, people do what they're
suposed to do, and there would be no trouble. but people drift and it
doesn't work that way.
He said that it was a collaborative effort. They had people
from ATC, airlines, equipment companies, etc coming in and got their
ideas, their thinking, what they were planning on doing. They also
Therefore they talked to controllers, the FAA (including people
doing research and development for future work at the FAA), MITRE,
Lincoln Labs, the ATC Association, pilots union, and not just
commercial work but also GA, AOPA, small airplanes, airport operators
and owners, etc. There was a tremendous group of people involved and
we have to talk to each about what they were thinking, not just to
find out what they have to say but also so they know their thoughts
are taken into account in the committee's decisions and that we're not
making completely unbased decisions. He says this is usually what
happens with a committee like this.
I asked him if he remembered who started ATCAC and why. He said he
thinks it was asked for by the FAA but he doesn't remember. He says
what usually happened was there'd be an air-to-air collisions He said
the situation is kind of like with automobiles where what you're
afraid of is that one crazy driver who'll crash into you, and that
most people think you'd be just fine if there were no other drivers
People flying in airplanes worry about the same thing, though
the emotional impact of being flown into by another airplane is much
larger. Somehow you just don't feel like that should happen, and you
know when it does that means pretty much that everyone dies, there's
no way around that. So every once in a while, there'd be a collision -
he said that there was one in Grand Canyon (this was mentioned in the
ATCAC report) where there were a lot of planes flying around with
people looking out the windows, and two planes crashed, killing a lot
of people. This immediately caused a big uproar, politican, and in
the papers, with people running around talking about doing something,
how something had to be done.
I asked him if the drifting attention of the public/politicians is one
of the reasons for the slow rate of doing things in ATC. He said.
There are several major reasons for slow adoption: The system is blamed
for accidents, and therefore is run conservatively. If you want to try
new things, or make major changes, to prove efficiency there are a lot
of questions. The FAA people in charge are also conservative because
they are held responsible. Therefore any changes are slow to take
effect. It takes a long time for the government to do anything, and it
takes time to build a complex ATC system. Therefore it takes a long
time to get anything done. You can only speed up the process by keeping
continual pressure on it. Have a stream of accidents, but of course
nobody wants that. He said you could look at it like a signal where
each pulse is an accident, but it decays in the time in between pulses.
He then compared air traffic control to the air force, saying
that Air Traffic Control takes longer than the Air Force because
they're not as concerned with safety. In the Air Force, the pilots
are getting shot at and they're more concerned with the problem of
getting shot at than the problem of safety. Also, while the Air Force
is practicing for much of the time, they're fighting wars for only a
small fraction of the time. They can start out with an entirely new
system, like Sage, deploy it, try it out, correct it, and the only
pressure is that they hope the enemy wont' attack while they're still
tweaking the system, which it normally doesn't. In Air Traffic
Control, the system is up 24 hours, 7 days a week, while they're
trying to fix and change it, which makes it harder.