On Wed, 06 May 2015 18:34:09 -0700, Bug Dout wrote:

Larry Dighera writes:

On Sun, 03 May 2015 17:26:04 -0700, Bug Dout wrote:

The cost-saving incentive of NextGen ATC is flawed, aircraft position will
become dependent on what the aircraft reports rather than empirical evidence of
its position, ATC will be wrest from government control, and in-flight safety
will be reduced, but that's okay, because Boeing will make a butt-load of cash
in user-fees. :-(

The big problem with current primary radar and Mode C transponders, as I
understand, is they're accurate to only within a mile. Not good enough
to squeeze anticipated future traffic into the same airspace.

That's hardly a cogent argument to compromise air safety by exclusively
implementing a satellite-based ATC system that is vulnerable to solar CMEs.

ADSB is
not designed to save money over the current Primary+Mode C system. It's
designed to prevent anticipated future congestion.


I have no delusions that anything connected with NextGen ATC will save money
despite the argument industry initially used to persuade FAA to consider a
satellite-based ATC system. I'm just disappointed that I haven't heard
anything from industry nor FAA that addresses the vulnerabilities of
satellite-based ATC.


I think you're too pessimistic. The FAA is somewhat incompetent for
sure, but there's no conspiracy or Machivellian scheme for GA user
fees, grabbing control or giving up all control, etc.


You erroneously infer pessimism where I implied safety concerns, redundancy and
conservatism. Let me try again:

1. What will the PIC do about the reduced separation resulting from NextGen
ATC when the satellite signals that enable that reduced separation are suddenly
unusable due to solar activity? Presumably there's a reason the current
separation criteria have been used over the past decades and are currently,
because those separation criteria have proved to be safe. Therefore, it is
reasonable to expect less separation will be less safe if the enabling
satellite-based technology were to suddenly become inoperative while aircraft
are operating with reduced separation.

See what I mean?

On the other hand, the sun is quite a ways away, and from the information he
http://www.swpc.noaa.gov/phenomena/coronal-mass-ejections "fast CMEs can
reach Earth in as little as 14--17 hours" So, CME response on Earth isn't as
sudden as I imagined.

So how about:

2. ADS-B is dependent on the position reported the aircraft rather than
empirical evidence (radio energy reflected off of it: radar) of its position.
Under normal circumstances that's not an issue. But what of a hostile flight
bent on masking its position by transmitting misleading position information
for nefarious purposes? Without radar to confirm the position reported by
ADS-B, ATC becomes vulnerable to attack under NextGen ATC, where it hadn't been
previously (except under military ECM). How can that potential issue be
overcome?

My point is, that NextGen ATC has the potential to introduce more hazards into
the ATC system, and I haven't heard any of the entities involved in
advocating/implementing it address those hazards. That is worrying...

And the whole notion that the sky NEEDS to accommodate ever more flights may
not be valid, nor desirable from environmental and safety standpoints.

Thank you for your thoughtful input on this subject. I appreciate the
opportunity it provides to inspire me toward further research.