Jim Carriere writes:

Hmm! At first glance that conclusion seems counterintuitive, but I
guess you learn something new every day.

The logic is straightforward.

The sky is a big place: 145 million square nautical miles, and at least ten
nautical miles deep. That's 1.5 billion cubic nautical miles.

A typical GA aircraft might occupy a cube 20 metres on a side (about 1/500,000
of a cubic nautical mile at most). If aircraft truly flew absolutely randomly
over the surface of the Earth, the chances of them ever colliding would be so
low that no ATC would be needed. Indeed, even visual separation would be
largely unnecessary. There just wouldn't be enough of a probability that
aircraft would ever be in the same place at the same time to justify any
precautions.

Thus, all the need for safety and traffic control to avoid midair collisions
is engendered by the fact that many aircraft like to fly in the same places as
the same time. Airports are the major factor here, as they force aircraft to
come into close proximity to take off and land. The problem is then greatly
exacerbated by airways and waypoints and fixes, all of which "attract"
aircraft to very small fractions of the total airspace. Aircraft are driven
to occupy the same altitude slots at the same lateral points at the same time,
and traffic separation becomes extremely important and difficult.

As navigation improves, the precision of waypoints and fixes and altitude
holds improves with it, and narrows the effectively used airspace even
further, dramatically increasing the likelihood of two aircraft being in the
same place at the same time. Inevitably, and even with the best of
precautions, this leads to an increase in the number of midair collisions.

Look to see how many midairs have occurred away from any airport or airway, at
random altitudes, and you'll see that they are scarce. Most midairs occur
because aircraft are trying to operate in the same highly restricted airspace
at the same time. In fact, an incident of this type provided much of the
impetus for the modern ATC system, when two airliners collided over the Grand
Canyon decades ago. Had they been flying _randomly_ over the Grand Canyon,
the accident never would have occurred; but since they were flying similar
routes to similar reference points at similar altitudes, the chances of them
meeting fatally in midair were hugely increased (by many orders of magnitude).
And while they had the technology to successfully navigate towards a fairly
small, specific spot in the sky, they lacked the technology to avoid colliding
with other aircraft.

A corollary of this is that, if you are flying VFR in an out-of-the-way place,
away from airways and airports and at an unusual or at least random altitude,
the chances of you hitting another aircraft are so low that they can actually
be ignored (although in practice it doesn't hurt to keep your eyes open).

On the other hand, if you have all the latest navigation gizmos and you can
accurately guide your aircraft to a 30-foot-wide spot in the sky with them,
you had better install TCAS to go with your other gadgets and hope that every
other pilot in the same area is similarly equipped.

The irony is that navigating accurately greatly increases your chances of
hitting someone else unless you also have an equally reliable way of avoiding
traffic. Unfortunately, technology for navigation today is outstripping
technology for collision avoidance. Looking out the window helps, but I think
it safe to say that the rate of collisions will continue to increase until
better technological means are found to help avoid collisions. GPS, for
example, is going to increase midair accidents, particularly among aircraft
that are not equipped with any type of collision-avoidance technology.

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