Anti Collision Warning

"Rory O'Conor" wrote in message
...
Mid Air collisions are a problem. Maybe we need to
pull together more information about them.

There are a number of different phases of flight
during which they occur:

Climbing phase (high Angle of Attack)
(power planes only)
Circuit phase (all planes)
Aerobatics (all planes)
IFR & low visibility flight (all planes)
Normal flight (all planes)
Thermalling (soaring planes only)

We need to understand the proportion of collisions
occurring in the different phases and the potential
contributory factors. Road Traffic Accidents happen
more often in good weather than bad. It is not
entirely clear that thermal collisions happen more
often in competition gaggles than when there are only
two in a thermal, whatever our instincts.

For the different flight phases, different factors
will be more or less important and the solutions and
devices to prevent collisions may be different.

Personnally I would be surprised if TCAS devices could
cope with resolving the trajectories of thermalling
gliders other than the basic level of identifying
another nearby plane. Thus I suspect that the main
detection instrument in thermals remains the eyeball.
In which case, every effort should be made to ensure
the best use of the eyeball in thermals.

There may be a role for such devices in other phases
eg normal flight and IFR.

The only power planes that regularly fly close
together are the military and aerobatic display teams.
I am sure that the Red Arrows are fitted with the
instruments that they best require, but I would be
most surprised if they have any electronic device
warning them that they are about to hit a team-mate.
I expect that they do a lot of training, have superb
lookout and excellent communications.

I would assume that a TCAS/GPS device will be making
noises at 1 mile and probably very loud noises at 1/4
mile (1500 ft). With a typical thermalling diameter
of 200-600 feet and circling period of less than 20
seconds, any normal TCAS would be screaming fit to be
turned off!

We are also entering the area where the margin of
error for a GPS (30 ft horizontally, 100 ft
vertically) is a significant issue. GPS is not
accurate enough to tell which side of the highway you
are driving on, nor probably to determine the correct
seperation of two thermalling gliders when the pilots
using their eyeballs consider that they are adequately
seperated.

I cannot envisage an electronic GPS device for
avoiding intra-thermal collisions, assuming that the
planes are going to remain in the same thermal.

Rory


And yet another....

Bill Daniels