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Who's At Fault in UAV/Part91 MAC?



 
 
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  #11  
Old April 24th 04, 04:57 PM
Larry Dighera
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On Sat, 24 Apr 2004 11:44:10 -0400, "Barry" wrote in
Message-Id: :

Fortunately, the chances you cite are not criteria for NAS design.

In engineering a workable NAS I would prefer that the designers employ
methodologies that _insure_ separation of air traffic, not merely
reduce the _chances_ of a MAC. Anything less is irresponsible
negligence.


In any system, there's always a small probability that a catastrophe will
occur. Aircraft certification rules and separation standards acknowledge this
and are established to keep the risk acceptably low. For example, for lateral
separation of two aircraft traveling at the same flight level on parallel
routes, the Target Level of Safety (TLS) set by ICAO (with FAA participation)
is 5 x 10^-9 per flight hour. That is, loss of lateral separation should
lead to no more than one accident every 200 million flight hours. The TLS is
not zero. Some people don't like to accept this, but it's just not realistic
to insist on zero risk.

Barry


Thank you for the information.

How would the TLS be affected if the Big Sky theory were relied upon
for aircraft separation as John T. suggested?

  #12  
Old April 24th 04, 05:33 PM
Barry
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How would the TLS be affected if the Big Sky theory were relied upon
for aircraft separation as John T. suggested?


I'm not very familiar with this subject, but you can read "Safety
Considerations for Operation of Small Unmanned Aerial Vehicles in
Civil Airspace" produced by the MIT International Center for Air
Transportation:

http://icat-server.mit.edu/Library/f....cgi?idDoc=205

They studied both midair collisions and exposure to people on the ground. The
relevant conclusions for midairs:

Significant Amount of Airspace with Exposure Risk
Below the Target Level of Safety
- Areas around major airports are above the TLS

Opportunities may exist to allow a class of small
UAVís to operate with limited restrictions
- Limiting operation in airspace near airports
may achieve TLS

Mitigation Strategies Are Available to Further Reduce the Risk
-Vehicles can be designed with capabilities to limit
likelihood of midair collisions

Barry





  #13  
Old April 24th 04, 05:41 PM
Tony Cox
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"John T" wrote in message
ws.com...

For all the VFR flight I've
done, the only time I have ever gotten close to another craft
unintentionally was near an airport. See and avoid? Perhaps, but I don't
recall ever maneuvering to avoid another aircraft during VFR cruise.


Perhaps your good fortune or lack of attention has lulled you into
a false sense of security. In my 500+ hours, I've been almost dinged
twice -- once some 20 miles out from Pasa Rubles and once in the
middle of nowhere. Both were near head-ons. And I'm willing to bet
that there have been more I've not been aware of, since in both cases
the occupants displayed no reaction to my presence whatsoever.


  #14  
Old April 24th 04, 06:10 PM
Stan Gosnell
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"Tony Cox" wrote in
ink.net:

Perhaps your good fortune or lack of attention has lulled you into
a false sense of security. In my 500+ hours, I've been almost dinged
twice -- once some 20 miles out from Pasa Rubles and once in the
middle of nowhere. Both were near head-ons. And I'm willing to bet
that there have been more I've not been aware of, since in both cases
the occupants displayed no reaction to my presence whatsoever.


I've had dozens of close calls, several of which required very abrupt
maneuvers to avoid collision, most of them far from airports. The big sky
theory is just that, a theory.

--
Regards,

Stan

  #15  
Old April 24th 04, 09:08 PM
Tony Cox
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"Barry" wrote in message
...

How would the TLS be affected if the Big Sky theory were relied upon
for aircraft separation as John T. suggested?


I'm not very familiar with this subject, but you can read "Safety
Considerations for Operation of Small Unmanned Aerial Vehicles in
Civil Airspace" produced by the MIT International Center for Air
Transportation:

http://icat-server.mit.edu/Library/f....cgi?idDoc=205

They studied both midair collisions and exposure to people on the ground.

The
relevant conclusions for midairs:

Significant Amount of Airspace with Exposure Risk
Below the Target Level of Safety
- Areas around major airports are above the TLS

Opportunities may exist to allow a class of small
UAV's to operate with limited restrictions
- Limiting operation in airspace near airports
may achieve TLS

Mitigation Strategies Are Available to Further Reduce the Risk
-Vehicles can be designed with capabilities to limit
likelihood of midair collisions


This study attempts to 'bound' the danger through a Bayesian
analysis of engine failure probability and chances of hitting
something at random in the airspace 'per flight hour'. In high
traffic areas, the probability is small (10-8). But the total
accident rate will depend on how many of these things are
flying around. There is nothing about 'accountability' in the
"Mitigation Strategies", which is very odd since accountability
looms very large in current aviation practice (and FAA regulation).

I'm concerned that the model for this sees a UAV "pilot" as a
sort of hands-on air traffic controller, rather than as a proper
"pilot" with the attendant certification and responsibility
requirements. This is a major departure from existing practice,
and potentially devastating for GA.






  #16  
Old April 25th 04, 09:34 PM
William W. Plummer
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"Tony Cox" wrote in message
ink.net...
"Barry" wrote in message
...

How would the TLS be affected if the Big Sky theory were relied upon
for aircraft separation as John T. suggested?


I'm not very familiar with this subject, but you can read "Safety
Considerations for Operation of Small Unmanned Aerial Vehicles in
Civil Airspace" produced by the MIT International Center for Air
Transportation:

http://icat-server.mit.edu/Library/f....cgi?idDoc=205

They studied both midair collisions and exposure to people on the

ground.
The
relevant conclusions for midairs:

Significant Amount of Airspace with Exposure Risk
Below the Target Level of Safety
- Areas around major airports are above the TLS

Opportunities may exist to allow a class of small
UAV's to operate with limited restrictions
- Limiting operation in airspace near airports
may achieve TLS

Mitigation Strategies Are Available to Further Reduce the Risk
-Vehicles can be designed with capabilities to limit
likelihood of midair collisions


This study attempts to 'bound' the danger through a Bayesian
analysis of engine failure probability and chances of hitting
something at random in the airspace 'per flight hour'. In high
traffic areas, the probability is small (10-8). But the total
accident rate will depend on how many of these things are
flying around. There is nothing about 'accountability' in the
"Mitigation Strategies", which is very odd since accountability
looms very large in current aviation practice (and FAA regulation).

I'm concerned that the model for this sees a UAV "pilot" as a
sort of hands-on air traffic controller, rather than as a proper
"pilot" with the attendant certification and responsibility
requirements. This is a major departure from existing practice,
and potentially devastating for GA.


I had an opportunity to speak with a Marine who operates UAVs as the remote
pilot. He said he and others doing that job must be instrument rated pilots
and the UAV must be on an IFR flight plan. Given that, why would the
accident rate for UAVs be any different than normal IFR traffic?


  #17  
Old April 26th 04, 12:58 PM
Tony Cox
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"William W. Plummer" wrote in message
news:rhVic.20812$YP5.1530448@attbi_s02...

I had an opportunity to speak with a Marine who operates UAVs as the

remote
pilot. He said he and others doing that job must be instrument rated

pilots
and the UAV must be on an IFR flight plan.


That may be true in his case (instrument rated pilot), but it isn't
required according to Larry's original post.

Given that, why would the
accident rate for UAVs be any different than normal IFR traffic?


1) Conventional traffic must "See and avoid" when in VMC even if
flying IFR.

2) The remote "pilot" doesn't need to keep alert to the extent that
the rest of us do because his life isn't on the line.



  #18  
Old April 27th 04, 12:47 PM
Teacherjh
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However, the "myth" of
the big sky is shattered everytime I go up VFR. For all the VFR flight I've
done, the only time I have ever gotten close to another craft
unintentionally was near an airport.


I see nearby aircraft all the time in cruise. I am more concerned about the
ones I don't see.

Jose

--
(for Email, make the obvious changes in my address)
  #19  
Old April 27th 04, 12:50 PM
Teacherjh
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He said he and others doing that job must be instrument rated pilots
and the UAV must be on an IFR flight plan. Given that, why would the
accident rate for UAVs be any different than normal IFR traffic?


Because the operations are not required to be conducted in IMC.

Jose

--
(for Email, make the obvious changes in my address)
  #20  
Old April 27th 04, 09:11 PM
Bob Jones
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"Larry Dighera" wrote in message


Once you show me *evidence* of lackadaisical attention to safety by
the owners and operators of those very expensive bits of hardware,


I'm happy to have you aboard. :-) Here is the information you
request:


Interesting that none of those cites indicate anything approaching "evidence
of lackadisical attention to safety".

Lessee... Inadvertent cloud entry. Reference to difficulty in landing.
Faulty assembly. Icing encounters (two of those). Mechanical failure due
to inadequate lubrication.

Sounds like a reading from the NTSB database.

The point is that none of these equate to "lackadaisical attention to safety
by the owners and operators".


 




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