Kevin
I am aware of the limitations with cell phone
technology. But they work surprisingly well in cities, buildings and
moving vehicles. The direct line of sight, short distance, dramatically
simplified protocol, single failure tolerance and lack of reflecting
obstructions between nearby aircraft offset the negatives. My comment
was a conceptual presentation, not a detailed design. There would be
details involving antenna, power and audio interface, and these can be
developed quickly.
Comparing the cell technology system with the perfect
system without regard to cost, size, weight, development time and
implementation time, the perfect system is most desirable.
I estimate that the cell technology based system
would save 98-99.9% of the lives that would be saved by the perfect
system.
More importantly, ADSB is not the perfect system. It
lacks some important features specified for the cell technology system.
I believe that the cell technology system would save MORE lives than
ADSB due to low cost, faster implementation and more features like
applicability to sky diving, ultralights, UAV’s, single failure
tolerance, obstructions and ground vehicle applications, like snow plows
and construction equipment, (recall the airliner that landed on a closed
runway and hit heavy construction equipment.
After ADSB is implemented we will still read about,
or be involved in, accidents that would have been prevented by the cell
based system but are not covered by ADSB. Perhaps after 20-30 more years
of needless accidents we will have another expensive box mandated for
those.
For several years at
Oshkosh I went to the FAA
booth on ADSB and asked.
1… What is the maximum capacity of the system?
2… Will we have to turn off ADSB when we come to
Oshkosh? They usually do not
know that we have to turn off our transponders going into
Oshkosh.
3… Will it provide protection after any single
failure?
The answer has always been the same. “I don’t know,
but we will get back to you.” So far nobody has.
ADSB would have been helpful in the twentieth
century. We should be building a twenty-first century system.
Regards,
Bill Hannahan
--- On Thu,
9/17/09, Kevin Stallard <Kevin@arilabs.net> wrote:
From:
Kevin Stallard <Kevin@arilabs.net>
Subject: [LML] Re: Hudson
airspace
To: lml@lancaironline.net
Date: Thursday, September 17,
2009, 9:17 PM
Bill,
I respect and
think that your idea would work on the surface, but I think you over
estimate the ability of a cell phone GPS receiver to be reliable
enough for this kind of task.
First of all,
GPS signals have a signal to noise ratio that is surprisingly
small. Secondly, you really have to mount a GPS antenna so that
it sees the sky.
I realize it
is tempting to look at the high availability of cells phones and see
it as a simple solution, but if you were to start to understand the
technical details, I think you may quickly realize the pit falls of
the technology and question its ability to perform as desired.
My personal
opinion is that if that solution were to be tried, it would fail to
deliver often enough that it would loose it’s
appeal.
Kevin
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