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.

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