It was in 1985, after a commuter aircraft narrowly missed having a midair collision with an aircraft that assuredly had to be detected by one of our radar sites, yet was NOT displayed on my “radar scope,” that I began to question why that could be. That is when I learned about “radar sort boxes” (possibly known now as "selective sort cell" or some such nomenclature) and the software process termed “selective rejection.” I learned from firsthand observation that an overwhelming amount of radar data is NOT utilized in the presentation of aircraft targets for the enroute air traffic controller.
That lead to my writing an Unsatisfactory Condition Report in 1988, which I entitled Selective Rejection of Low Altitude Radar Data at Air Route Traffic Control Centers: An Unsatisfactory Compromise (see paper at SelRej.pdf). The 1989 response to my UCR was “...the methods used to filter and display radar data are sound, including the selective rejection process.” I disagreed with that conclusion, and went on to author a 1991 paper entitled, Real Targets – Unreal Displays: The inadvertent Suppression of Critical Radar Data. It was later republished in the Journal of Air Traffic Control.
“Selective rejection” continued to exist well in to, at least, 2006 (possible future link). After discovering that, I decided to give new life to a slide show I created back in February 2000. That newer slide show was based upon the slide show I created for my RTUD presentation at the Sixth International Symposium on Aviation Psychology back in 1991.
Why can’t we process all radar data, from all radars, all the time, so as to be certain that we don’t lose an aircraft from the enroute air traffic controller’s display? The answer I got in 1992 centered around the fact that the current processing model was based on a uniprocessor, such that “only one function is executed at any one instance.” I suspect that things haven't changed in that realm.
The disappearance of American Airlines Flight 77 from the Indy Center radar displays on 9/11 was related to the low-altitude unsatisfactory compromise that I addressed throughout most of my career. View the presentation I created, entitled Radar Sort Boxes in the area of American Airlines Flight 77's Turnaround/Disappearance.
Some may think of my concerns as outdated. However, the late Williard C. Meilander never did believe the solution can be arrived at with the uniprocessor radar data processing methods. He continued to think it was a time for a paradigm shift. Learn more here (possible future link...or contact me if no linked material and you're truly interested).
Thomas G. Lusch
August 1, 2021
Note: This website is a continuation of my previous websites (which first appeared in Feb 2000). Around June 2014 I converted to a Google Site after a friend was unable to continue hosting my site. Other than adding a few things here and there, it remained the same until August 1, 2021. Because Google Sites created an upgraded version of their hosting software, I had to do the conversion or I'd lose my site. We'll see how the transition works. How much I may work on this newer site is unknown, as life is real busy. I mainly wish to maintain the availability of the older papers I wrote, as they may be relevant for some air traffic controller who may find it useful if radar data processing methods haven't evolved much.
September 6, 2021 note: As noted above, I created my first web site back in Feb 2000. As time passed by, I had to move the site to different servers. I just realized that one can "go back in time" and review much of my earlier work, by utilizing the "Wayback Machine". Simply follow this link and enter a URL listed below. After doing that, you'll be able to select archives of my earlier work. In some of those past renditions I delved into other radar issues, like the "P4 problem" that came about with the launch of Mode S. The "P4 problem" made some transponders, especially Terra transponders, invisible to Mode S interrogations. I experienced that personally, both as a pilot, and as an air traffic controller. Here are those older URLs...
Archives (100+) occurred from 04/19/2000 thru 12/08/2008.
Just a couple archives (02/07/2011 & 07/09/2013).
Just a couple archives (10/30/2013 & 01/06/2014).
Archives from 12/23/2014 thru 03/03/2021 thus far.
(previous) March 16, 2018 note: Our Meadows At Winchester community sits directly adjacent to the Pickerington Ponds Metro Park. Unfortunately, access to the park is restricted. Back in 2013 I submitted an idea to Metro Parks that could alleviate that. I have resurrected my PARK PERIMETER TRAIL idea, and just sent it via the Metro Parks contact page. If you like the idea, you may similarly wish to write to the Metro Parks. My letter can be viewed via this url...
(previous) Dec 10, 2017 note: I haven't had much time to do much with this website since I moved it here approximately 3 years ago. Nevertheless, I'm dropping in here to post two pictures from nearly 50 years ago. I am hopeful that many of my classmates from Saint Thomas will be able to attend the St Thomas Alumni Association gathering in the autumn of 2018. I've decided to post a picture of us from our 1968 graduation class. And look at all your beautifully written signatures on the back of my picture! Abe Hatem, Arthur Marchi, Paul (Ted) Bukowski, Marian Shanahan, Patty Van Echo, Amber Churches, Helen Bunfill, Diane Hickey, Chris Leister, David Purdue, Jody Tanner, Connie Clarke, John Killilea, Michael L. Ransom, Debra O'Cain, Leslie Hale, Marie Salva, Monica Lang, Linda Compton, Pamela Willis, Paul Welsh, John McFadden, Paul Vincent Lisska, Brian Bonaventura, and Mary Jones.
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