One homeland security technology we're not likely to see anytime soon is the Soft Wall idea conceived only 10 days after Sept. 11 by University of California – Berkeley electrical engineering and computer sciences professor Edward Lee.

Lee, it may be recalled, proposed that the avionics software in the computers onboard commercial jetliners be modified in such a way that the aircraft will refuse to enter pre-specified no-fly zones, such as the air space over major metropolitan areas like New York City and Washington, D.C., and infrastructure assets like the Golden Gate Bridge, Hoover Dam and nuclear power plants.

The boundaries of these no-fly zones Lee called Soft Walls.

"If an aircraft is equipped with the Soft Walls system, then if the pilot, or anyone else at the controls, attempts to enter a no-fly zone, the airplane will refuse to respond and will divert itself," Lee said at the time.

The system was to be non-networked and non-hackable.

Alas, it was not bulletproof. Pilot unions were quick to shoot the idea down. Soft Walls remains comatose.

"The project is not active. We were never able to get funding for the work," Lee told Homeland1 recently.

When "soft walls" was first proposed, the Airline Pilots Association responded with angst. The union mentioned several scenarios in which removing flight control from pilots was not a good idea. Pilots need undiluted authority to respond to emergencies, including unexpected weather conditions, possible collisions with other aircraft or other obstacles, turbulence, on-board equipment failures, fires, or other problems. What if a plane needs to veer into a no-fly zone protected by Soft Walls to avoid a crash?

Lee responded to those objections by pointing out that a pilot’s responsibility now extends beyond the aircraft, crew and passengers all the way to the people on the ground and that no on-board emergency is severe enough to justify endangering large numbers of people on the ground.

Lee said that since Sept. 11, the safety of the people on the ground trumps pilot authority. “There is no emergency that justifies attempting to land on Fifth Avenue."

In the Soft Walls system, a database of no-fly zones would be established to include not just urban areas and critical infrastructure assets, but also natural obstacles like mountains. Thus, the same system that keeps the airplane from flying into the Sears Tower can keep it from flying into Mt. Whitney.

Several papers, as well as a lengthy, informative FAQ, are available on the Soft Walls Web site.