How do we prevent airline hijackings? Already we're hearing proposals to put plainclothes sky marshals back on board--presumably to shoot it out with bad guys. After all, the end of skyjackings to Cuba roughly coincided with the arrival of the first generation of sky marshals...or was it Fidel's jailing of a few of these just-arrived revolutionaries? All I am sure of is gunfire and aircraft are a deadly combination, no matter who fires first.

Improved airport security is another way to make planes safer. But eventually the perceived threat decreases while the impatience of passengers increases. Once these two lines cross we end up back where we were Tuesday morning. And, of course, it's impossible to keep all knives off airplanes unless the meals are changed to Jell-O and PowerBars.

WHAT WE NEED is a way to make planes impossible to hijack. My friend Steve Kirsch thinks he has just such an idea, using mostly proven, off-the-shelf technology. We started trading e-mails about this Wednesday morning and after about three exchanges, I decided this is something I need to share with the AnchorDesk community for your comment.

First, however, an introduction is in order. Steve is best known as the founder of Infoseek, the search engine and Web portal he sold to Disney while the selling was good. Previously, Steve has founded several other companies, including Mouse Systems and Frame Technology--he describes himself as a "serial entrepreneur." His newest company is called Propel and creates software to eliminate database bottlenecks.

Steve and his family also put tremendous energy into do-gooder work. A few years ago, he used a million of his own dollars, got several million of Bill Gates' dollars, and raised other millions in order to save the United Way in San Jose from a huge budget deficit.

ANYWAY, HERE'S STEVE'S IDEA, which is based on the fact that all modern-day planes have global positioning systems (GPS) and are capable of landing on autopilot.

"(Install) 'safe mode' panic buttons that put the plane on forced autopilot that cannot be overridden, except in special circumstances," Steve says. He'd have them mounted in the cockpit, one for each side, with additional optional buttons in crew areas on each side of the plane in both the forward and aft cabins.

Once a plane is in safe mode, suggests Steve, it would randomly select one of the 10 nearest airports capable of accommodating that plane type, and automatically land the aircraft there.

"This technique works because you take both the pilots and the terrorists out of a control situation," he explains. "A terrorist can no longer threaten the pilot to 'Do this or I will kill people' because the terrorist knows that the pilot can't accommodate the demand no matter what."

UNDER STEVE'S PLAN, the terrorist can't get what he wants. His only option then is to kill all the people on the plane, and if his only objective is loss of life, a plane is a mighty tough target when there are easier ones (like buses) available.

Bottom line: there's no more motivation to hijack a plane. All that the hijacker could accomplish is causing the plane to land at a randomly selected airport.

"In fact, it's much worse than hijacking a bus because in the plane case, the hijacker is completely locked up and directly transported to a random jail location that he can't plan for," Steve notes.

Under what circumstances could forced safe mode be overridden? Further details (including more about his idea) are on Steve's Web site at www.skirsch.com, but here are some highlights.

• Safe mode disables on touchdown so the pilot can raise flaps, put on the brakes, and reduce the throttle.
• Safe mode can be disabled twice per flight if the pilot keys in a 4-digit recall code within 20 seconds of the safe button being pushed. Each pilot has his own 4-digit code that can be used only once per flight. So disabling two false alarms requires the cooperation of both pilots. There are audio warnings in the cockpit as well as lights flashing when someone hits the safe button. If there are further panic button presses after that, the plane will be forced down.
• The pilot is allowed to manually vary the altitude of the plane between 15,000 and 40,000 feet above ground level, even when safe mode is engaged, to enable the pilot to maneuver around obstacles and some weather. The pilot can also inform the autopilot of weather areas to avoid.
• As soon as a panic button has been pressed, whether accidental or not, ground crews are notified.

The big benefit of Steve's proposal is not necessarily that it is ever used, but that just a belief that it exists and works would be enough to prevent skyjackings. In this way, I see safe-mode jetliners as accomplishing what time-lock safes did for convenience stores and fast-food joints. Sure you can rob them--but only if you are willing to hang around 10 or 20 minutes for the safe to open. Steve's plan likewise takes the incentive out of skyjacking.

Steve is hoping that someone out there in AnchorDesk-land can punch holes in his idea or, alternately, help present it to the FAA, the airlines, aircraft manufacturers, the pilot's union, passenger organizations, and others who might help make our skies safer. Please leave comments on the TalkBack board and we'll see where this goes.

Note to readers: We will be discussing this idea with Steve, as well as talking about some of the privacy issues I raised yesterday, on Friday's R & D Radio Hour show at noon PT. To listen, tune in www.cnetradio.com.

Will Steve's plan eliminate skyjackings? What other ideas do you have? TalkBack to me.