Honeywell test pilot Markus Johnson taxis his plane toward a runway at Paine Field overlooking Puget Sound when over his radio headset a female voice announces, "Approaching one-six right."

The advisory is not a courtesy call by a helpful air-traffic controller at the busy airport where new Boeing planes roll off the assembly line, but rather it's from an onboard program that, like a patron saint, watches out for the safety of pilots and their passengers.

Aviation safety experts say that if Comair Flight 5191 had been outfitted with runway-awareness technology, it might have helped the pilots catch their fatal error on Sunday morning when they took off on the wrong runway at Blue Grass Airport in Lexington, Ky. The plane crashed beyond the end of the general aviation runway that was too short for the regional jet, killing 49 of the 50 people aboard.

This system also could help reduce the probability of runway incursions, collisions and other mishaps on the ground at several hundred airports served by the approximately 8,000 planes in the U.S. commercial fleet, according to aviation experts, who say government-led runway-safety efforts are lagging.

The computer-generated information provided in the Runway Awareness and Advisory System, which is made by Honeywell Aerospace and based on global-positioning system technology, corroborates Johnson's understanding of precisely where he is on the airfield.

He lines up his Beechcraft King Air on Runway 16R for takeoff, much like a motorist would follow directions that were mapped out to go straight or turn left in a car equipped with a GPS navigation system.

"On Runway one-six right," the aural voice advisory confirms, and the muscular twin-engine business plane darts down the runway and lifts off over the water and heads toward Whidbey Island.

'Helper in the cockpit'

The advisories are "like having a helper in the cockpit to tap you on the shoulder and say, 'Does this make sense to you?"' said Johnson, director of aerospace flight operations at Honeywell. "If everything doesn't add up in your head, you then stop the plane and review your flight plan and checklist."

Acquiring this extra margin of runway safety is as easy as inserting a compact disc into a computer. The $18,000 price tag is modest when compared to the value of a jet aircraft, as well as the loss of life and the hundreds of million of dollars in litigation after a major fatal accident.

The technology isused by only five airlines worldwide--Alaska Airlines, FedEx, Air France, Lufthansa and Malaysia Airlines--though United Airlines is studying joining the list. "We are pleased by what we have seen so far," said United spokesman Brandon Borrman.

The Honeywell system, which has been available for three years but is not federally mandated on commercial or private aircraft, would have given the Comair pilots an additional alert.

Even if the crew somehow missed or ignored the computer-driven advisory that they mistakenly entered the shorter Runway 26 at Blue Grass Airport, instead of the 7,003-foot Runway 22 as directed by the control tower, the runway-awareness program would have told the pilots how much takeoff distance was available on Runway 26, said Tommy Littlejohn, director of flight operations for Honeywell Aerospace.

"The system is totally automated and tells you exactly where you are, based on a worldwide database, and what you are doing," Littlejohn said.

As the Comair plane began its takeoff roll on the first 100 feet of the 3,500-foot runway at Lexington, he said the computer voice would have alerted the pilots, "3,400 remaining." The computer voice is programmed to continue counting down the distance left.

The runway alert system also tells pilots if they are trying to take off on a taxiway instead of on a runway. The warning "On taxiway! On taxiway!" is triggered by excessive taxi speeds, above 40 knots.

The runway system's other features remind pilots which runway they are headed toward on final approach to land and give a verbal nudge if pilots are sitting on an active runway for more than 90 seconds.

It's hard to believe that the combination of runway location and distance alerts would not have staved off the Comair tragedy, said Jim Hall, chairman of the National Transportation Safety Board from 1994 to 2001.

"For less than the price of a box at the Kentucky Derby, you probably could have saved 49 lives at the Lexington airport," Hall said.

The Lexington accident represents the deadliest case in the U.S. of a plane taking off on an unintended runway. But mistakes involving pilots entering the wrong runway, leading to potentially deadly runway incursions, occur numerous times each year at the nation's larger airports, too, according to incident reports filed with the Federal Aviation Administration. A runway incursion occurs on average once a day in the U.S., agency records show.

Danger on the ground

The message from the statistics is grim and indisputable: Airline passengers are much more likely to die on the ground than in the air.

But the FAA has encountered setbacks for more than a decade researching and developing technology to improve the monitoring of aircraft moving across airport runways and taxiways. In addition, budgetary constraints have delayed the widespread implementation of a new airport-based system that the FAA says will help prevent collisions between airplanes by alerting both pilots and air-traffic controllers to potential dangers. Known as Airport Surface and Detection Equipment Model X (ASDE-X), it will replace an older system that has been prone to giving false alarms.

O'Hare International Airport was scheduled to receive the new system in 2009 at the earliest, but a spate of five serious runway incursions this year at O'Hare prompted the FAA to push up deployment to 2007.

The FAA has another system called Automatic Dependent Surveillance-Broadcast that uses a moving-map technology to track planes at an airport.

But the FAA said it has no plans to require airlines to install the already developed and FAA-approved Honeywell system, or any similar technology under development.

"We think it is a great technology, but we are . . . not looking at requiring the Runway Awareness and Advisory System," said FAA spokeswoman Laura Brown.

Aviation safety advocates point out that the technology in the runway-awareness system is available as a software upgrade to a cockpit warning system that the FAA has for many years required on all commercial planes to warn pilots about obstructions near the ground.

The FAA certified the Honeywell runway-awareness system in 2003. Its list price is $18,000 per aircraft, though airlines pay a discounted price on bulk purchases, officials said.

The five carriers currently using the Honeywell system have outfitted about 600 planes, and 700 more units are on order, Honeywell said.

United Airlines, with about 460 planes, is the largest carrier that is considering joining the list. Officials reviewed the system this week at a training center near Denver, said Borrman.