It's a heart-stopping image, yet one that is all too possible at any of the nation's congested airports: Two jets, packed with passengers, take off simultaneously on converging runways and crash in a fireball.
In an effort to prevent such a disaster, aviation experts are testing the first technology to stream warnings about probable runway accidents directly to the pilots of the planes at risk.
In a dramatic, real-life demonstration of the experimental system, two planes were sent on a collision course last week at Syracuse Hancock International Airport in upstate New York.
The control tower cleared a Sabreliner for takeoff on Runway 10. The pilot spooled up the twin engines to full power and released the brakes. Within seconds, the executive jet was a third of the way down the runway, accelerating toward its wheels-up speed of about 135 m.p.h.
"Caution! Caution!'' rang out in the pilot's headset.
A Beechcraft King Air plane roared down Runway 15, heading for a collision where the two runways intersect. Neither plane stopped. A more urgent alert screamed to both pilots just before their planes reached liftoff speed: "Warning! Traffic! Traffic! Converging traffic! Con- verging traffic!''
The pilots applied emergency brakes and engine thrust reversers, and both aircraft screeched to a halt, stopping 1,500 feet short of a fiery crash and throwing passengers forcefully against their seat restraints.
The goal of delivering real-time data straight to the flight deck is to shave crucial seconds off the alerting process, correcting human errors that occur every day at airports in the U.S. and threaten to produce catastrophic results.
Under the existing runway safety system, the pilots of planes in danger of crashing into each other are generally the last to receive alerts, because radar that monitors the movement of planes and vehicles on the airfield transmits collision warnings to the airport control tower. Controllers then radio alerts to pilots--if it's not too late.
"The key benefit to our system is a safety logic that chirps advisories to the pilots if it determines these guys are going to potentially touch each other," said Tony Lo Brutto, vice president and general manager of air-traffic systems at Sensis Corp., which is developing the cockpit alerting technology with Honeywell International.
The collaboration pairs Sensis' new Airport Surface Detection Equipment Model X (ASDE-X) radar, which was activated at O'Hare International Airport in early August to detect movement on the airport surface, with Honeywell's Traffic Collision Alerting System (TCAS) that informs pilots about the whereabouts of other aircraft.
The Honeywell-Sensis endeavor still is in the conceptual phase, but officials say they hope to bring a federally certified product to market in as little as two years.
There is no time to lose.
The No. 1 threat to airline passengers looms on the runways and taxiways of congested airports. Planes, and sometimes vehicles, pass too closely about once a day somewhere in the U.S., according to the Federal Aviation Administration. A more serious incident creates an immediate collision hazard about once every 10 days.
In the fast-paced, high-traffic airport environment where planes travel thousands of feet in seconds, the system can be unforgiving of a pilot making a wrong turn, or one blowing through the equivalent of a stop sign while another plane is landing or taking off, or an airtraffic controller making a mistake.
A spate of recent close calls across the nation--including a near-collision of two airliners at Los Angeles International Airport on Aug. 16 and a less serious runway safety breach at LAX nine days later--has aviation safety officials worried that the next runway incursion won't be just another bloodless scare.
The FAA convened an emergency summit the day before the first Los Angeles incident to devise short-term solutions, while promising to step up research into more sweeping safeguards using new technologies.
The National Transportation Safety Board has been prodding the FAA for several years to work with the private sector to create a system that warns pilots of potential runway conflicts between aircraft.
FAA and NTSB officials keenly observed some of the demonstrations in Syracuse last week, but they were careful to avoid issuing an endorsement.
"While we welcome the development of new technology that furthers the board's efforts to improve aviation safety, we don't evaluate any specific product. We will leave that to the FAA," said safety board spokesman Peter Knudson.
Crash scenarios programmed
More than 40 potentially fatal accident scenarios have been programmed into the Honeywell- Sensis prototype cockpit alerting system, officials said. They include a case in which a plane strays onto an active runway just as another plane is descending to land.
"Runway occupied! Runway occupied,'' the computer voice alerts the pilot of the airborne plane, providing time to power up the engines and circle for a second landing attempt.
The advance warning to pilots can range from 15 seconds to 45 seconds, depending on the speed of the aircraft and other factors, Lo Brutto said.
Looking ahead, long-range strategies are aimed at flowing data to pilots that give them a fuller picture of what is going on at any airport they fly to, whether it is O'Hare or a one-runway airport in the middle of Oklahoma.
"There is no silver bullet to preventing runway incursions. But ultimately we envision a system where there is a moving map in the aircraft that has a picture of the airport surface and your position on it, along with all the other aircraft," said Rick Berckefeldt, marketing manager of aerospace safety systems at Honeywell.
"That's the dream state we all want to get to."