SAFETY & TECHNOLOGY
Combating runway incursions
Solutions include airport diagram prestudy, continuous monitoring during taxi, cockpit alerts, GPS equipment.
Universal Avionics EFI890R flat panel display and UCDT III flight bag shows “own ship” with correct heading orientation overlaying an airport chart with moving map technology.
The approach chart switches automatically to the airport chart 15 sec after touchdown, reducing heads-down chart flipping during rollout. Elbit Systems dispenses with the need for GPS or database.
Its Kollsman All Weather Window enhanced flight vision system (EFVS) improves SA during ground ops at night, in fog or other reduced-visibility situations, thus helping to prevent runway incursions.
An infrared image of the airport environment, including buildings, ground vehicles, lighted and unlighted aircraft, and terrain is delivered to the pilot on any raster-capable head-up display (HUD) or head-down display (HDD), such as a CRT or LCD.
While there are no alerts or warnings, the ability to “see through” low-visibility conditions greatly increases SA.
Relatively few airports have installed runway incursion prevention technology. Airport Surface Detection Equipment–Model X (ASDE-X) uses radar and satellite technology to enable air traffic controllers to detect potential runway conflicts by providing detailed coverage of movement on runways and taxiways.
By collecting data from the surface movement radar on the air traffic control tower or remote tower, multilateration sensors, ADS-B sensors, terminal automation system and aircraft transponders, ASDE-X can determine the position and identities of aircraft and transponder-equipped vehicles on the airport movement area, as well as those of aircraft flying within 5 miles of the airport.
Controllers in the tower see this information presented as a color display of aircraft and vehicle positions overlaid on a map of the airport runways, taxiways and approach corridors. Essentially, the system creates a continuously updated map of the airport movement area which controllers can use to spot potential collisions.
It is especially helpful at night or in poor visibility. The first ASDE-X was activated for operational use and testing at MKE (Mitchell, Milwaukee WI) in Jun 2003 and declared ready for national deployment in Oct 2003.
FAA recently accelerated the ASDE-X schedule and now projects that all 35 systems will be deployed by fall 2010—a year earlier than originally anticipated. ASDE-X is designed to integrate with future components of NextGen, such as automated dependent surveillance–broadcast (ADS-B).
In a test demonstration combining Sensis Corp’s ASDE-X ground-based system with Honeywell's Mode S and TCAS avionics, the aural conflict alerts provided to air traffic controllers were also transmitted almost instantaneously to the cockpits of the affected aircraft.
ASDE-3, the predecessor to ASDE-X, provides only radar surveillance of aircraft and airport service vehicles at high-activity airports, while ASDE-X provides both surveillance and identification of all transponder-equipped aircraft and vehicles on the airport movement surface.
ASDE-3 provides data to controllers about arriving aircraft only, while ASDE-X provides data about arriving and departing aircraft. Airport Movement Area Safety System (AMASS) is an add-on enhancement to the host ASDE-3 radar which provides automated alerts and warnings of potential runway incursions and other hazards.
It does this by prompting tower controllers visually and aurally to potentially dangerous situations. While AMASS extends the capability of ASDE-3 and enhances surface movement safety, one limitation of airport warning systems such as AMASS is the requirement for human processing of the automated alerts provided to air traffic controllers.
While the controller is detecting, evaluating and deciding on a course of action, the collision is getting nearer. ASDE-X Safety Logic (AXSL) is an enhancement to ASDE-X in terms of the SA it provides to air traffic controllers.
AXSL uses surveillance information from ASDE-X to determine if the current and/or projected positions and movement characteristics of (tracked) aircraft and vehicles present a potential collision situation.
Visual and audible alerts to controllers include critical information about the targets, such as identification and position. Color maps in the tower cab provide color coding based on aircraft size—heavy aircraft are shown as a yellow icon, others as white is.
Two alarms go off when a conflict is sensed—an audible alarm which tells controllers to instruct a landing plane to go around (for example) and a visual alarm on the controller’s screen that circles the 2 airplanes and/or vehicles and draws a line between them.
FAA is now testing and deploying a warning system called Runway Status Lights (RWSL). This is the first airport system to give direct warning to pilots (and drivers of ground vehicles) of a potential runway incursion or collision.
RWSL warns when it is unsafe to cross or enter a runway, or begin the takeoff roll, and does so via a series of red lights embedded in the pavement. Initial field evaluations of RWSL showed a 70% reduction in runway incursions.
Pilots approaching a runway at ground level see red lights illuminate if the airport’s ground surveillance radar—either ASDE-3 or ASDE-X—detects traffic on or approaching that same runway.
Pilots must stop when they see the red lights. After the lights go off, the pilot must verify clearance before proceeding. If a runway is unsafe for entry or crossing, the runway entrance lights are illuminated.
Likewise, red takeoff hold lights indicate that the runway is unsafe for departure. RWSL is being tested at DFW and SAN, and at LAX, where testing began in April this year. Recently, FAA chose Sensis to deploy RWSL at 22 airports.