Tackling runway excursions with energy awareness
is in hot pursuit of a new family of cockpit aids to help airline pilots better manage the takeoff and landing phases of their flights. The avionics maker is close to rolling out a takeoff-roll acceleration-monitor software upgrade as part of its enhanced ground proximity warning system (Egpws), and is in the midst of researching a more comprehensive landing-and-takeoff performance monitor upgrade that will include a dedicated display area on the primary-flight or navigation displays.
The technology addresses the growing problem of runway excursions, both from flawed approaches and problematic takeoffs. The most likely cause on departure is a high-speed rejected takeoff (RTO), possibly for a failed engine, blown tire or system-warning configuration problem.says roughly 75% of RTOs are initiated below 80-kt. airspeed “and rarely result in an accident,” while about 2% occur at speeds greater than 120 kt., often leading to an overrun. In an study of incidents and accidents in 1985-2010, overruns ranked No. 1, accounting for 400 of the nearly 1,000 reported incidents.
Airbus is developing its own suite of runway excursion preventatives under its Runway Overrun Prevention System (ROPS) product line, which was recently rolled out as an option for thefamily after initial operations on the began in 2009. ROPS provides pilots with a “runway too short” alert at 500 ft. above the airport if an aircraft's energy is too high on an approach. Pilots will ideally abort an unstablized approach, but if they do not, the system provides reverse-thrust and braking alerts on the roll out. Airbus says “several overruns” have already been avoided for operators who have installed the ROPS option.
While Honeywell is currently marketing similar excursion preventatives in the form of the SmartRunway or SmartLanding systems, both add-ons to Egpws, the new takeoff and landing performance monitors will be the first to provide pilots a real-time visual assessment of runway performance based on the aircraft's expected versus actual acceleration or deceleration, weight, braking action, winds, reported runway conditions and other factors.
“This has been talked about for many, many, many decades,” says Ratan Khatwa, senior chief engineer for human factors at Honeywell Aerospace. “The key challenge is taking into account all the different operational variables required to generate the alert.”
Whereas SmartLanding today provides too high, too fast, unstable and long-landing text and audio call-outs as well as distance-remaining call-outs when on the runway, the landing performance monitor, informally called SmartRunway2, will display tactical information in a visual format mapped on a runway graphic or in an acceleration format near the airspeed tape on the primary flight display.
Honeywell demonstrated an engineering prototype of the system to Aviation Week on Dec. 4 at its labs in Redmond. One version of the landing monitor featured a real-time graphical display showing the position on the runway where the aircraft would stop, along with suggestions for maximum braking, deploying spoilers and other excursion preventatives.
Khatwa says the monitor is being designed for two-pilot cockpits, with the pilot-not-flying monitoring the system and providing advisory call-outs to the active pilot.
Similar onboard information is used for the takeoff performance monitor, although Khatwa says the takeoff computations are the most challenging. In the engineering prototype, two bands overlay the runway graphic, one in brown and one in blue, along with a marker for the “V1” speed, beyond which the crew will typically take off even if there are problems, and a marker for the rotation point. The brown band shows where the aircraft can be stopped before the end of the runway if the takeoff is aborted; the blue band indicates where the aircraft can take off and reach a height of 35 ft. by the time it reaches the runway end.
Honeywell has an unnamed airline customer for the takeoff-roll-acceleration monitor, though no launch date has been set. The system compares the actual acceleration of the aircraft with tables loaded with the nominal acceleration values at 80-kt. airspeed, typically in the neighborhood of 3-4 kt. per sec. If the actual acceleration is too low, the system will issue an audible “Acceleration! Acceleration!” alert.