The verdict has been in for a long time: a stabilized approach is an essential part of a safe landing. Airlines and business aviation operators almost universally require pilots to fly stabilized approaches, but until now there has been no way to monitor approach performance in real time other than an alert fellow pilot to warn the flying pilot that he might be venturing beyond the boundaries of track, glidepath, proper configuration, airspeed and sink rate. Honeywell aims to change that with its new SmartLanding, a software extension of the company’s enhanced ground proximity warning system (EGPWS).
SmartLanding warns pilots via verbal announcements and messages on the EGPWS display when they are flying outside predefined standard operating procedure (SOP) criteria during approach to landing. The software stays silent if there is no deviation outside the SOP tolerances.
SmartLanding is Honeywell’s second software-based extension to the EGPWS hardware system. The first was the SmartRunway system, and both take advantage of EGPWS’s airports and terrain database and other capabilities.
The SmartRunway system is designed to help prevent runway incursions, said Michael Grove, Honeywell marketing director for safety and information management surveillance systems and also a key member of the EGPWS development team. SmartLanding was developed to prevent runway excursions by helping pilots avoid runway overruns.
In research for its approach-and-landing accident reduction (ALAR) tool kit, the Flight Safety Foundation (FSF) found that, between 1984 and 1997, unstabilized approaches “were a causal factor in 66 percent of 76 approach and landing accidents and serious incidents worldwide.”
The FSF and NBAA recommend that approaches be stabilized at 1,000 feet above airport elevation on IFR approaches or 500 feet VFR. “The stabilized approach requires the aircraft to be established on the desired track, glide- path, in landing configuration and with airspeed and sink rate constant,” according to NBAA. The FSF ALAR briefing note gets into more detail, but the bottom line is that if the approach isn’t stabilized by the required altitude, pilots should initiate an immediate go-around. The benefits of a stabilized approach, according to the FSF, are that “landing performance [is] consistent with published performance.”
Honeywell research found that runway excursions are far more prevalent than incursions and, by a factor of about 10, account for far greater accident- and industry-related costs. “It’s a significant problem, and one that enhanced ground prox is pretty well suited to help address,” Grove told AIN.
The concept behind SmartLanding is not new, but making it work depended on modern databases and GPS capability. Honeywell worked with airlines and aircraft operators for two years to find out how SmartLanding might help them, and the company asked airlines what kind of exceedances they were seeing from flight operational quality assurance (FOQA) or flight data monitoring (FDM) system data. It also ran simulator trials.
For an operator, the ideal setup is to have SmartLanding, FOQA and/or FDM all working together. Analysis of the FOQA/FDM data can show where pilots might be exceeding criteria in a specific area, such as approaches. SmartLanding can then help pilots avoid these exceedances because the operator can configure the system to address specific criteria.
SmartLanding has dozens of parameters. Some criteria are built- in, such as the approach gradient, which is determined based on each airport’s own configuration. The standard gradient is a three-degree glidepath. SmartLanding is typically set up to remain silent as long as pilots remain within one degree on the up side of the glidepath.
Another important parameter is approach speed. SmartLanding normally is set to reference speed plus 25 knots, but this is configurable, too. Airbus, for example, uses a more aggressive Vapproach plus 15 knots.
When SmartLanding calls out an alert–in a choice of actual male or female voices–the first and second calls (or three in the case of flaps) state the nature of
the exceedance. A speed above the Vref+25 standard, for example, would generate a “too fast, too fast” verbal annunciation and a text annunciation on the EGPWS display (usually the PFD). If the pilot slows and remains within the required speed, SmartLanding remains silent. But once the aircraft gets below 450 feet and is above the exceedance speed, or too high or in the incorrect flaps configuration, then SmartLanding announces and displays “unstable, unstable.” “At that point,” said Grove, “we expect the pilots to go around.”
SmartLanding can be purchased separately from SmartRunway, or operators with SmartRunway can add SmartLanding and the two systems work together. For an EGPWS-equipped aircraft, Smart- Landing will cost roughly an additional $20,000, but if Smart-Runway is already installed, Smart- Landing will cost less. Fleet pricing will also be available. Certification of SmartLanding as a supplemental type certificate installation was due to be completed last month and the first two approvals were expected for Honeywell’s own Hawker Beechcraft King Air C90 and Convair CV-580, followed by a United Airlines jetliner.
Honeywell engineers are busy developing additional products that live on and take advantage of the EGPWS platform (see box). One is a new altimeter-monitoring system to help pilots avoid mis-setting the altimeter, either when transitioning into Class-A airspace or setting the altimeter properly before beginning an instrument approach.
“The most prevalent situation is to set [the altimeter] off by one inch, about a 1,000-foot difference,” said Grove. “That digit is significant enough that it can get you into trouble, and sometimes it results in an altitude bust if you’re lucky. But if you’re not so lucky, it can result in a controlled-flight-into-terrain accident.”
The altitude-monitoring system determines correct altitude based on the geometric altitude for the aircraft’s GPS-derived location as well as radar altimeter data, when available. The system is capable of detecting errors as small as 150 feet. “This has a lot of uses other than just the safety aspect,” he said. “We feel it’s going to be important for people transitioning to RNP because RNP operations today are still based on barometric altitude for vertical [separation].”