|Boeing Technology Demonstrator|
Boeing shows off
a forward-thinking suite of cockpit upgrades designed to
improve pilots’ situational awareness and make airline operations safer and more efficient.
By Jan W. Steenblik, Technical Editor
Air Line Pilot, April 2003, p. 21nical Editor
Observers of the transport air plane manufacturing industry may remember 2002 as the year that the Boeing Commercial Airplanes Company shelved its plans for the Sonic Cruiser and announced that it would shift its design focus to a new, super-efficient subsonic airliner, the 7E7.
But these observers should also note that 2002 was the year that the aerospace giant also unveiled a conventional airplane—a new B-737-900 destined for Alaska Airlines—outfitted with nine new and emerging technologies designed to improve the safety and efficiency of airline operations and airspace capacity.
Called the Boeing Technology Demonstrator, the airplane flew a number of demonstration flights for invited representatives of aviation authorities and the airline industry, including ALPA, during March and April 2002.
After the demo program was over, most of the demonstrated avionics were removed, and the airplane was completed as Alaska Airlines had ordered it.
Boeing described the Technology Demonstrator as "a flying testbed that allows Boeing to work with airlines, suppliers, regulatory agencies, and technology developers to demonstrate and evaluate new flight deck technologies in a real-world [airline] environment."
Of the nine "technologies" featured on the Demonstrator, two already have been in airline service on late-model B-737s; another four are or were in the FAA certification process; and three are "emerging" technologies that will not appear in the cockpits of production airplanes for some time, if ever.
Quiet Climb System
Some of the advanced avionics that were gathered together in the Technology Demonstrator’s cockpit already have been flying on Boeing products in service.
The Quiet Climb System (QCS) is one. An advanced feature in the flight management system (FMS), and currently offered on the B-737, QCS automatically reduces engine thrust during noise-abatement takeoffs to meet the noise-abatement departure profiles outlined in FAA advisory circular AC 91-53A, which include a minimum thrust cutback altitude. QCS is designed to maintain a safe climb and airspeed, eliminating the need for the flight crew to manually reduce thrust multiple times to reach the proper thrust and climb angle.
Boeing test pilot Mike Carriker noted, "We’ve been asked, ‘What’s the benefit of the QCS versus just derating the engines?’
"With QCS," he said, "we can achieve a more significant thrust reduction than is typically available through a standard derate. Also, QCS automatic thrust reductions help the flight crew fly noise-abatement procedures accurately while reducing pilot workload."
At John Wayne/Orange County Airport in southern California, fines against airlines for exceeding noise level limits can run as high as $500,000. Other noise-restricted airports may not be as punitive as Orange County, "the tail that wags the dog" in U.S. airport noise abatement, but they are becoming increasingly more severe.
To avoid such penalties, airlines using manual procedures for noise-abatement departure profiles often reduce takeoff weight to make sure that the airplane does not exceed the noise limit. Boeing maintains that QCS "would potentially eliminate the need for such reduced takeoff weight, therefore allowing airplanes to carry more passengers or cargo—an added economic benefit."
Another "leading edge" technology installed on the demonstration airplane, and already in service on some B-737s, was the captain’s head-up display (HUD)—in this case, the Rockwell Collins Flight Dynamics HUD familiar to an increasing number of ALPA members who fly late-model Seven Threes.
The HUD expands operational capability and enhances safety by providing conformal flight path information to the pilot. What does "conformal" mean? Just that the display conforms with, or overlies, the outside real world—for example, during approach and landing, the lines in the HUD display that portray the edges of the runway will, in fact, overlie the actual edges of a standard air carrier runway.
Other important information portrayed on the HUD includes flight- path vector (where the airplane is actually going, which is seldom the same as where it is pointed), an indication of required thrust, stall margin, and a number of other enormously helpful types of information not conveyed by conventional instruments.
The HUD also shows the information that conventional instruments show—e.g., airspeed, altitude, pitch, heading, bank angle, and localizer and glideslope deviation.
As a result, the HUD improves manual flightpath control and touchdown performance—which also translates to lower takeoff and landing weather minimums, which in turn translates to fewer delays and diverts.
In fact, Alaska Airlines more than a decade ago began flying Category IIIA manual approaches—to a 50-foot decision height and 700 RVR—in HUD-equipped B-727s. Later, the airline obtained FAA certification for takeoffs in Category IIIB conditions with an RVR of only 400 feet.
The HUD also can serve as a platform for future enhanced and synthetic vision systems; more on that later in this article.
ALPA has been a strong proponent of HUDs for airline operations for decades. The Association’s line pilot aviation safety representatives and staff have worked closely with manufacturers (including Boeing and Flight Dynamics) and regulatory authorities literally for decades on the development and evolution of airline HUDs—from basic concepts and display philosophy to simulator studies and real-world operational evaluations.
Navigation Performance Scales
Meanwhile, head-down on the pilots’ primary flight displays (PFDs), Boeing has introduced another enhancement —Navigation Performance Scales, up/down and left/right path indicators to provide precise position awareness and navigation performance. The NPS is intended to minimize flight delays and increase airspace capacity by allowing the airplane to navigate through a much narrower flightpath with higher accuracy. It is geared to the required navigation performance (RNP) concept that is already mandatory in Europe and will be phased in during the next few years for aircraft flying at jet altitudes in U.S airspace.
A charted RNP value (e.g., RNP 1.0) is the navigational accuracy, in nautical miles, required for flight operations within a given airspace.
Actual navigation performance (ANP) is the estimated real-time measure of the quality of an airplane’s navigation system. To calculate ANP, the flight management computer analyzes navigational signal inputs (e.g., inertial reference systems, GPS, and ground-based navaids) to estimate current aircraft position and position uncertainty.
"However," Boeing observes, "neither RNP nor ANP contains any data that indicate how closely the airplane is flying to the desired track."
The NPS display is based on the familiar concepts of a display of centerline, scale limits, and deviation pointers, such as used during ILS approaches. With the NPS display, pilots’ situational awareness is improved because they can monitor the dynamic relationship among RNP, ANP, and current flightpath deviations. The display shows current position in relation to the desired track and the allowed deviation—as RNP changes during a flight, bars expand along the scale from the scale’s limits toward its center to show that RNP has been reduced, and shrink back laterally when RNP is relaxed.
According to Boeing, the NPS feature is expected to allow RNP 0.1 (0.1 nm) operations—a tighter tolerance than currently used. Airlines thus will be able to fly LNAV/VNAV approaches they could not previously use.
Boeing adds, "Because Navigation Performance Scales provided enhanced awareness and alert the flight crew to the airplane position deviations, the airplane’s RNP rating can be reduced. This reduction will help increase airspace capacity and will minimize delays by allowing the crew to navigate through a much narrower flight corridor, avoiding noise-sensitive areas and restricted airspace. The feature also could make it possible to perform simultaneous precision approaches on closely spaced runways."
The NPS feature was FAA-certified and delivered to Malev Hungarian Airlines in January.
Integrated Approach Navigation
Integrated Approach Navigation (IAN) is an enhancement to the air-plane’s existing flight management computer (FMC) approach capability. This feature adds operational flexibility and simplifies pilot procedures by allowing the FMC-calculated path to be provided to the autopilot’s approach mode just like an ILS path. All key functions of the approach mode are invoked.
Boeing points out that 18 types of instrument approach procedures now exist: ILS, LOC, LOC-DME, LDA, BCRS, SDF, VOR, VOR on airport, VOR-DME, VOR-ARC, NDB, NDB on airport, NDB-DME, NDB-NDB, ASR, PAR, RNAV 3-D, and RNAV 2-D.
The IAN feature minimizes pilot workload and training by allowing a common "integrated approach procedure," reducing the 18 types of approaches to one; you fly the "needles" —the path deviation pointers on the EADI—just like for an ILS.
Boeing suggests that fleetwide use of IAN could reduce the number of approach procedures pilots have to learn or review in training. The company also argues that such an "integrated approach procedure" may also reduce landing weather minimums by placing—and keeping—the airplane on a stabilized approach path in the best position for pilots to see the runway for landing in low weather.
Provided by Boeing, the IAN function involves upgrades to the FMC, autoflight system, display system, EGPWS, and the flight recording system. IAN is available for the B-737, and is being considered for other models.
GPS Landing System
The Global Positioning Landing System (GLS) is a highly accurate landing system that uses the satellite-based Global Positioning System (GPS) augmented by two ground-based systems designed to increase the accuracy of GPS position determination. GPS alone does not meet all of the accuracy requirements for precision approaches; GPS signals must be augmented to provide better integrity and accuracy.
The Wide Area Augmentation System (WAAS) is based on a network of approximately 25 ground reference stations in the United States, Canada, and Mexico. The WAAS ground station determines the differential correction that needs to be applied to GPS signals, which it then transmits to the satellites for rebroadcast to a WAAS-capable receiver.
WAAS is expected to significantly improve basic GPS accuracy to approximately 7 meters vertically and horizontally. WAAS is not currently intended to provide the level of system redundancy required for use as a landing system.
The Local Area Augmentation System (LAAS), however, is designed to meet this stringent requirement, and supposedly will eventually support Category IIIb autoland. LAAS differs from WAAS by transmitting GPS position error corrections and airport approach procedure information via VHF radio to aircraft in the local airport area. Intended as a complement to WAAS, LAAS is a safety-critical system designed to improve basic GPS navigational accuracy to 1 meter or less and enable precise approach, departure, and missed-approach procedures.
During the demo flights, Boeing autolanded on six runway ends where autolands previously were not available.
LAAS stations that will be used to provide GLS capability at airports generally provide a coverage radius of 23 nm. Boeing reports, however, that during flights of the Technology Demonstrator, pilots received the LAAS signal at distances "well beyond" 23 nm.
According to Boeing, "Coupled with the position, velocity, and time outputs of LAAS, RNAV and flight management systems will make it possible to adhere very precisely to defined flightpaths.… As a result, protected airspace for an aircraft can be reduced significantly. This improves airspace capacity and operations by allowing more aircraft within a finite airspace.
"Increases in accuracy and integrity of LAAS-augmented GPS combined with the autonomous and flexible flight path definition possibilities of the FMC allows for curved and segmented approach paths. It also makes possible cooperative decision-making between air traffic controllers and pilots conducting three- and four-dimensional approaches."
GLS requires airplanes to have an upgraded multimode receiver, new GPS antennae, and a new airplane personality module (APM). The airplane also needs upgraded FMCs, flight control computers, autoflight system, audio control panel, displays, central fault/maintenance computer systems, and navigation control panel or multifunction control display unit.
The three approach methods—ILS, IAN (FMC data) and GLS—all use the same procedures, which reduces the variability in training, while increasing safety margins by making every approach the same.
Vertical Situation Display
"Getting the Big Picture into the Cockpit," January 1987, reported on a series of papers presented at the Society of Automotive Engineers’ annual Aerospace Technology Conference and Exposition in October 1986.
"Pilots tell engineers that flight crews need more intuitive situation displays in airliner cockpits to reduce workload and improve safety," said the blurb. "A common theme of all the papers was pilots’ need for better vertical situation information," the article noted.
Roger Houck of Boeing, in 1986, discussed his company’s preliminary work on an integrated display for vertical situation awareness in civil transports. He pointed out that ASRS reports from pilots substantiate the view that, in current aircraft, "vertical situation information…[is] dispersed throughout the flight deck, imposing high cognitive demands on the pilot."
Moreover, Houck added, various airlines had said flight crews need more and better vertical situation information, particularly for planning and monitoring vertical navigation (VNAV) autopilot modes. He explained that "the pilot’s problem appears to be a lack of information [that relates] present position with future requirements…."
Houck said Boeing was evaluating a side-view vertical situation display (VSD)—i.e., one that would appear like the profile view on instrument approach charts. He concluded that "a well-developed VSD could become as fundamental to vertical navigation as the map display has been to lateral navigation," especially during time-critical or high-workload situations.
Now, some 16 years later, Boeing has incorporated the VSD, which was on display in the Boeing Technology Demonstrator, in its display and flight management software and offers it as an available option. Immediately intuitive, the VSD—fit into the bottom portion of each pilot’s nav display—provides an unambiguous picture of the airplane’s vertical position relative to the terrain, with waypoints, projected vertical flight path, glideslope, plus other critical information.
The airplane’s enhanced ground proximity warning system (EGPWS) and its associated terrain database drive the software that creates the VSD’s real-time, continuous contour of the terrain. Given that controlled flight into terrain (CFIT) remains one of the most prevalent causes of airline fatalities and hull losses worldwide, the role of the VSD in improving pilots’ situational awareness by showing terrain, flight path, and aircraft energy cannot be overstated.
As Boeing says, "VSD reduces [flight] crew workload and enhances situational awareness by eliminating the need for the flight crew to mentally integrate airspeed, vertical speed, altitude, and waypoint information—data available from various instrumentation—into a mental image of the airplane’s vertical position and path trend."
On stepped descents, the pilots can see vertical waypoints and determine if their flight path will comply with them. The VSD also lets the flight crew adjust descent speed to ensure accurate glideslope capture.
The VSD involves updates to the EGPWS, the FMS software, and the display software.
Surface Guidance System
Three of the new systems on the Technology Demonstrator were "emerging" technologies—i.e., Boeing, airlines, and regulatory agencies have been evaluating them.
One that has been the subject of considerable research by NASA is the Surface Guidance System (SGS), an adjunct to the HUD that derives position data from LAAS and displays taxiways, upcoming turns, hold lines, turn trend vectors, and other critical information, conformal with the real world outside the cockpit.
SGS as envisioned will initially portray standardized, preapproved ground routes between the airport terminal and the runway, contained in the FMC system database and selected by the flight crew. Advanced SGS applications would include datalink transmission of taxi clearances and GPS-based automatic dependent surveillance-broadcast (ADS-B) to keep ground controllers aware of aircraft position at all times.
Seen through the HUD combiner (glass plate), the real-world taxi route is defined on both sides of the airplane with cones; the centerline, with dots. As the airplane moves closer to these objects and taxiway or runway edges, the cones and dots change to conform to expected depth-perception images. A turn vector shows the airplane’s predicted immediate future path, and a guidance cue helps the pilot align the airplane on the approved route.
Also included in the SGS display are current and target speed, direction and distance to next turn, a deceleration scale and cues to optimize braking, distance to the hold line, and position of landing gear.
The potential of the SGS to reduce runway incursions is obvious. What might not be so obvious is the system’s potential to increase airport capacity—e.g., by helping pilots anticipate upcoming turns and holds, even at unfamiliar airports and in bad weather and darkness, the SGS could allow pilots to taxi at preferred speeds without compromising safety.
Enhanced Vision System
Another "emerging" technology is the Enhanced Vision System (EVS), which uses sensors such as the forward-looking infrared (FLIR) sensors installed on the Technology Demonstrator to produce a "thermal video" of the scene in front of the airplane, which is then projected onto the HUD combiner or a video-compatible head-down display.
Detecting minute differences in the temperatures of distant objects and terrain features, the EVS gives pilots enhanced, real-time images of terrain, runways, taxiways, other aircraft, and potential obstacles that might be obscured during darkness or poor visibility. Depending on the type of visibility obscuration, the EVS can portray the airport environment as far as 10,000 feet ahead of the airplane.
Synthetic Vision System
The Synthetic Vision System (SVS), which NASA has studied for use on a possible future hypersonic civil transport, is an experimental concept. Unlike the EVS, the SVS head-down image is generated entirely by the aircraft’s onboard computer databases, including a terrain database of very large scale.
The SVS has the potential—displayed on the Technology Demonstrator—to generate the so-called "pathway in the sky," or "tunnel guidance." This concept portrays the airplane as flying through a series of approaching rectangular frames or flying through or alongside a thin wall that depicts the centerline of the desired flightpath.
Eventually, says Boeing, "SVS could also display aircraft hazards such as traffic and weather, in addition to hazards presented by the terrain."
Moreover, "as air traffic procedures become increasingly complex, tunnel guidance may be required even when a procedure is fully automated."
Air Line Pilot gladly accepted Boeing’s invitation to fly on one of the final flights of the Technology Demonstrator—a night flight from Boeing Field in Seattle to Moses Lake, Wash., and back.
The QCS performed flawlessly; the HUD was familiar, and the Navigation Performance Scales proved illuminating. The EVS displayed hangars, pavement, taxiway lights, other aircraft, passing fuel trucks, and many other aspects of the airport environment in bright, sharp, vivid contrast. The SGS obviously greatly increased situational awareness of the airport surface.
Perhaps most exciting from a pilot’s perspective, however, were the VSD and the "whifferdill" FMS approach the airplane flew to Moses Lake.
The FMS approach began with the airplane crossing over the middle of the landing runway and beginning a curving descent of roughly 270 degrees to a 1.0-mile final approach leg. The radius of turn changed, tightening up toward the end of the "whiffer-dill," but the airplane flew the maneuver smoothly and precisely, putting itself on final without ever getting very far from the airport.
The VSD demonstration alone was worth the trip. As Boeing test pilot Mike Carriker descended east of the Cascade Mountains toward Moses Lake, he asked for and received a clearance to turn west, back toward the mountains, while continuing to descend. As the nose of the airplane swung smoothly westward, the terrain contour displayed in the VSD changed dramatically and almost continuously as the B-737’s heading changed and the threatening mountain range loomed nearer.
If a picture can truly be worth a thousand words, the VSD spoke volumes—cumulogranite ahead, and this is where you’re headed.
The Boeing Technology Demonstrator as a whole presented an intriguing look at the present and the future of airline technology—subsonic, to be sure, but equipped with an array of technologies that could help airlines take full advantage of the multi-year, multi-billion-dollar efforts under way to modernize the U.S. National Airspace System. Maximizing airline safety and efficiency and improving airport and airspace capacity will require a joint effort of all parties, including ALPA, working together to make sure the airplanes and the overall air transportation system work in concert.