Business & GA, Commercial

Bizjet Avionics: In the Vanguard

By William Reynish | June 1, 2003
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Almost 21 years ago, in September 1992, Boeing invited a group of journalists to fly from Seattle to Chicago, to mark the first customer delivery, to United Airlines, of the company’s new, twin-aisle, B767. Most of the group were travel writers who paced the passenger cabin, tested the seats and watched the in-flight movies. But a small number of us, mostly pilots, focused our attention on the flight deck and, particularly, on the revolutionary Rockwell Collins electronic instrumentation display screens–the first to be certified in a commercial aircraft.

We were deeply impressed. Rectangular, TV-like, color cathode ray tubes (CRTs) had not only replaced the round dials and pointers of each pilot’s attitude director indicator (ADI) and horizontal situation indicator (HSI), but also were displaying the equally critical center panel gauges showing temperatures, pressures and numerous other essential parameters. Our avionics lexicon also expanded, adding the significant letter "E" (for electronic) prefix to those familiar former acronyms, giving us the new EADI and EHSI terms, to be known collectively as the electronic flight instrument system (EFIS). And the two center panel tubes gave us the engine instrument and crew alerting system (EICAS). The term "glass cockpit" may well have been born on that flight.

However, it wasn’t just the transfer of symbology from the electromechanical instruments to the CRTs that captured our attention. It also was the new concepts the CRTs enabled, particularly on the EHSI. This now sprouted a trend vector, showing the aircraft’s position two, four and six minutes ahead, plus a readout of current wind speed and direction, as well as the weather radar returns. Amazing!

But the icing on the cake to pilot observers was the EHSI’s ability to convert the traditional HSI compass rose into a dramatic, +/- 35-degree, "look ahead" sector presentation, showing our track superimposed on the local airways and navaid structure. (We learned later that certification graybeards in the Federal Aviation Administration fretted about pilots becoming disoriented when using this new EHSI presentation. They insisted that provision for instant reversion to the old 360-degree compass rose be included in the B767 and its B757 sister. For the record, no pilots became disoriented, and very few used the full compass rose.)

Fortunately, 21 years later, the graybeards have long since retired. And it’s just as well. What would they think of flight deck displays like Dassault’s avant garde EASy (Enhanced Avionics System) concept? While traditional mechanical airspeed, altitude, vertical speed, radio magnetic indicator (RMI) and other instruments surrounded the B767’s EFIS and EICAS, the EASy flight deck is totally glass, even down to its standby attitude indicator.

EASy is the latest iteration of corporate aircraft display systems to demonstrate that, after a slow start, business pilots have now clearly overtaken their airline brethren in terms of advanced technology and sophistication. In some ways, in fact, the airline industry is even seen to be moving backwards. One United Airlines B777 captain recently reported that his large twinjet’s flight management system (FMS) was less capable in certain ways than that of the smaller, and older, Airbus A320 he flew previously.

But what does advanced technology and greater sophistication actually buy you? Basically, it buys increased situational awareness, where the pilot is able to fly the desired profile more efficiently, while "staying ahead of the airplane." The latter issue was a common problem encountered following the introduction of increasingly complex "glass cockpit" systems since their initial introduction in the B767. Until recently, what happened was that the avionics design engineers developed more functions than many pilots could always handle, giving rise to the frequently heard question, "Why is it doing that?"

This is changing. Original equipment manufacturers (OEMs), such as Dassault, Gulfstream and Bombardier, as well as avionics firms, such as Honeywell, Rockwell Collins and Thales Avionics (whose respective Primus Epic, Pro Line 21 and TopDeck systems are setting the pace), now insist on involving customer pilot groups in the flight deck design from the very beginning. The results are systems with more advanced capabilities, but which require significantly fewer control inputs–Dassault claims 50 percent fewer–while providing much more intuitive, pilot-friendly operation.

Pleasing the Customer

And "one size fits all" no longer applies. While Honeywell’s Primus Epic was selected by both Dassault for EASy and Gulfstream for its Plane View flight deck, the operational philosophy of the two systems is different in many ways, due to customer pilot inputs.

For example, the Dassault pilot/engineer design team felt that the FMS control and display unit (CDU) screens were a potential source of pilot input error. So Honeywell eliminated the screens and transferred the data to EASy’s centrally mounted multifunction display units (MDUs).

Conversely, the Plane View cockpit indicates no such concerns at Gulfstream. The company’s GV-SP will provide three, power-quadrant-mounted CDUs, each with its own screen. Similarly, Gulfstream pilots will control their system via individual inverted "coolie hats," while Dassault pilots will use computer-like trackballs.

But both pilot groups will relish the four large 14-inch display screens and their accompanying capabilities and operating flexibility. Not least of these capabilities will be the screen rendition, in pinpoint sharp color, of airport instrument approach plates which, ever since Elroy Jeppeson first developed them while flying the mail in the 1920s, have been printed on single, pocket-book-size sheets of paper stored alphabetically in a bulky binder. For that breakthrough alone, coupled with the end of manual binder updating every 28 days–now to be performed electronically in seconds–pilots will be eternally grateful.


Another area where corporate aviation has moved rapidly ahead of the air carriers is in its adoption of infrared enhanced vision system (EVS) add-ons to head-up displays (HUDs). Several airlines have installed HUDs in their aircraft, but none yet has taken the next step by incorporating EVS, although these units–built by Kollsman, CMC Electronics, Max-Viz and others–are now almost standard equipment in the newer large business jets like Gulfstream’s GV, Bombardier’s Global Express, and the next-generation Dassault Falcons.

While the HUD projects flight instrument indications onto a transparent screen to allow the pilot to both fly on instruments and look ahead for the runway, it does not increase the pilot’s visibility. The EVS, on the other hand, overlays the HUD screen data with an infrared image that "looks" ahead through cloud, rain or darkness to significantly improve the pilot’s situational awareness.

Synthetic Vision Systems

EVS is sometimes incorrectly called a synthetic vision system (SVS), but the latter is quite different. The SVS technique is based on a detailed terrain map stored in the system’s memory which, when combined with the aircraft’s position, altitude and heading, produces an artificial, or synthetic, "view" of the outside world. Besides providing another layer of situational awareness, SVS can be an extremely valuable aid in avoiding controlled flight into terrain, by showing high ground ahead well before a terrain awareness and warning system (TAWS) would sound an alert.

Universal Avionics Systems Corp. and Chelton Avionics are SVS pioneers in the corporate and general aviation community, having developed presentations for their respective multifunction displays. Their systems, which are FAA-approved for situational awareness, but not navigation, provide a synthetic three-dimensional view of the aircraft in relation to the flight plan and surrounding terrain. The FAA has selected Chelton’s SVS MFD for its Capstone II project in Alaska.

Universal’s "exocentric" perspective on the MFD is as if the camera is situated behind, above and slight to the right of the aircraft. The terrain database is housed in the Vision 1 processor, and terrain imagery is presented via a video graphics adapter (VGA) output.

On a synthetic landscape, with terrain appearing in shades of greens and browns (similar to aviation sectional charts) and water in blue, the pilot can overlay the flight plan from the flight management system along with deviation indicators, trend vectors and a compass symbol with course and heading information.

Again, no airline currently uses SVS, and few have terrain mapping equipment, although terrain mapping is an integral part of many corporate avionics installations and standard in the new business jet avionic suites. Nevertheless, FAA is cautious about pilot over reliance on SVS, since its images represent conditions as they were at the time the data was recorded and may not always represent the real world outside.

To illustrate the difference between EVS and SVS, let’s assume you’re flying an aircraft equipped with both systems, approaching a runway on which another aircraft is lined up and awaiting take off clearance. The infrared EVS sensor would detect and display the aircraft on the runway, particularly by its hot exhaust plume. However, the SVS would show an unoccupied runway, since its database memory would not include any objects, such as aircraft and vehicles, which are likely to move.

Incorporating Weather

Then there’s the one thing that every corporate pilot agrees on: Timely and accurate weather information is the staff of life. Fortunately, there’s no shortage today of companies providing uplinked–or, from satellites, downlinked–weather to the flight deck on a fee-paying basis, for presentation on the aircraft’s multifunction display.

Depending on the service provider and, of course, the fees, the weather information is provided in multiple formats, from basic text to graphic, virtually real-time, color depictions of actual conditions en route. (In the early days of data-linked weather system portrayals, some suggested that these offered few advantages to pilots with weather radar. However, the wide acceptance of the data-linked "God’s eye" view of the total weather picture, over many hundreds of miles in all directions, has given the lie to that claim.)

Yet behind all these remarkable flight deck presentations stand equally remarkable design and engineering concepts, which promise to bring avionics systems reliability–and therefore dispatch reliability–to levels never achieved before. Advanced maintenance and diagnostic capabilities will rapidly isolate faults and speed avionics shop repairs, thereby greatly reducing down time.

Similarly, the new software architectures assure system growth to accommodate future requirements, such as controller pilot data link communications (CPDLC), automatic dependent surveillance-broadcast (ADS-B) and required navigation performance/area navigation (RNP/RNAV). These capabilities are still in the development stage but are expected to enter wide operational service in the future.

So the avionics service and support personnel, as well as the corporate pilots, will enjoy the benefits of the new systems. Meanwhile, the airline folks will wonder how they got left behind.

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