The Glass Revolution

No one would call them cheap but primary flight displays with solid-state gyros are now real hardware.

Its not a pretty sight to watch a grossly non-current pilot try to keep an airplane upright on instruments, never mind actually fly an approach. The problem is usually two-fold: his basic instrument scan is shot and if there’s any mental bandwidth left over, it wont be enough to run the radios and set up the navs.

Minor advances in panel instruments-chiefly the HSI, the ADI/flight director and the advent of the T-layout have helped but filtered through the eyes of an industrial designer, even modern flight instrumentation is hopelessly antiquated. It requires the abstract information from six instruments just to fly headings, maintain altitudes and navigate courses. The concept hasnt changed appreciably in 60 years, a lack of progress thats blamed for accidents and, in part, slack sales of airplanes.

As the new century progresses, were suddenly seeing the long-promised technology thats supposed to change all this, the much vaunted PFD or primary flight display. On the one hand, our reaction is: its about time. On the other, this stuff is expensive, even though industry insiders expect it to decline in price as the volume increases.

If youve got the wallet for it, however, the PFD is real technology. You can buy at least one system now and a couple of others will be certified within a year to 18 months. In this article, we’ll survey whats available now or soon to be available. In future issues, beginning with the Avidyne system, we’ll present detailed flight reports on each product.

PFD Defined
The term primary flight display has come to mean any device that combines disparate instrument displays on a single screen of some kind, be it a flat panel or cathode ray tube. The first widespread use of PFDs for civil use was in the original glass cockpit airliners of the late 1980s, which used cathode ray tubes to combine the basic gyro flight instruments: attitude indicator and heading indicators, into integrated displays. This technology found its way into general aviation bizjets but was far too costly and large to shoehorn into anything smaller.

A fortuitous intersection of technologies has made the PFD practical and somewhat more affordable for light aircraft. First, thanks to the computer industry, flat panel active matrix LCD displays have become better, lighter and cheaper and have displaced the CRT for light aircraft use.

Second, thanks to the automotive industry, the solid state gyros, accelerometers and pressure transducers necessary for the sensors which drive a primary flight display are now nearly mass market devices.

A clarification of terms here: some companies call the remote gyro box an ADHRS for attitude and heading reference system while others use the acronym ADAHRS, to add air data input to the attitude and heading mix. Regardless of what its called, the boxes do essentially the same thing.

Although the ADHRS are the most expensive single component of the system, automotive volume has made these devices reachable for owners of GA aircraft. (Reachable in this context means a total system costs between $50,000 and $100,000 for a certifiable system.)

And speaking of certification, the FAA has now accumulated enough experience with glass PFDs to make certification of them a realistic goal for companies smaller than, say, Boeing or Honeywell.

Still, many companies will face daunting costs as they try to obtain supplemental type certificates for retrofits. For that reason, the initial target market for these devices will be turboprops and high-end piston singles and twins and new aircraft in the single piston-engine realm.

Nonetheless, were sure more than a few moneyed owners will find a way to install them in even mid-price piston singles, but this wont comprise the majority of the PFD market.

The first new single to be certified with a PFD may be the Cirrus SR22, which will be available sometime next year with Avidynes new Entegra PFD. Lancair has also announced plans to certify the Entegra PFD.

Different Strokes
Although certification hoops shape the design of most avionics, the PFDs weve seen thus far exhibit a surprising amount of variation. S-TEC/Meggitts Magic system, for example, is a conservative, electronic rendering of conventional electromechanical instruments. At the opposite end of the developmental spectrum are systems from Chelton and Goodrich, both of which employ the oft-mentioned synthetic vision/highway-in-the-sky or SV/HITS display proposed by NASA and developed under contract by Avidyne and AvroTech. With color sky/ground displays and three-dimensional perspective symbology, this is true cutting edge stuff.

In between is Avidynes Entegra system, whose attitude display features a vivid blue/brown color scheme with military-style tape indicators for airspeed and altitude but without the HITS fly-through-the-windows 3D display.

Further, at the moment, it looks as though each company offering a PFD to the general aviation market will tweak its marketing plan to reflect its own strengths.

S-TEC/ Meggitt, for instance, is a marriage of a flight instrument and an autopilot company so its logical that its PFD should have an autopilot to go with it and thats exactly what the Magic 2100 Digital Flight Control System is. You can buy just the PFD itself but the autopilot is designed specifically to work with the display technology.

Building on its strength as a supplier of multi-function displays, Avidynes Entegra is based on a pair of flat screens, one for the flight display, a second for a navigation map/multi-function display that will take advantage of Avidynes expertise in integrating airborne weather radar and datalink into a single display.

Did we mention Garmin? No, not yet. Garmin doesnt yet have a horse in this race but we expect it soon will. Last November, Garmin bought the assets of Sequoia Instruments, Inc., a research company that had developed the ADHRS technology Garmin will need for its own PFD. Garmin is mum on details and schedule, but we expect to see something from them in a year or two. Our guess is that it will be an entirely new display technology and not some kind of an add-on module for the popular GNS530.

Avidyne Entegra
At this years EAA AirVenture, we were somewhat startled to see a Cirrus SR22 equipped with a largish flat screen where the conventional flight instruments would normally be, with three steam gauges along the lower lip of the panel. We knew Avidyne had this system in the works but, frankly, we didnt expect it so soon.

The Entegra system consists of two, side-by-side flat screens, each 10.7 X 8.5 inches. The screens can be purchased in either horizontal or vertical format, to suit the aircraft. In the Cirrus, the right screen occupies the center of the panel and is essentially the same EX5000 MFD thats standard equipment in both the SR20 and SR22.

The primary flight display is placed front and center in the pilots view and has a split screen containing an attitude direction indicator-EADI in PFD-speak-on top and an EHSI on the lower portion of the screen. The EADI consists of a brown, earth-tone background with a blue sky above it. Overlayed on this are the basic attitude display, with pitch and roll angles and tape indicators for airspeed and altitude, plus six-second trend indicators for airspeed, altitude and heading. Although it was instrumental in developing it, Avidyne chose not to use the HITS symbology on its inaugural PFD but will use it in future iterations.

The Entegra PFD is entirely self-contained in the display unit which resides in front of the pilot, including the ADAHRS solid-state gyro, heading and air data system, which is a box small enough to easily fit into the palm of your hand. Its plumbed with pitot/static sources to provide air data input.

The beauty of single-box design is installation, of course, especially for new aircraft such as the Cirrus SR22. The PFD merely needs power, data from a GPS for position and the pitot/static plumbing and its ready to go. Other systems use remote ADAHRS boxes wired into the flat panel displays. There are pros and cons for each design strategy. Remote mounting gives more options in tight cockpits but the necessary wiring runs increase cost and decrease reliability.

Avidyne has identified its primary target market as new aircraft, from sophisticated singles on up and turboprops of all ilks. Not that it wont support retrofits in older piston aircraft, but one-time approvals for any of this equipment will be enormously expensive. As the retrofit market inevitably develops, Avidyne will support refit centers that specialize in the kind of major upgrade the Entegra represents.

And make no mistake, this is a major upgrade. In the Cirrus SR22, the Entegra will replace most-but not all-of the conventional flight instruments, so the upgrade cost is relatively reasonable as upgrades go: it will be a $24,500 option on an aircraft retailing for about $320,000.

For the retrofit market, Avidyne says the Entegra system will sell for about $60,000, not to include external sensors and GPS sources. As currently construed, the system is highly integrated with Garmins 400 and 500 series navigators.

S-TEC is we’ll known and we’ll regarded for its line of autopilots so when the United Kingdom-based Meggitt Avionics bought S-TEC, it was a natural fit that soon bore fruit.

The S-TEC/Meggitt Magic system was the first certified primary flight display for small aircraft to hit the market, arriving as standard equipment in Pipers Meridian single-engine turboprop about 18 months ago. It has since been approved for the 35-series Bonanza, Piper Mirage, Citation I and II and Twin Commander.

Other approvals are in the works but we don’t expect rapid development of STCs in the piston-single market. This system is primarily for turboprops and perhaps sophisticated piston twins. (That said, the Magic system is flying in a Cessna 182 demonstrator and AOPA installed it in a Bonanza for promotional purposes.)

As noted, the S-TEC/Meggitt Magic is a conservative design approach; no fancy HITS display, no 3D symbology, just the basic flight displays. In that sense, its reminiscent of the early glass displays in Boeing airliners, but vastly cheaper.

The Magic system has two screens, mounted vertically. The top is the primary flight display, with a basic ADI and flight director, bank-angle indicator rolling digit tapes for airspeed and altitude, glideslope and localizer needles and basic trend indication for altitude.

The lower screen is an EHSI, which S-TEC/Meggitt calls an ND or navigation display. The ND has three modes: HSI, arc and map. The HSI has standard functions for that instrument, including rudimentary digital nav information, such as course selected and DME distance.

The arc and map view-which can be selected at will-depict course and flightplan details, plus some airport symbology. These displays arent nearly as rich in detail as is an MFD, say the UPSAT/Apollo MX-20, but its assumed that a larger map elsewhere in the cockpit will carry that additional map detail.

The cost of the Magic system-hardware only-is currently $53,900 for a three-box system, the two displays and the remote ADAHRS to drive it. For a single-side set-up, certification doesnt require electrical redundancy because, as noted in the sidebar at left, virtually all of these systems will be backed up with conventional instrumentation.

The Magic system will also have a glass engine instrument package called a EIDS for engine instrument display system. Although most of us would kill to have this level of instrumentation in a piston airplane, alas, the Magic EIDS is for turboprops only.

Chelton FlightLogic
Another Brit company not familiar to most American aircraft owners is Chelton, an aerospace conglomerate with products in most sectors of the aircraft business.

A year ago, following the same strategy Meggitt has employed, Chelton bought Boise, Idaho-based Sierra Flight Systems, a start-up company specializing in ADHRS and PFD technology. At the time, Sierra was pursuing PFDs for the experimental market but has now switched gears, angling for both spam cans and homebuilts.

Cheltons certified PFDs will be marketed under the brand FlightLogic while the experimental systems will be sold under the Sierra Flight Systems nameplate. Sierra has about 50 to 60 systems in use, all in experimental aircraft, mostly Lancairs. Cheltons FlightLogic systems are being certified on roughly the same time line as its competitors-next year sometime-but its unique in that it will deliver the SV/HITS display right from the start.

Further, the FlightLogic system is unique for including its own IFR-certified GPS-including approaches-along with the PFD system. Once WAAS is approved for GPS sole means, all you would need for legal IFR flight would be comm radios.

The ADAHRS, of course, is plumbed into the aircraft pitot-static system and as noted on page 24, steam gauges will provide the back-up unless youre willing to provide a redundant ADAHRS system.

Like the others, the FlightLogic is a two-display system, the SV/HITS on top of what basically serves as an EHSI/MFD type display. (The displays can also be mounted left or right.)

The lower screen can cycle through various views such as a birds-eye map, an arc view nav display or a standard EHSI and it can also duplicate the SV/HITS display. However, the top PFD cant be view cycled by the pilot; it serves only as the primary attitude flight display.

Although we couldnt fly it for this report, weve seen the FlightLogic SV/HITS demonstrated and were impressed with it. The basic highway display shows a course line in three dimensions and a series of five skyway boxes through which the pilot flies the airplane.

The boxes are drawn in vanishing point perspective and increase in size as distance to them decreases, giving the powerful three-dimensional speed and attitude cues thats supposed to make HITS a hit.

From an external traffic avoidance sensor, aircraft threats are also displayed three-dimensionally, as is local terrain, which is depicted schematically from a terrain database.

FlightLogic is expected to sell in the $60,000 to $70,000 range, making it comparable with other PFD offerings.

Goodrich SmartDeck
One of the first PFDs to show up full-blown at Oshkosh a couple of years ago was Goodrichs SmartDeck, another SV/HITS design. When it first appeared, we gave it short shrift because we thought it would be years in development and then only applicable for turboprops and jets. Okay, so we were wrong.

Schedule wise, Goodrich appears competitive with the other major contenders, with products to be available in late 2003. It may be even more competitive in price; a Goodrich spokesman told us SmartDeck will sell for under $50,000 with a target market of light turboprops, piston singles and twins. It will be marketed to new aircraft first, with retrofits to follow.

Goodrich is taking the same tack as Avidyne on the display; no SV/HITS for the launch system but this will become available later. Borrowing a term from the computer industry, SmartDeck will be highly scalable says Goodrich, meaning it will be specifically designed to work with an array of remote sensors, including Goodrichs own Stormscope, Skywatch traffic avoidance equipment, radar, datalink and ground prox systems, with terrain displayed in three dimensions.

Although Goodrich isn’t saying as much, we wonder if we’ll be seeing three-dimensional Stormscope dots overlayed on NEXRAD radar images. The possibilities are intriguing.

When we first learned of primary flight displays being proposed for light aircraft, our reaction was: fat chance. Too expensive, too big, too complex. Even ahead of delivering the first system, these companies have proven that view wrong. These systems are real hardware and soon to be certified. We wont be surprised to see them as standard OEM equipment within five years. Counting Garmins entry, there are five serious contenders with more on the way.

Plan on installed prices between $50,000 and $70,000. That may sound like an absurdly large sum but as a percentage of the total cost of a new airplane, we don’t see it as a huge hit when you factor in the cost of the instruments and/or displays the PFD may replace.

As for retrofits in older aircraft, PFDs will find their way into these cockpits for two reasons: one, some owners can afford and will pay $60,000 to have one and second, all the players in this market agree that the cost of certified PFDs will decline with increasing volume, especially as the solid-state ADAHRS become cheaper.

Thus far, we think the two leaders in the light aircraft retrofit market will probably be Avidyne and Chelton, pending what Garmin has up its sleeve. Avidyne has a respectable marketshare in MFDs and thus experience in retrofits and Chelton, with its experimental systems, has the most systems flying.

And of all the displays weve seen thus far, weve been most impressed with Cheltons SV/HITS. we’ll publish more detail in a future flight report on all of these systems.

Also With This Article
Click here to view “Steam Gauges: Theyll Be Around.”
Click here to view “Addresses.”