Improving air safety by thinking inside the box

 - August 4, 2008, 11:31 AM

It is impossible to ignore the role technology has played in making the art of powered, heavier-than-air flight incrementally safer for the successive generations of aviators who have laid witness to a remarkable 100-year history.

Last year was the safest ever for U.S. airlines, with no fatalities and just nine serious injuries in accidents involving airline flights. Thanks in large measure to the development of advanced avionics such as terrain awareness and warning equipment, traffic collision avoidance systems, enhanced digital moving maps and a host of other advanced cockpit gear in more aircraft, pilot situational awareness has been improved and crew workload markedly reduced.

The lesson is simple: technology can and does save lives. Accident statistics collected by the NTSB show that the trend for the airlines, which has been headed in the right direction for the last several years, coincides with the introduction of new types of cockpit safety systems and federal mandates to carry such equipment. As one example of technology’s ability to tip accident rates toward the safer end of the spectrum, consider that to date there has never been a CFIT accident involving an aircraft carrying an approved terrain awareness and warning system (TAWS)–now required in most new turbine-powered airplanes registered in the U.S. and soon to be mandated in the existing turbine fleet.

There seems little reason to believe that progress toward the FAA’s goal of further improving the safety of commercial air travel in the next decade and beyond won’t continue into the predictable future. Pilots are better trained, equipment is less prone to failure and the tools at the pilots’ disposal are more sophisticated and helpful than ever.

But for general aviation, especially private/pleasure flying by non-professionals, the safety record isn’t nearly as good–some argue that it is downright abysmal and point to a “technology gap” as a major reason accident rates for lighter and smaller airplanes remain disproportionately high.

Some GA pilots have been known to assert that the most dangerous part of their flying isn’t the flight at all, but the drive to and from the airport. While this well-worn axiom may help to ease anxieties of worried passengers, it unfortunately contradicts a sobering reality: close scrutiny of NTSB accident records shows that these types of operation continue to suffer more than their fair share of mishaps when compared with commercial air travel and corporate operation. A leading causal factor in most of these crashes continues to be poor pilot judgment and loss of situational awareness–two areas where technology can serve an important role in helping to improve safety.

Perhaps this helps explain the reason many pilots are so intrigued by the recent certification of a new avionics system that combines a so-called synthetic-vision system (SVS) with highway-in-the-sky (HITS) guidance cues and TAWS. The FlightLogic cockpit from Chelton Flight Systems of Boise, Idaho, is a $75,000 integrated avionics suite developed and priced primarily for the high-performance piston, turboprop and light jet markets. It combines 3-D synthetic-vision views of terrain and obstacles with HITS course boxes and traffic symbology and projects this information on the PFD in front of the pilot.

FAA certification of the system is an important milestone for the company and should clear the way for similar products from other manufacturers in the near future. A subsidiary of the Chelton Group with just 26 employees in Idaho, Chelton Flight Systems was able to obtain a blanket STC for FlightLogic in more than 600 aircraft, the first time the FAA has issued such approval. Wide latitude was given to the company so that its avionics could be used in Phase II of the Alaska Capstone Project, an ambitious evaluation of advanced technologies whereby the federal government provides avionics to commercial aircraft at no cost to test emerging concepts.

The Dawn of Synthetic Vision

Until now Chelton’s EFIS had been flying primarily aboard kit-built airplanes as experimental avionics–but this is about to change. The company is targeting the new TSO’d package to all Part 23 aircraft, which are covered by the blanket STC.
The FAA approval has led to interest (and orders) from a wide array of aircraft owners, including King Air and Citation I and II operators.

Included with the package are a PFD and MFD, each measuring 6.25 inches wide and 5.5 inches high. Remote-mounted equipment consists of an attitude and heading reference system (AHRS), air-data computer and GPS WAAS receiver.

FlightLogic also integrates a Class-C TAWS, which may be upgraded to Class-A or Class-B TAWS (free to the first 300 buyers). It can also interface with traffic and weather sensors, including the Ryan 9900BX traffic awareness system, L-3 Strikefinder/Stormscope, airborne weather radar and WSI’s datalink weather service.

HITS technology is a long-touted idea that never quite got off the ground before now. FlightLogic’s HITS display is simple and straightforward, creating a series of constantly shifting boxes through which the pilot flies to stay on course. As long as the HUD-like flight path symbol goes through the HITS box, the pilot can be assured he or she is right on course.

During a demonstration in Chelton’s Cessna 421, company president Gordon Pratt dialed in the ILS approach to Runway 28 into Stewart International Airport in Newburgh, N.Y., and handed over the controls to me. Flying the approach and full miss with one turn in the holding pattern by hand was a breeze, made so by the HITS cues on the PFD.

On the MFD, a moving airplane symbol traveled around the circuit precisely on course. The flight-path marker on the primary display shows the airplane’s projected flight path corrected for wind and allows the pilot to guide the aircraft through each of the boxes, which tilt whenever a turn is required and rise and descend as altitude changes are called for. At the same time, the PFD displays real-time 3-D terrain modeling, with mountains that shift as the aircraft flies along.

In its normal mode the view of terrain on the display is similar to looking through a wide-angle camera lens, allowing hills and mountains to either side to be more easily seen. Zooming in provides a more accurate view, but with the scene to either side somewhat restricted. Also included on the display are airspeed, groundspeed, altitude, height above terrain, density altitude, vertical speed, angle of attack, heading, decision height, actual winds aloft, crosswind component and OAT.

Pratt calls the technology “virtual VFR” because of its ability to depict a convincing electronic view of the outside world on a flight display. To create its digital surroundings, the Chelton SVS combines an internal database of the earth’s topography, attitude and heading data, and position input from the GPS WAAS receiver (one of the only IFR-certified boxes currently on the market). The result is a video-game-like view of the world ahead of the airplane that pilots find reassuring in bad weather, said Pratt.

Hitting the Nail on the Head

“Those within the FAA who’ve flown the system love it,” he said. “Those who haven’t are skeptical. But that’s not surprising– unless you’ve seen it in action it’s hard to appreciate all the system can do.”

Slowly, FlightLogic has been changing the minds of those who might worry that technology needs reigning in before machines take over. Pratt cited a University of Alaska study in which a 40-hour private pilot with no instrument training and who had never flown an instrument approach was asked to fly a full ILS followed by the missed approach using the Chelton system. Early in the exercise, Pratt said, the instructor noted that the student seemed completely at ease, and for a time even had one elbow resting on the back of the instructor’s seat. “Funny thing is,” said Pratt, “he flew that approach to ATP standards.”

After the approach into Stewart, it took only several minutes in the 421 to reach the first major peaks of the southern Adirondack Mountains, where Pratt demonstrated the system’s TAWS. Terrain on the MFD appears in shades of brown, with yellow and red not displayed unless a potentially dangerous situation exists. This is in contrast to TAWS devices from other manufacturers, which as a matter of course show terrain in red, yellow and green. Otherwise, the Chelton TAWS was similar to other boxes. Pratt said he has heard from Honeywell’s lawyers, who threatened to slap his company with a lawsuit for patent infringement. He added that the U.S. Patent Office has offered an opinion saying that the Chelton TAWS is sufficiently different from Honeywell’s Enhanced Ground Proximity Warning System that it does not infringe EGPWS patents. Honeywell has filed lawsuits against three other competing makers of TAWS avionics.

The system’s navigation display contains a moving map that uses Jeppesen NavData. The map shows flight path and terrain that is near or above the aircraft’s current altitude. Unique features of the moving map are a horizontal projected path showing a wind-corrected track of the aircraft one minute into the future and a dead-stick glide area depiction that is constantly corrected to account for turns, wind and terrain. A conventional HSI/ RMI presentation is also included on the nav display.

The system’s displays have been designed to minimize the information density on the screen by setting priorities and limiting the information that is to be shown. “Unusual Attitude” mode, for example, automatically declutters the screen when the aircraft exceeds 25 degrees pitch up or down. This reduces the time it takes for the pilot to recognize the appropriate corrective action.

Yingling Aviation in Wichita this past spring installed the first FlightLogic package in a Cessna Caravan for a private owner in Taiwan.