Clearing the way forward to zero-zero operations

FAA and EASA execs, test pilots, scientists and engineers move closer to EFVS 0/0 landings.

By Glenn Connor
Pres, Discover Technology Intl ATP, Cessna 425

Dassault Falcon 50 lands as early morning fog lifts at MLI (Moline IL). Industry and regulators are developing new standards for vision systems operating in low visibility at most airports with published instrument approaches and vertical guidance.

Landing when the pilot cannot see was a fundamental barrier to aviation in the 1920s. This visibility barrier was so big that the practical commercial uses of the airplane were limited. The development of cockpit instruments and moving dials then led to what became known as blind flying.

But you would think that having to call any operation in aviation “blind flying” may be (at least metaphorically) somewhat limited when it comes to landing. Not to be constrained by reality, old action serial movies during the same time frame like Flash Gordon and Buck Rogers saw a different future—one where the pilot looked at a viewing device, able to see their flightpath even without a front window.

And now it seems this future vision is about to be standard fare in the newest bizjet flightdeck programs. The vision barrier was breached with the first enhanced flight vision systems (EFVS) certified in 2001 by Gulfstream and Kollsman, followed by Bombardier in 2005 and FedEx in 2008.

This new operational capability is also a result of a change of FAA regulations that allowed the use of “electronic means to see” as described in FAR 91.175 (l) and (m), and the certification of a sensor that could see in fog. FAA has also become aggressive in terms of helping to define the benefit of new flightdeck technology.

Many times a flight department sees a new widget for the boss’s airplane which has obvious advantages (to us), but a problem when communicating to management. For at least the NextGen avionics road map, there is an understanding by FAA that investment in new flightdeck technology has to have a definitive value.

To put an exclamation on this point, FAA spoke out at NBAA 2008 and said that it had:

The specific group, designated RTCA Special Committee 213, is made up of many of the world’s leading engineers and test pilots on the subject. The group’s current tasking is to define the road to zero/zero operations with vision technology, focused first on vision system operations for landing in 1000 ft RVR.

From the regulatory agencies, leadership of this group comes from FAA, EASA and NASA—not a fringe eccentric segment of mad scientists. The plan for the new EFVS operations is for airports with a published instrument approach with vertical guidance and limited to less than 10° offset.

The airport visibility requirement for this operation may be reduced to either 1000 ft RVR at airports with a transmissometer, or if no transmissometer is available then 1/4 mile visibility (equal to 1600 ft RVR) reported.

Landing with EFVS would be permitted—an expansion of the EFVS operations today that require the pilot to transition from EFVS to visual cues at 100 ft in order to continue the approach and land.

In addition to the new EFVS operations, reviews are also being conducted to investigate the potential of EFVS on a head-down display, and to what operational credit can be given for synthetic vision systems (SVS).

SVS operations

Rockwell Collins Pro Line Fusion developments, including SVS and advanced taxi and runway alerting systems, are shown in this lab in Cedar Rapids IA. SVS developments at Rockwell Collins include the study of details such as runway surface microtexture and use of detailed terrain and flight instrumentation.

The issue for SVS is getting operational credit. Specifically, can you get lower than standard minimums using an SVS display for the approach? The obvious advantages of SVS when making an approach are that the digital terrain image will remain on the pilot’s display no matter how bad the visibility is outside.

The HUD-like symbology overlaid on the SVS displays now used also integrates flight guidance and a synthetic image of the outside world, making it difficult for even the least experienced pilot to become overwhelmed in low visibility.

In fact, the use of SVS as the PFD is becoming standard in most new aircraft, and both Rockwell Collins and Honeywell have put into place programs that provide aftermarket upgrades that include SVS PFD capability.

FAA defines synthetic vision as “a computer-generated image of the external scene topography from the perspective of the flightdeck, derived from aircraft attitude, high-precision navigation solution, and database of terrain, obstacles and relevant cultural features.”

FAA and the industry have formalized the vision aspect of SVS by stating, “A synthetic vision system is an electronic means to display a synthetic vision depiction of the external scene topography to the flight­crew.”

Accuracy, pilot ease of use and maneuvering with a perfect picture of the terrain are highlights of the SVS technology. But the functional value of SVS displays is similar to the step increase made with a flight director over raw localizer and glide­slope.

In days of old, the combination of flight director and attitude indicator made it less stressful, and resulted in a more accurate approach. The accuracy and quality of the SVS PFD are designed to assure the pilot that clearance from the ground and arrival within the lateral confines of the runway is going to occur on a regular basis.

The debate now centers on how low FAA will venture, and with which combinations of aircraft systems. Another aspect of SVS that will be of interest to bizjet aviation is when it is combined with EFVS on a HUD. Several manufacturers have programs in the works for SVS on a HUD.

The Rockwell Collins Pro Line Fusion program for Bombardier is on track for the Global Vision flightdeck, and Honeywell seems intent in its efforts to lead rather than follow, so the competition is on.

At NBAA 2009 Rockwell had a functioning HUD with SVS, displaying the concept of operations alone. The obvious benefits of SVS and EFVS are that the 2 technologies together provide a view of the area you are navigating over 100% of the time.


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