EFVS DEVELOPMENT

Clearing the way forward to zero-zero operations

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


Gulfstream demonstration of EFVS (top L) compared with unaided view (top R), and SV-PFD (bottom L) versus standard PlaneView display on PFD (bottom R). When displayed on the HUD the EFVS image includes flight symbology.

As you approach minimums, the EFVS sensor can be used to allow you to “see” to continue the approach. And under the new operational concept being developed you could land with EFVS. The SVS image database, driven with a high degree of navigational accuracy by GPS/WAAS or combined with the INS could ensure at least WAAS positional assurance.

The lateral accuracy of WAAS was originally contracted by FAA for a minimum of 7.6 meters, but industry tests show an average of 1.5 meters laterally is a more typical value. So having a digital terrain image that includes the position of the runway using SVS is a far better use on a PFD instead of the voltmeter concept developed in 1929.

Advanced vision testing

NASA Langley’s work in this area, led by Randy Bailey, Lynda Kramer and Lance Prinzel, has become the definitive work on SVS in the US. In simulation and flight trials NASA has evaluated display sizes, visual data requirements and pilot performance improvements for approach, landing and taxi in low visibility with SVS. NASA also evaluated combined vision system concepts on a HUD.

Tests of specific cases for information content in the SVS, as well as field of view issues, have also been evaluated. Most recently a series of small scale demonstrations and briefs by industry is also being done for SVS operations, led by industry experts from Garmin such as Test Pilot Tom Carr and Engineer Merlin James, Rockwell Collins’ Tim Etherington and RTCA Co-Chair Theo Feyereisen of Honeywell, and Universal’s Patrick Krohn. This industrywide collaboration is boring down on new uses of SVS in all phases of flight.

XVS testing

RTCA Special Committee 213 EFVS/SVS members and affiliations. (L–R) Bruce Mahone (SAE), Lynda Kramer (NASA), SC 213 FAA Leader Lou Volchansky (FAA), Gerard Holtorf (SAIC), Richard Jenkins (Rockwell Collins) and SC 213 Co-Chair Tim Etherington (Rockwell Collins).

The testing of vision technology for landing and taxiing is also being fully vetted by OEMs. A recent external vision system (XVS) test program by Gulfstream and NASA was a demonstration using a HUD and high-definition camera as the means to fly and land based on EFVS-like visual maneuvers.

In the covered cockpit of a NASA Mc­Donnell Douglas F18, Gulfstream Test Pilot Gary Freeman, who led the flight test and certification of enhanced vision, flew a series of day and night visual maneuvers.

These same tests also included FAA and NASA pilots verifying the results. The NASA and Gulfstream tests have also been briefed to the US/European industry working the EFVS and SVS standards as part of the discussion on new landing operations with EFVS.

Related work has also been done in Europe by the German Aerospace Re­search Labor­atory (DLR) on a range of simulation efforts, focused more on EFVS and SVS for head-down displays.

Landing with EFVS

Regulatory support behind the vision technology programs in the US for EFVS and SVS is built around the NextGen avionics road map.

This plan, stimulated by the success of the avionics industry and bizjet OEMs, has defined both goals and benefits for vision technology. These include low visibility/ceiling approach operations, low visibility and ceiling landings, takeoffs, even surface movement guidance for scheduled air carriers.

The ultimate goal is what is now called EVO, or maintaining a VFR-like tempo in IMC. FAA’s basis for this new procedure begins in its official definition of EFVS. FAR Part 1 says EFVS is “an electronic means for a pilot to see the forward field topography, natural or man-made.” So extension of the current EFVS procedures to landing seems to be the correct next step.

EFVS operational improvements will also soon focus on lower takeoff minimums—possibly as low as, say, 300 ft RVR—and taxi and surface movement in very low visibility. FAA efforts in new rulemaking for EFVS are also moving in several areas, including a planned operational exemption for NetJets and FedEx, and are expected to provide expanded operations for EFVS similar to that in Europe.

Pilots and engineers from around the world are part of SC 213, including (L–R) Lowell Foster (FAA), Tom Horne (Gulfstream), Thea Feyereisen (Honeywell), Mark Humphreys (FAA), Terry Neal (UK CAA) and Merlin James (Garmin).

In 2008, EASA approved a 1/3 visibility credit for enhanced vision operators. Rather than get stuck holding, if you are EFVS equipped and trained you can begin a standard Cat I (1800 ft RVR) approach in reported visibilities down to 1200 ft RVR. At minimums you must (under current rules) see with EFVS or natural vision to continue the approach, and at 100 ft you are still required to transition to visual cues for landing.

From a pilot’s point of view landing with EFVS is no different than current visual procedures. During the landing phase the pilot flying will use the HUD to see with EFVS and maneuver based on aircraft instruments and guidance and the visual scene, either EFVS or natural.

Crossing the runway at 50 ft (HAT) you would see most the entire ground segment needed to flare and land with natural vision anyway because of the 1000 ft RVR normal visibility required. Aided by HUD symbology such as the flightpath vector and the EFVS sensor, it is really a non-event—it only frightens those who have not seen it and the autoland societies.

International elements of SC 213 include (L–R) Kerry Doherty (Esterline CMC Electronics), Co-Chair Patrick Krohn (Universal Avionics), Frans van Gorkum (EASA), Dror Yahav (Elbit) and Mike Abrahami (Israeli Ministry of Transportation).

The ultimate test for these flightdeck technologies is that it must perform its “intended function.” Confidence is high by regulators and manufacturers that the phase for EFVS for landing and operational credits for SVS will be in place soon.

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