GAMECHANGER FAR 91.176

Landing without natural vision

FAA's new authorization permits touchdowns for aircraft using approved EFVS.

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


Landing with Enhanced Flight Vision (EFVS) enables the pilot to see the required visual cues in low visibility. FAA's historic announcement of a new regulation furthers the operational benefit of the technology.

Enhanced Flight Vision Systems (EFVS) have always been intended for one purpose—the elimination of low visibility in flight operations. After Jimmy Doolittle's famous 1929 blind flying experiments, he said pilots needed an invention that would see in bad weather with "penetration of fog by light rays."

But even with such a device, he would have needed an FAA operational regulation to let him use it. And now 70 years later a real flying regulation has emerged that will allow pilots to land with technology that sees through fog similar to what Doolittle dreamed of.

This past July the FAA published a proposal for a new instrument approach regulation that will "permit operators to use an Enhanced Flight Vision System (EFVS) in lieu of natural vision to continue descending from 100 feet above the touchdown zone elevation to the runway and land."

And for commercial operations the FAA will "permit certain operators using EFVS-equipped aircraft to dispatch, release, or takeoff under IFR, and to initiate and continue an approach, when the destination airport weather is below authorized visibility minimums." The new regulation is historic, and may be a challenge for OEMs and avionics suppliers to reach the full potential of the new operation.

In fact aviation may soon witness something akin to the space race, with avionics companies competing for supremacy in EFVS technology. And this race will also open the doors to new suppliers of vision based technology, challenging even those around since Doolittle.

This operational rule is for all aircraft and operations, from rotorcraft, Part 135 operation, 91K and Part 91 as well as the airlines. And, although not discussed much in public, remotely piloted air vehicles will no doubt be early adopters as well. Ultimately, this means that you the pilot could soon see in every day practice EFVS operations for night, smog, smoke, clouds and zero visibility in fog.

History of EFVS development

New EFVS technology is under development by Sierra Nevada Corporation (SNC). Shown here is a new 94GHz imaging radar sensor that penetrates practically all low visibility and fog. SNC flight testing has been ongoing in both fixed wing and helicopters.

This idea was debated early on, and much of the early concept work was sponsored by Fred Smith at FedEx (the Magic Window Program). But in 1998, Gulfstream and Kollsman ventured forward with the FAA in Los Angeles and certified the first EFVS on the Gulfstream V. The FAA's first steps with regulations to support the technology came soon after, led by Les Smith in Washington DC, a former Coast Guard and long haul pilot.

Published in January of 2004, this rule allowed pilots with "Enhanced Flight Vision" (an original FAA term) to continue the approach from the published minimums using a vision sensor to 100 ft, where a transition to natural visual cues was needed to land. If you can see at minimums with EFVS or an equivalent magic flashlight, then legally you can proceed into the visual segment.

FedEx became the world's first air carrier with EFVS technology. And Bombardier and Dassault have now made their own mark of distinction with the use of vision systems. These tools have expanded the operational boundaries of their aircraft and introduced a new range of safety features for night, IFR and an amazing new instrument cue called the Flight Path Vector.

Competing with Kollsman, Esterline CMC Electronics' sensor developments now include a new high definition IR sensor that is used with Bombardiers Global Vision aircraft. CMC's products are also on Falcons and the BBJ. Many in the industry expect to see fusion developments with all the sources of imagery and data available to the flightdeck to eliminate any question of the aircrafts situation in terrain, on approach and even in low visibility taxi operations.

Bombardier was the first to certify Synthetic Vision Systems (SVS) on a HUD for situational awareness. Dassault's flightdeck concepts included the world's first Bizjet CatIII HUD and later with EASy II flightdeck and EFVS, a complete forward thinking view of flightdeck design. Kollsman passed the 1000th EVS II system delivery at NBAA 2012 and is the first supplier to an airline with its deliveries to the FedEx fleet.

Taking a look at FAR 91.176, the new EFVS rule

CVS or Combined Vision Systems being developed by Honeywell integrates the modern flight instrument with EVS to enable a greater range of options for vision based flightdecks.

New EFVS regulations are aimed at furthering the operational utility of vision systems for all phases of flight. A team led by Terry King at FAA in Washington D.C. has developed the new FAR 91.176 specifically to address the approach, landing and rollout, and has no limit of visibility to the operation—this is performance based. In fact the FAA even updated Cat II and Cat III operations (FAR 91.189) to permit the use of EFVS.

Hallmarks of the FAR 91.176 operational rule is that it allows landing with EFVS, but also address other practical issues. For operators that need it, the new rules will also permit EFVS-equipped aircraft to be dispatched, released, or to initiate a flight when the reported or forecast visibility at the destination airport is below authorized minimums
(§§ 121.613, 121.615, 125.361, 125.363, 135.219).

Most significant to commercial operators is the ability to initiate or continue an approach when the destination airport visibility is below authorized minimums (§§ 121.651, 125.325, 125.381, 135.225).

The world stage has also begun to weigh in on EFVS operations, with ICAO forming a panel recently that included members from the US, Australia, Sweden, Germany and the UK. An amendment to ICAO's Annex 6 features details for EFVS, Combined Vision Systems (CVS) and SVS technology. This ICAO Annex 6 amendment provides the rest of the world with an explanation of EFVS and other technologies and their operational value.

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