Let's look at FAA's final rule on EFVS use published Dec 13, 2016

Evaluation took time but now ruling lets you land straight in with EFVS in lieu of out-the-windscreen visibility if you have approved equipment, training and LoA or Ops Spec.

By Bill Gunn
ATP/CFII. Pro Pilot Regulations
& Compliance Specialist

FAA's final rule on EFVS will permit descent to touchdown without outside visual references.

The FAA published the final rule on enhanced flight vision systems (EFVS) on December 13, 2016.

This proposed change to EFVS use when landing had a long gestation period and brings numerous changes to the rules as well as how EFVS may be used in the landing and takeoff phases of flight.

History of civil CVS, EVS and EFVS

FAA currently defines EFVS in FAR 1.1 as an electronic means to provide a display of the forward external scene topography (the natural or manmade features of a place or region especially in a way to show their relative positions and elevation) through the use of imaging sensors, such as a forward looking infrared, millimeter wave radiometry, millimeter wave radar, [and] low light level image intensifying.

Enhanced vision systems (EVS) can be viewed heads down or heads up without necessarily displaying flight data. An EFVS is the combination of EVS and a head-up display (HUD) which includes all basic flight symbology. Combined vision systems (CVS) include synthetic vision (a computer-generated image from a database) in an EVS or EFVS.

Elbit Kollsman's was the first EVS certificated in Gulfstream V aircraft in 2001. This EVS displays imagery from a cooled forward looking infrared (FLIR) camera through a HUD. Several other CVS/EVS/EFVS receivers and HUD units have been developed since.

In 2004, the FAA revised FAR 91.175 adding parts (l) and (m) to permit descent to 100 feet above the touchdown zone elevation (TDZE) using EFVS for runway environment acquisition. Although the EFVS has to be certificated in the aircraft, 91.175 does not mandate training requirements, system use currency or crew proficiency requirements for a Part 91 operation beyond basic familiarity requirements in Part 61.

Additionally, 91.175 does not address EFVS use to benefit Category II or III approaches. System certification of EFVS or EVS for each airframe under the 2004 rules has been slow as there are no uniform airworthiness standards for these systems, but this new final rule addresses all of these issues.

91.175 today

Since the 2004 rule covering EFAS for approach, technology has advanced extensively, and the requirements of 91.175 limit this growth. Part (l) of 91.175 states:
Approach to straight-in landing operations below DH, or MDA using an enhanced flight vision system (EFVS). For straight-in instrument approach procedures other than Category II or Category III, no pilot operating under this section or §§121.651, 125.381, and 135.225 of this chapter may operate an aircraft at any airport below the authorized MDA or continue an approach below the authorized DH and land unless—

(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and, for operations conducted under Part 121 or Part 135 of this chapter, the descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

(2) The pilot determines that the enhanced flight visibility observed by use of a certified enhanced flight vision system is not less than the visibility prescribed in the standard instrument approach procedure being used;

(3) The following visual references for the intended runway are distinctly visible and identifiable to the pilot using the enhanced flight vision system:
(i) The approach light system
(if installed); or
(ii) The following visual references
in both paragraphs (l)(3)(ii)(A)
and (B) of this section:
(A) The runway threshold, identified by at least one of the following:
(1) The beginning of the runway
landing surface;
(2) The threshold lights; or
(3) The runway end identifier lights.
(B) The touchdown zone, identified by at least one of the following:
(1) The runway touchdown zone
landing surface;
(2) The touchdown zone lights;
(3) The touchdown zone markings; or
(4) The runway lights

Part (l) (4) of 91.175 then outlines the natural visual cues through the windscreen required to continue to touchdown at 100 feet above the TDZE. Further, 91.175 only requires that domestic Part 91 operators meet the training and familiarity requirements of Part 61. It also requires foreign operators to meet their own country's requirements for EFVS use when flying in the US NAS. And other operators (Part 121, 135, etc) must meet their approved operating specifications. FAR 91.175 does not permit EFVS use as a sole reference to touchdown.

New rules added

Profile depiction of 91.175. Cat I straight-in approaches may only descend to 100 ft above the TDZE when EFVS is the sole reference. The last 100 ft require positive outside visual acquisition to continue to the runway. This new final rule will permit EFVS use all the way to touchdown.

FAA has created 91.176 to encompass EFVS as a sole reference to touchdown. Additionally, 91.175 (l) will move to 91.176 to address EFVS as a sole reference to 100 feet above the TDZE. Advisory Circulars 90-106A and 90-176A are the revised ACs dealing with EFVS use and airworthiness approval.

FAR 1.1 will add a definition for EFVS operation, described as an operation in which visibility conditions require an EFVS to be used in lieu of natural vision to perform an approach or landing, determine enhanced flight visibility, identify required visual references, or conduct a rollout.

Additionally, the definition of an EFVS system will be slightly revised. And FARs Parts 23, 25, 27 and 29 will be revised with respect to pilot compartment view dealing with vision system displays. It is noteworthy that the revision to the compartment view is stated as …such as a heads up display, head mounted display, or other equivalent display… which allows for new technology (other equivalent display) and the civilianization of previously military display systems (head mounted display).


1 | 2 |