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the flight information, navigation guidance, and sensor imagery on a HUD or equivalent display allows the pilot to continue looking forward along the flightpath throughout the entire approach, landing, and rollout. 

Sections 91.175(c) and 91.176 specify two means of operating visually below DA/DH or MDA in the visual segment of an IAP. One means is by using natural vision under § 91.175(c), and the other is by using enhanced vision provided by an EFVS under § 91.176. When the runway environment cannot be visually acquired using natural vision, a pilot may use an EFVS to continue descending below DA/DH or MDA under § 91.176. An EFVS operation is 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. There are two types of EFVS operations – EFVS operations to touchdown and rollout and EFVS operations to 100 feet above the touchdown zone elevation (TDZE). An EFVS operation to touchdown and rollout is an operation in which a pilot uses the enhanced vision imagery provided by an EFVS in lieu of natural vision to descend below DA or DH to touchdown and rollout [Figure 4-10B]. These operations may be conducted on standard instrument approach procedures (SIAPs) or special instrument approach procedures (IAPs) that have a DA or DH (e.g., Precision or APV approach). 

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An EFVS operation to 100 feet above the TDZE is an operation in which the pilot uses the EFVS in lieu of natural vision to descend below DA/DH or MDA down to 100 feet above the TDZE [Figure 4-10C]. To descend below 100 feet above the TDZE, however, natural vision must be used. EFVS operations to 100 feet above the TDZE may be conducted on SIAPs or special IAPs that have a DA/DH or MDA. 

While the regulations do not prohibit EFVS from being used during any phase of flight for situational awareness, EFVS displays are not designed, installed, certified, or intended as a sufficient visual system to conduct circling maneuvers. EFVS may only be used during a circle-to-land maneuver provided the visual references required throughout the circling maneuver are distinctly visible to the pilot using natural vision throughout the circling maneuver. Therefore, 

an EFVS cannot be used to satisfy the requirement that an identifiable part of the airport be distinctly visible to the pilot during a circling maneuver at or above MDA or while descending below MDA from a circling maneuver. 

The visual information provided by an EFVS serves as independent verification of the position information provided by the aircraft’s displays and systems. An EFVS also enables a pilot to assess the enhanced flight visibility and identify required visual references, helps a pilot align the aircraft with the runway, and provides position, roll, rate of closure, and distance remaining information. Sections 91.176(a) and 91.176(b) permit a pilot to use an EFVS to identify the required visual references and to determine that the enhanced flight visibility provided by the EFVS is not less than the visibility prescribed in the IAP to be flown. Both the visual reference and enhanced flight visibility requirements of the regulations must be met before the pilot can descend below DA/DH during an EFVS operation to touchdown and rollout or below DA/DH or MDA during an EFVS operation to 100 feet above the TDZE. The aircraft also must continuously be in a position from which a descent to landing can be made on the intended runway at a normal rate of descent using normal maneuvers. For EFVS operations to touchdown, § 91.176(a)(2)(vi) requires that the descent rate must allow touchdown to occur within the touchdown zone of the runway of intended landing for all operations. Section 91.176(b)(2)(v), operations conducted to 100 feet above the TDZE, requires the descent rate to allow touchdown to occur within the touchdown zone of the runway of intended landing for operations conducted under 14 CFR Parts 121 and 135. 

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It is important to understand that using an EFVS does not result in obtaining lower minima with respect to the visibility or the DA/DH or MDA specified in the IAP. For example, a pilot who is using an EFVS on a Category I ILS approach that specifies a DA of 200 feet and a required visibility of RVR 2400 feet must comply with a 200-foot DA and an enhanced flight visibility of 2400 feet, even though the pilot may not have 2400 feet of flight visibility using natural vision or a reported 

