Aeronautical Information Manual (AIM), page 395

Index   394 -- Page 395 -- 396

(1) The runway threshold, identified by at
least one of the following: the beginning of the run-
way landing surface, the threshold lights, or the
runway end identifier lights (REIL).

(2) The TDZ, identified by at least one of
the following: the runway TDZ landing surface, the
TDZ lights, the TDZ markings, or the runway lights.
2. Comparison of Visual Reference Require-
ments for EFVS and Natural Vision. The EFVS
visual reference requirements of 14 CFR part 91.175
(l)(3) comprise a more stringent standard than the
visual reference requirements prescribed under 14
CFR part 91.175 (c)(3) when using natural vision.
The more stringent standard is needed because an
EFVS might not display the color of the lights used
to identify specific portions of the runway or might
not be able to consistently display the runway mark-
ings. The main differences for EFVS operations are
that the visual glide slope indicator (VGSI) lights
cannot be used as a visual reference, and specific
visual references from both the threshold and TDZ
must be distinctly visible and identifiable. However,
when using natural vision, only one of the specified
visual references must be visible and identifiable.

3. Visual References and Offset

Approaches. Pilots must be especially knowledge-

able of the approach conditions and approach course

alignment when considering whether to rely on EFVS

during a non-precision approach with an offset final
approach course. Depending upon the combination of
crosswind correction and the lateral field of view
provided by a particular EFVS, the required visual
references may or may not be within the pilot's view
looking through the EFVS display. Pilots conducting
any non-precision approach must verify lateral align-
ment with the runway centerline when determining
when to descend from MDA.

4. When to Go Around. Any pilot operating
an aircraft with an EFVS installed should be aware
that the requirements of 14 CFR part 91.175 (c) for
using natural vision and the requirements of 14 CFR
part 91.175 (l) for using an EFVS are different. A
pilot would, therefore, first have to determine
whether an approach will be commenced using
natural vision or using an EFVS. While these two sets
of requirements provide a parallel decisionmaking

process, the requirements for when a missed
approach must be executed differ. Using EFVS, a

missed approach must be initiated at or below DA or
MDA down to 100 feet above TDZE whenever the
pilot determines that:

(a) The EFV is less than the visibility minima
prescribed for the IAP being used;
(b) The required visual references for the run-
way of intended landing are no longer distinctly
visible and identifiable to the pilot using the EFVS
(c) The aircraft is not continuously in a posi-
tion from which a descent to a landing can be made
on the intended runway, at a normal rate of descent,
using normal maneuvers; or

(d) For operations under 14 CFR parts 121
and 135, the descent rate of the aircraft would not
allow touchdown to occur within the TDZ of the
runway of intended landing.
5. Missed Approach Considerations. It
should be noted that a missed approach after passing
the DA, or beyond the missed approach point (MAP),
involves additional risk until established on the pub-
lished missed approach segment. Initiating a
go-around after passing the published MAP may res-
ult in loss of obstacle clearance. As with any

approach, pilot planning should include contingen-

cies between the published MAP and touchdown with

reference to obstacle clearance, aircraft performance,

and alternate escape plans.

c. EFVS Operations At and Below 100 Feet
Above the TDZE. At and below 100 feet above the
TDZE, the regulations do not require the EFVS to be
turned off or the display to be stowed in order to con-
tinue to a landing. A pilot may continue the approach
below this altitude using an EFVS as long as the re-
quired visual references can be seen through the
display using natural vision. An operator may not
continue to descend beyond this point by relying
solely on the sensor image displayed on the EFVS.

1. Required Visual References. In order to
descend below 100 feet above the TDZE, the flight
visibility--assessed using natural vision--must be
sufficient for the following visual references to be
distinctly visible and identifiable to the pilot without
reliance on the EFVS to continue to a landing:

(a) The lights or markings of the threshold, or

(b) The lights or markings of the TDZ.

Arrival Procedures 5-4-59

Page 395 of the Aeronautical Information Manual (AIM.pdf)
AIM: Official Guide to Basic Flight Information and ATC Procedures

Index   394 -- Page 395 -- 396