title-14-part-91-sec91-171

707

Federal Aviation Administration, DOT

§ 91.171

the visibility will be at least 3 statute
miles.

(ii)

For helicopters. At the estimated

time of arrival and for 1 hour after the
estimated time of arrival, the ceiling
will be at least 1,000 feet above the air-
port elevation, or at least 400 feet
above the lowest applicable approach
minima, whichever is higher, and the
visibility will be at least 2 statute
miles.

(c)

IFR alternate airport weather mini-

ma. Unless otherwise authorized by the
Administrator, no person may include
an alternate airport in an IFR flight
plan unless appropriate weather re-
ports or weather forecasts, or a com-
bination of them, indicate that, at the
estimated time of arrival at the alter-
nate airport, the ceiling and visibility
at that airport will be at or above the
following weather minima:

(1) If an instrument approach proce-

dure has been published in part 97 of
this chapter, or a special instrument
approach procedure has been issued by
the Administrator to the operator, for
that airport, the following minima:

(i)

For aircraft other than helicopters:

The alternate airport minima specified
in that procedure, or if none are speci-
fied the following standard approach
minima:

(A)

For a precision approach procedure.

Ceiling 600 feet and visibility 2 statute
miles.

(B)

For a nonprecision approach proce-

dure. Ceiling 800 feet and visibility 2
statute miles.

(ii)

For helicopters: Ceiling 200 feet

above the minimum for the approach
to be flown, and visibility at least 1
statute mile but never less than the
minimum visibility for the approach to
be flown, and

(2) If no instrument approach proce-

dure has been published in part 97 of
this chapter and no special instrument
approach procedure has been issued by
the Administrator to the operator, for
the alternate airport, the ceiling and
visibility minima are those allowing
descent from the MEA, approach, and
landing under basic VFR.

(d)

Cancellation. When a flight plan

has been activated, the pilot in com-
mand, upon canceling or completing
the flight under the flight plan, shall

notify an FAA Flight Service Station
or ATC facility.

[Doc. No. 18334, 54 FR 34294, Aug. 18, 1989, as
amended by Amdt. 91–259, 65 FR 3546, Jan. 21,
2000]

§ 91.171

VOR equipment check for IFR

operations.

(a) No person may operate a civil air-

craft under IFR using the VOR system
of radio navigation unless the VOR
equipment of that aircraft—

(1) Is maintained, checked, and in-

spected under an approved procedure;
or

(2) Has been operationally checked

within the preceding 30 days, and was
found to be within the limits of the
permissible indicated bearing error set
forth in paragraph (b) or (c) of this sec-
tion.

(b) Except as provided in paragraph

(1) Use, at the airport of intended de-

parture, an FAA-operated or approved
test signal or a test signal radiated by
a certificated and appropriately rated
radio repair station or, outside the
United States, a test signal operated or
approved by an appropriate authority
to check the VOR equipment (the max-
imum permissible indicated bearing
error is plus or minus 4 degrees); or

(2) Use, at the airport of intended de-

parture, a point on the airport surface
designated as a VOR system check-
point by the Administrator, or, outside
the United States, by an appropriate
authority (the maximum permissible
bearing error is plus or minus 4 de-
grees);

(3) If neither a test signal nor a des-

ignated checkpoint on the surface is
available, use an airborne checkpoint
designated by the Administrator or,
outside the United States, by an appro-
priate authority (the maximum per-
missible bearing error is plus or minus
6 degrees); or

(4) If no check signal or point is

available, while in flight—

(i) Select a VOR radial that lies

along the centerline of an established
VOR airway;

(ii) Select a prominent ground point

along the selected radial preferably
more than 20 nautical miles from the

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14 CFR Ch. I (1–1–24 Edition)

§ 91.173

VOR ground facility and maneuver the
aircraft directly over the point at a
reasonably low altitude; and

(iii) Note the VOR bearing indicated

by the receiver when over the ground
point (the maximum permissible vari-
ation between the published radial and
the indicated bearing is 6 degrees).

pendent of each other except for the
antenna) is installed in the aircraft,
the person checking the equipment
may check one system against the
other in place of the check procedures
specified in paragraph (b) of this sec-
tion. Both systems shall be tuned to
the same VOR ground facility and note
the indicated bearings to that station.
The maximum permissible variation
between the two indicated bearings is 4
degrees.

(d) Each person making the VOR

operational check, as specified in para-
graph (b) or (c) of this section, shall
enter the date, place, bearing error,
and sign the aircraft log or other
record. In addition, if a test signal ra-
diated by a repair station, as specified
in paragraph (b)(1) of this section, is
used, an entry must be made in the air-
craft log or other record by the repair
station certificate holder or the certifi-
cate holder’s representative certifying
to the bearing transmitted by the re-
pair station for the check and the date
of transmission.

(Approved by the Office of Management and
Budget under control number 2120–0005)

§ 91.173

ATC clearance and flight plan

required.

No person may operate an aircraft in

controlled airspace under IFR unless
that person has—

(a) Filed an IFR flight plan; and
(b) Received an appropriate ATC

clearance.

§ 91.175

Takeoff and landing under

IFR.

(a)

Instrument approaches to civil air-

ports. Unless otherwise authorized by
the FAA, when it is necessary to use an
instrument approach to a civil airport,
each person operating an aircraft must
use a standard instrument approach
procedure prescribed in part 97 of this
chapter for that airport. This para-

graph does not apply to United States
military aircraft.

(b)

Authorized DA/DH or MDA. For the

purpose of this section, when the ap-
proach procedure being used provides
for and requires the use of a DA/DH or
MDA, the authorized DA/DH or MDA is
the highest of the following:

(1) The DA/DH or MDA prescribed by

the approach procedure.

(2) The DA/DH or MDA prescribed for

the pilot in command.

(3) The DA/DH or MDA appropriate

for the aircraft equipment available
and used during the approach.

(c)

Operation below DA/DH or MDA.

Except as provided in § 91.176 of this
chapter, where a DA/DH or MDA is ap-
plicable, no pilot may operate an air-
craft, except a military aircraft of the
United States, below the authorized
MDA or continue an approach below
the authorized DA/DH 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 un-
less that descent rate will allow touch-
down to occur within the touchdown
zone of the runway of intended landing;

(2) The flight visibility is not less

than the visibility prescribed in the
standard instrument approach being
used; and

(3) Except for a Category II or Cat-

egory III approach where any necessary
visual reference requirements are spec-
ified by the Administrator, at least one
of the following visual references for
the intended runway is distinctly visi-
ble and identifiable to the pilot:

(i) The approach light system, except

that the pilot may not descend below
100 feet above the touchdown zone ele-
vation using the approach lights as a
reference unless the red terminating
bars or the red side row bars are also
distinctly visible and identifiable.

(ii) The threshold.
(iii) The threshold markings.
(iv) The threshold lights.
(v) The runway end identifier lights.
(vi) The visual glideslope indicator.
(vii) The touchdown zone or touch-

down zone markings.

(viii) The touchdown zone lights.
(ix) The runway or runway markings.