719
Federal Aviation Administration, DOT
§ 91.121
(d)
Overtaking.
Each aircraft or vessel
that is being overtaken has the right-
of-way, and the one overtaking shall
alter course to keep well clear.
(e)
Special circumstances.
When air-
craft, or an aircraft and a vessel, ap-
proach so as to involve risk of colli-
sion, each aircraft or vessel shall pro-
ceed with careful regard to existing
circumstances, including the limita-
tions of the respective craft.
§ 91.117
Aircraft speed.
(a) Unless otherwise authorized by
the Administrator, no person may op-
erate an aircraft below 10,000 feet MSL
at an indicated airspeed of more than
250 knots (288 m.p.h.).
(b) Unless otherwise authorized or re-
quired by ATC, no person may operate
an aircraft at or below 2,500 feet above
the surface within 4 nautical miles of
the primary airport of a Class C or
Class D airspace area at an indicated
airspeed of more than 200 knots (230
mph.). This paragraph (b) does not
apply to any operations within a Class
B airspace area. Such operations shall
comply with paragraph (a) of this sec-
tion.
(c) No person may operate an aircraft
in the airspace underlying a Class B
airspace area designated for an airport
or in a VFR corridor designated
through such a Class B airspace area,
at an indicated airspeed of more than
200 knots (230 mph).
(d) If the minimum safe airspeed for
any particular operation is greater
than the maximum speed prescribed in
this section, the aircraft may be oper-
ated at that minimum speed.
[Doc. No. 18334, 54 FR 34292, Aug. 18, 1989, as
amended by Amdt. 91–219, 55 FR 34708, Aug.
24, 1990; Amdt. 91–227, 56 FR 65657, Dec. 17,
1991; Amdt. 91–233, 58 FR 43554, Aug. 17, 1993]
§ 91.119
Minimum safe altitudes: Gen-
eral.
Except when necessary for takeoff or
landing, no person may operate an air-
craft below the following altitudes:
(a)
Anywhere.
An altitude allowing, if
a power unit fails, an emergency land-
ing without undue hazard to persons or
property on the surface.
(b)
Over congested areas.
Over any
congested area of a city, town, or set-
tlement, or over any open air assembly
of persons, an altitude of 1,000 feet
above the highest obstacle within a
horizontal radius of 2,000 feet of the
aircraft.
(c)
Over other than congested areas.
An
altitude of 500 feet above the surface,
except over open water or sparsely pop-
ulated areas. In those cases, the air-
craft may not be operated closer than
500 feet to any person, vessel, vehicle,
or structure.
(d)
Helicopters, powered parachutes,
and weight-shift-control aircraft.
If the
operation is conducted without hazard
to persons or property on the surface—
(1) A helicopter may be operated at
less than the minimums prescribed in
paragraph (b) or (c) of this section, pro-
vided each person operating the heli-
copter complies with any routes or al-
titudes specifically prescribed for heli-
copters by the FAA; and
(2) A powered parachute or weight-
shift-control aircraft may be operated
at less than the minimums prescribed
in paragraph (c) of this section.
[Doc. No. 18334, 54 FR 34294, Aug. 18, 1989, as
amended by Amdt. 91–311, 75 FR 5223, Feb. 1,
2010]
§ 91.121
Altimeter settings.
(a) Each person operating an aircraft
shall maintain the cruising altitude or
flight level of that aircraft, as the case
may be, by reference to an altimeter
that is set, when operating—
(1) Below 18,000 feet MSL, to—
(i) The current reported altimeter
setting of a station along the route and
within 100 nautical miles of the air-
craft;
(ii) If there is no station within the
area prescribed in paragraph (a)(1)(i) of
this section, the current reported al-
timeter setting of an appropriate avail-
able station; or
(iii) In the case of an aircraft not
equipped with a radio, the elevation of
the departure airport or an appropriate
altimeter setting available before de-
parture; or
(2) At or above 18,000 feet MSL, to
29.92
″
Hg.
(b) The lowest usable flight level is
determined by the atmospheric pres-
sure in the area of operation as shown
in the following table:
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