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14 CFR Ch. I (1–1–14 Edition)
§ 91.179
be crossed at or above the applicable
MCA.
[Doc. No. 18334, 54 FR 34294, Aug. 18, 1989, as
amended by Amdt. 91–296, 72 FR 31678, June
7, 2007; Amdt. 91–315, 75 FR 30690, June 2, 2010]
§ 91.179
IFR cruising altitude or flight
level.
Unless otherwise authorized by ATC,
the following rules apply—
(a)
In controlled airspace. Each person
operating an aircraft under IFR in
level cruising flight in controlled air-
space shall maintain the altitude or
flight level assigned that aircraft by
ATC. However, if the ATC clearance as-
signs ‘‘VFR conditions on-top,’’ that
person shall maintain an altitude or
flight level as prescribed by § 91.159.
(b)
In uncontrolled airspace. Except
while in a holding pattern of 2 minutes
or less or while turning, each person
operating an aircraft under IFR in
level cruising flight in uncontrolled
airspace shall maintain an appropriate
altitude as follows:
(1) When operating below 18,000 feet
MSL and—
(i) On a magnetic course of zero de-
grees through 179 degrees, any odd
thousand foot MSL altitude (such as
3,000, 5,000, or 7,000); or
(ii) On a magnetic course of 180 de-
grees through 359 degrees, any even
thousand foot MSL altitude (such as
2,000, 4,000, or 6,000).
(2) When operating at or above 18,000
feet MSL but below flight level 290,
and—
(i) On a magnetic course of zero de-
grees through 179 degrees, any odd
flight level (such as 190, 210, or 230); or
(ii) On a magnetic course of 180 de-
grees through 359 degrees, any even
flight level (such as 180, 200, or 220).
(3) When operating at flight level 290
and above in non-RVSM airspace, and—
(i) On a magnetic course of zero de-
grees through 179 degrees, any flight
level, at 4,000-foot intervals, beginning
at and including flight level 290 (such
as flight level 290, 330, or 370); or
(ii) On a magnetic course of 180 de-
grees through 359 degrees, any flight
level, at 4,000-foot intervals, beginning
at and including flight level 310 (such
as flight level 310, 350, or 390).
(4) When operating at flight level 290
and above in airspace designated as Re-
duced Vertical Separation Minimum
(RVSM) airspace and—
(i) On a magnetic course of zero de-
grees through 179 degrees, any odd
flight level, at 2,000-foot intervals be-
ginning at and including flight level 290
(such as flight level 290, 310, 330, 350,
370, 390, 410); or
(ii) On a magnetic course of 180 de-
grees through 359 degrees, any even
flight level, at 2000-foot intervals be-
ginning at and including flight level 300
(such as 300, 320, 340, 360, 380, 400).
[Doc. No. 18334, 54 FR 34294, Aug. 18, 1989, as
amended by Amdt. 91–276, 68 FR 61321, Oct.
27, 2003; 68 FR 70133, Dec. 17, 2003; Amdt. 91–
296, 72 FR 31679, June 7, 2007]
§ 91.180
Operations within airspace
designated as Reduced Vertical
Separation Minimum airspace.
(a) Except as provided in paragraph
(b) of this section, no person may oper-
ate a civil aircraft in airspace des-
ignated as Reduced Vertical Separa-
tion Minimum (RVSM) airspace unless:
(1) The operator and the operator’s
aircraft comply with the minimum
standards of appendix G of this part;
and
(2) The operator is authorized by the
Administrator or the country of reg-
istry to conduct such operations.
(b) The Administrator may authorize
a deviation from the requirements of
this section.
[Amdt. 91–276, 68 FR 70133, Dec. 17, 2003]
§ 91.181
Course to be flown.
Unless otherwise authorized by ATC,
no person may operate an aircraft
within controlled airspace under IFR
except as follows:
(a) On an ATS route, along the cen-
terline of that airway.
(b) On any other route, along the di-
rect course between the navigational
aids or fixes defining that route. How-
ever, this section does not prohibit ma-
neuvering the aircraft to pass well
clear of other air traffic or the maneu-
vering of the aircraft in VFR condi-
tions to clear the intended flight path
both before and during climb or de-
scent.
[Doc. No. 18334, 54 FR 34294, Aug. 18, 1989, as
amended by Amdt. 91–296, 72 FR 31679, June
7, 2007]
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