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Federal Aviation Administration, DOT 

§ 121.661 

for instrument approach procedures on 
all runways of an airport. However, if 
the latest weather report, including an 
oral report from the control tower, 
contains a visibility value specified as 
runway visibility or runway visual 
range for a particular runway of an air-
port, that specified value controls for 
VFR and IFR landings and takeoffs and 
straight-in instrument approaches for 
that runway. 

§ 121.657 Flight altitude rules. 

(a) 

General. 

Notwithstanding § 91.119 

or any rule applicable outside the 
United States, no person may operate 
an aircraft below the minimums set 
forth in paragraphs (b) and (c) of this 
section, except when necessary for 
takeoff or landing, or except when, 
after considering the character of the 
terrain, the quality and quantity of 
meteorological services, the naviga-
tional facilities available, and other 
flight conditions, the Administrator 
prescribes other minimums for any 
route or part of a route where he finds 
that the safe conduct of the flight re-
quires other altitudes. Outside of the 
United States the minimums pre-
scribed in this section are controlling 
unless higher minimums are prescribed 
in the certificate holder’s operations 
specifications or by the foreign country 
over which the aircraft is operating. 

(b) 

Day VFR operations. 

No certificate 

holder conducting domestic operations 
may operate a passenger-carrying air-
craft and no certificate holder con-
ducting flag or supplemental oper-
ations may operate any aircraft under 
VFR during the day at an altitude less 
than 1,000 feet above the surface or less 
than 1,000 feet from any mountain, hill, 
or other obstruction to flight. 

(c) 

Night VFR, IFR, and over-the-top 

operations. 

No person may operate an 

aircraft under IFR including over-the- 
top or at night under VFR at an alti-
tude less than 1,000 feet above the high-
est obstacle within a horizontal dis-
tance of five miles from the center of 
the intended course, or, in designated 
mountainous areas, less than 2,000 feet 
above the highest obstacle within a 
horizontal distance of five miles from 
the center of the intended course. 

(d) 

Day over-the-top operations below 

minimum en route altitudes. 

A person 

may conduct day over-the-top oper-
ations in an airplane at flight altitudes 
lower than the minimum en route IFR 
altitudes if— 

(1) The operation is conducted at 

least 1,000 feet above the top of lower 
broken or overcast cloud cover; 

(2) The top of the lower cloud cover is 

generally uniform and level; 

(3) Flight visibility is at least five 

miles; and 

(4) The base of any higher broken or 

overcast cloud cover is generally uni-
form and level and is at least 1,000 feet 
above the minimum en route IFR alti-
tude for that route segment. 

[Doc. No. 6258, 29 FR 19222, Dec. 31, 1964, as 
amended by Amdt. 121–144, 43 FR 22649, May 
25, 1978; Amdt. 121–206, 54 FR 34331, Aug. 18, 
1989; Amdt. 121–253, 61 FR 2615, Jan. 26, 1996] 

§ 121.659 Initial approach altitude: Do-

mestic and supplemental oper-

ations. 

(a) Except as provided in paragraph 

(b) of this section, when making an ini-
tial approach to a radio navigation fa-
cility under IFR, no person may de-
scend an aircraft below the pertinent 
minimum altitude for initial approach 
(as specified in the instrument ap-
proach procedure for that facility) 
until his arrival over that facility has 
been definitely established. 

(b) When making an initial approach 

on a flight being conducted under 
§ 121.657(d), no pilot may commence an 
instrument approach until his arrival 
over the radio facility has definitely 
been established. In making an instru-
ment approach under these cir-
cumstances no person may descend an 
aircraft lower than 1,000 feet above the 
top of the lower cloud or the minimum 
altitude determined by the Adminis-
trator for that part of the IFR ap-
proach, whichever is lower. 

§ 121.661 Initial approach altitude: 

Flag operations. 

When making an initial approach to 

a radio navigation facility under IFR, 
no person may descend below the perti-
nent minimum altitude for initial ap-
proach (as specified in the instrument 
approach procedure for that facility) 
until his arrival over that facility has 
been definitely established.