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AIM

10/12/17

4

−4−4

ATC Clearances and Aircraft Separation

locations, flights may be vectored if necessary for
control purposes or on pilot request.

NOTE

The pilot is responsible for obstacle or terrain clearance.

REFERENCE

14 CFR Section 91.119, Minimum safe altitudes: General.

d.

Special VFR clearances are effective within

Class B, Class C, Class D, and Class E surface areas
only. ATC does not provide separation after an
aircraft leaves the Class B, Class C, Class D, or
Class E surface area on a special VFR clearance.

e.

Special VFR operations by fixed

−wing aircraft

are prohibited in some Class B and Class C surface
areas due to the volume of IFR traffic. A list of these
Class B and Class C surface areas is contained in
14 CFR Part 91, Appendix D, Section 3. They are
also depicted on sectional aeronautical charts.

f.

ATC provides separation between Special VFR

flights and between these flights and other IFR
flights.

g.

Special VFR operations by fixed

−wing aircraft

are prohibited between sunset and sunrise unless the
pilot is instrument rated and the aircraft is equipped
for IFR flight.

h.

Pilots arriving or departing an uncontrolled

airport that has automated weather broadcast
capability (ASOS/AWSS/AWOS) should monitor
the broadcast frequency, advise the controller that
they have the “one

−minute weather” and state

intentions prior to operating within the Class B, Class
C, Class D, or Class E surface areas.

REFERENCE

Pilot/Controller Glossary Term

− One−minute Weather.

4

−4−7. Pilot Responsibility upon Clearance

Issuance

a. Record ATC clearance.

When conducting an

IFR operation, make a written record of your
clearance. The specified conditions which are a part
of your air traffic clearance may be somewhat
different from those included in your flight plan.
Additionally, ATC may find it necessary to ADD
conditions, such as particular departure route. The
very fact that ATC specifies different or additional
conditions means that other aircraft are involved in
the traffic situation.

b. ATC Clearance/Instruction Readback.

Pilots of airborne aircraft should read back
those parts

 of  ATC  clearances  and  instructions

containing altitude assignments, vectors, or runway
assignments as a means of mutual verification. The
read back of the “numbers” serves as a double check
between pilots and controllers and reduces the kinds
of communications errors that occur when a number
is either “misheard” or is incorrect.

1.

Include the aircraft identification in all

readbacks and acknowledgments. This aids control-
lers in determining that the correct aircraft received
the clearance or instruction. The requirement to
include aircraft identification in all readbacks and
acknowledgements becomes more important as
frequency congestion increases and when aircraft
with similar call signs are on the same frequency.

EXAMPLE

“Climbing to Flight Level three three zero, United Twelve”
or “November Five Charlie Tango, roger, cleared to land
runway nine left.”

2.

Read back altitudes, altitude restrictions, and

vectors in the same sequence as they are given in the
clearance or instruction.

3.

Altitudes contained in charted procedures,

such as DPs, instrument approaches, etc., should not
be read back unless they are specifically stated by the
controller.

4.

Initial read back of a taxi, departure or landing

clearance should include the runway assignment,
including left, right, center, etc. if applicable.

c.

It is the responsibility of the pilot to accept or

refuse the clearance issued.

4

−4−8. IFR Clearance VFR−on−top

a.

A pilot on an IFR flight plan operating in VFR

weather conditions, may request VFR

−on−top in lieu

of an assigned altitude. This permits a pilot to select
an altitude or flight level of their choice (subject to
any ATC restrictions.)

b.

Pilots desiring to climb through a cloud, haze,

smoke, or other meteorological formation and then
either cancel their IFR flight plan or operate
VFR-on-top may request a climb to VFR-on-top. The
ATC authorization must contain either a top report or
a statement that no top report is available, and a
request to report reaching VFR-on-top. Additionally,
the ATC authorization may contain a clearance limit,