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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,