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AIM 

6/17/21 

or route different from that requested by the pilot. In 
addition, flow patterns have been established in 
certain congested areas or between congested areas 
whereby traffic capacity is increased by routing all 
traffic on preferred routes. Information on these flow 
patterns is available in offices where preflight 
briefing is furnished or where flight plans are 
accepted. 

2. 

When required, air traffic clearances include 

data to assist pilots in identifying radio reporting 
points. It is the responsibility of pilots to notify ATC 
immediately if their radio equipment cannot receive 
the type of signals they must utilize to comply with 
their clearance. 

d.  Altitude Data. 

1. 

The altitude or flight level instructions in an 

ATC clearance normally require that a pilot 
“MAINTAIN” the altitude or flight level at which the 
flight will operate when in controlled airspace. 
Altitude or flight level changes while en route should 
be requested prior to the time the change is desired. 

2. 

When possible, if the altitude assigned is 

different from the altitude requested by the pilot, ATC 
will inform the pilot when to expect climb or descent 
clearance or to request altitude change from another 
facility. If this has not been received prior to crossing 
the boundary of the ATC facility’s area and 
assignment at a different altitude is still desired, the 
pilot should reinitiate the request with the next 
facility. 

3. 

The term “cruise” may be used instead of 

“MAINTAIN” to assign a block of airspace to a pilot 
from the minimum IFR altitude up to and including 
the altitude specified in the cruise clearance. The pilot 
may level off at any intermediate altitude within this 
block of airspace. Climb/descent within the block is 
to be made at the discretion of the pilot. However, 
once the pilot starts descent and verbally reports 
leaving an altitude in the block, the pilot may not 
return to that altitude without additional ATC 
clearance. 

REFERENCE

 

Pilot/Controller Glossary Term

 Cruise. 

e.  Holding Instructions. 

1. 

Whenever an aircraft has been cleared to a fix 

other than the destination airport and delay is 
expected, it is the responsibility of the ATC controller 
to issue complete holding instructions (unless the 

pattern is charted), an EFC time, and a best estimate 
of any additional en route/terminal delay. 

2. 

If the holding pattern is charted and the 

controller doesn’t issue complete holding instruc-
tions, the pilot is expected to hold as depicted on the 
appropriate chart. When the pattern is charted, the 
controller may omit all holding instructions except 
the charted holding direction and the statement 

AS PUBLISHED

, e.g., 

“HOLD EAST AS 

PUBLISHED.”

 Controllers must always issue 

complete holding instructions when pilots request 
them. 

NOTE

 

Only those holding patterns depicted on U.S. government 
or commercially produced charts which meet FAA 
requirements should be used. 

3. 

If no holding pattern is charted and holding 

instructions have not been issued, the pilot should ask 
ATC for holding instructions prior to reaching the fix. 
This procedure will eliminate the possibility of an 
aircraft entering a holding pattern other than that 
desired by ATC. If unable to obtain holding 
instructions prior to reaching the fix (due to 
frequency congestion, stuck microphone, etc.), hold 
in a standard pattern on the course on which you 
approached the fix and request further clearance as 
soon as possible. In this event, the altitude/flight level 
of the aircraft at the clearance limit will be protected 
so that separation will be provided as required. 

4. 

When an aircraft is 3 minutes or less from a 

clearance limit and a clearance beyond the fix has not 
been received, the pilot is expected to start a speed 
reduction so that the aircraft will cross the fix, 
initially, at or below the maximum holding airspeed. 

5. 

When no delay is expected, the controller 

should issue a clearance beyond the fix as soon as 
possible and, whenever possible, at least 5 minutes 
before the aircraft reaches the clearance limit. 

6. 

Pilots should report to ATC the time and 

altitude/flight level at which the aircraft reaches the 
clearance limit and report leaving the clearance limit. 

NOTE

 

In the event of two

way communications failure, pilots are 

required to comply with 14 CFR Section 91.185. 

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4.  Amended Clearances 

a. 

Amendments to the initial clearance will be 

issued at any time an air traffic controller deems such 

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ATC Clearances and Aircraft Separation