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6/17/21 

AIM 

b. 

To convert from Standard Time to Coordinated 

Universal Time: 

TBL 4

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Standard Time to Coordinated Universal Time 

Eastern Standard Time  . . . . . . . . .   Add 5 hours 
Central Standard Time  . . . . . . . . .   Add 6 hours 
Mountain Standard Time  . . . . . . .   Add 7 hours 
Pacific Standard Time  . . . . . . . . .   Add 8 hours 
Alaska Standard Time  . . . . . . . . .   Add 9 hours 
Hawaii Standard Time  . . . . . . . . .   Add 10 hours 

NOTE

 

For daylight time, subtract 1 hour. 

c. 

A reference may be made to local daylight or 

standard time utilizing the 24

hour clock system. The 

hour is indicated by the first two figures and the 
minutes by the last two figures. 

EXAMPLE

 

0000  . . . . . . . . . . . . . . . . . . . . . . .   zero zero zero zero 
0920  . . . . . . . . . . . . . . . . . . . . . . .   zero niner two zero 

d. 

Time may be stated in minutes only 

(two figures) in radiotelephone communications 
when no misunderstanding is likely to occur. 

e. 

Current time in use at a station is stated in the 

nearest quarter minute in order that pilots may use this 
information for time checks. Fractions of a quarter 
minute less than 8 seconds are stated as the preceding 
quarter minute; fractions of a quarter minute of 
8 seconds or more are stated as the succeeding quarter 
minute. 

EXAMPLE

 

0929:05  . . . . . .  time, zero niner two niner 
0929:10  . . . . . .  time, zero niner two niner and 

one

quarter 

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13.  Communications with Tower when 

Aircraft Transmitter or Receiver or Both are 
Inoperative 

a.  Arriving Aircraft. 

1.  Receiver inoperative. 

(a) 

If you have reason to believe your receiver 

is inoperative, remain outside or above the Class D 
surface area until the direction and flow of traffic has 
been determined; then, advise the tower of your type 
aircraft, position, altitude, intention to land, and 
request that you be controlled with light signals. 

REFERENCE

 

AIM, Paragraph 4

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13 , Traffic Control Light Signals 

(b) 

When you are approximately 3 to 5 miles 

from the airport, advise the tower of your position and 
join the airport traffic pattern. From this point on, 
watch the tower for light signals. Thereafter, if a 
complete pattern is made, transmit your position 
downwind and/or turning base leg. 

2. Transmitter inoperative. 

Remain outside 

or above the Class D surface area until the direction 
and flow of traffic has been determined; then, join the 
airport traffic pattern. Monitor the primary local 
control frequency as depicted on Sectional Charts for 
landing or traffic information, and look for a light 
signal which may be addressed to your aircraft. 
During hours of daylight, acknowledge tower 
transmissions or light signals by rocking your wings. 
At night, acknowledge by blinking the landing or 
navigation lights. To acknowledge tower transmis-
sions during daylight hours, hovering helicopters will 
turn in the direction of the controlling facility and 
flash the landing light. While in flight, helicopters 
should show their acknowledgement of receiving a 
transmission by making shallow banks in opposite 
directions. At night, helicopters will acknowledge 
receipt of transmissions by flashing either the landing 
or the search light. 

3.  Transmitter and receiver inoperative. 

Remain outside or above the Class D surface area 
until the direction and flow of traffic has been 
determined; then, join the airport traffic pattern and 
maintain visual contact with the tower to receive light 
signals. Acknowledge light signals as noted above. 

b.  Departing Aircraft. 

If you experience radio 

failure prior to leaving the parking area, make every 
effort to have the equipment repaired. If you are 
unable to have the malfunction repaired, call the 
tower by telephone and request authorization to 
depart without two-way radio communications. If 
tower authorization is granted, you will be given 
departure information and requested to monitor the 
tower frequency or watch for light signals as 
appropriate. During daylight hours, acknowledge 
tower transmissions or light signals by moving the 
ailerons or rudder. At night, acknowledge by blinking 
the landing or navigation lights. If radio malfunction 

Radio Communications Phraseology 

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