International Phonetic Alphabet



Aviation has its own unique vocabulary, phraseology, and acronyms. The International Civil Aviation Organization (ICAO) is the controlling agency for worldwide aviation activities. To avoid miscommunications in a worldwide air transportation system, ICAO chose English as the official language of aviation.

Everything pertaining to aviation is controlled and approved by the ICAO. Radio frequencies, runway light colors, runway and taxiway markings, airport and airway identifiers, and navigation aids are ICAO approved.

Letter and numeral pronunciation can be so easily misunderstood (such as hearing an "S" for an "F" or a "B" for a "D"). Because of that, letters and numerals in aviation are spoken using the International Phonetic Alphabet. This alphabet substitutes an entire word to represent one letter. The first letter of the word is the letter of the alphabet it represents. It would be difficult to confuse "Sierra" (the letter "S") for the letter "F" (said as "Foxtrot").

The numeral "nine" (Number # 9) is pronounced "niner." The accepted reasoning is that "nein" is a common German word that means no. By eliminating that pronunciation, confusion was to be avoided.


Normally questions requiring a "yes" or "no" answer are answered using yes and no. However, in aviation the answers are "affirmative" for yes and "negative" for no.

Verbal communications are possibly more prone to confusion and misunderstanding than those that are written. Whether the person is a controller or pilot, what the sender (or speaker) transmits is not always what the receiver (or listener) receives or hears. When a controller transmits a clearance, the clearance is "read back" by the crewmember receiving the message. The "read-back" is used to confirm that the message received was indeed the message sent. Shorter words are more often misunderstood than longer words. It seems talkers start talking before listeners start listening.

“Affirmative” (af - fir - ma - tive) indicates a yes response.

“Negative” (neg - a- tive) indicates a no response.

“Over “(o - ver) is use when completing a radio transmission

                                                          
                                                        
                                                             EXAMPLES



EXAMPLE:
500..............................................FIVE HUNDRED

EXAMPLE:
4500.............................................FOUR THOUSAND FIVE HUNDRED



Numbers above 9900 shall be spoken by separating the digits preceding the word "thousand"


EXAMPLE:
10,000.............................................ONE ZERO THOUSAND

EXAMPLE:
13,500.............................................ONE THREE THOUSAND FIVE HUNDRED


Transmit airway or jet route numbers as follows:

EXAMPLE:
V12.............................................VICTOR TWELVE
J533...........................................J FIVE THIRTY-THREE



All other numbers shall be transmitted by pronouncing each digit


EXAMPLE:
10.............................................ONE ZERO

When a radio frequency contains a decimal point, the decimal point is spoken as "POINT."

EXAMPLE:
122.1.............................................ONE TWO TWO POINT ONE

NOTE.- ICAO Procedures require the decimal point be spoken as "DECIMAL" and the FAA will honor such usage by military and all other aircraft required to use ICAO Procedures.

ALTITUDES must be added when it applies

EXAMPLE:
(magnetic course) 005.............................................ZERO ZERO FIVE

EXAMPLE:
(true course) 050.............................................ZERO FIVE ZERO TRUE

EXAMPLE:
(magnetic bearing) 360.............................................THREE SIX ZERO

EXAMPLE:
(magnetic heading) 100.............................................ONE ZERO ZERO

EXAMPLE:
(wind direction) 220.............................................TWO TWO ZERO

SPEEDS

The separate digits of the speed followed by the word "KNOTS." Except, controllers may omit the word "KNOTS" when using speed adjustment procedures, e.g., "REDUCE / INCREASE SPEED TO TWO FIVE ZERO."

EXAMPLES:
(speed) 25O.............................................TWO FIVE ZERO KNOTS
(speed) 190.............................................ONE NINER ZERO KNOTS
The separate digits of the mach number preceded by "MACH."

EXAMPLES:
(mach number) 1.5.............................................MACH ONE POINT FIVE
(mach number) .64.............................................MACH POINT SIX FOUR
(mach number) .7.............................................. MACH POINT SEVEN

TIME

FAA uses Greenwich Mean Time (GMT or Zulu) for all operations.

To Convert from Standard Time to Greenwich Mean 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

NOTE.- For Daylight Savings Time subtract 1 hour.


The 24-hour clock system is used in radiotelephone transmissions. The hour is indicated by the first two figures and the minutes by the last two figures.

EXAMPLE:
0000.............................................ZERO ZERO ZERO ZERO

EXAMPLE:
0920.............................................ZERO NINER TWO ZERO

Time may be stated in minutes only (two figures) in radio telephone communications when no misunderstanding is likely to occur.

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 eight seconds are stated as the preceding quarter minute; fractions of a quarter minute of eight seconds or more are stated as the succeeding quarter minute.


For an example, let's consider the time to be "1539Z".

Writing it or saying it would be  "One five three niner Zulu"


EXAMPLE:
0929:05.............................................TIME, ZERO NINER TWO NINER

EXAMPLE:
0929:10.............................................TIME, ZERO NINER TWO NINER AND ONE QUARTER


Click               Coordinated Universal Time (UTC) Zulu Time


FLIGHT LEVELS

Up to but not including 18,000 feet MSL - state the separate digits of the thousands, plus the hundreds, if appropriate.

EXAMPLE:
12,000.............................................ONE TWO THOUSAND

EXAMPLE:
12,500.............................................ONE TWO THOUSAND FIVE HUNDRED

At and above, 18,000 feet MSL (FL 180) state the words "flight level" followed by the separate digits of the flight level.

EXAMPLE:
190.............................................FLIGHT LEVEL ONE NINER ZERO


DIRECTIONS

The three digits of bearing, course, heading or wind direction should always be magnetic.