When most people hear pilots or air traffic controllers speak on the
radio, they think they're hearing another language! In this
edition of Spotting 101, we will dispel that myth, and show you how
easy it is to follow what they are saying, what they intend to do, and
how they do it in as little time as is required.
The first thing you will need is a VHF
communications receiver to listen in on the action. These are more commonly known as
scanners. They are available from electronic supply shops for
anywhere from $75-$100, and can go much higher. Many scanners have
different bands that they can pick up. A band is a range of
frequencies that are all grouped together for specific purposes.
The main requirement is that your scanner be able to pick up the
"aircraft band", that is 108.0 MHZ to 136.975 MHZ. There are two
types of signals used in aviation, communication and
The range we will be concerned with is the
communications range, as this is where pilots and air traffic control
speak back and forth. The navigation range is used for VHF radio
navigation. You can pick up signals from VOR's on your scanner
with no problem, however, those signals are usually directed toward the
sky, and are difficult to pick up near the ground. If you do tune
one in, you can expect to hear the morse code identifier of that VOR,
and possibly a voice-over on top of that, broadcasting some type of
weather information, such as HIWAS (hazardous inflight weather advisory
service). The VOR at KIAH is an example of this. You have to
be fairly close, but if you are nearby, tune in 116.6 on your scanner
and you will pick this up.
Once you have a scanner that can pick up the
aircraft band, its time to start listening in. The first thing
you'll need is frequencies.
Airnav.com has all
of the frequencies, plus a lot more information, of each airport in the
US. HoustonSpotters has compiled a list of the most commonly used
frequencies in the Houston area, on the
Frequency guide page.
There are also links to airport diagrams, if the FAA has provided them.
When you are on the ground, it is not uncommon
to only hear one side of the conversation. You may hear a
transmission, then nothing for about 5 seconds. This is due to the
fact that you are just too far away from the other transmitting station
(either tower or plane), and the 5 seconds of silence is the other side
responding to the transmission you just heard. There are some areas where you can hear
both sides, but you usually get good reception on one side, or poor on
both, but very seldom get good reception on both sides of the
conversation, without a large antenna to boost the signal, or a high
vantage point, close to the airport.
Once you have all of the frequencies you want
to listen to, program them into your scanner. The scanner will
loop through each frequency very quickly until it finds activity on a
particular frequency, when it does, it will stop and let you listen to
Now that we are prepared for listening in, lets
talk about what they are actually saying.
There are different people that a pilot will
talk to, and knowing which person the pilot is talking to will make it
easier to understand, and even anticipate, what the pilot will say next!
||ATIS (Automatic Terminal Information Service),
is a recording that pilots can tune into at certain airports to
get the latest weather reported at that airport. Pilots
only listen to ATIS, they do not transmit on these frequencies.
||Ground control is who the pilot speaks to when
they want to get clearance to move around the airport surface.
||Clearance delivery is a special frequency
(sometimes other than Ground, but also sometimes shared with
ground) that pilots use to activate their instrument flight
||Tower are the air traffic controllers in the
tower who control all of the traffic in their airspace.
||Approach control manages the flow of air traffic
to an airport, prior to the interaction with the tower
||Departure control manages the flow of air
traffic from an airport, after handoff from
||Center handles the Enroute air traffic between
approach and departure.
Every transmission made in aviation follows a
simple flow of four steps. The words pilots use, and the order in
which they use them is all standardized. This helps to reduce
errors and people on both sides of the conversation know what the other
is trying to say. Even if they don't receive the entire transmission
because of radio noise, they would still get the main intention of the
transmission. Of course if they just plain don't understand what
was said, there are 3 magic words that can save you: "Say again please".
The flow is as follows:
||(Who you are calling)
||(Who you are)
||(Your request and additional information)
Each transmission will follow this flow.
Some may vary slightly but in general, every transmission will have this
information, in this order. When ATC issues a command to a pilot,
they are usually required to read back the information to verify that
the intention was clear as to what ATC wants the pilot to do.
There are some basic rules for speaking on the
Speak clearly and concisely, and as quickly
a possible, but take the time you need to get your message across.
When spelling out letters, use the phonetic
alphabet (see below)
When saying frequencies or headings, or
altitudes, always say out each number individually (see the examples
Each letter in the alphabet has a phonetic word
associated with it. These words are meant to be spoken in lieu of
saying a, b, c, etc. This is to reduce the chance that your
transmission is not recieved correctly. For example, if you speak
the following letters:
B, C, D, E, G, P, Z
They all have the same phonetic sound to them,
and if you're transmitting this on the radio, it could get very
confusing. However, if you say this:
Bravo, Charlie, Delta, Echo, Golf, Papa,
Then the chance of miscommunication is greatly
reduced, and none of those words sound alike, unlike saying only the
Lets look at some examples of each category of
and what they might sound like:
Remember, all letters use the phonetic
alphabet, and all numbers are spoken out individually.
||One zero thousand, five hundred feet
||WUN ZEE-RO thousand, FIFE hundred feet
||One two five point three zero
One two five decimal three zero
|WUN TOO FIFE point TREE ZEE-RO
WUN TOO FIFE decimal TREE ZEE-RO
||One zero minutes
||WUN ZEE-RO minutes
ATIS is a listen only transmission.
ATIS codes are given a letter from the phonetic alphabet for each
time they are updated. They are usually updated once per hour,
near 50 minutes past, unless severe weather requires an update
||"Hobby airport information sierra,
two two five zero
Zulu weather, wind one five zero at eight, visibility one zero, sky
condition, few clouds at three thousand, temperature two eight, dew point
two six, altimeter two niner niner eight."
||"Hooks Ground Cessna November one two three four, at the T hangars, request
taxi, north departure with Sierra"
||"Cessna November one two three four, Hooks ground, taxi to runway one seven
right, via taxiway Kilo, Charlie."
||"Taxi to runway one seven right, via taxiway Kilo,
Cessna November one two three four"
||"Sugar land clearance delivery, Cessna November one
two three four, IFR to San
||"Cessna November one two three four cleared to San Antonio airport as filed,
climb and maintain two thousand, expect six thousand one
zero minutes after departure, departure frequency is one one
Niner point seven."
||"Cleared to San Antonio airport as filed, climb and
maintain two thousand, expect six thousand one zero minutes
after departure, departure frequency is one one niner point
||"Cessna November one two three four, read back correct, contact ground on one
two one point four."
||"Hobby tower, Cessna November one two three four ready for departure, one
seven right at golf intersection"
||"Cessna November one two three four, Hobby tower, cleared for takeoff, one
seven right at golf"
||"Cleared for takeoff, one seven right at golf, Cessna
November one two three four"
||"Houston approach, Continental two two five three, with you, six
thousand, heading two seven zero"
||"Continental two two five three, Houston approach, radar contact,
descend and maintain three thousand, turn left heading two
||"Descend and maintain three thousand, turn left heading
two four zero, Continental two two five three"
||"Houston departure, Jetlink two one eight five with you, one thousand
five hundred for four thousand"
||JetLink two one eight five, Houston departure, roger, climb and
maintain one zero thousand, turn left heading zero one zero,
proceed on course."
||"Climb and maintain one zero thousand, turn left heading
zero one zero, Jetlink two one eight five"
||"Houston center, Continental three five heavy with you, flight
level three five zero, heading two three zero"
||"Continental three five heavy, Houston center, roger, contact
Houston approach on one three four point zero"
||"Going to one three four point zero, Continental
For a more in depth discussion of radio
communications, visit the FAA's AIM chapter on
Radio Communications Phraseology and Techniques