What are Pilots Saying to Air Traffic Controllers and What Does it Mean?
Let me make up a transcript of the communications for a typical airline flight. This is of course just an
example, and may not be entirely accurate because each airline has its own specific procedures.
1. Clearance Delivery: Pilots get their IFR (instrument flying) clearance here as a first step.
"Oakland clearance, United one three five ready to copy IFR Portland."
United 135 has a pen and paper ready to take down the details of their clearance.
"United one three five, cleared to Portland via radar vectors to Scaggs Island then as filed. Fly runway
heading. Climb and maintain six thousand feet; expect one five thousand fifteen minutes after departure.
Departure on 120.9, squawk 0351."
Clearance is telling United 135 that after takeoff they should fly runway heading and climb to 6,000 feet.
Then ATC will vector them to the Scagg's Island fix, and from there they will pick up their filed flight route.
After takeoff they should contact departure control on 120.9 MHz. The squawk is a transponder code; the
number you enter into the transponder appears on ATC's radar screen, so they know which blip is which
"Cleared Portland via vectors to Scaggs then as filed, fly runway heading, up to six thousand feet,
departure 120.9, squawk 0351, United 135."
Pilots always read back instructions given to them for confirmation.
2. ATIS: This is the automated weather broadcast. Pilots tune in and listen to get the latest weather.
"Oakland automated airport information sierra, 0115Z. Winds 280 at 10. Visibility 6 miles. Few clouds at
6,000 feet. Temperature 15, Dewpoint 10. Altimeter 29.90. Landing and departing runway 29. Taxiway
sierra closed. Ground hold in effect for aircraft departing Los Angeles, Las Vegas, and San Diego. All
aircraft read back hold short instructions. Caution: birds near airport. Advise on initial contact you have
The pilot now has weather information S (sierra). Every hour new weather information is broadcast and the
letter identifier changes. This way controllers know if the pilot has the latest weather and other information
required and does not have to repeat it.
At 01:15 Greenwich mean time, at Oakland, winds were out of 280 degrees for 10 knots. Temperature was
15 degrees C, dew point 10 degrees C. Barometric pressure was 29.9 inHg. There were some minor
taxiway closures, and departures to some airports were delayed for traffic congestion purposes.
2. Pushback, etc.: At big airports, pilots contact other frequencies to get their pushback clearance, start
clearance, etc. We'll skip over these.
3. Ground: Once the airplane is ready to taxi, and is released (no longer being ground-held for traffic
abatement), the pilot contacts ground control and gets clearance to taxi to the runway.
"Oakland ground, United one three five ready to taxi IFR, with sierra."
United 135 is letting ground know they have the latest weather information. "United one three five, follow
the company Airbus onto taxiway uniform, then whiskey to two niner."
United 135 has been instructed to follow another United Airbus (another type of aircraft) onto taxiway U,
then turn onto taxiway W, then stop at runway 29. All taxiway names are a letter(s), or a letter and a
number (like A3).
"Follow the company airbus to uniform, then whiskey two-niner, United 135."
4. Tower: Once holding short and ready for takeoff, the next step is to ask tower for permission to enter the
runway and takeoff.
"Oakland tower, United one three five ready for takeoff IFR, runway two-niner."
"United one three five, winds two eight zero at eleven, cleared for takeoff."
Tower is letting the pilot know that the winds are out of 280 degrees and blowing at 11 knots, and that the
pilot is cleared to takeoff.
"Cleared for takeoff runway two-niner, United 135."
5. Departure: Now that the airplane is off the ground, the next step is to contact departure control to be
sequenced out of the busy airport airspace. This starts with a check-in.
"NorCal departure, United one three five, one thousand climbing six thousand."
A check-in always has you state your current altitude and, if you are climbing or descending, the altitude
you are going to.
"United 135, NorCal, radar contact."
At some point, departure will give them clearance to go to their cruising altitude.
"United 135, climb and maintain one five thousand."
"Up to one five thousand, United 135."
6. Center: Once the airplane is free of departure's airspace, Departure clears them to contact the center
controller. There is a center controller for every major area of the United States. They handle airplanes
cruising at high altitudes.
"United 135, contact Oakland Center on 127.8."
"127.8 for United 135, good day."
[United 135 switches frequencies.]
"Oakland Center, United 135, level one five thousand."
"Oakland Center, roger, altimeter 30.15."
Center will give pilots periodic updates to the barometric pressure so they can set their altimeters to read
the correct altitude.
At some point, United 135 will move from Oakland Center's airspace to that of Seattle Center.
"United 135, contact Seattle Center on 127.6, good day."
"127.6 for United 135, good day."
"Seattle Center, United 135, level one five thousand."
"United 135, roger."
7. Approach: As the airport nears its destination, it will be handed off to approach control (which is really
the same as departure control). Approach control will inform the aircraft as to how it will be landing at the
airport and will get them in a position to perform the landing.
"United 135, contact Portland approach on 118.1."
"Going to 118.1, United 135, good evening."
"Portland approach, United 135, level fifteen thousand."
"United 135, Portland approach, turn left heading three two zero, descend and maintain nine thousand."
Portland is getting United 135 into position for the approach to the airport.
"Left to three two zero, down to nine thousand, United 135."
"United 135, turn right heading zero six zero, descend and maintain five thousand, slow to two two zero
"Right to 060, down to 5,000, slowing to 220 knots, United 135."
"United 135, intercept the localizer runway two eight right, cleared ILS two eight right."
"Cleared ILS two eight right, United 135."
United 135 has been cleared for the ILS (instrument landing system) approach into runway 28R. They will
line up with 28R and then use their ILS receiver to stay on the runway approach path. They don't need to
see the runway to accomplish this; the ILS receiver will give them steering guidance.
"United 135, contact Portland Tower 118.7."
"Going to 118.7, United 135