When outside Class B, C, and D airspace, pilots may contact a nearby approach control facility or the air route traffic control center, ARTCC, having jurisdiction over the area. While VFR pilots are not required to communicate with air traffic control in Class E or G airspace, additional services, such as VFR flight following, may be obtained by doing so.
To request flight following, contact the controlling air traffic control facility with your position and request. For example, "Kansas City Center, Cessna Two Four Six Kilo Echo, five miles south of Kirksville, request VFR flight following".
The controller might respond, "Cessna Two Four Six Kilo Echo, Kansas City Center, Squawk four five two one. Say type aircraft and destination".
When a pilot requests flight following, the controller will track the flight's progress. Should the controller observe another aircraft in your vicinity, a traffic advisory will be issued, unless the controller's workload does not allow for it.
For example, "Cessna Two Four Six Kilo Echo, Traffic two o'clock, six miles, northeast bound, altitude indicates two thousand eight hundred".
Twelve o'clock is off the nose, three o'clock is off the right wing, six o'clock is behind you, and nine o'clock is off the left wing. In this case, the pilot should look to the two o'clock position (about 60 degrees to the right of the airplane's nose). Inform the controller whether you see the traffic by responding with, "Traffic in sight", "Negative contact", or "Looking for traffic".
If you are unable to see the traffic, and are uncomfortable with the proximity to your aircraft, you may request assistance in maneuvering away from the traffic. For example, "Cessna Two Four Six Kilo Echo, previously issued traffic now one o'clock, two miles, altitude indicates three thousand two hundred. Traffic appears to be converging and climbing through your altitude". You might respond, "Cessna Two Four Six Kilo Echo, request vectors around that traffic". The controller would then issue a turn to take you behind and clear of the other aircraft.
When you are clear of the other aircraft, the air traffic controller will advise you, "Traffic no factor".
When looking for traffic remember that the controller's radar shows your airplane's ground track. When an o'clock position is issued, the controller is referencing your radar track direction. When you are flying with a wind correction, the o'clock direction may be off, since you're facing a different direction than your airplane is tracking over the ground.
If departing from a towered airport, you should advise the ground controller on initial contact that you are requesting flight following.
A Few Things About Flight Following
Air traffic control can not see all other air traffic on radar. The pilot is responsible for seeing and avoiding other traffic.
Air traffic control will not separate you from other air traffic. Radar vectors will only be provided upon specific pilot request. The controller will expect you to maneuver as necessary to see and avoid other air traffic, as well as maintain VFR clearance from clouds.
Keep the controller informed if you wish to leave the frequency for a moment or cancel VFR flight following. The controller will assume the worst if you turn up missing from the frequency with no explanation. In this situation, air traffic control would watch your track to try to determine if your radio has failed, your aircraft has been hijacked, or you are experiencing some other type of emergency.
Receiving flight following service from air traffic control does not give you permission to enter Class B, C, or D airspace areas. Should you approach on of these airspace areas, the air traffic controller will terminate flight following to allow you to contact the air traffic control facility in charge of the airspace you are approaching.