VFR flight following (also sometimes called 'radar advisories') is a service provided on an as-available basis by air traffic control to aircraft flying VFR.
Great, I can hear you saying, what the hell does that mean? And why should I care?
You probably only care if you are a pilot or are interested in aviation. But let me try to do a better job of explaining it. If you fly under IFR, your aircraft will always be under the control of an air traffic controller - whether an airport tower controller, a departure controller, a Center controller, or an approach controller - you'll always be talking to (and following the directions of) one of them. This is because until recently, it was impossible for aircraft to see and avoid other traffic in IMC - and even with modern technology like ADS-B and TCAS, it's much safer to have a single external control point managing the whole of air traffic in a region - that way, the airspace can be utilized as safely and efficiently as possible since the controller can see the 'big picture.'
VFR pilots are responsible for their own aircraft, and are responsible for avoiding all other traffic as well as navigating and managing their aircraft at all times. This is made possible by the fact that VFR pilots are only permitted to fly when visibility permits this. However, it can be a lonely sky up there - especially if you're a student pilot, or are flying in unfamiliar airspace. There are many situations where you might need to speak to someone on the ground - if you have an emergency, or if you get lost, for example. Both of those situations involve heavy workloads in the airplane, and having to first find someone to talk to might not be feasible.
In a nutshell, VFR flight following involves an air traffic controller providing many of the same services he or she provides to IFR aircraft to an aircraft operating VFR. Since the VFR aircraft does not require them legally in order to operate, they are only offered on an 'as available' basis - if the controller has too many other aircraft to track, generally, they can decline to provide flight following. However, if they have the time and attention to spare, it can be an invaluable service.
Flight following is requested by aircraft already in flight and able to contact the controlling facility. Generally, to request flight following, you would do the following:
- Tune your radio to the proper frequency for the ATC facility for your area, wait for a lull in traffic, and make radio contact. ("Boston Approach, Skyhawk 12345.")
- Wait for their acknowledgement. ("Skyhawk 12345, Boston Approach.")
- Tell them where you are, what you're doing, and request flight following. ("Boston Approach, Skyhawk 12345 is five miles north of Seven Bravo Two at four thousand feet going to five thousand five hundred, en route to Kilo Lima Charlie India via Echo Echo November and Charlie Oscar November, request VFR flight following.")
- If the controller does not have the time available, they will tell you at this point. ("Skyhawk 12345, flight following not currently available, continue VFR.")
- Or, if they do have the time, they will generally instruct you to squawk a particular code to ensure they can identify you on their systems. ("Skyhawk 12345, squawk four-four-zero-two.")
- Acknowledge and comply. ("Boston Approach, Skyhawk 12345 is squawking four-four-zero-two.". Set your transponder as appropriate.)
- There may be a short delay, during which ATC may interact with other aircraft on the channel. However, eventually, you should receive confirmation that they have you identified, their read of your altitude from your Mode C transponder for verification, and the current altimeter setting. ("Skyhawk 12345, radar contact at five thousand feet, altimeter two niner eight five.")
At this point, you are under VFR flight following. Although you are not required to conform to ATC's routing instructions (and they will almost never issue them to you) you would be a fool not to if they do tell you to do something. On your side, it is considered good form to notify ATC if you are going to deviate from the course you provided during the initial contact. In the above example, Skyhawk 12345 has declared that it is enroute to KLCI (Laconia Airport, Laconia NH) via the Keene and Concord VORs. ATC will expect 12345 to fly generally directly to the Keene VOR, then to the Concord VOR, then to Laconia airport. You don't need to inform ATC if you correct for winds or drift, or if you wobble around a bit, but if you decided to land at an intervening airport, or decided to skip the Concord VOR leg and fly directly from Keene to Laconia, you should let them know so they don't wonder where you're going - because they'll be using their knowledge of your course to route any other traffic in your vicinity.
When you reach your destination (really, when you're within sight of your destination) you should notify ATC that you would like to terminate flight following. Your controller will acknowledge and clear you to change frequency and perhaps to squawk VFR. I have had controllers give me information on any traffic between me and my destination before signing off. Sometimes, if you're in an area that isn't too busy and they know you're going to be on the ground only for a short time, they may tell you to continue to squawk the assigned transponder code, so they know when you reappear who you are and what you're doing.
While you are under flight following, you can expect the following services from ATC, although you should not rely on them:
- Traffic advisories. ATC will alert you if other traffic comes near you, and may inform you whether that other traffic has you in sight or not. They will likely inform you of the other traffic's course and intentions.
- Weather advisories. If severe or dangerous weather conditions exist or crop up, or if flight conditions begin to deteriorate and drop below VFR minimums anywhere in your area, ATC may inform you of that fact. You may be able to inquire of ATC if they have any adverse weather in view along your flight path if they don't volunteer it. Also, ATC may be able to give you informal PIREPs (pilot reports) from other aircraft in the area of conditions (turbulence, temperature, icing, winds, clouds, etc.)
- Altimeter updates. A difference of one inch on the altimeter setting (29.92 to 30.92) can change your indicated altitude by approximately a thousand feet. You don't want the air pressure to change like that without you knowing. ATC will keep you updated of the current altimeter settings as you traverse the area.
- Clearances. In order to enter Class C or Class D airspace, you must make radio contact with their control facility. If you are under flight following, you are already 'in contact' with air traffic control, and may enter and traverse Class C or Class D airspace without further contact required - ATC will coordinate your traversal, and if problems crop up they will reroute you or warn you off. This way you don't have to change frequencies and make contact with every airport tower along the way - if Approach wants you to talk to the tower, they'll tell you, and give you a frequency to make contact on. You'll still need to ask them before entering a Class B, but you can request clearance from your controller rather than switching freqs.
- Contact. If you get lost, or if you have an emergency, you don't need to worry about who you should talk to - you already have a controller on your frequency who knows who you are and where you are. If you have problems, you can request assistance, anything from a position fix or vector to a waypoint up to positive control if you have an emergency or fly into cloud. Remember - if you get lost, CCCCC - Climb, Conserve, Communicate, Confess, Comply. The last three are easy if you've already got a controller on the line.
Plus, courtesy. If you're going anywhere near a controlled airport, it's good piloting to make sure that airport's controllers know about you. Under flight following, you can be sure they'll be informed, or that you'll be routed around anything they're doing that you shouldn't be near. In general, therefore, even if you're flying on clear blue sky days, Air Traffic Control still has much to offer you. Request VFR flight following. Hey, at least you'll have something to listen to! It's always fun to hear airliners and sometimes even military aircraft talking to your controller, and vice versa. Makes you feel like a Real Pilot(tm).
(IN 5 21/30)