Who am I?
You are the Tower! You are the god of the runways that you control. You can clear people for takeoff and to land, (but you'd better make sure they're actually clear...). You control the order that people depart, and the order in which they land. You also get to talk to people just "passing through" your airspace on their way to other places, to help make sure they don't hit someone in your traffic pattern.
Where is my airspace?
You are responsible for all the airspace within five miles of your airport, from the ground up to and including 3,000 feet above the field. (So if your airport is at 1,000 MSL, you get up to 4000 MSL...) (There are a few exceptions to this rule, at SNA, BUR, LGB, LAX and ONT where you don't go up as high...) There are a few exceptions though - if two airports might lay a claim to the same area cause their circles overlap, the "more important" airport gets the sky. (For example, LAX and HHR - LAX wins... Between VNY and BUR, BUR wins... Between VNY and WHP, VNY wins....) You'll always have enough sky though to have a traffic pattern inside your sky.
What is a traffic pattern?
It's a kind of racetrack around your runway, which is where VFR planes depart, circle round the field, and arrive from. There are six legs to the pattern: The 45-degree Entry, Upwind, Crosswind, Downwind, Base and Final, and if you don't know these, check out the FS tutorial to get a better idea of how they work. Because you can do a pattern on EITHER side of the runway, get used to thinking of things like "Left Downwind", "right base". The patterns themselves are called "Left Traffic" and "Right traffic", as in "Enter Left Traffic runway 8".
Which pattern you use is up to you... and you can even use both if you want. At some fields though, a pattern might get too close to someone else's pattern, or might be too close to a mountain, in which case you don't have a choice. We've tried to put some pattern information below for you...
What am I responsible for?
Your primary job is to patrol the RUNWAY. Everything else is less important. However you -do- spend a lot of time doing other things, mostly putting your arrivals into a landing order, by telling planes to follow each other. In most towers you don't actually have a radar screen, so you rely on position reports, "report on downwind", "report abeam the tower", "report 3 miles out" to get an idea in your head where people are.
Because VFR pilots are responsible for missing other planes, you don't
actually need to separate them from other planes, but it's a good idea
to tell them about each other. So if two guys call you from the southeast, tell
them about each other: "N4324 C172 also inbound from the SE", "Helicopter
34L, use caution a learjet departing the airport southwestbound", etc.
If two VFRs hit, and you've told them about each other, it's not
actually your fault unless they hit on the RUNWAY in which case you're
in big trouble.
How do I get the planes in the pattern?
Generally, you have two things to worry about... the first is giving people
traffic advisories, so if someone is coming from the Southeast, you want to
know that so you can tell other planes coming and going from the Southeast.
You might also want to know how FAR southeast, so you could ask the plane to
tell you that. (Of couse, with ASRC, you'll actually KNOW where
they are, but that's sort of cheating!
The best thing to do for sequencing is get everyone on a downwind, so you can better gauge who should go first. This isn't all that different from vectoring planes to an ILS, except you aren't issuing any headings to these guys - they're doing this on their own... Ask them to call you when they are "downwind abeam". Then do one of two things: You can tell a plane to follow someone else, "Follow the B737 ahead", "Follow the Cessna over the reservoir", etc., or you can tell him "Extend downwind, I'll call your base", and if you do that, remember to tell him to "turn base" when it's OK for him to come in towards the runway.
AS far as navigation is concerned, never forget that LA is full of FREEWAYS. Many a controller owe their careers to the fact that it's sometimes easier to say, "follow the freeway ahead" than to give a vector. And a great way to separate planes is to say, "Stay on the west side of the freeway" and to tell the other guy to "stay on the east side". Same thing goes for shorelines!
How about departures?
They're easier. Once they're off the runway, you can tell them to "make right downwind departure", "make right crosswind departure", "make straight out departure". As soon as they don't have any conflicts with other reported planes who are inbound or overflying, you can tell them to get lost, "frequency change approved".
If someone is "transitioning" your area and will be in your sky, he may call you. If you want, pin him down to a route "follow the freeway",or maybe "fly directly overhead the field at or above 2,500 feet. ". That last one is GREAT if you want to make sure he's not in the way of your departures.
What about IFR guys?
Depending on the kind of tower you are, you may or not be responsible for separating IFR planes. Most towers are NOT radar certified, and can't do things like vector IFR planes, assign IFR altitudes, etc, or handoff a plane to a radar controller. In fact if you're not radar certified, you're technically not allowed to use a radar screen at all to ensure separation between planes. Still, some of these VFR towers do have radar screens, and you can use an IDENT to give yourself an idea where a plane is, and a facility that IS radar certified can leave the name tag on the blip and you can use that to get an idea where to look out the window for a plane.
Of course with ASRC, these guys are going to have a name on their tag anyway, and it's silly not to use the radar if it's there with the right name on the plane. Point is, all your job is is to tell them about each other, and not to worry if they get really close. They both are looking out the window after all, and that's THEIR job.
Because IFR planes need separation though from other IFR planes, approach control will hold onto these arrivals until there's no other IFR planes for them to hit, and then give them to you to clear them to land. You'll generally want to work your VFR planes around your IFR arrivals, but if you need to move the IFR plane to another runway, the phraseology is "Circle to runway XX". Once he can see the field, treat him like another VFR guy, and you can even tell him to follow someone else if you want... AS far as separating an IFR guy from a VFR guy? That's the responsibility of the VFR plane, so don't worry about doing anything more than telling them about each other.
The few towers that ARE radar-certified are the ones inside Class C or B airspace, (Burbank, SNA, ONT, SAN, etc.) In some ways, they are like another radar sector, and they can radar identify planes, vector them and turn them. But again, you don't do this normally with VFR planes. However, inside Class B and C airspace, the tower DOES separate IFR from VFR planes (if the blips overlap, they have to do it by more than 500 feet), and they are also REQUIRED to tell VFR planes about other VFR planes. This extra rule is mostly because these airports are much busier, and carry commercial jets which require more separation.
What about Approach control?
You own the area from the ground to 3,000 AGL (except where noted below...). Approach control has all the stuff above you, and the area outside your airspace (except if it's another tower...) If he is working a plane which is coming to you, he should tell him to call you well in time for him to call you before he's 5 miles out... If he doesn't, call him on the phone and remind him that it's a beautiful sunny day and he's stuck in a dark radar room. If you're working a plane and he asks for flight following, you can tell him to call approach. Otherwise, you might find that approach might be too busy with IFR planes to want to talk to him. Of course, if the pilot is going to enter a Class B or C area, he'll HAVE to talk to approach...
How do I use the RADAR?
Keep in mind that unless you're a radar certified tower, you CAN'T use handoffs for VFR planes. If you want to find a plane, ask him to IDENT. If you want to put a note to yourself about the plane (maybe where he is going...), feel free to use the ADD REMARKS bit to put a note there, but remember, VFR planes DO NOT have to file a flight plan, and can generally go wherever they want.
Even though you can't vector planes, you ARE allowed to suggest headings. If a plane is lost, or can't find you, or is really in the way of someone, you CAN say, "suggest heading 350, vector for the field, for traffic, etc." It's a semantic/legal difference of course which we won't bore you with here...
How about altitudes?
If it's a VFR guy, you're not supposed to give him a HARD altitude, "maintain 3,500". In class C airspace, you can give him a RANGE of altitudes to fly, "transition at or below 3,500 feet", "cross the runway above 1,000 feet", etc. This is cause it's hard to avoid clouds and other planes if you're stuck at one height... In any other kind of airspace, you shouldn't assign altitudes at all.
What separation is required?
Again, the rule is "see and be seen", and the VFR planes do all their own separation. All your job requires is to tell planes about each other.
How do I ship planes to other towers?
If you want to be authentic and not use handoffs, before you start, jot down the frequencies of the towers near you, and just say, "contact Van Nuys tower now on 120.2". Of course if you use the handoff feature to do that, we're not going to complain...
A special rule applies though for fast planes and close airports. If a plane is a jet, or a turboprop (like a King Air), most towers follow the tradition of calling the next tower before he clears a guy for takeoff, to warn him, and to find out how the next controller would want the plane to enter the pattern. You tell the pilot that before shipping him to the next guy cause he's so fast, there's not much time to get it wrong.
How about runway separation?
Here's a little known point... because we're not talking IFR separation here, it's possible to clear a whole bunch of people for takeoff at almost exactly the same time... Here's the rule:
If everyone is a "small plane", (less than 12,500 pounds, which is most Cessnas, etc...), you can clear a plane for takeoff right behind someone else as long as the first guy is 1.) Airborne, and 2.) 3,000 feet down the runway.
If the second plane is a twin, you'll need 4,500 feet down the runway...
If EITHER plane is a jet, (the front or the back one), you'll need 6,000 feet (which is just more than a mile, if you want to measure it on the scope...) it's more fun for multiplayer guys to be right up someone else's tailpipe, so if you can go for minimum separation, go for it!
There's similar rules for separating arrivals and departures, and successive arrivals. if you really want to know them, look them up in the FAA Order 7110.65, located on the ZLA main page or search the FAA official site.
It should be noted that the information contained here is written primarily from a U.S. FAA point of view - however the fundamental principles at play here are fairly universal, and other countries will have similar rules to those described here to address these issues.