atc — air traffic controller game


atc [-u?lstp ] [-gf game name ] [-r random seed ]


atc lets you try your hand at the nerve wracking duties of the air traffic controller without endangering the lives of millions of travelers each year. Your responsibilities require you to direct the flight of jets and prop planes into and out of the flight arena and airports. The speed (update time) and frequency of the planes depend on the difficulty of the chosen arena.


Print the usage line and exit.
Same as -u
Print a list of available games and exit. The first game name printed is the default game.
Print the score list (formerly the Top Ten list).
Same as -s
Print the path to the special directory where atc expects to find its private files. This is used during the installation of the program.
-g game
Play the named game. If the game listed is not one of the ones printed from the -l option, the default game is played.
-f game
Same as -g
-r seed
Set the random seed. The purpose of this flag is questionable.


Your goal in atc is to keep the game going as long as possible. There is no winning state, except to beat the times of other players. You will need to: launch planes at airports (by instructing them to increase their altitude); land planes at airports (by instructing them to go to altitude zero when exactly over the airport); and maneuver planes out of exit points.

Several things will cause the end of the game. Each plane has a destination (see information area), and sending a plane to the wrong destination is an error. Planes can run out of fuel, or can collide. Collision is defined as adjacency in all three dimensions. A plane leaving the arena in any other way than through its destination exit is an error as well.

Scores are sorted in order of the number of planes safe. The other statistics are provided merely for fun. There is no penalty for taking longer than another player (except in the case of ties).

Suspending a game is not permitted. If you get a talk message, tough. When was the last time an Air Traffic Controller got called away to the phone?

The display

Depending on the terminal you run atc on, the screen will be divided into 4 areas. It should be stressed that the terminal driver portion of the game was designed to be reconfigurable, so the display format can vary depending on the version you are playing. The descriptions here are based on the ascii version of the game. The game rules and input format, however, should remain consistent. Control-L redraws the screen, should it become muddled.


The first screen area is the radar display, showing the relative locations of the planes, airports, standard entry/exit points, radar beacons, and ``lines'' which simply serve to aid you in guiding the planes.

Planes are shown as a single letter with an altitude. If the numerical altitude is a single digit, then it represents thousands of feet. Some distinction is made between the prop planes and the jets. On ascii terminals, prop planes are represented by a upper case letter, jets by a lower case letter.

Airports are shown as a number and some indication of the direction planes must be going to land at the airport. On ascii terminals, this is one of `^', `>', `<', and `v', to indicate north (0 degrees), east (90), west (270) and south (180), respectively. The planes will also take off in this direction.

Beacons are represented as circles or asterisks and a number. Their purpose is to offer a place of easy reference to the plane pilots. See Sx THE DELAY COMMAND section below.

Entry/exit points are displayed as numbers along the border of the radar screen. Planes will enter the arena from these points without warning. These points have a direction associated with them, and planes will always enter the arena from this direction. On the ascii version of , this direction is not displayed. It will become apparent what this direction is as the game progresses.

Incoming planes will always enter at the same altitude: 7000 feet. For a plane to successfully depart through an entry/exit point, it must be flying at 9000 feet. It is not necessary for the planes to be flying in any particular direction when they leave the arena (yet).

Information area

The second area of the display is the information area, which lists the time (number of updates since start), and the number of planes you have directed safely out of the arena. Below this is a list of planes currently in the air, followed by a blank line, and then a list of planes on the ground (at airports). Each line lists the plane name and its current altitude, an optional asterisk indicating low fuel, the plane's destination, and the plane's current command. Changing altitude is not considered to be a command and is therefore not displayed. The following are some possible information lines:

B4*A0: Circle @ b1
g7 E4: 225

The first example shows a prop plane named `B' that is flying at 4000 feet. It is low on fuel (note the `*'). Its destination is Airport #0. The next command it expects to do is circle when it reaches Beacon #1. The second example shows a jet named `g' at 7000 feet, destined for Exit #4. It is just now executing a turn to 225 degrees (South-West).

Input area

The third area of the display is the input area. It is here that your input is reflected. See the Sx INPUT heading of this manual for more details.

Author area

This area is used simply to give credit where credit is due. :-)


A command completion interface is built into the game. At any time, typing `?' will list possible input characters. Typing a backspace (your erase character) backs up, erasing the last part of the command. When a command is complete, a return enters it, and any semantic checking is done at that time. If no errors are detected, the command is sent to the appropriate plane. If an error is discovered during the check, the offending statement will be underscored and a (hopefully) descriptive message will be printed under it.

The command syntax is broken into two parts: Immediate Only and Delayable commands. Immediate Only commands happen on the next update. Delayable commands also happen on the next update unless they are followed by an optional predicate called the Delay command.

In the following tables, the syntax [0-9] means any single digit, and Aq Em dir refers to a direction, given by the keys around the `s' key: ``wedcxzaq''. In absolute references, `q' refers to North-West or 315 degrees, and `w' refers to North, or 0 degrees. In relative references, `q' refers to -45 degrees or 45 degrees left, and `w' refers to 0 degrees, or no change in direction.

All commands start with a plane letter. This indicates the recipient of the command. Case is ignored.

Immediate only commands

"a [ cd+- ]" number
Altitude: Change a plane's altitude, possibly requesting takeoff. `+' and `-' are the same as `c' and `d'.

a number
Climb or descend to the given altitude (in thousands of feet).
ac number
Climb: relative altitude change.
ad number
Descend: relative altitude change.

Mark: Display in highlighted mode. Plane and command information is displayed normally.
Ignore: Do not display highlighted. Command is displayed as a line of dashes if there is no command.
Unmark: Same as ignore, but if a delayed command is processed, the plane will become marked. This is useful if you want to forget about a plane during part, but not all, of its journey.

Delayable commands

"c [ lr ]"
Circle: Have the plane circle.

Left: Circle counterclockwise.
Right: Circle clockwise (default).

"t [ l-r+LR ] [ dir ] or tt [ abe* ]" number
Turn: Change direction.

Turn to direction: Turn to the absolute compass heading given. The shortest turn will be taken.
"tl [ dir ]"
Left: Turn counterclockwise: 45 degrees by default, or the amount specified in Aq dir (not to Aq dir . ) `w' (0 degrees) is no turn. `e' is 45 degrees; `q' gives -45 degrees counterclockwise, that is, 45 degrees clockwise.
"t- [ dir ]"
Same as left.
"tr [ dir ]"
Right: Turn clockwise, 45 degrees by default, or the amount specified in Aq dir .
"t+ [ dir ]"
Same as right.
Hard left: Turn counterclockwise 90 degrees.
Hard right: Turn clockwise 90 degrees.
"tt [abe*]"
Towards: Turn towards a beacon, airport or exit. The turn is just an estimate.
"tta" number
Turn towards the given airport.
"ttb" number
Turn towards the specified beacon.
"tte" number
Turn towards an exit.
"tt*" number
Same as ttb.

The delay command

The Delay (a/@) command may be appended to any Delayable command. It allows the controller to instruct a plane to do an action when the plane reaches a particular beacon (or other objects in future versions).

ab number
Do the delayable command when the plane reaches the specified beacon. The `b' for ``beacon'' is redundant to allow for expansion. `@' can be used instead of `a'.

Marking, unmarking and ignoring

Planes are marked by default when they enter the arena. This means they are displayed in highlighted mode on the radar display. A plane may also be either unmarked or ignored An ignored plane is drawn in unhighlighted mode, and a line of dashes is displayed in the command field of the information area. The plane will remain this way until a mark command has been issued. Any other command will be issued, but the command line will return to a line of dashes when the command is completed.

An unmarked plane is treated the same as an ignored plane, except that it will automatically switch to marked status when a delayed command has been processed. This is useful if you want to forget about a plane for a while, but its flight path has not yet been completely set.

As with all of the commands, marking, unmarking and ignoring will take effect at the beginning of the next update. Do not be surprised if the plane does not immediately switch to unhighlighted mode.


Plane A: turn left at beacon #1
Plane C: circle
Plane G: turn towards exit #4 at beacon #2
Plane M: altitude: climb 2000 feet
Plane S: turn to 315
Plane X: ignore

Other information

New games

The Game_List file lists the currently available play fields. New field description file names must be placed in this file to be playable. If a player specifies a game not in this file, his score will not be logged.

The game field description files are broken into two parts. The first part is the definition section. Here, the four tunable game parameters must be set. These variables are set with the syntax:

"variable = number;"

Variable may be one of: update indicating the number of seconds between forced updates; newplane indicating (about) the number of updates between new plane entries; width indicating the width of the play field; or height indicating the height of the play field.

The second part of the field description files describes the locations of the exits, the beacons, the airports and the lines. The syntax is as follows:

(x y) ... ;
(x y direction) ... ;
(x y direction) ... ;
[ (x1 y1) (x2 y2) ] ... ;

For beacons, a simple x, y coordinate pair is used (enclosed in parenthesis). Airports and exits require a third value, which is one of the directions wedcxzaq For airports, this is the direction that planes must be going to take off and land, and for exits, this is the direction that planes will be going when they enter the arena. This may not seem intuitive, but as there is no restriction on direction of exit, this is appropriate. Lines are slightly different, since they need two coordinate pairs to specify the line endpoints. These endpoints must be enclosed in square brackets.

All statements are semi-colon (;) terminated. Multiple item statements accumulate. Each definition must occur exactly once, before any item statements. Comments begin with a hash (#) symbol and terminate with a newline. The coordinates are between zero and width-1 and height-1 inclusive. All of the exit coordinates must lie on the borders, and all of the beacons and airports must lie inside of the borders. Line endpoints may be anywhere within the field, so long as the lines are horizontal, vertical or exactly diagonal.

Field file example

# This is the default game.
update = 5;
newplane = 5;
width = 30;
height = 21;
exit:           ( 12  0 x ) ( 29  0 z ) ( 29  7 a ) ( 29 17 a )
                (  9 20 e ) (  0 13 d ) (  0  7 d ) (  0  0 c ) ;
beacon:         ( 12  7 ) ( 12 17 ) ;
airport:        ( 20 15 w ) ( 20 18 d ) ;
line:           [ (  1  1 ) (  6  6 ) ]
                [ ( 12  1 ) ( 12  6 ) ]
                [ ( 13  7 ) ( 28  7 ) ]
                [ ( 28  1 ) ( 13 16 ) ]
                [ (  1 13 ) ( 11 13 ) ]
                [ ( 12  8 ) ( 12 16 ) ]
                [ ( 11 18 ) ( 10 19 ) ]
                [ ( 13 17 ) ( 28 17 ) ]
                [ (  1  7 ) ( 11  7 ) ] ;


Files are kept in a special directory. See the Sx OPTIONS section for a way to print this path out. It is normally /usr/share/games/bsdgames/atc

This directory contains the file Game_List which holds the list of playable games, as well as the games themselves.

The scores are kept in /var/games/bsdgames/atc_score


Ed James, UC Berkeley:, ucbvax!edjames

This game is based on someone's description of the overall flavor of a game written for some unknown PC many years ago, maybe.


The screen sometimes refreshes after you have quit.