Aerial Combat Modeler Pilot Manual

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Package Name: acm‑7.1‑dlc Version: 20200524

This minorly updated version released 2020‑05‑24
by David L. Craig available at
was derived from the first version of acm-7.0-dlc released 2020‑02‑02
which was derived from the majorly enhanced version released 2010‑01‑09
by Umberto Salsi available at
which was derived from the last release of the original
by Riley Rainey (unfortunately no longer available online).

Screenshot of landing the F-16

Landing the F‑16 with Head‑Up Display in the default Sahara scene

Table of Contents

Each line in the following two columns is a clickable link to the actual section. When reading this manual to learn the content, cover‑to‑cover is the best approach. Click through the links when you need a particular pesky detail really soon.

You can click on, as an example, the [DIS] link to read what that notation means or (if links are not supported by the version of this manual you are reading), refer to the [DIS] item under the Explanation of Notations subsection immediately following to access that information.

Front Page

Table of Contents

Explanation of Notations

Quick Start (How To Take-Off)



Changes Not Already Described

ACM History and Acknowledgments

Known Issues and Support

Launching An ACM Session

ACM Graphical User Interface

Panel You

Panel Instruments

Panel Scene

Panel Drones

Panel Configure

ACM Command Line Syntax

Option ‑airspeed‑kt

Option ‑altitude

Option ‑arcade

Option ‑cmap

Option ‑copyright

Option ‑da

Option ‑depth_steps

Option ‑dis [DIS]

Option ‑dis‑absolute‑time [DIS]

Option ‑dis‑appl [DIS]

Option ‑dis‑exercise [DIS]

Option ‑dis‑site [DIS]

Option ‑display

Option ‑downward_view_angle_deg

Option ‑drone‑mode

Option ‑end‑game

Option ‑eye_to_screen_cm

Option ‑frame‑rate

Option ‑fuel

Option ‑geometry

Option ‑groundc

Option ‑gust

Option ‑heading

Option ‑help

Option ‑hud‑mode

Option ‑init

Option ‑js

Option ‑latitude

Option ‑lighting

Option ‑longitude

Option ‑mouse‑mode

Option ‑name

Option ‑no‑dis

Option ‑no‑sound

Option ‑objects

Option ‑payload

Option ‑plane

Option ‑scene

Option ‑stealth

Option ‑subject‑entity‑id

Option ‑team

Option ‑team_1

Option ‑team_2

Option ‑threshold‑range

Option ‑transfer‑entity‑mode

Option ‑update‑rate

Option ‑version

Option ‑visibility

Option ‑watch‑frame‑rate

Option ‑wind

Other Initialization Parameters

File default.acmscene

File object‑map.txt

File munition‑map.txt

File inventory

.obv Files

Axis Control

Keystick Facility

Changing To the Keystick

Changing From the Keystick

Keysym Layouts (typical US keyboard)

Main Mode Layout

Browse Mode Layout

KeyStick Layout

Legacy Keypad Layout (Deprecated)

Non-Keypad View Keys Layout

Non-Keypad Hints Keys Layout

Pilot Commands

Events (Quick Reference)

Events: Glyphless Keys

Events: Non‑Alphanumeric Keys

Events: Alphanumeric Keys

Events: Buttons

Events: Terminal Facility Commands


Original Table of Pilot Actions

ACM Aircraft Systems

Magnetic Compass

Classic Instrument Panel

Turn and Slip Indicator

Airspeed Indicator

Artificial Horizon (Attitude & Bank)

Altitude Indicator

Vertical Speed Indicator (VSI)

Head‑Up Display

HUD Ladders

HUD Compass

HUD Angle of Attack

HUD G Meter

HUD Weapon Status

HUD Turn and Slip

HUD Mach Meter

HUD Radar Altimeter

Horizontal Situation Indicator (HSI)

HSI for VOR Stations

HSI for ILS Stations

HSI for RNAV Calculator

Automatic Direction Finder (ADF)

[AS] Autopilot Systems

[AC] Coordinate Roll/Yaw (AutoCoordinate)

[AW] Hold Turn/Wings Level (AutoWings)

[AP] Hold Altitude/Rate of Climb (AutoPilot)

[AT] Hold True Airspeed (AutoThrottle)

[AN] Navigate to VOR (AutoNavigate)

[AL] Land Using ILS (AutoLand)

Lights Panel


Electronic Counter‑measures

Weapon Systems


Air‑To‑Air Missles

Ballistic Bombs

Other ACM Components and Concepts

About Screen Configuration

About Planes

About Drones

About Origin Situations

About Meteorological Conditions

Visibility and Haze


Day and Night

Clouds and Fog


Temperature, Pressure, and Humidity

About Resupply

About Stealth Mode

About the Default Scene

DLC — David L. Craig Airbase

ICO — Umberto Salsi Airbase

NP_ — North Pole Airbase

RRA — Riley Rainey Airport

SP_ — South Pole Airbase

TDC — Tristan da Cunha Airport

Programmer Topics

Building ACM on UNIX Systems

X Keyboard Configuration

Defining New Scenes

Team Locations — TEAMLOC, TEAM_x Records

Ground Color — GROUNDC Record

Runways — RNW, RNW2 Records

NAVAIDs — NAV Record

Instrument Landings — ILS Record

Scenery Ornamentation — FEATURE Record

Defining New Aircraft

Defining New Objects

IEEE 1278.1 (DIS) Compliance

Transfer Control Protocol

Transfer Control Request PDU

Transfer Type

ACM for Microsoft Windows

Source Code

Developer Studio Setup

Setting Up an ACM Session

Starting ACM



Units of measurement

Suggested Further Reading

Explanation of Notations

The notations employed in this Pilot Manual are really terse, so here is a list of the terms and the verbose explanations of what they signify. The list is sorted according to the alphanumeric characters.

[DIS] the event—action or ACM Command Line Option is unavailable if the CFLAGS environment variable did not include ‑DHAVE_DIS when ACM was built.
[FIX] the event—action is unavailable if the CFLAGS environment variable did not include ‑DFIXME_INCOMPLETE_OR_BUGGED when ACM was built (but this notation means it's broken so you probably don't want to mess with it unless you're trying to be a hero by fixing it).
[SG] (safeguard); the event—action must be armed by one trigger event followed by a second trigger event within two seconds to execute the action. If the armed state times out, the next trigger event rearms the action. Note: This safeguard is only operative for main mode commands—browse mode commands require only one keypress to invoke the pilot command.
[SK] the event—action is unavailable if the CFLAGS environment variable did not include ‑DSPECIAL_KEYS when ACM was built
[SNP] the event—action is dependent upon the C macro SWITCH_TO_NEXT_PLAYER_ENABLED being defined when ACM was built (this is hardcoded in the distributed version of events.c so it should be available unless the program has been modified).
[‑V] the aircraft does not have a visual description file in the objects directory so the chase view is not available for it nor can it be seen by any observers.
[+b] the event—action is available in both the main and browse modes.
[‑b] the event—action is available only in main mode, not in the browse mode (look up or down one or two lines for the same event with a different action that may be available). Note: As this is true of most pilot commands, this status can be assumed in the absence of ‑m and +b.
[+j] the event—action is available only if a working joystick has been successfully accessed by ACM through the device path specified via the ‑js ACM option .
[‑m] the event—action is available only in browse mode, not in the main mode.
[+s] the event—action is available only if the CFLAGS environment variable included ‑Dsun; i.e., Sun keyboard, when ACM was built.
[‑s] the event—action is available only if the CFLAGS environment variable did not include ‑Dsun; i.e., Sun keyboard, when ACM was built (look up or down one or two lines for the same event with a different action that may be available).


Newbie note: If piloting an aircraft, real or simulated, is a new endeavor for you, be advised it is significantly more complex than driving an automobile, and it took you a while to learn to do that well, did it not? Teaching you how to fly is beyond the scope of this manual, although it attempts to be comprehendable by beginning pilots who have not yet absorbed the basics, so don't stop reading. The ACM man page discusses briefly how to get airborne without a lot of bother (in a shell window such as xterm, cd into the acm‑7.1‑dlc distribution directory whereever it was installed, then invoke man ‑l src/ to view it). Also, in this section are many links to Wikipedia articles about terms and acronyms that may be meaningless to you at this time.

Real pilots in the USA reference the Federal Aviation Administration's official publications, especially the Pilot Handbook (a 54 MB PDF). You'll use that if you're running X-Plane 11 or possibly for FlightGear but ACM appeared before those simulators and is oriented toward simplicity while still adhering to aerodynamic realities. So if all you're going to pilot is this simulator, you can ignore a lot of what's in the Handbook (or the Aeronautical Information Manual (AIM) for that matter) but "Chapter 4: Principles of Flight" and "Chapter 5 Aerodynamics of Flight" are fundamental (though presented for post-high school readers).

The FAA is the regulatory part of the Federal government for aviation, but NASA is the the R&D group. They offer a Web-focused collection of age-appropriate (yes, many children can learn to fly this simulator) material on aeronautics and aerodynamics—visit to dive in.

Also, reading “Stick and Rudder: An Explanation of the Art of Flying” by Wolfgang Langewiesche is highly recommended for sorting out all the apparent contradictions you are about to encounter.

ACM‑7.1‑dlc is a distributed multiplayer air combat simulation that runs on Unix-like platforms, such as Linux and Solaris. Players can engage in air‑to‑air combat with infrared missiles and cannon (the Su‑30 also drops bombs), but civil aircraft are available, as well. Users can add more aircraft models and more sceneries, and this manual explains how all that can be done, too.

Aircraft are simulated as 6 degrees of freedom bodies:
 Translation: (1) forward/backward, (2) left/right, (3) up/down, and
 Rotation:   (4) yaw, (5) pitch, (6) roll
and every model gets described and then behaves according to its aerodynamic properties. Landing gear dynamics/ground handling, engines, atmosphere properties including wind, and (naturally) control inputs, are also simulated, so you can experiment with the different behaviors of the aircraft in different flying conditions.

The “world” of ACM is round, but the terrain is uniformly colored and lacks any detail apart from haze and some facilities here and there. This poor rendering is intentional because it makes the program so light and fast, performing 25 frames per second with a CPU load nearly zero, without the need for highly accelerated video hardware nor specialized graphical libraries. ACM‑7.1‑dlc is also suitable for instrumental flight (IFR), since it provides many airports and related radio-navigation aids, including VOR, DME, ADF, RNAV, and ILS.

Quick Start (How To Take-Off)

[adapted from the original man page]

By default, your mouse is the control stick. The neutral position is the center of your application's X window. Moving the mouse away from you (the mouse cursor goes higher) pitches the plane's nose down, while pulling it back pitches the nose up. Left and right inputs roll the aircraft in the corresponding direction. On the ground at speeds up to 50 knots, nose wheel steering controlled by mouse left/right movements guides the aircraft, but get it back to center before hitting that velocity.

If you're not certain what aircraft you're piloting, press the shifted D key to display debugging information in the upper-left of the window—the first line will tell you the answer. You may press the shifted D key again to turn the debugging information display off again.

To take off for the first time, select 20 degrees of flaps (press h twice), then press the full throttle key (the 4 key on the main keyboard) and the b key to release the brakes. Keep the mouse in the neutral position until you are moving at about 50 knots for the C-172 or 150 knots for anything else, then pull the mouse about two-thirds of the way down the view window. You should pitch up and lift off the ground fairly easily. Gently but not slowly push the mouse away to return the cursor to the middle of the window without inducing a turn by straying to the left or right. Gently adjust the mouse forward if airspeed is dropping or backward if airspeed is increasing too quickly. Controlling thusly your airspeed and flight direction (straight!), let your airspeed continue to steadily build and as it passes 70 knots for the C-172 or 190 for anything else, raise the flaps (press y twice) and landing gear (press g). If you're flying a B-747, get those flaps up before you reach 220 knots, but not too fast or you'll fall out of the sky.

Congratulations, you're flying a precision piece of very expensive machinery. Now land it safely...

"A great landing is when the pilot can walk away from it. An outstanding landing is when the aircraft can be reused the next day."  —Chuck Yeager


Summary of the main features currently implemented (changes for this release are noted as [New]):

  • Source code provided with GPL license
  • Simulation with 6 degrees of freedom
  • Landing gear simulation
  • Limited vertical positive/negative load
  • Standard atmosphere
  • Weather: daylight/night, fog, wind
  • Classic instruments
  • Head‑up display (HUD) system and inertial reference which can be toggled with the display of a classic instrument panel via the [H] key
  • Navigation
    • HSI with RNAV calculator
    • ADF
  • Support for key release event handling, including detailed tracing of key and button events to stderr [New] The most recent information is now also shown in the Debug display
  • By default, the aircraft control stick is simulated via the joystick if its device path is specified via the ‑js program argument and is successfully accessed; otherwise, the mouse is used
  • The pilot may at any time toggle between the stick control default and the use of a keyboard stick facility termed keystick, which allows the mouse to be used for X purposes while ACM ignores it
  • Keystick control uses arrow keys
    • [↑] (stick forward because the keycap arrow points away from the pilot and is usually further from the pilot than the other key)
    • [↓] (stick back because the keycap arrow points toward the pilot and is usually closer to the pilot than the other key)
    • [←] (stick left)
    • [→] (stick right)
    (layout of the keystick keys is depicted here)
  • The color and brightness of the HUD, messages, [D] and [F1] key displays can be changed in-flight via the [C] and [B] keys, respectively
  • The GROUND_COLOR, TEAM1_LOC and TEAM2_LOC scene records have been replaced with multiple GROUNDC and TEAMLOC definitions using simple mnemonic tags that are selected via a TEAM_1 and TEAM_2 scene record as well as -groundc, -team_1, and -team_2 command line and init file options—oh, and the [G] key cycles through all the GROUNDC colors in-flight
  • Auto‑pilots [AS]
    • [AC] Roll/yaw coordination enabled via [X] key
    • [AW] Wing leveler enabled via [|] key (bar)
    • [AW] 3.0° turn (standard rate) enabled via [<] (left) and [>] (right) keys
    • [AW] 1.5° turn enabled via [,] (left) and [.] (right) keys
    • [AW] Maximum Bank panel knob adjusted using [(] (down) and [)] (up) keys, having settings of 15, 20, 25, 30, and 35; default is 25°
    • [AP] Hold altitude enabled via [Z] key
    • [AP] Hold rate of climb rate enabled via [A] key, and the [5], [6], [%], and [^] keys adjust the target rate of climb
    • [AT] Hold speed enabled via [T] key
    • [AN] Follow VOR radial enabled via [N] key
    • [AL] Follow ILS glide path enabled via [L] key
  • Several aircraft models implemented, both civil and military
  • Several senarios that use actual aviation facilities (Note: These have not yet been converted to the new acmscene record formats)
    • Dallas, Texas, USA
    • Italy
    • Nellis AFB, Nevada, USA
    • Baghdad, Iraq
  • The default scene, allworlds, centers in the no‑man’s land of the Sahara Desert with minimal and ficticious facilities, and includes airports at the geographic poles and the island of Tristan da Cunha in the South Atlantic. It also includes VOR/DME stations along the Equator, Prime Meridian, Anti-Meridian, 90W meridian, and 90E meridian, plus latitudes 87N and 87S. All magnetic variances and runway numbers were adjusted to the state of the Earth's magnetic field circa 2014.
  • Annotated “aerial photographs” and other screenshots in this manual document the allworlds scene
  • Navigation charts in PDF format for the ACM‑5.0‑ico scenery
  • Note that the X architecture permits customization of the input devices ACM uses to enable the pilot to control his aircraft (see X Keyboard Configuration for further information)
  • [New] The keypad facility has been deprecated (though it still functions as before) to remove the keypad hardware requirement for platforms running ACM (see next page for details)
  • [New] The [F2] key is defined as a toggle for the testkeys mode that displays the Pilot Action name associated with the key pressed instead of performing the action.

Changes Not Already Described

This manual documents the ACM‑7.1‑dlc‑* release, basically the ACM‑7.0‑dlc version with some minor additions and corrections: