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DULLES TOWER Version 1.00 Copyright (C) 1988 by John McKeown PROGRAM OVERVIEW DULLES TOWER is an Air Traffic Control (ATC) simulator that provides a realistic representation of the responsibilities incurred while working in a real airport control tower. While using DULLES TOWER, you must guide inbound traffic to active runways and vector departing aircraft toward their destinations, all while maintaining proper separation. Five different skill levels are available; additionally, each simulation is different, as the available runways/destinations and number/type of aircraft change. It is your responsibility to control each aircraft by issuing various keyboard commands and tracking their progress and status on a very active console display. System requirements include: - PC/XT/AT/386 with - 384 K of RAM - DOS 2.1 or higher - Color graphics adapter and the - 8 files included with this program: DULLES.001 ┐ DULLES.002 ├ Opening graphics screens DULLES.003 ┘ DULLES.DAT - Aircraft/airport data DULLES.DOC - Documentation DULLES.EXE - Program DULLES.HLP - On-Line Assistance DULLES.REG - User registration form All 8 files must be located in the startup directory; otherwise, you will be greeted with a "MISSING FILES!" error and execution will be halted. DULLES TOWER is distributed as user supported shareware; if you like and continue to use DULLES TOWER, please send a nominal donation to: John McKeown P.O. Box 277 Chantilly, VA 22021-0277 If you have questions or comments, feel free to contact me through CompuServe 17531,3435. Contributors of $18.00 or more will receive by return mail, a FREE DULLES TOWER T-SHIRT! Please order by completing the questionnaire within DULLES.REG and be sure to include your shirt size! DOCUMENTATION OUTLINE I. Introduction A. The Airport B. Some Vocabulary/Explanations II. The Simulation A. Skill Levels B. The Screen Layout/Windows 1. Radar 2. Extended Range 3. Pending 4. Command 5. Status 6. Callsign C. Command Set/Key Assignments III. Using the Simulator A. Near Miss/Mid-Air Collisions B. Airspace Exits C. Landing/Departures D. Examples E. Scoring IV. Potpourri INTRODUCTION The Airport Dulles (DUL-les) International Airport is located west of Washington, D.C. in northern Virginia. As one of the capital area's main airports, it services thousands of travelers each year; as a result, scores of aircraft must be controlled annually. Departing traffic are directed to an active runway, cleared for takeoff, and issued departure vectors, and eventually handed off to Dulles Departure Control. Conversely, arriving aircraft must be directed to an active runway, cleared for an approach, and cleared to land. This is precisely the simulated scenario while using DULLES TOWER. Some Vocabulary/Explanations Every effort has been made to make this program as accurate as possible. Since I've never been an Air Traffic Controller or a pilot, certain liberties have been exercised to make up for a lack of expertise. But there are a few things that I do know that may help to get you started. At the airport itself, there are 3 very long pieces of asphalt with numbers on each end. For our purposes, we will assume that all runways are at sea level. Because you can land or takeoff in either direction, that means 6 runways are available. Each is referred to by the number on each end. So what numbers are used? Stay tuned.... As the controller, you can order an aircraft to fly in a certain direction by assigning it a heading. A heading is a number between 0 and 360 that corresponds to a compass direction. For example, if you wanted a particular aircraft to fly straight east, you'd issue a heading of 090; south and west would be headings 180 and 270, respectively. The heading concept can be summarized by the following diagram: 360 000 north 325 045 northwest │ northeast │ 270 west ──────┼───── 090 east │ 225 │ 135 southwest southeast 180 south Thus, you as a controller have 360 different headings to choose from. How does this relate the runway numbers? Runway numbers are based on the heading that a landing aircraft will fly in order to land, minus the last digit. For example, let's assume that a runway is number 09; simply add a zero to the end to get 090 as the approximate heading you would assume to land. Because one piece of pavement is available for landings in two directions, you would also be able to land flying west (heading 270) on runway 27. These are the numbers you will see on the end of each runway. For example, Runways 09/27 09 27 ->- ├──────────────────────┤ -<- Aircraft flying heading 090 Aircraft flying heading preparing to land on 270 preparing to land on runway 09. runway 27. Major airports may have parallel runways and are distinguished by suffixes of L for left and R for right. Dulles has six runways: 01L/19R, 01R/19L, and 12/30. Understanding the day's prevailing wind patterns help you to understand why certain runways are open on one day and closed another. By landing or taking off into the wind, a pilot can effectively increase the amount of air moving over the plane's wings or a helicopter's rotor blades. This tends to reduce the amount of runway needed to takeoff/land. If the winds are calm, it's theoretically possible to open runways in opposite directions (but operationally, it would keep the laundromats busy!) Thus, if you have a good grasp on headings and the runway numbering system, you're ready to sit down at the console and start controlling aircraft. THE SIMULATION After typing DULLES at the DOS prompt, you will be greeted with the opening screen/copyright notice. After reading the second screen, simply press any key to view the available skill levels. Use the up/down arrow keys on your keyboard to select a skill level. Skill level 1 (STUDENT) This level makes 5 of the 6 runways available, with a total of 7 aircraft to control throughout the simulation. Each departing aircraft does not have to be directed to any specific destination. Also, at this level, you control special planes; these planes never run out of fuel! This is a great place to get familiar with the command set and the console. It won't take you long to move onto other, more challenging levels. Once all 7 aircraft have been handled, the simulation will end. Skill level 2-5 These configurations are designed to add more realism to your simulation. At these levels, you must not only successfully land inbound traffic, but departing aircraft must be directed to their assigned VOR (Very High Frequency Omnidirectional Range Station). The VOR system will be explained shortly. Within this group of skill levels, you must also keep an eye on the fuel level within each aircraft. You may also see erroneous radar returns; these occasional "equipment problems" will always seem to come up at the worst times. Note that the number of aircraft you are assigned to control increases with each skill level. Again, the simulation ends when all aircraft are handled, or when one aircraft runs out of fuel or a mid-air collision occurs. The Screen Layout There are many active windows on the DULLES TOWER console screen. The overall screen looks something like this: ┌─────────────┐ Extended Range Window - Shows inbound and outbound │ ┌───────┐ │ radar returns. ---> │ │ . │ │ │ │ │ .│ │ └───────┘ │ Pending Window - Aircraft not shown on Main Radar. ╞═════════════╡ American Airlines Flight 232 - awaiting takeoff ----> │ ██ AA232 │ 37 Delta - inbound. Note that aircraft with "N" ----> │ N8437D │ callsigns are usually non-commercial and are │ │ identified by the last three characters in their │ │ callsign, e.g. "37 Delta". │ │ │ │ Command Window - Keyboard commands to each aircraft ╞═════════════╡ are echoed here. ---> │ │ Status Window - Shows active aircraft's: ╞═════════════╡ - Current/Assigned Altitude ---> │A: 0400 060 │ - Current/Assigned Heading ---> │H: 130 140 │ - Current Airspeed/Fuel Level ---> │S: 197 ▄▄▄▄ │ - Current Position shown as a ├─────────────┤ range/radial from Dulles. ---> │ 12.3 280 │ - Type of Aircraft/Destination ---> │ B727 IAD │ ├─────────────┤ - Current Status ---> │ ARRIVAL │ ┌─────────────────────────────────────────────────────╘═════════════╡ │ 42 X-RAY <---- Callsign Window - Shows active aircraft's callsign │ └───────────────────────────────────────────────────────────────────┘ Each one of the windows is more fully described below. Radar Window - The Radar Window is the biggest window on the screen; the name of the game is to issue keyboard commands to the active aircraft to climb, turn, etc. Aircraft shown in the Radar Window carry with it a datatag. The datatag is a block of text that describes the aircraft's ID, altitude (in hundreds of feet), if the return is climbing, descending, level or low on fuel, and its airspeed (in tens of knots). A typical datatag may look something like this: . / AA424 021 19 This information tells you several things about the aircraft: AA424 - Aircraft ID is American Airlines Flight 424. Note that commercial traffic is identified with a two character company ID, followed by the flight number. Some of the carrier abbreviations are not intuitive; those used in the industry are: Abbreviation Carrier -------------------------------------- AA American Airlines AL US Air BA British Airways CN Continental DL Delta EA Eastern NW Northwest PA Pan Am TW Trans World UA United Airlines There are many more major airlines in the world, but these are the major airlines that service Dulles. 021 - Aircraft is currently at 2100 feet Climbin/Descending arrows may also be shown. If a red box is seen in this position, the aircraft is low on fuel. Low fuel means the aircraft will crash unless it reaches its destination within approximately 10 minutes. 19 - Airspeed is about 190 knots. Active runways are also shown in the Radar Window. Runways that are open in both directions are shown as a string of dots. However, if a runway is only available in one direction, chevrons will point in the active direction. If a runway is closed in both directions, it will not appear on the screen. The blue triangles are navigational markers that help you line up planes for final approach. Active VOR gateways are shown in red around the perimeter of the Radar Window. Extended Range Window - This box shows inbound/outbound aircraft not seen on the Radar Window, as well as a scaled down version of the Radar Window. Pending Window - Aircraft that are inbound (but not yet visible in the Radar Window). Aircraft IDs with a blue box to their left are those aircraft awaiting takeoff. A dot in the center of the box means that you've cleared the aircraft for takeoff and it is rolling down the runway. Note: if a red box appears, that aircraft is low on fuel and must reach its destination within 10 minutes! Command Window - Keyboard commands are echoed here. Status Window - As the controller, you select one aircraft as the ACTIVE aircraft. This will be the recipient of all of your instructions until you switch active aircraft. The ACTIVE aircraft's callsign will appear in the Callsign Window. Generally, the Status Window is a rich source of information about the ACTIVE aircraft's current status, intentions, and destination. Specifically, you can check the ACTIVE aircraft's: 1) - Current Altitude - Hundreds of feet 2) - Assigned Altitude (if different from current altitude) - Hundreds of feet 3) - Climbing/Descending 4) - Current Heading - Degrees 5) - Assigned Heading (if different from current heading) - Degrees 6) - Airspeed - Knots 7) - Fuel Level (Skill Levels 2-5 only) where consumption starts when the aircraft first appears in the Radar Window or as an aircraft awaiting takeoff. For our purposes, 30 minutes represents a full tank; note that I realize that that is somewhat unrealistic but I tried to come up with just one more way to make things difficult! 8) - Range/Radial from Dulles - Miles/degrees 9) - Aircraft type - Possible aircraft are: Manufacturer Model Abbreviation ----------------------------------------------------- Boeing 727 B727 Boeing 737 B737 Boeing 747 B747 Boeing 757 B757 Boeing 767 B767 Lockheed L-1011 L101 McDonnell Douglas DC-9 DC9 McDonnell Douglas DC-10 DC10 McDonnell Douglas MD-80 MD80 Beech Aircraft 99 BE99 Gates - Lear 23 LR23 Gulfstream America Gulfstream III G3 Dasault (Falcon) 50 DA50 Cessna 152 C152 Cessna 182 C182 You will discover that each aircraft has substantially different performance characteristics (landing speeds and rates of climb/descent) which makes for some interesting situations! 10) - VOR Destination - (Skill Levels 2-5 only) This is an excellent opportunity to explain the VOR system and why each aircraft has different destinations (and what do those abbreviations mean anyway?) VORs are simply radio beacons that broadcast continuously. There are scores of them across the United States. While the pilot is preparing the trip's flight plan, he/she identifies the key VORs between Dulles and their final destination. By flying from VOR to VOR, the pilot can play a game of "connect the dots". A particular aircraft's position relative to a specific beacon can be described by two pieces of information. 1) The VOR radial: The radial references the aircraft's direction from the beacon in heading degrees. A 727 may report being on the "180 radial" from Casanova. This simply means that the aircraft is located straight south from the Casanova VOR. Note that it says nothing about the aircraft heading; the plane may be flying north, south, east, or west, but at that particular moment, it is straight south from the beacon. 2) The VOR range: This information describes the distance from the aircraft to the beacon. You might hear, "TWA 412 is 11.3 miles from Martinsburg on a 325 radial". This translates to Trans World flight 412 is 11.3 miles northwest of the Martinsburg beacon. As the controller, it is your responsibility to direct each aircraft to the first VOR in their flight plan. DULLES TOWER has 7 different VORs (destinations) around the airport. Departing aircraft may select from any of these after takeoff. As the skill levels increase, so do the possible VORs. In order to properly handle a given aircraft, you must identify their destination, and route them off of the screen to the proper VOR. To make things more difficult, I've arbitrarily selected 6000 feet as the exit altitude. If you direct a plane to an incorrect destination or altitude, an "Illegal Airspace Exit" will be charged to your performance record. Possible VORs are summarized below. VOR Abbreviation Radial from Dulles ----------------------------------------------------- WESTMINSTER EMI 041 BALTIMORE BAL 089 NOTTINGHAM OTT 128 BROOKE BRV 181 CASANOVA CSN 233 SHAWNEE EEY 303 MARTINSBURG MRB 337 DULLES IAD N/A I realize that you may wonder why "EEY" is an abbreviation for "Shawnee"; rest assured that I didn't make these up. On the air navigation charts for the greater Washington area, that's the way it really is. With so many VORs around the country, using the abbreviations that would make the most sense would inevitably cause duplication. So, that explains the two range/radial entry in the Status Window. Now lets get back to the two final areas of the main screen. 11) - Current Status - Displays ACTIVE aircraft's current activity. Possible entries are: Status Meaning ---------------------------------------------- RWY xxx Ready for takeoff, runway xxx APP xxx On approach for runway xxx FINAL xxx On final approach for runway xxx ARRIVAL Arriving aircraft DEPARTURE Departing aircraft xxx represents one of the six runways at Dulles, those being runways 1L, 1R, 19L, 19R, 12, and 30. - Callsign Window The window located across the bottom is shows the callsign of the active aircraft. To reiterate, in order to save time, controllers refer to those aircraft with an identification beginning with "N" by the last three characters in that identification. "42 X-RAY"'s complete ID might be N4342X. To ensure accurate communications, the international phonetic alphabet is also used to describe any letters that may appear in the description. The following table may be helpful. International Phonetic Alphabet --------------------------------------------------------------------- A - Alpha B - Bravo C - Charlie D - Delta E - Echo F - Foxtrot G - Golf H - Hotel I - India J - Juliet K - Kilo L - Lima M - Mike N - November O - Oscar P - Papa Q - Quebec R - Romeo S - Sierra T - Tango U - Uniform V - Victor W - Whiskey X - X - Ray Y - Yankee Z - Zulu To summarize what's been explained so far: - As the skill levels increase, so do the number of aircraft to handle and the possible destinations. - With skill levels 2-5, each aircraft must be vectored off of the screen to the correct VOR at 6000 feet. - The main screen is divided up into several windows, each describing a different aspect of the simulation. The Command Set/Key Assignments As mentioned earlier, you must issue keyboard commands to the ACTIVE aircraft by ordering turns, takeoffs, etc. Remember that each simulation is different and there will be different active runways and VORs for each simulation; however, the following commands apply to all simulations, regardless of aircraft type or destination. Note that the active aircraft's callsign is shown in the Callsign Window located at the bottom of the screen. To Change: Command Comments xxx ┌───────────┬──────────────┬──────────────┬─────────────────────────┐ │ Heading* │ Lxxx │ Left turn │ Compass headings │ │ │ Rxxx │ Right turn │ (000-360) │ ├───────────┼──────────────┼──────────────┼─────────────────────────┤ │ Altitude │ +xxx │ Climb │ Altitude - hundreds │ │ │ -xxx │ Descend │ of feet (10-100) │ ├───────────┼──────────────┼──────────────┴─────────────────────────┤ │ Aircraft │ xxxxx<space> │ Aircraft callsign (e.g. AL212 or 37D) │ └───────────┴──────────────┴────────────────────────────────────────┘ To Order: ┌───────────┬──────────────┬────────────────────────────────────────┐ │ Takeoff │ Txxx │ │ ├───────────┼──────────────┤ xxx identifies runway (e.g. 1L or 30) │ │ Approach │ Axxx │ │ ├───────────┼──────────────┼────────────────────────────────────────┤ │ Landing │ C │ Clears approaching aircraft to land │ └───────────┴──────────────┴────────────────────────────────────────┘ * All aircraft turn at approximately 180 degrees/minute. All of these commands must be followed by a carriage return, except for switching the ACTIVE aircraft, which requires the callsign to followed with a space. After the instruction is accepted, the COMMAND window will briefly flash white and two tones will be heard. If an invalid command is entered, all aircraft will ignore your instruction. Function Keys Eight of the 10 function keys have been given specific assignments. F1 = Help: Once the simulation has been initiated, you may request assistance at any time. On 8088 machines, these screens may appear to paint rather slowly. F2 = Pause: Not surprisingly, this temporarily suspends play; the simulation is resumed by striking any key. F3 = Sound: Toggles sound on/off. F4 = Speed: This controls the tempo of the simulation. A default speed index of 5 is assigned to each simulation. You may slow the pace to an index equivalent to the skill level or increase the index to a maximum of 9. For example, if you've selected skill level 3, the index can be set from 3-9. If you choose to operate the simulator at a higher level, you will be rewarded with more points in the REPORT section. F5 = Save: You may save the current status of any simulation with this key. A file will be created called DULLES.SAV that contains all of the necessary data to reload at a later time. F6 = Load: Loads a previously saved simulation. F7 = Report: This feature temporarily suspends operation and presents you, the controller, with a status report on your performance. F8 = A:/>: Immediately switches the console to a simulated DOS prompt. The function keys are disabled during the cycle of recalculation necessary to track the progress of the aircraft. So if the keyboard seems somewhat unresponsive, simply try again. USING THE SIMULATOR As you can imagine, the object of the exercise is to route all aircraft to their desired destination. A few interesting surprises may occur along the way. Near Miss/Mid-Air Collisions If two aircraft pass within a 3 mile lateral separation while also within 1000 feet of vertical separation, a near miss situation will occur. The radar traces of the aircraft involved will turn red and you will hear an attenuation squawk. Unless you intervene, the aircraft may continue on a collision course. Once they pass within 0.5 miles and 500 feet, a mid-air collision will occur and the simulation will be aborted. Air Space Exits Also note that if aircraft do not exit the airspace correctly, an attention tone will be heard. If the destination is incorrect, the correct VOR will be superimposed on the datatag. Remember that exiting aircraft must have an altitude of 6000 feet. Incorrect altitudes will be boxed in red at the time of exit. At the higher skill levels, the VORs are marked but not labeled. Thus, it's up to you to learn your airspace! Landing/Departures All aircraft must be cleared for landing. Once they have been cleared for the approach to a particular runway, sometime before touchdown, they must also be cleared to land. When clearing aircraft for the approach, best results are seen when they are vectored directly toward the blue triangles indicating the navigational marker for that runway. You may see improper in no responses if wide radical turns are expected from each aircraft. Thus, try to aim an aircraft directly at that imaginary line that extends from the end of the runway called the glideslope. If they are heading toward the glidepath and are cleared for the approach, the aircraft will automatically turn toward the runway and descend at the proper rate for landing. However, an occasional aircraft will abort the landing, called a Missed Approach. You will spot these as the plane overflies the end of the runway and levels at 200-1000 feet. This may occur if the aircraft does not have ample room for landing, a mechanical failure, etc. When these occur, simply vector the aircraft for another approach. Let me try to further explain the various commands with a few examples. Esamples Example 1: Assume that N8437D enters the Radar Window at 8000 feet on a heading of 125, and you want him/her to land on runway 12. Remember, the object of the exercise is to help the plane find the glide slope. Thus, you might command the plane to fly south until the glideslope is intercepted and then automatically turn to a heading of 120 to line up with the runway. Commands would read: Command - Meaning --------------------------------------------------------------------- 37D(space) - Makes 37 Delta the active aircraft. R180(CR) - Orders plane to turn right to heading 180. A12(CR) - Clears aircraft for the approach to runway 12. C(CR) - Clears aircraft to land on approach runway. Note: (space) means hit the space bar, (CR) means strike the carriage return or the ENTER key. Example 2: Suppose that the Status Window show you that Delta 002 is ready for takeoff on runway 1 right, i.e. RWY 1R appear in the lower right; also assume his destination is Casanova (CSN). These instructions would read: Command - Meaning --------------------------------------------------------------------- DL002(space) - Makes Delta 002 the active aircraft. T1R(CR) - Clear aircraft for takeoff. After the status window shows DEPARTURE, that flight is ready to accept altitude/heading instructions. After takeoff, all aircraft will fly a runway heading and automatically level at 2000 feet until further directed. You must now direct it to its desired destination, Casanove, marked CSN. L225(CR) - Turns aircraft from current heading to 225 degrees. +60(CR) - Orders aircraft to climb to exit altitude, 6000 feet. You may have to fine tune each heading to ensure exit through the VOR gate. Improper exits are indicated with squawks and "braps". Watch and listen!! Scoring When you generate a performance report (F7), a SCORE is calculated. This is based on: Points for each -------------------------- + 1000 aircraft handled - 2500 minute in near miss situations - 500 illegal airspace exit/destination - 300 uncleard landing The total is then multiplied by a speed coefficient, which is calculated by taking the number of minutes you have simulated by the number of minutes that have elapsed since the start of the simulation. Thus, if you have the SPEED (F4) set at 8, you will simulate 15 minutes of aircraft activity in about 10 minutes. So, the coefficient is about 1.5. In other words, the faster the game, the better your score. POTPOURRI DULLES TOWER is written in Borland's Turbo Basic, Version 1.10. To date, it has been a fairly well behaved program and runs on most any compatible. However, in testing this program on as many machines as possible; a few notes may help. 1) Some autoswitching EGA video cards may need to be set to CGA manually, instead of depending on the automatic switching of the card. This has been the case on a few tested. 2> Some circa 1985 portable computers that have CGA video built into the system board have had trouble with the opening screens. Program execution seems OK once the program begins. 3> One unit tested used a monochrome card coupled with a utility that allowed monochrome cards to emulate CGA; this one would not show the help screens properly. 4> All VGA cards tested had no trouble with CGA emulation. 5> 4.77 Mhz 8088 based machines were painfully slow in loading and screen painting. A math coprocessor helps significantly! 6) The program may trip on a few not-so-well behaved TSRs (Terminate and Stay Resident or RAM resident) programs. Cleaning those out of memory will help. After typing this list, I thought "What a picky program!". Actually, I've been very pleased with the compatibility, it's just that in good conscience, I couldn't withhold any known problems. Anything that you have to contribute, please let me know; I'd like to be able to pass it on to others. I hope that you enjoy DULLES TOWER. If interest warrants it, I may write a new version with bug fixes, EGA support, wake turbulence, etc. Your feedback and support is sincerely appreciated. John McKeown Chantilly, VA July 1, 1988