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2004b: Microsoft Flight Simulator: Where do you want to fly today?

(by Dennis Kenney; December 2004)

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Microsoft Flight Simulator

Microsoft Flight Simulator

Where do you want to fly today?

By Dennis Kenney


Every kid daydreams one time or another of flying like a bird or becoming a pilot. Maybe you want to become an avionics engineer or aircraft mechanic and feel you have to get a hands-on feel of what's involved in piloting an aircraft. Learning aircraft systems and flight operations is not an easy task and hanging around an airport or visiting the cockpit during a commercial flight has become more difficult with the implementation of tougher airport security. Or maybe you just want to play at being a pilot. The Microsoft Flight Simulator is the cheapest way to do all of these things and as you'll see, the newer versions are very realistic with great scenery, weather for nothing, and many aircraft types. And it's good enough for the MIT graduate students in the Aero department (MIT's Department of Aeronautics and Astronautics).

Independent Activities Period (IAP)

IAP at MIT is a special term that allows students and the MIT community a chance to participate in learning opportunities that might be difficult to fit into the normal semester terms. IAP 2005 will run from January 3 through January 28. The complete schedule is online at I'll mention some of the classes even though it'll irritate about 100 class leaders whose classes are equally deserving of mention--Intellectual Property, Geographical Information Systems, Tae Kwon Do, Emacs, Extravehicular (space) Activities, Perl, Bioinformatics, Chandra X-ray Observatory, Traveling the Silk Road, Evolution, Poetry, Physics, Mexico, Home Repairs for Women, and Terrorism. I couldn't find the Aero class described in the hard copy IAP schedule although it was listed on bulletin boards. The following is a description of the Aero course given every year.


Introduction to Boeing 767 Systems and Automation

Chuck Oman of the MIT Department of Aeronautics and Astronautics introduced the class to the course objectives and schedule. He was assisted by Brian Nield, Manager, New Airplane Product Development, Boeing Commercial Airplane Group, with one session given by active 767 Captain Alan Midkiff. The class was divided in half for parallel simulator and Computer-Based Training (CBT). The groups would alternate their use of the simulators and aircraft systems CBTs during the lab periods from 3 to 5 pm and from 6 to 8. Only 10 students could use the simulators or the CBT computers at a time, limiting the size of the class. Many qualified students had to be turned away because of the 20-person limit on the class size. The class was 3 days long with an additional optional 2-day class on aircraft accident investigation by Brian.



Automation is the use of computers and failure modes so that an aircraft system degrades or adapts in a manner that seems logical to the flight crew. People who depend on automation without understanding it or who blindly use automation are called the Children of the Magenta. Boeing continuously works to improve the human/machine interface in order to reduce the pilot's workload and aid his situational awareness. Moving map displays and use of the global positioning system (GPS) were great advances in improving the pilot's awareness. Sensors and better data visualization techniques with programmable displays promise even further improvements in the future.

Flight Crews

Only one crew member (pilot) is required when flying a light aircraft like a Cessna 172 or a Beech(craft) Bonanza. She normally sits in the left seat even as a student pilot with an Instructor Pilot (IP) in the right seat. The seating in helicopters is the opposite way. The controls are duplicated on each side of the aircraft even though all the instruments might not be, to save weight or cost. Some controls, like the autothrottles, flaps, and landing gear handle, are on the centerline of the cockpit, within reach of both pilots.


In large aircraft requiring two pilots, the senior pilot sits in the left seat with the co-pilot or First Officer (F/O) in the right seat. The shuttle crew follows the example of waiters in Germany< /st1:country-region>--every waiter is a head waiter, as in Herr Ober(kellner). In the shuttle the Commander sits in the left seat and the Pilot sits in the right seat.


In the Flight Simulator (as in a jumbo jet) we distinguish between the pilot flying (PF) and the pilot not flying (PNF). The students change roles to reinforce learning the procedures, and to learn all the tasks normally performed by the Captain or the First Officer. The teaching assistants (TAs) in the Hanger Mezzanine where the simulators are installed are, of course, instructor pilots (IPs).


An important third crewmember on many aircraft is the crew chief (he really owns the aircraft but don't tell the pilots). On the (Las Vegas) Riviera Hotel Gulfstream II-B, the crew chief's primary qualification was that he was a gourmet chef.


It's easier to get a job flying corporate jets if you also have an A & E (airframe and engine mechanic certification), since a corporate aircraft is often away from its home base and the support of corporate mechanics. Corporate flight crews usually have a Mutt and Jeff look. One pilot is usually short and small so that he can easily crawl around the inside of the aircraft while the other is tall so that he can put radios into the various avionics (electronic boxes) bays.


The flight crew must communicate well to accomplish the mission of a safe flight. The PF and the PNF share tasks with finger-pointing gestures in a challenge/response procedure. Bad flight crew communication has always been a contributing factor in many accidents. Automation and workload reduction provided by avionics has allowed the B767 to fly with only two crewmembers, where previously larger flight crews were required in airliners. I'm old-fashioned but I personally like three engines and three crewmembers. The final responsibility, however, is always with the flight crew.


The biggest problem is the payload.

767/A320 Captain Alan Midkiff, American Airlines, got the job of describing the real life gotchas involved in flying the 767 and the piloting profession in general. He compared flying the Airbus A320, the aircraft type that he flew before transitioning to the 767, with Boeing aircraft. A major concern with him is to make sure that he has enough reserve fuel. His first action when receiving his flight plan is to check his assigned fuel, the route, alternate airports, and the weather, so that he can request more fuel, if he wants to, while the fuel truck is still near his aircraft. Requiring the fuel truck to return to the aircraft after the truck has left the area could delay the departure of the flight.

Microsoft Flight Simulator 2000

Bruce Artwick, the developer of Flight Simulator, ended up at the University of Illinois in 1973 planning to study computer engineering. He switched to EE and did some research at the Aviation Research Laboratory as a student. Bruce became a pilot while doing his thesis work on 3-D graphics for flight simulation, receiving an MS EE in 1976. He moved back to Illinois after working for a while in the Los Angeles area.


Don't mess with Murphy.

One of the places Bruce Artwick worked was at Hughes Aircraft in Culver City, California. I worked at Hughes Aircraft putting a video recorder in the Apache (AH-64) helicopter. That was where I met and worked with Murphy of Murphy's Law fame and notoriety. Murphy's Law can be stated in its simplest form as, if there is a way for something to go wrong it will. Usually "at the worst possible time" is quickly added to the basic statement. Murphy first stated the law on a project where the subject of rapid deceleration on a rocket sled had the accelerometers needed to verify the deceleration data installed with their active axis at right angles to the deceleration. Naturally the "test pilot" had to be subjected to the deceleration test a second time.


Bruce wrote a simulation program and a few articles about the program while he was at Hughes. Bruce founded his first company, SubLOGIC, in Los Angeles in 1977 after one of his magazine editors told him that some of the magazine's readers wanted to buy the program. Bruce's graphical programs ran on several of the 8-bit computers and became the top selling program on the Apple.


Then the call came from Microsoft. IBM also called but Bruce decided to go with Microsoft. FS became a bestseller on the new IBM-compatible PCs. Us new users used the program to test video cards for (IBM) PC-compatibility, including the graphics adapter in my first 16-bit computer, the 8 MHz Compaq with an Intel 8086. Bruce also wrote several technical books.


Flight Simulator as a Killer App

10 million copies were sold of FS98. A total of about 30 million copies have been sold of all versions of Flight Simulator.


Situational Files

Scenarios can be started in any phase of flight with any initial conditions or aircraft type. For example, on the flight from KBOS (Logan airport in Boston, Massachusetts) to KATL (Hartsfield airport in Atlanta, Georgia) you can jump the boring part of the enroute at altitude portion of the flight and restart just before the start of descent on the approach portion of the route.


Hot Spots

Hidden mouse click areas can be used to expedite certain functions and avoid the use of complex keyboard combinations. For example, clicking an area next to the control display unit (CDU) line select key (LSK) 1L (top left) enables keyboard entry into the CDU. "KA" appears above the hotspot and all keyboard assignments are cancelled until the KA feature is removed by clicking on the KA hotspot. The PIC manual hints not to use the "KA" mode while airborne.


Boeing 767-300

The Boeing 767-300 has a typical zero fuel weight (ZFW) of 245,000 pounds and a fuel plus reserves weight of 30,000 to 80,000 pounds. The ZFW and a typical fuel weight are not even close to the maximum takeoff gross weight of 408,000 pounds.


Ground Power

Power is applied to the aircraft from ground sources to provide for the comfort of the ground crews as they service the aircraft. A separate isolated ground power system in the cargo compartment can only be used on the ground. Of greater interest to the pilots is the ground electrical and pneumatic power used to start the engines or the auxiliary power unit (APU).


Auxiliary Power Unit (APU)

The APU in the aircraft provides an independent source of electrical power and pneumatic air, and can be used up to 18,000 feet. The duct air used for normal engine starts has a pressure greater than 25 psi. The APU is a good backup for the aircraft engine and ground electrical and pneumatic power. The parking brake must be on in the simulator to use the APU electric power or air.


Aircraft Electrical Power

The aircraft batteries provide direct current (DC) power in the absence of all other power and can run certain critical systems for 30 minutes. 24 volts DC is the "native" power for batteries in most small and older airplanes. DC generators, if present, output about 27 VDC. Small inverters were added to aircraft when the need for alternating current (AC) (for motors, electric razors, etc.) became apparent. This was before the need for entertainment systems, flight phones, laptops, and internet connections appeared. 115 volts AC (400 Hz instead of the domestic 60 Hz in North America and 50 Hz in Europe) is now native in commercial aircraft, which come equipped with extensive food-preparation galleys. The use of solar panels and fuel cells might reduce the percentage of AC to DC, especially in spacecraft.



Hydraulic pressure for the hydraulic systems--flaps, brakes, landing gear, etc. is usually provided from pumps on the engines but can also be provided from electrically driven pumps.


Fuel and engines

The two wing tanks can each hold 40,700 pounds of fuel. If more fuel is required the large capacity (80,400 pounds) of the central tank can be used. The fuel, if any, in the center tank is used first. Fuel pumps provide for the flow of fuel to the engines and can be cycled for expending fuel in one fuel tank to balance the aircraft (keep the center of gravity within a small specified volume). Normally the engine on the right side is started first.


Honeywell Flight Management System (FMS)

The Flight Management Computers (FMCs) are hidden in the avionics bay--they're the equipment that the beserko in the latest airplane action-thriller is chopping up with the emergency axe while the stewardess is trying to land the 747 during hurricane gales. The Automatic Flight Director System (AFDS) includes the FMCs, which are the brains of the aircraft, and the three autopilots and their attached hydraulic systems, could be considered to be the muscles. FMS acronyms vary from airframe manufacturer to manufacturer and change with the evolution of flight control systems.


What the pilot sees are the control display units (CDUs) mounted in the cockpit center pedestal. A CDU has a CRT for display and a keypad and line select keys (LSKs) for data input. The CDUs are intelligent--the ones I've seen the internals of had Intel 8085s or 80186s inside (no Intel inside logo--bong, bong, bong, bong).


Lateral navigation or area navigation functions were developed first and most airline pilots feel comfortable with them. The moving map display shows the progress of the aircraft over the ground. The lateral navigation (LNAV) mode (and the vertical navigation (VNAV) mode) is usually engaged from 300 feet to about 1000 feet above the ground. Pilots first learned to fly air data modes--climb to altitude, altitude hold, climb or descent modes, or airspeed/mach hold. Now these modes are integrated with IRS and GPS data through the FMS in vertical navigation functions. The short story is that once the route, performance data, and winds (if time of arrival (TOA) is important) are inputted, the FMS can practically fly and land the aircraft by itself. The long story is download the 108-page FMC manual from Wilco Publishing. Wilco Publishing provides the FS panel add-on that enables the B767 functionality. The Panel Operation and System Manual will also be useful. Boeing CDUs are gold-colored while Airbus and Douglas use brown and gray paint on theirs. There are subtle differences in the FMS procedures from the different airframe manufacturers, as well as airline customizations. Look for flat panel displays and the elimination of the CRT fans in future CDUs and instrument panels.


One of the problems with learning to fly, as with some other intellectual pursuits, is that anything you learn has prerequisites which need to be learned first, which themselves have prerequisites. All one can do is start and loop around covering material a little deeper with each loop. Programming the FMC is a little isolated without the procedures being performed simultaneously. Nevertheless, I'm going to describe them enough to explain their context. I'm not going to try to duplicate the tutorials of Flight Simulator and the use the Wilco add-on FMC manual; it's better to use the original materials. Flight Simulator and the Wilco manuals would have been handy to have, even at Honeywell, to help orient new engineers on the FMS and various aircraft systems.


FMS Programming

The FMS CDU isn't displayed when you first load the instrument panel. Use <shift><6> or the FMC button on the main panel to display the CDU. The first page that is displayed on the CDU is the MENU page, since there can be multiple systems which will be initialized by the CDU. If additional systems have been added to the aircraft, which have to be initialized by the CDU, a prompt will be provided for the system on the MENU page. There are no other systems in the simulator so only the < FMC prompt appears on the simulation MENU page (at LSK 1L). Pressing LSK 1L transfers the CDU control to the FMC.


The IDENT page is the first page displayed for the FMC. Originally this page was the first page that was displayed on power-up of the FMC. It is especially important to check the software information if a CDU or FMC has been swapped out recently. Day to day, the important information is the currency of the Navigation Database which changes every 28 days. If the old data has expired then the next issue must be activated to update the NDB. Pressing LSK 6R will select the POS(ition) INIT(iation) page (POS INIT >). Pressing LSK 6L (< INDEX) will bring up the INITREF INDEX page, which allows the pilot random access to the various INIT pages. The normal sequence of initialization, starting with POS INIT allows accessing the various pages sequentially in a logical manner as initialization progresses.


Input the geographical coordinates of the gate where the aircraft is parked manually into the scratch pad or use data, which is already available on the POS INIT page. The square blocks indicate that the data to be inputted is required. Normally GPS data is shown at LSK 1R or the last aircraft position may be available. Press the proper LSK to select the data you want to use and transfer it to the scratch pad (last line of the CDU display area) and then press LSK 5R to enter the data into the inertial reference units (IRSs). Messages or old data in the scratch pad can be cleared completely by pressing the blank function key or a character at a time with the <CLEAR> function key. The IRSs will not align without initialization data. The IRS data was of prime importance before the advent of GPS. If the IRS initialization data weren't as accurate as possible the aircraft position would be updated at a spot on the airport with more accurate position initialization data or "tweaked" by a radio navigation update as soon as VOR/DME (radio navigation) data was available in the air.


Route Data

Press the LSK 6R (ROUTE >) to select the ROUTE page. The ROUTE page can also be selected at any time by pressing the RTE function key. Note that if a page requires multiple screens it is indicated in the title line on the right, i.e., 2/3. Use the NEXT/PREV PAGE function keys to change screens.


Routes can be canned (pre-planned) or input using data from the NDB. In the real FMS you can input a pre-planned route at LSK 3R, replacing the dashes. It is necessary to distinguish the procedures in FS200x from the procedures associated with the company routes that would be in the FMS--in FS200x you have to create the route in FS2000 flight planner or a 3rd party tool that saves the plan in the FS format with a .pln extension. The .pln filename can have 10 characters and is saved in the FS2000\PILOTS folder. At Douglas Aircraft Company (acquired by Boeing) the flight test plans corresponded to flight test cards with the details of the flight standardized. These flights were normally round robin--the departure airport (ORIGIN) was the same as the DEST(ination) airport. If a company route is available, cycle through the screens to examine the waypoints in the flight plan. Note that the pages are titled RTE 1. A second route can be entered to make route changes easier to implement (RTE 2).


To input a route manually enter the departure airport and the destination airport, say KBOS and KLAS (Las Vegas), in the line data fields for LSK 1L and 1R respectively, on the first page of RTE 1. Next enter the departure runway, for example 14R in line 2R. The flight number is optional and is entered in line 2R where FLT NO appears in small caps in the upper section of the line. Press the NEXT PAGE function key to start inputting the waypoints for the route. VIA and TO appear in small caps in the upper (title block) section of line 1 in the initial and last column of the page. Waypoints are entered in the TO column and Jet (high) or Victor (low) airways are entered in the VIA column.


Waypoints can be entered manually for the whole route or groups of waypoints from an airway can be inputted with the help of the navigational database (NDB). Entering a waypoint on an airway, the airway in the next line in the VIA column, and the last waypoint to be used on the airway will result in the intermediate waypoints (if any) being automatically inserted into the route. A standard instrument departure (SID) or a standard terminal arrival route (STAR) will normally be used to build up the route. See the Wilco FMC manual for details.


The route is activated by pressing LSK 6R (ACTIVATE >). Pressing the EXEC(ute) function key executes activation of the route and the flight plan appears in the map displayed on the electronic horizontal situation indicator (EHSI) (at Douglas we called this the navigation display (ND) and the EADI, the flight display or director (FD). The prompt PERF INIT > replaces the ACTIVATE > prompt. Normally LSK 6R would be pressed now to allow initialization of the performance data on the PERF(ormance) INIT(ialization) page.


Performance Data

As usual, the required data insertion fields are indicated by blocks. Inputting weights in thousands of pounds for either the gross weight or the zero fuel weight allows the FMC to calculate the remaining value using the FMS calculated fuel weight. The fuel weight may be entered manually if the pilot doesn't like the CALC(ulated) value. The gauges for measuring fuel quantity are notoriously temperamental. A standard value for the COST INDEX is 80.


There are three formats for entering the desired cruise altitude (CRZ ALT) into the line 1R data block. 40,000 feet may be entered as 40000, 400, or (flight level) FL400.


Speeds and Bugs

The FMS calculates certain critical airspeeds based on the performance data, which the pilot has inputted (can be initialized by a ground data link in which case the pilot must verify the data). White reference bugs are set on the airspeed indicator to help the flight crew identify these critical speeds. The first bug set is set to V1. V1 is the speed at which the pilot is committed to takeoff. See the takeoff section for further details.


If an aircraft is rotated to the takeoff attitude, there is more drag on the aircraft; rotation should be held off until the aircraft is ready to fly. V2 is the takeoff safety speed, at which an aircraft can climb at a specified rate with one engine operating. VR, the speed of rotation, is the airspeed that will allow V2 to be achieved at 35 feet of altitude with only one engine operating. The moveable cursor is placed over V2. The cursor can be used to input airspeed commands to the flight director just as altitude commands can be input with the altitude window on the mode control panel (MCP).


Vref30 is the FMC-calculated approach speed with 30 of flaps, which is a function of aircraft weight--it will be less after fuel is burned during the flight. The value can be obtained from the FMS LANDING page. White reference bugs are set before takeoff at Vref30 + 20, Vref30 + 30, Vref30 + 60, and Vref30 + 80 kts. The angle of the flaps is reduced at these airspeeds during climb out.


Load the situational file for the flight and do the COCKPIT PREPARATION checklist. The FMS is usually initialized after the APU and engines are started, before pushback by a ground tractor. The aircraft can't be moved during the 10 minutes that it takes to align the IRSs.


Takeoff Page

The TAKEOFF REF page displays the Vspeeds used for takeoff. The only additional data needed by the FMC is the flap setting and the assumed air temperature if reduced thrust is desired on takeoff. Putting a temperature higher than the outside air temperature (OAT) in the assumed air temperature is the means by which the thrust is reduced during takeoff. The 767-300 can use 5 or 15 degrees of flaps during takeoff.


Clicking the mouse hot spot at the bottom left corner of the airspeed indicator updates the airspeed bugs based on the TAKEOFF REF page Vspeeds. Completion of data entry on the TAKEOFF REF page should make the pre-flight status next to LSK 6R display COMPLETED. If the pre-flight status is INCOMPLETE then the initialization pages must be revisited until all the data is inputted.



The APPROACH REF page lists the FMC-calculated Vspeeds for the approach. The flight crew can review the selected destination runway data and ILS information during approach.


767 Pilot in Command (PIC)



Wilco (Will comply) Publishing of Drogenbos, Belgium provides the B767 add-on (~$39) to provide the B767 characteristics to Flight Simulator 2000. 767 PIC emphasizes the emergency procedures real pilots must master to stay current and pass their Prof(iciency) Check. The 767 PIC add-on requires at least Microsoft FS2000. The B767 and the newer and bigger B777-300 are native aircraft in FS2002. Maybe Wilco will develop an add-on for the B777 and the new 7E7 that will bring the added functionality of their B767 add-on to FS2002.


Go with the Flow or

Use the Flow, Luke

Flows are a method of rapidly covering large areas of the control panels while preparing for different phases of flight. The checklist is used to verify absolutely essential steps. For example, the overhead panels can be scanned and switches set by going down on the first panel section, up on the second, down on the third, up on the fourth, and finally down on the fifth panel section.


Engine Start

Pneumatic air for engine starting is provided from ground sources or the auxiliary power unit (APU). Only the APU is available after pushback. The fuel pumps for an engine are turned on at a certain N1 (percentage of maximum allowed revolutions per minute) and the engine accelerates to the idle N1 with the starter automatically disengaging itself.



At Logan clearance is required from Ground Control in the tower before the ground crew performs a pushback. The aircraft is pushed back from the gate after the passengers have been seated, by ground tugs or tractors. Performing the pushback simulation is quite prone to pilot error resulting in trips through VIP lounges, various yellow-painted pieces of ground equipment, and other aircraft.



The length of the takeoff roll is a function of the aircraft's weight, airport altitude, air temperature and humidity, and throttle setting. Pilots will calculate a rule of thumb that the aircraft must be going a certain speed at a certain runway marker to reach an airspeed that will permit the aircraft to climb into the air before the end of the runway. After this simple and necessary procedure, the next go/no go decision is whether there is enough runway left to stop the heavily loaded aircraft in case an emergency such as the loss of one engine occurs. V1 is the calculated airspeed, which will allow the aircraft to stop before the end of the runway. The pilot is committed to a takeoff after V1, aborting the takeoff only under extreme circumstances--the aircraft is likely to sustain damage and subject the passengers to a crash of severity increasing with the ground speed.


Takeoff Emergencies

Loss of an engine, obstacles on the runway, and engine fires are the most common causes of takeoff emergencies.


Climb Out

Derating or using less than the maximum amount of engine power on takeoff, for reducing engine wear or noise abatement, is the prime consideration in setting the engine throttle positions.


Airports and Airways



The aircraft is parked at Delta gate in the east end of terminal C for the KBOS-KATL scenario. Taxiways at Logan are named after the letters of the alphabet. The Logan airport diagram shows that you use M to get to K, turn left on K, and use T to get on R15R. Taxi using the outside viewpoint (Shift S, S to return to the cockpit view). Use the yoke like a steering wheel (if you're using a yoke). Normally directional control is through the use of the rudders and differential braking (braking just the right or left main gear).


General Edward Lawrence Logan International (BOS)

The flight deck of an aircraft carrier is higher than the runways at Logan--20 feet at 15R and 15 feet at 22L. The weather is near freezing with low visibility and gusts out of the north so the pilot lets the First Officer (F/O) do the walk around (inspection). If we were in Honolulu on a normal day then the pilot would do this himself and let the First Officer tidy up the cockpit. Oh, the privileges of rank and seniority!


Kick the Tires and Light the Candle

The first simulator tutorial of the session consists of a rectangular traffic pattern, departing from and performing an instrument landing system (ILS) landing on R22L at Logan. The traffic pattern will be familiar to anyone who's ever been a student pilot, except for the greater airspeeds and 3000 feet of altitude on the downwind leg.



The situational file makes the first flight as simple as possible but it's still pretty involved for a first (solo) flight. The aircraft is located on the taxiway leading onto R15L. Taxi out onto the runway and follow the takeoff procedure.


In Flight

Downwind is a course parallel to the runway, going with the wind. Landing, of course, is into the wind on final. Maintain an altitude of 3000 feet downwind. Use 5 (degrees) of flap and an airspeed of 200 nautical miles per hour (kts) on downwind. The crosswind track is nominally 90 to final; use 15 of flaps and 190 kts.



The localizer for the instrument landing system (ILS) tells the pilot his position with respect to the runway centerline. The glide slope part of the ILS monitors the position of the aircraft with the ideal glide slope to the runway touchdown point. The aircraft heads crosswind towards the WAXEN waypoint, that is on the localizer for R15L. The localizer and glide slope are armed with the FMS still flying the leg to WAXEN. The usual procedure is for the pilot to set a heading that will intersect the localizer with the usual arming of the localizer and glide slope. In the B717 ( formerly the Douglas Super 80 or military C-9) the flight control computer (FCC or autopilot to us old-timers) controls the ILS landing with the FMS handing off control to the FCC as the localizer is captured. I'm not sure how it's implemented in the newer Boeing aircraft.


25 or 30 of flaps are used on final for a normal daylight visual approach. When the aircraft has captured the glideslope (glideslope indicator centered) drop the flaps to 30. Fly the appropriate approach airspeed for 30 of flaps (about 175 kts).


If we were standing at Logan and set up a spinning gyro that was constrained so that it could only point in a horizontal plane, the gyro would end up pointing to true north (TN). The precession to true north is caused by the torque produced by the earth's rotation and allows an inertial navigation system to determine TN as well as latitude, a surface position's angular displacement from the equator. This process is called alignment in an INS or IRS. Determination of longitude, the angular displacement from the Prime Meridian that goes through Greenwich near London, requires the use of a chronometer.


An IRS is position-keeping which means that the initial position must be input for alignment to complete. If there's an error in the position used for initialization, the error is carried throughout the flight unless the position is updated. A GPS is position-determining which means it can determine its 4D position by itself--latitude, longitude, altitude, and time. The IRS initial position is normally provided by the GPS in the newer GPS-equipped jumbo jets.


A magnetic compass, such as the one that is mounted near the top of the center windshield, points towards the magnetic north pole, which is located somewhere around the Hudson Bay in Canada. The magnetic field of the earth tilts about 11 from its axis of rotation. Solar activity can change surface magnetic bearings by several degrees and the disruption can be even greater in space. Compass needles are balanced to show only the horizontal component of the magnetic field. The magnetic dip or vertical component isn't used but was well known to the sailors plying the spice routes and routes to the new world. Pointing at the true North Pole with your right arm and the magnetic north pole with your left arm at Logan will result in a difference in direction between your two arms of 13 --a magnetic variation of 13 degrees west. Airways are followed by their magnetic heading and airport runways are named for their magnetic heading rounded off to the nearest 10 degrees. The direction (heading) of the longitudinal axis of an aircraft can be described in either magnetic (MH) or true heading (TH). The precession of a gyro as it seeks true north is how an IRS aligns itself during alignment. The IRSs are turned to NAV(igate) soon after power is established and take about 10 minutes to align. The stability augmentation system isn't operational until it gets attitude (pitch and roll) and directional (yaw) information from one of the (usually 3) IRSs.


How do the gyros know what is locally level, you might ask. The devices that detect gravity or acceleration due to movements of the aircraft are called, simply enough, accelerometers. In an inertial navigation system, the gyros are gimbaled and are torqued to the local level, using signals from the accelerometers. Values different from the local gravity field will be detected until the gimbals are leveled. In a strap down IRS the leveling is virtual. Once the platform (frame supporting the gyros and accelerometers) is level, integration of the level accelerations allows the associated computer to calculate the aircraft velocity and movement along the earth's surface. In the case of an inertial reference system (IRS) there is no local leveling and no mechanical gyros. Such a system is called a strap-down system and inertial angular rates are measured using the properties of split coherent light beams interfering with each other under angular acceleration.


The student pilot plots a true course on an aeronautical chart, converts it to a magnetic heading using the magnetic variation and flies using magnetic references. Very high frequency (VHF) omnidirectional ranges (VORs) use magnetic radials and these radials are used to describe the airways, the legs of which go from VOR to VOR. The BOS(ton) VOR has a frequency of 112.7 megahertz (MHZ), slightly higher than your favorite FM radio station. The airways normally correspond to rhumb lines, lines of constant magnetic heading. If the local magnetic variation varies too much over the length of a leg, a point may be designated where the magnetic heading is changed by a small amount to be closer to the true heading between the two VORs forming the leg.



An FMS can show magnetic references for the benefit of a pilot or to navigate an airway or ILS but it thinks natively with true references in great circles (the shortest distance between two points on a sphere), and spherical trigonometry. This is most useful when flying DIRECT, as on the great circle routes over the arctic regions. On the airways, an aircraft flies from VOR to VOR so the difference between flatland trigonometry and spherical trig is hardly noticeable.


The difference between the aircraft heading and its path over the ground (track) is called drift. Drift is caused by winds, which will vary in strength and direction with altitude. The drift angle will decrease with increasing aircraft speed, assuming the wind velocity remains constant. The student pilot must sort out these things as well as a computational method called dead reckoning (DR). She must do the calculations manually that an FMS does for the professional commercial pilots. DR is simply that, if you know where you are at a certain time and how fast and in what direction you are traveling, after a certain period of time you can calculate where you are. How true airspeed varies with altitude and temperature also has to be sorted out if the FMS isn't doing it for you. Did I mention that going faster than the economically optimum airspeed and flying below the economically optimal altitude burns more fuel and that the winds aloft used to calculate your arrival time act in mysterious ways?


The FMS computes this stuff for you but needs data like the winds aloft, the aircraft's zero weight, the weight of the fuel and reserve fuel, and a cost index (the trade-off between fuel costs and fixed costs, such as the aircrew salaries--a corporate policy item). Errors in the winds aloft as well as other errors can be corrected as the flight progresses by the FMS continuously recomputing the remainder of the flight.


Naughty, Naughty

My old sedan always had miles per hour and kilometers per hour. What's with these knots and nautical miles? The simple answer: if the world were a perfect sphere, one minute (') along the equator or along a longitude would be a nautical mile (NM), about 1.1 statute miles. 60 minutes of arc equal one degree of arc. If the earth's divided into 360 by lines of longitude running from the north pole to the south pole, that's 21,600 minutes or nautical miles around the equator or on any great circle on the earth. Knots (kt) are nautical miles per hour. These ancient units from the days of sailing ships are still useful for navigating the globe and the FMC has to be able to correct for the shorter angular distances on courses at latitudes anywhere but on the equator. The distance along a line of latitude between a minute of longitude grows shorter trigonometrically as one approaches the poles.


Live and Die, by your ADI

The attitude director indicator (ADI) is unquestionably the most important instrument in an aircraft. If the horizon can't be seen because of reduced visibility, the ADI is the only way that a pilot can fly straight and level. A student (low level of experience) pilot will control his airspeed with the elevator. In the all too common graveyard spiral, a pilot will be disoriented by an erroneous horizon such as a cloudbank or pattern of lights from a city. As the aircraft banks and dives the pilot will pull back on the yoke or stick in an attempt to reduce his airspeed, increasing the bank and tightness of the turn. A stall, loss of control, or impact with the ground follows. The backup attitude indicator (AI) can run for 30 minutes with a complete loss of electrical power. If the pilot rejects the reading from the ADI and flies "by the seat of his pants", it's usually the pilot who's wrong.


The director part of the ADI tells the pilot how much to climb or dive, and how much to bank to follow the path that the FMS has computed as optimal. When the autopilot (FCC) is coupled and flying properly, the flight director commands are zeroed (no error, centered in the ADI sphere). The pilot will only fly the flight director if the autopilot has failed. The director commands can be useful if the pilot is flying manually and wants to see how he is varying from what the FMS would do.


Dive and Drive

Usually the pilot is not allowed to let the FMS fly an optimal performance descent to a perfect time of arrival at touchdown. The pilot usually must manually fly the aircraft on portions of the descent or input altitude restrictions at various waypoints to satisfy air traffic control (ATC) instructions. When ATC clears him to a lower altitude and he descends to and captures this altitude, he must wait to be cleared to another lower altitude as he approaches his destination airport. The pilot can request altitude clearances for his own convenience. Such a request is within acceptable airway etiquette and can be given by ATC if it doesn't conflict with the flight paths of other aircraft.


Douglas Aircraft Company (DAC)

I taught four sections of a four-week "brown bag" lunch hour class on Navigation and Flight Control Systems at Douglas. This was around the time that Microsoft bought Flight Simulator from Bruce Artwick. I used FS to demonstrate the cockpit instruments and simple flight operations because of the limited time I could get the class around the real simulators. The class used the famous (with Douglas customers) (Larry) Lamm Schematics for studying the aircraft systems. Larry was one of three real estate millionaires that hung around one of the DAC coffee lounges. I asked Larry one time why he wasn't retired in Cancun and he just laughed; he just liked working with airplanes and he didn't have to pay for the coffee at Douglas.


DAC was based in Long Beach, California (LGB) just miles from the Long Beach naval shipyard, and at the time, the Spruce Goose and the Queen Mary II. The remote airport used for DAC flight test (Ken Hing Ching called it fright test) was in Yuma, Arizona on the "dying" Colorado River. In the historic novel "The Crossing" a native American comments while walking over a bridge over the Colorado River that when he got to Yuma the cars were slow and the river was fast; now the cars are fast.


The Super 80 (formerly called the DC-9, then the MD-80, and later the Boeing 717) competed with the Boeing 737 for the regional carrier market. The Super 80 test bed aircraft had lost its tail on the runway during a nose high landing before I joined the crew. I was told that the tail had been welded back on since no duct tape was available. Sperry, now a part of Honeywell, supplied most of the MD-80's avionics, which were pre-FMS and IRS. Now the Boeing name is displayed in large letters on the high-rise that was the center of the DAC campus.


The FMS in the Douglas C-17 military transport is called a Mission Computer. The idea is the same, just customized for military operations.


Instrument Flight Rules (IFR)

The first (ignoring the student/learner's permit) piloting license, the Private license, takes about 60 hours of flying experience and doesn't allow a pilot to fly for pay. The first step in becoming a professional pilot is earning an instrument rating, although a pilot might opt to do some work on his commercial rating first. Instrument training involves flying an aircraft solely by reference to instruments as one would have to do in bad visibility. IFR are the rules under which an aircraft is piloted under reduced visibility or in controlled airspace above 18,000 feet. The FS and other simulators are even more realistic than flying under a hood (flying with your vision blocked from seeing outside references) because you can actually fly heads-up under reduced visibility, which is different from no external visibility at all.


Submarine Races

If I learned one thing as a field and flight test engineer or as an avionics tech(nician) in the Air Force National Guard/Reserves, it was never to throw a switch without permission. Usually I'd ask the crew chief to set up the power or ground support equipment for me. At Lear I was the only engineer allowed in the hanger or on the airplane (Lear 55). One of the senior engineers would hang ten on the sill of the hanger door and wave to me so he could give me directions or whatever information I needed from engineering. I never did find out why he was on a restraining order from the hanger. Now the simulated B-767 student pilots were punching buttons and pulling handles like a tour busload of senior citizens at a penny slot machine casino in Las Vegas.


One flight crew of female students utilized the extension of runway 22L (overshot the paved runway on landing) and ended up in Boston Hahba. When asked by the instructors what they did after that they answered that they just taxied back onto the grass and returned to their assigned gate. And the P key (pause) was great when the flight crew got a little behind the airplane.


Bookmark these sites! - Microsoft's game directories - Massachusetts Institute of Technology IAP schedule - Flight Simulator history - System manuals and diagrams - Wilco Publishing in Belgium 767 PIC information



Push the Pause (P) Key.

Flight Simulator 2002 has a Professional Edition for people who want more features. The Professional Edition includes the Beechcraft King-Air 350 and the Mooney Bravo as well as the new additions to the Standard Edition--the Mach 2 Concorde and the Boeing 777-300. Only the professional edition was available at the Micro Center in Cambridge (~$70). FS2002 has more than 20,000 airports worldwide including six new detailed cities (12 in the Professional Edition including Boston). I think that this database is about the same size as the navigational database (NDB) in Honeywell's FMS. See Microsoft's game Web site for more details.


The events of September 11th and security was a big concern with the course planners given MIT's international community. It's a good thing that bin Laden doesn't know about Flight Simulator (Microsoft FS has been found in the caves of Afghanistan< /st1:country-region>.) After all, the two 767 flights that hit the World Trade Center towers departed from Logan. At Microsoft, FS 2002's release was delayed to include a patch that would eliminate the World Trade Center towers in the New York scenery. Some people have suggested that the old version of the scenery should have been retained in memory of the tragedy.


Microsoft's Web site details add-on and support software for those who need even more features. Programmers will be interested in the various SDKs (software development kits) for Flight Simulator. See


Give him the earth and he wants the whole solar system and distant galaxies.

I can't wait to get my hands on Bruce Artwick's new creation, Space Simulator. In Space Simulator, you fly a spaceship through space, in what is said to be the most sophisticated PC simulation yet. But Bruce, you have to get a real job. You can't just play around with toy flight simulators your whole life.


Bookmark these sites!


How am I driving? Updated Cinco de Mayo, 2004.


Shut Down Checklist Complete ;-(


Copyright © 2004 Dennis Kenney

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