aoa_777_groundwork_fms-autoflight_transcript.pdf

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Autoflight-Autopilot and FMS Script Writer: Michael Pittman

Lesson Introduction Welcome to the 777 Autopilot and FMS Lesson by Angle of Attack. Get ready to set aside those wrinkled old enroute charts as your primary way of knowing where you are. Make way for the 777’s fancy Flight Management System with an advanced autopilot. When we teach you how to operate and program this system correctly, your workload will be so drastically reduced, you might even have time to talk about all of the important things in life like: what’s for dinner tonight and who’s buying? We will talk about the following topics:

Flight Management System (FMS) components

The Flight Management Computer (FMC)

The Air Data Inertial Reference System (ADIRS)

Global Positioning System (GPS)

Autopilot Flight Director System (AFDS)

Autothrottles (A/T) You are cleared for takeoff for this lesson. Precede forward, full throttle!

Flight Management System (FMS) Components The Flight Management System (FMS) is a collection of components that work harmoniously to help you know where you are, how you get to where you want to go, how much fuel you will land with, and adjusts several elements to make your flight as efficient as possible. Here is a basic idea how the systems work as a team: The pilot inputs route, flight and performance data into the Flight Management Computer (FMC) Control Display Unit (CDU). The FMC uses this data, in conjunction with its stored departure, enroute, arrival, and approach chart database to compile a route. The Global Positioning System (GPS) and Inertial Reference System (IRS) give the FMS a current aircraft position to place on this map so you can view and track your progress. Pilot or data uplinked performance information inputted into the FMC CDU gives the autothrottle (A/T) system information to calculate thrust required for different phases of flight. The autopilot system will follow the lateral (LNAV) and vertical navigation (VNAV) paths if it is engaged in those two modes. Properly programmed, the FMS can greatly reduce pilot workload. Improperly programmed, and you will be looking confused at your co-pilot wondering why the airplane is turning left instead of right. The Flight Management Computer (FMC) The Flight Management Computer or FMC, is the brains of the navigational system. It will make your job a whole lot easier in calculating your fuel burn, optimizing aircraft performance, and helping you fly more direct routes. Like any computer, it is only as “smart” as the data inputted into it. This is where you come in. You get to input information into the FMC Control Display Unit (CDU). The CDUs provide the pilot with a “keyboard and monitor” to enter data that the “computer” needs to make its calculations. The FMC technically

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has 3 Control Display Units (CDUs). There are two primary CDUs on each pilot’s side. It does not matter which CDU you enter information into. The FMC CDUs are kind enough to automatically share information together. In case of the rare event of a failed CDU, the center CDU will automatically take over for the failed CDU. Now, let’s break down the actual CDU and its fancy buttons. No matter what page or menu you are at on the CDU, the screen will always have this basic format. The top of the screen or header will always show the title of what you are doing in large letters. To the right of the title, you will see which page within that specific menu you are on. Just below the title in the body of the CDU screen are the left, center, and right fields. This is where data is displayed and blanks are left for you to input data. On the bottom the screen in the footer is the Scratchpad. This is where letters and/or numbers you type into the CDU are first displayed. To the left and right of the CDU screen are the all-important Line Select Keys. On the left side, these are referred to from top to bottom as 1L, 2L, 3L, etcetera. Obviously, the right line select keys would start on the top with 1R and continue sequentially to the bottom 6R. These keys have two main functions. The first is when you have something in the scratchpad and want it inputted into the top left of the CDU, you would select 1L. This data disappears from the scratchpad and magically appears next to 1L. Second, the line select keys allow you to grab a specific line’s information and transfer it into the scratchpad. For example, if you didn’t want to risk making a mistake entering lengthy coordinates manually, simply select the 4R line select key to “grab” this value and put it into the scratchpad. Now you can use this value on this page, or even another page. Your value stays in the scratchpad until it is put somewhere with the line select key or cleared out by you. Below the CDU screen and the mode keys are a keyboard with letters A-Z and a numeric keypad. As we discussed before, letters or numbers selected are shown on the scratchpad first. In addition, you will notice the CLR key. This is much like your computer’s backspace button in that it deletes letters and/or numbers in the scratch pad one by one each time it is pressed. Tip: To delete everything in the scratchpad quickly, hold the CLR key for a moment. Uh oh, it looks like your friends at air traffic control no longer want you speed restricted across your next fix. To delete data on the CDU screen, simply press the DEL key. “DELETE” is now shown in the scratchpad. Press the line select key where you want to delete data, and tah-dah, the data is gone. It’s always a good thing to keep ATC happy, especially when begging for a shortcut to catch the end of the ballgame. Since there is no space bar on this keypad, the SP key is there to save the day in case you need a space in what you are entering in the FMC. Sometimes, like on cold days, you will need to put in a negative number in the FMC. The plus/minus (+/-) key toggles between a positive or negative number in the scratchpad to solve this issue. Next, we will briefly talk about each FMC CDU mode key. You will get much more experience into all of the menus and sub-menus of the FMC in Flightwork. It is much easier and more exciting to learn the intricacies of the FMC hands-on. For now, we will give you a brief overview of each Menu button and what it is used for.

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INIT REF The INIT REF mode key is known around the aircraft industry as a pilot’s best friend. If you get lost in the FMC menus and are not sure what to do next, hit the INIT REF key and it will bring you to the appropriate page for the phase in flight you are at. If what is being displayed is still not what you want, use the 6L line select to choose “INDEX” to display the INIT/REF INDEX Menu where you will have a variety of options. Since there is limited space on the CDU for Mode keys, the additional modes are displayed here.

RTE Selecting the RTE key brings up your origin and destination airports. This mode also lets you enter routes to your destination airport. This function is mostly used during pre-flight after you get your clearance from ATC. On the 2nd page of this mode, you can enter in victor airways, jet airways, or direct in the VIA column and each point you are going to in your flight plan in the TO column

LEGS Just like your common handheld GPS, the LEGS page shows your basic turn by turn directions to reach your destination, though it has a few more functions of course. To the right of each fix are two values with a slash in between them. These are the speeds and altitudes you want (or ATC wants) to cross each fix. This is used for VNAV climb and descent planning. The LEGS page is mostly used in flight and on the ground to check the route you entered during pre-flight. DEP ARR Pressing the DEP ARR key brings up several departure, arrival, and instrument approach procedures. If you have a runway entered already, only the applicable procedures to that runway will be displayed. Any selections made on these pages will automatically transfer to the RTE and LEGS pages.

ALTN The weather is getting worse at your destination. You start to think, “Will I be able to make it to my alternate airport with enough fuel and how long will it take to get there?” Fortunately, the ALTN key is a single push away from showing you your distance, ETA, and predicted arriving fuel if you diverted right now to your alternate airport. How’s that for a lifesaver?

VNAV Pressing the VNAV key displays climb, cruise, or descent vertical navigation information depending on what the airplane is currently doing. The FMC helps you make all of the complex calculations at when you should start down to cross a certain fix at a certain speed. This is also the page you access when the flight attendant keeps interrupting your filet mignon dinner to ask how much longer until initial descent.

FIX

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Let’s say you’re comfortably cruising at 37,000 feet and you wonder, “Where is that old airport that I used to do short field landings during private pilot training?” The FIX page will help you satisfy your curiosity by displaying bearing and distance from any waypoint you enter. Still curious when this point will be right off of your left or right wing? You can also press the “ABEAM” line select key to put the abeam coordinates in the scratchpad. Then simply put these coordinates in your route on the LEGS page to show when you will be abeam that fix.

HOLD It is a lot harder to turn the wrong way in a hold with the HOLD page. Simply press this key and enter in ATC holding instructions in each of the appropriate fields to draw a nice pretty picture of the hold on your ND. You can also do a present position (PPOS) hold as well in case you feel like going around in circles at the spur of the moment.

FMC COMM The FMC COMM key shows the FMC CDU pages where you can access datalink. Datalink is a fancy name for basically a text messaging service. You can send the company messages, receive ATIS textually, receive gate assignments without calling ops, and receive performance as well as route data automatically. Unfortunately, you probably don’t want to use it to send a love message to your favorite dispatcher.

PROG “Are we there yet, are we there yet?” The PROG page answers this question as well as many others. Your destination and next two fixes’ ETA and estimated fuel remaining after crossing each are displayed.

MENU The MENU key displays a page used to access other aircraft subsystems through the CDU. This is how you would alternatively control an EFIS control panel or display select panel.

NAV RAD Conveniently, the FMC automatically tunes navigational stations such as VORs and VORTACs to help it verify your position at all times. It is constantly looking for better stations to help it more accurately pinpoint your exact location. Also, as long as you have an approach entered and are within 150 nautical miles of your destination airport, the FMC will automatically tune the frequency for the approach. In case you want to monitor or modify this auto-tune function, select the NAV RAD key. In the unlikely event of an FMC failure, this key displays the ALTN NAV RADIO page on the CDU. NEXT PAGE and PREV PAGE These function keys allow you to step through the various pages in each FMC menu.

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EXEC Finally, the all-important EXEC key. This key makes all of the pending changes of information in the FMC permanent. When there is a pending change such as you selecting direct to a fix, there light above the EXEC key illuminates. This allows you time to look visually on your Navigation Display (ND) to see if the change is what you want and to confirm with your other pilot. The change does not become active until your press the EXEC key and the light goes out. FMC Tips Like we said before, this has served as a basic foundation to the FMC. You will become an FMC whiz in Flightwork. Before we press on to the Air Data Inertial Reference System, we’ll leave you with a few FMC tips to help you during Flightwork:

When first entering data in the FMC during preflight, the next logical menu to enter information is accessed by selecting the 6R line select key.

Dash prompts on the FMC are optional data fields you can enter. However, filling these fields will give the FMC extra information so it can make more accurate predictions on fuel burn and ETA.

Box prompts represent required data for the FMC to operate during flight.

Small font values represent pre-calculated FMC values such as speed and altitudes it thinks you will cross a fix. Large font numbers are stored database or pilot entered values such as ATC directed crossing altitude and/or speed restrictions.

The easy way to tell if you have entered all of the required takeoff data for the FMC is to go to the TAKEOFF REF page. If “PRE-FLT” is shown next to the 6R line select key, there is still data that needs to be entered. This will disappear when the minimum information has been entered into the FMC.

Air Data Inertial Reference System (ADIRS) We just talked about the complex computer system that computes a route, calculates performance, and manages the aircraft during flight. However, all of this information would not be useful without knowing exactly where you are. The Air Data Inertial Reference System, ADIRS, saves the day. It is a complex array of sensors that calculate aircraft position, altitude, speed, and attitude for the several of the aircraft’s systems, including the FMS of course. The ADIRS system is made up of two units where it gets its data, the Air Data Inertial Reference Unit (ADIRU) and Secondary Attitude and Air Data Reference Unit (SAARU). Let's break down how these units work. The ADIRU is made up of 3 main parts: a power supply, Inertial Reference Units (IRUs), and the Air Data Reference (ADR). The power supply is normally 115V AC but it can also be powered by 28V DC battery power for a limited amount of time. Don’t drain your battery by leaving the ADIRU ON after leaving the airplane with only battery power! The dual IRUs are made up of three laser gyros and three accelerometers. These instruments are extremely sensitive to even the slightest movement. They are able to sense how fast the aircraft is accelerating and in what 3 dimensional plane it is moving towards (hence three of each). Once the system is up and running, it is

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extremely accurate. The Global Positioning System and Radio Navigational Aids update the current position in flight to make sure to correct even the slightest errors in the IRUs. For all of this to work, it is really important that initially the IRUs know exactly where the aircraft is located as well as what is the level plane parallel to the earth’s surface. To accomplish this, on initial aircraft power up you will align the ADIRU by moving the ADIRU switch to the ON position before the aircraft is moved. This starts a process where the Inertial System establishes the level North/East plane and finds the direction of true North. All you have to do is on the FMC POS INIT page, enter the aircraft’s estimated present position. Don’t worry, the system does a “makes sense” test to whatever you enter. If you put North instead of South on the aircraft present position coordinates, INERTIAL/ORIGIN DISAGREE will be displayed on the CDU scratchpad. Tip: For the most accurate present position, on the first POS INIT page move the GPS current position into the scratchpad. Next drop the GPS coordinates into the SET INERTIAL POS boxes. Normally, it will take around 10 minutes for the IRUs to align. The farther you are from the equator, the longer it takes the IRUs to align. It is really important to do a full alignment before moving the aircraft, especially when you are departing using an Area Navigation (RNAV) departure that requires a certain accuracy of the FMC called Required Navigation Performance (RNP). The ADR portion of the ADIRU uses 3 pitot tubes and several static systems to gather air data to supply to Flight Instruments such as the altimeter and airspeed indicator. This is discussed in more depth during the Flight Instruments section. Finally, the second component of the ADIRS is the SAARU. This system automatically takes over in the rare event that the ADIRU fails. You still receive aircraft heading, attitude, and air data; however, the dreaded NAV ADIRU INERTIAL EICAS message will appear which means you will not receive inertial aircraft position information. Your position will be solely based on GPS information. You will also have to reset heading every 10-15 minutes on the CDU POS INIT page to account for gyroscopic precession. If this ever happens to you, it will give you a newfound appreciation of the Inertial Reference System! The ADIRS works harmoniously with the FMC to make your job much easier in figuring out where you are in relation to your route. Next we will briefly discuss how the GPS helps enhance the precision of your position at all times, no matter where you are on Earth.

Global Positioning System (GPS) You are probably familiar with GPSs in other aircraft you have flown, in your car, or on your phone. In the 777, the “job” of the two independent GPS receivers is to supply accurate position data to the FMC. There are two components to the Global Positioning System: the receiver and satellites. The main GPS system used by aircraft consists of 24 satellites with a few spares. You must be receiving 4 satellites at a time to receive accurate 3-D positional data. You stand a very good chance at receiving this many as 5 satellites are in view at all times pretty much anywhere on Earth. Each of these satellites has a specific code that it transmits which is recognized by the aircraft’s GPS receiver. The time it takes this signal to be relayed to the GPS receiver as well as each satellite’s distance gives the receiver all the information it needs to figure out the exact location of the

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aircraft. This position helps correct small errors in the ADIRU’s accelerometers and laser gyros. While the GPS is not required for long range extended overwater ocean crossings, it greatly helps backup the ADIRU position. If you are ever curious to see your current GPS position, simply go to the 3rd POS REF page. You will see both the left and right GPS position. You will know the GPS is being used for position updates by the word “GPS” showing on your ND. The GPS automatically functions at all times unless you decide for some reason to turn it off on the POS REF page using the GPS NAV prompt. If you ever have a dual GPS failure or both aren’t available, the EICAS message “GPS” will appear. Now that you’ve learned how to get where we’re going, let’s make someone else fly so you can enjoy that delectable cup of fresh coffee. Engage the autopilot and let George take it from here.

Autopilot Flight Director System (AFDS) We have come a long way from the first autopilot system created in 1912. In the 777, the Autopilot Flight Director System (AFDS) works harmoniously with the FMC and any modes the pilot selects on the Mode Control Panel (MCP). When engaged, it automatically manipulates the flight controls in the pitch, roll, and even yaw axis. This system is so accurate that it can be used to automatically land the aircraft and even controls the nosewheel on rollout if engaged! Let’s break down the “magic” of the AFDS and how it works. The flight director is one of the most important components of any autoflight system. Based on what the pilot selects on the MCP, the flight director will show command bars on the pilot’s PFD. The command bars show where you should pitch and roll the airplane to maintain your mode selections. The AFDS also boasts 3 Autopilot Flight Director Computers (AFDCs). Each of these computers provides control of the flight directors and autopilot. This is very important to increase redundancy and accuracy of the system. When signals are actually sent from the AFDS to the Primary Flight Computers (PFCs) for manipulation of the flight controls, the PFCs select which signal to use. A bad signal is thrown out and ignored. This process is called “Voting” or “Mid-Value Selection.” After an AFDS signal is lucky enough to be selected, the PFCs then change this complex signal into movement commands for the flight controls. From there, the Actuator Control Electronics (ACEs) tell the Power Control Units (PCUs) how far to move each flight control. The busy PFCs also create movement on the cockpit yoke and rudder pedals so you can feel and see what the autopilot is doing. These are called backdrive commands. As you can tell, there is a lot of behind the scenes work that occurs when you mash that A/P engage button. Note: The AFDS does NOT operate servos like some smaller aircraft. It actually manipulates the elevators, ailerons, flaperons, pitch trim, and spoilers. Now that we know how the “magic” of the AFDS works, let’s talk about how to operate MCP to get the aircraft autopilot to do exactly what you want. Before we start, it is important to discuss the difference between what is selected on the MCP and what is displayed on the Flight Mode Annunciator (FMA) located at the top of the PFD. The MCP is similar to asking your parents for something, whether it be for a pack of gum in a store or a new baseball glove. The FMA represents

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what your parents actually give you. Just because you press a mode button on the MCP does not mean you actually “receive” that mode unless it shows up on the FMA. Active FMA modes are shown with large green letters. Armed, but not active modes (such as a glideslope when being vectored on an instrument approach) are shown in small white letters at the bottom of the FMA boxes. Armed modes will become active when you intercept that armed signal. Now that we have got that straight, let’s discuss the various controls on the MCP and what you should see on the FMA when you push these buttons:

F/D ON/OFF On the ground, whoever is flying will turn their flight director switch on first. This arms the flight director for takeoff in the roll and pitch modes of TO/GA. On both PFDs, you will see “TO/GA” displayed in the FMA. Since the flight director is engaged but not the autopilot, the AFDS Status Annunciation located just above the attitude indictor will show “FLT DIR”. Flight director command bars are only displayed on PFD when the respective side’s switch is in the ON position. If you ever turn the flight director switch off in flight and the autopilot happens to be ON, the autopilot will engage in its default modes of Vertical Speed (V/S) or Flight Path Angle (FPA) and Attitude hold (ATT) or HDG/Track Hold (HDG HLD/TRK HLD). These are really not modes you want to be in so leave these switches ON inflight when the autopilot is ON.

A/P The “take a sigh of relief” A/P Engage buttons allow the autopilot to be engaged by either the Captain or First Officer. The autopilot will engage in whatever mode or modes are being displayed on the FMA. To be certain the autopilot did in fact engage and you can relax, the light on the A/P engage button should illuminate and “A/P” should be displayed in the AFDS Status Annunciation. If you are doing an Autoland approach, you may get “LAND 3”, “LAND 2”, or “NO AUTOLAND” displayed in the AFDS Status Annunciation as well. LAND 3 means all 3 autopilots are engaged and working for autoland (a very good thing). LAND 2 basically means that 2 out of the 3 autopilots are available (not quite as good). NO AUTOLAND means… well I am sure you can figure that one out.

A/P Disengage Bar Pulling down on the A/P Disengage Bar is one of several ways to disengage the Autopilot. This is not usually the preferred method of disengaging the autopilot unless there is a major problem with the system and it is not to be further engaged. As long as this bar is pull down, autopilot engagement is not allowed and bank protection is removed. Anytime, for whatever reason, the autopilot is disengaged, you will get an aural warning, flashing master warning lights, and an EICAS warning message AUTOPILOT DISC. This signals break time is over.

A/T ARM switches

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Before the autothrottle can be engaged, it must be armed with these switches. There is a switch for each respective engine’s autothrottle. Normally, pilots will turn on these switches prior to takeoff to make their job a lot easier when setting takeoff thrust. As long as the autothrottle system is armed, the thrust levers will move automatically when a pitch or speed mode is engaged. In flight, positioning these switches to OFF will cause an EICAS AUTOTHROTTLE DISC message to popup as well as generate an aural alert. We will discuss the autothrottle system in more depth later.

CLB/CON This button is a thrust mode switch mostly used during climb out. With both engines operating, the engine thrust limit will be set to the FMC selected climb thrust. If you have lost an engine, the thrust limit is set to max continuous. This will give you the max thrust available on the operating engine during climb so you can avoid those mountains just past the runway. In either case, you should see “THR REF” in the left FMA box. This means the autothrottles are set to the EICAS thrust limit. Note: This button is disabled on the ground and below 400 feet AGL.

A/T As long as the autothrottles are armed and you are above 400 feet AGL, pushing the A/T Engage Switch will either engage THR, THR REF, IDLE, or SPD autothrottle modes. If you do not have a pitch mode selected, your MCP speed window will be open allowing you to select a desired speed for the autothrottles to maintain. In this case, “SPD” will be displayed in the FMA. Note: The autothrottle will not exceed speed limitations for Vmo/Mmo, slats, gear, or flaps. Pretty nice feature wouldn’t you say! THR will be displayed in the FMA if you have a specific vertical speed selected that you want the aircraft to maintain. IDLE will obviously move the thrust levers to idle if needed by the selected pitch mode. This is normally seen during a VNAV descent as the most efficient descent for a jet is at idle power. THR REF is mostly annunciated in the FMA when the CLB/CON button is pressed or during climbout.

IAS/MACH Speed Window If you want to control the aircraft’s selected speed instead of the computer, you have come to the right place. Below this window is a knob you rotate to select the speed you want the autothrottle to maintain. If this speed window happens to be blank, the FMC is controlling the speed. To wrestle away control from the FMC, simply push the speed selector knob. This is known in the professional aviation world as speed intervention. In this case, SPD will be displayed in the autothrottle portion of the FMA. You can also open this window by selecting FLCH SPD and TO/GA pitch modes that we will discuss later. Right above the window is a small toggle button to change between an IAS or Mach airspeed display.

LNAV

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To get the flight director to follow the lateral path you spent so much time inputting into the FMC, you will need to press the Lateral Navigation (LNAV) button. Like any other mode on the MCP, it is really important to not only check that the light on the LNAV button illuminates, but also pay attention to the roll portion of the FMA. Let’s say you are being vectored by ATC to intercept a jet airway. In this case, HDG SEL will be in green letters in the FMA and when you push the LNAV button, LNAV will be below HDG SEL in white letters to show it is armed, but not engaged. When you get within a few degrees of your FMC course, LNAV will turn green in the FMA and HDG SEL will disappear since you are now following the FMC lateral path. If you are not on an intercept heading for the course in the FMC when you push LNAV, the FMC will even correct you by saying NOT ON INTERCEPT HEADING in the CDU scratchpad. Now let’s say instead that you are on a departure and cleared direct to a fix. Simply go to the FMC LEGS page, bring that fix to the top, execute the change, and hit LNAV on the MCP. LNAV will almost instantaneously move into the green on the FMA.

VNAV When you were entering all those performance numbers into the CDU during pre-flight and started to wonder why the FMC needs this data, well this is it! When the Vertical Navigation (VNAV) switch is pressed, the autopilot, flight director, and autothrottles will work together to maintain a pitch and airspeed that will match the FMC calculated vertical path. The VNAV light on the button will illuminate showing VNAV is either armed or engaged. However, there are several pitch modes under the VNAV umbrella so it is very important to look at the FMA to see which of the following modes you are operating in:

In VNAV SPD, the flight director issues pitch commands to hold a target airspeed. In the autothrottle portion of the FMA, either THR REF, THR, IDLE, or HOLD will be displayed depending on the phase of flight.

In VNAV PTH, the flight director issues pitch commands to either maintain the FMC’s target altitude or the vertical path. The autothrottle maintains speed. When you are in cruise, the autothrottles will be in SPD mode. Depending on what descent you have programmed in the FMC, either IDLE, HOLD, or SPD mode will be shown on the autothrottle FMA.

VNAV ALT is displayed for two reasons. One: The MCP altitude in lower than the VNAV altitude in a climb or two: The MCP altitude is higher than the VNAV altitude in a descent. The autothrottle will operate in SPD mode in either situation.

One word of advice, if VNAV is ever doing something that catches you off guard, you can always select another pitch mode and VNAV will disengage. You can rest assured that VNAV will never climb you above or descend you below the altitude you have selected in the MCP. So it is definitely a good idea to make extra sure that the MCP has the correct ATC assigned altitude or you’ll be shamefully jotting down a number from the control tower.

FLCH SPD In a lot of older aircraft, the FLCH and SPD are separate buttons on the MCP. In the 777, the two buttons are combined into one FLCH SPD button. Pressing this button is one of the ways to open the speed window. Initially

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either the FMC target speed or if this doesn’t exist, then the current aircraft speed is displayed. The pilot is able to manipulate the actual climb, cruise, or descent speed in the speed window. When the FLCH SPD button is pressed, the autothrottles will go to THR mode and FMA pitch mode of FLCH SPD will climb or descend the aircraft to the MCP selected altitude in 125 seconds. During a descent, the autothrottles may go to HOLD mode if the thrust levers reach idle.

HDG/TRK Window Just as the name of it says, the HDG/TRK window shows the selected heading or track. To switch between having heading or track displayed, right above the window is a small toggle button. One nifty trick with this window is when a localizer or approach is captured, the heading or track will be automatically set to the front course heading.

HDG/TRK Selector Like many of its predecessors, the 777 has a heading select knob where the middle portion controls the heading or track displayed in the window above it. The outer knob controls the amount of bank during a HDG SEL or TRK SEL roll mode. One major difference on the MCP; however, is there is no HDG SEL independent button. Instead, this is found on the inner push button of the HDG/TRK selector. Pushing this inner button engages HDG SEL or TRK SEL as the FMA roll mode.

HDG/TRK HOLD If you find yourself in a situation where you want to just maintain wings level and stay on a specific heading or track, feel free to press the HDG/TRK HOLD button. When pushed, HDG HOLD or TRK HOLD will display in the roll FMA. V/S-FPA Switch Let’s say Air Traffic Control wants you to descend from 10,000 to 9,000 feet and you are still 70 miles from the airport. There is no reason to hurry down so the V/S-FPA switch is an easy way to slowly start down. Simply use the up/down toggle wheel to set the desired pitch angle you want. On the ND, you can see where the computer estimates you’ll be at 9000 feet by the green arc ahead of your airplane. In the FMA, you will see either V/S or FPA in the pitch mode and the autothrottle in SPD mode. By the way, just above the V/S-FPA window is a way to toggle between V/S and FPA.

Altitude Selector The inner part of this knob is the all-important altitude selector. Rotate this knob to select the ATC assigned altitude the airplane needs to climb, cruise, or descend to. The aircraft will not start a descent to a lower MCP altitude if you are in VNAV until you hit the top of descent, such as in a pilot’s discretion descent. You can override this by selecting “DES NOW” in the FMC. The outer portion of this knob allows you to toggle 1,000 and 100 foot increments for the altitude selector.

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Altitude HOLD Just like it sounds, the altitude HOLD button holds the present altitude. ALT is displayed as the pitch mode on the FMA. As long as you have your correct level off altitude in the MCP, you really do not have to use this button. This is more of an “ooops” button when you are climbing through an altitude you shouldn’t or ATC suddenly wants you to level off at an altitude you are about to climb through. You can also use this button to open up the speed window if you’re currently in any VNAV mode.

Approach Switches The LOC and APP switches are for arming localizer and ILS approaches. When you hit the LOC button with a valid localizer frequency tuned, LOC will be armed in white as the roll mode. For ILS approaches, LOC will also be armed when you press the APP button and G/S will be armed as the pitch mode as well. Note: For VOR or ADF approaches, you will notice there is no VOR or ADF button on the MCP. For these approaches, you will load the approach in the FMC and use LNAV to do the approach. The FMC is auto tuning the frequency for the selected approach. While this concludes all of fancy switches, buttons, and windows on the MCP, there are a few very important Flight Mode Annunciations that would be a great help to you in Flightwork… TO/GA When you hear pilots talking about togas, unfortunately they probably aren’t telling you about a Greek party. Instead, they must be talking about the Takeoff/Go Around FMA mode. TO/GA is one of the few modes that is a pitch and roll mode. It is first shown on the FMA during the pre-flight stage when the first flight director switch is turned on. You will see the flight director go to a fixed pitch attitude of about 8 degrees up and roll command of wings level. On takeoff, pressing the TO/GA switches on the power levers engages the autothrottle THR REF mode. The thrust levers will be automatically advanced to the takeoff thrust limit. Prior to 80 knots, the pilot monitoring will fine tune the thrust levers to maintain engine limitations. After 80 knots, the autothrottles go into a HOLD mode that maintains the current thrust lever position. After lift-off, you can engage the autopilot as well as your desired pitch and roll mode. If you happen to press the TO/GA switches after lift-off, the thrust levers will go to maximum takeoff thrust. You would use this if you had an engine failure on takeoff. The other part of TO/GA is go-around. You’ve just worked a 15 hour day and are ready to go home. All is going well, the runway is in sight, then a fuel truck decides to cross your runway and tower yells at you to go around. Pressing the TO/GA buttons on the thrust levers automatically advances the thrust levers to go around thrust and puts the pitch and roll FMA to TO/GA.

Auto-land FMA Modes When you get tired of landing the aircraft and decide to give the computer a shot, you will see the FLARE and ROLLOUT FMAs. FLARE is a pitch mode right before touchdown that uses the aircraft’s radio altitude to start

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pitching up the aircraft for a smooth touchdown. ROLLOUT is a FMA roll mode that tells you when it is active; the autopilot is controlling the nosewheel in the rollout to maintain the runway centerline. A lot of old timers will tell you, sometimes if you want something done right; you have to do it yourself. We wrap up our discussion of the autopilot with some ways to actually disconnect the autopilot:

Button on either pilot’s control wheel

MCP autopilot disengage bar

Applying override force on the control column or control wheel. The force required is much greater during auto-land.

Moving stabilizer electric pitch trim Now that the computer has done most of the flying in this lesson so far, let’s hit those TO/GA switches and continue on to the Autothrottle System.

Autothrottle System (A/T) By now, you have probably figured out that the Autothrottle (A/T) System is a way to automatically control thrust from takeoff all the way to landing. The autothrottle system operates independently from the autopilot system. The A/Ts work just fine without the autopilot and flight director engaged. The A/T has its own separate computer used to calculate thrust settings depending on the MCP or FMC commanded speed. The thrust levers are automatically moved by servos commanded by the A/T computer. When the autothrottles are engaged, the pilot can override the autothrottles by moving the thrust levers to desired thrust. Normally, after manually positioning the thrust levers, the A/T system will reposition the thrust levers to comply with the active A/T FMA mode. However, if the autothrottles are in THR mode, you do run the risk of changing the A/T mode to HOLD. The only way to re-engage the A/T system is to level at an altitude, put the thrust levers in the green N1 limit on the EICAS, or near stall limit protection. If the autothrottles are doing something that you did not expect or want, they are easily disconnected by pushing either thrust lever A/T disconnect switch or moving the MCP A/T arm switches to OFF. When doing this, you will get an aural alert and “AUTOTHROTTLE DISC” EICAS message. Note: The A/Ts will automatically disconnect when the engines are put into reverse thrust on the ground.

Lesson Summary As you have just learned, the 777 has so many automatic features that one might start to wonder where the pilot actually flying the aircraft fits in. However, with great technology comes a lot of responsibility. It would be quite easy to become complacent eating your fresh Atlantic salmon and garlic mashed potatoes while the Autopilot and FMS is flying you around. Yet, it becomes even more important to understand how all the magic works so when something weird does happen, you can say “I know how to fix this. I learned this from Angle of Attack!” Make sure to expand on your FMS and Autopilot knowledge in Flightwork. For your review, here are the topics we covered:

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Flight Management System (FMS) components

The Flight Management Computer (FMC)

The Air Data Inertial Reference System (ADIRS)

Global Positioning System (GPS)

Autopilot Flight Director System (AFDS)

Autothrottles (A/T)

We hope you have enjoyed learning about the FMS and Autopilot of the 777. Feel free to explore other related systems such as Flight Instruments and the Heads Up Display. Until then, Throttle On!

aoa_777_groundwork_fms-autoflight_transcript.pdf

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