Guide to Airliner Simulation - Part 1

The Flight Deck

For those of us who have an interest in civilian flight simulation, at some stage in our virtual flying career we are likely to want to start flying airliners. However, jets have a reputation for being highly complex machines, taking hours of pre-planning and following complex procedures before we can even start pushing back from the gate. So, in this new series, we will unravel some of the mysteries behind flying airliners from flight planning to configuring the systems and programming the Flight Management Computer (FMC). We will also explain how to prepare for our arrival and departure from cockpit preparation to securing the aircraft after a successful flight.

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Getting started

If you are equipped with the right flight planning tools and are familiar with a particular aircraft type, you can be taxiing to the active runway in a remarkably short time. Furthermore, there are several free or payware flight planning tools available designed to help us find routes, fuel requirements and get us airborne expeditiously.

Before going any further, I think it would be prudent at this point to offer one piece of important advice, which is, you should pick one aircraft type and stick with it while you are getting to grips with flying jetliners. Personally, I would recommend a study-level sim as the process involved in mastering aircraft with a high degree of fidelity is more rewarding; however this isn’t essential. The most important criteria to use when deciding on an aircraft is to select a type that can simulate the systems and FMC in enough detail for you to follow the upcoming tutorials.

For FSX and Prepar3D, I find the PMDG 737NGX is an excellent choice. It is a very hands-on machine and will give you a solid foundation for moving on to other Boeing types. However, if you are more of an Airbus person, there are several examples available. For a full study-level aircraft, there is the FS Labs A320 or the less complex Aerosoft A320. The systems modelling isn’t as deep on the latter but I find it does a good job of simulating normal procedures.

Other options include the PMDG 777/747, the 737/747 from iFly and a new rising star in the form of TFDi Design’s 717 (see a full review on page 22). Even classics such as the PMDG MD-11 or Level-D 767 still do an excellent job of simulating the operational principles of jetliners. X-Plane users also have a selection of aircraft to choose from such as the IXEG 737-300, Flight Factor’s 757/767 and the A320 Neo from JARDesign. Although the virtual world is awash with a variety of both old and new airliners, the real world is dominated by Boeing and Airbus.

So, to begin this series of tutorials, we will focus on these two types. The systems logic on McDonnell Douglas aircraft is very much a mish-mash of Boeing and Airbus, so we will cover those later at a later date.

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The Flight Deck

We are going to start with a brief overview of the flight deck displays and associated controls. While Boeing and Airbus have very different philosophies, there is a lot of commonality with respect to the design and layout of the flight deck. The airliner industry has made significant progress in making the cockpit environment as streamlined as possible, so there is a logical commonality in terms of layout. As a result, all aircraft manufacturers follow this industry standard. So, let’s begin with a tour of a typical airliner cockpit.

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Airbus (top) and Boeing (bottom) have a lot in common when it comes to the layout of the flight deck, despite having different operating philosophies.

Primary Flight Display

The Main Instrument Panel (MIP) houses six liquid crystal display (LCD) screens. Early jets were fitted with cathode ray tube (CRT) displays which were heavy and had slower refresh rates than we have today. The first on the left is the Primary Flight Display (PFD). It consists of the flight instruments including the attitude indicator (AI), often referred to as the ADI (Attitude Direction Indicator), with the indicated airspeed speed tape and Mach number on the left and the barometric altimeter and vertical speed on the right. The PFD also has other snippets of information such as radio altitude, decision height, QNH (barometric pressure setting), ILS information and the flight director (more on that later). Along the top, we can also see the active and armed modes for the autopilot. PFDs are fitted to both the captain’s and first officer’s side.

Navigation Display

To the right of the PFD we have the Navigation Display (ND) – this is on the left for the first officer. This provides us with information on navigation, for example the route programmed into the FMC is drawn on the ND and the distance/time to the next waypoint is displayed in the top right, with true airspeed (TAS), ground speed (GS) and wind speed/direction in the top left. On the bottom of the screen we can also see the distance to active VOR/ADF ground stations. The ND can be switched between different modes, ie ‘PLAN’ which we use when entering a flight plan and ARC mode when we are following a flight plan. We also have VOR and Approach modes. If our aircraft is fitted with a weather radar, precipitation is also drawn on the ND so we can use it to avoid turbulence. Similarly, terrain information can also be displayed on the ND, which is very useful when flying through mountainous terrain when we can’t see the ground, such as at night or during bad weather. The Traffic Collision Avoidance System (TCAS) system even shows us other aircraft in the vicinity. Finally, we can also bring up airports, navaids and waypoints on the ND.

Engine displays

Engine instruments and systems are on the upper and lower Electronic Centralised Aircraft Monitor (ECAM) displays between the captain’s and first officer’s NAV displays. This is where Boeing and Airbus differ slightly. Airbus calls this the ECAM whereas Boeing refers to them as Engine-Indicating and Crew-Alerting System (EICAS) but they essentially perform a similar function.

The upper ECAM displays the status of the engines, fuel quantity and any critical status messages. The lower display enables us to switch between secondary engine indications and pages which monitor the status of various systems such as the hydraulics, electrics and pressurisation. The amount of information varies between types. Airbus has a comprehensive set of pages with information on the status of the electrics, hydraulics, pressurisation, doors etc. Long-haul Boeings take a similar approach while the 737 is the odd one out, as many of the warning systems are displayed on the overhead panel. Although the 737NG has undergone a complete overhaul since the first aircraft took flight in the late 1960s, we can still trace some of the systems design back to those days.

Finally, the main instrument panel (MIP) houses the standby instruments, consisting of an attitude indicator, airspeed and altimeter and a radio magnetic indicator (RMI). Other systems can include autobrakes, gear lever and the clock.

Overhead panel

The overhead is one of the more complex panels as it houses all the controls for the aircraft’s systems, including electrical, hydraulic, pneumatic/pressurisation as well as anti-ice, auxiliary power unit (APU), the panel for the external lights and the inertia reference system (IRS). These are laser-driven gyros that keep track of the aircraft’s position without relying on an outside signal. However, in modern jets the IRS works with GPS and ground-based navaids to fix the position of the aircraft extremely accurately. In place of IRS units, Airbus jets (and the Boeing 777) use something called an air data inertial reference unit (ADIRU), which supplies airspeed, angle of attack, along with the position and altitude of the aircraft, used by the flight controls and autopilot.

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The IRS units in conjunction with GPS receivers can provide extremely accurate positional information, enabling aircraft to cross vast and remote areas without the danger of getting lost.

In simple terms, we navigate the systems on the overhead using what is called ‘flows’. Essentially, we use a top-down to bottom-up scan pattern, starting on the top left and working our way down each panel section and up the next, setting up various systems along the way. Space doesn’t permit us to go into more detail but we will shall do so in a later tutorial.

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We use a top-down to bottom-up pattern to navigate the overhead panel, starting on the top-left and working our way down each panel section and up the next, setting up various systems along the way.

Centre Pedestal

The centre pedestal consists of the throttle quadrant (TQ), which is where the thrust levers, flap lever and speed brakes live along with the elevator trim wheels. Behind the TQ we have the radios and VOR/ ADF receivers. Other items which can be found here are the transponder, controls for the weather radar and fire suppression systems (although on some types they are on the overhead panel). The aileron and rudder trim switches are usually located right at the back of the centre pedestal.

Mode control panel

The Mode Control Panel (MCP), Airbus calls this panel the Flight Control Unit (FCU), enables you to set different modes, such as heading and altitude hold and flight level change. Of all the modes, Lateral Navigation (LNAV) and Vertical Navigation (VNAV) are the most automated. In LNAV, the aircraft follows the flight plan programmed in the FMC while VNAV follows the vertical flight profile and will adhere to any speed and altitude constraints in the flight plan.

Next to the MCP we have the EFIS (Electronic Flight Instrument System) control panel. This is a subpanel which we use to change the range and switch to different modes on the Navigation Display (ND).

We also use this to adjust the barometer and set the minimums on the radio altimeter; although in some cases this is set up in the Control Display Unit (CDU). The master caution lights are also here, which illuminate if we have a technical problem. An amber light denotes a small (ish) problem, while a red light means we are in serious trouble.

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In LNAV and VNAV mode, the aircraft will follow the plan programmed into the FMC, VNAV follows the vertical flight path, adhering to any speed and altitude constraints.

Flight Director

Perhaps the most misunderstood instrument on the flight deck is the Flight Director. This is a set of crosshairs that overlays the attitude indicator and provide lateral and vertical guidance depending on what mode is selected on the MCP. It can follow a predetermined flight plan in LNAV/VNAV mode or can be set to follow headings and vertical profiles such as vertical speed.

Once you have the right mode selected on the MCP, you simply steer the aircraft to keep the nose in the centre of the Flight Director and it will predict intercept angles and gently lead you in on to the path you have selected. It is a very useful tool to help you fly more accurately and is particularly useful during an ILS approach. When in autoflight mode, the Flight Director guides the autopilot in a similar manner to when flying manually.

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The Flight Director displayed on the PFD (on the left) is a great tool that helps you fly more accurately and is particularly useful when handflying an ILS approach. The weather radar draws precipitation on the Navigation Display (shown on the right), enabling us to avoid turbulence.

The FMC

A Flight Management System (FMS) is the heart of all modern airliners. Essentially, it consists of a Flight Management Computer, which is usually located in a cabinet underneath the flight deck floor. It takes inputs from the IRS and air data computers (ADC) to work out the vertical and lateral paths, taking into account the performance of the engines as well as wind and the aircraft’s weight.

"Air Data Computer (ADC) calculates the calibrated airspeed, Mach number, altitude and altitude trend data from an aircraft’s pitot-static system."

We interface with the FMC using the Control Display Unit (CDU), which consists of a small screen and keyboard. If you think of how you work your computer, with a mouse and keyboard and monitor, you won’t be far off the mark. It even has a copy and paste function called a scratchpad, which displays information you have entered. Soft keys on each side of the screen act like shortcuts when entering data. These are called line select keys (LSK) and are numbered 1L (top left) to 6L bottom left and 1R (top right) to 6R (bottom right). The CDU is used to input flight plans but it can also calculate take-off and landing speeds. The flight plan is displayed on the ND and generally appears as a magenta line. Again, there are subtle differences; Boeing uses magenta lines, while Airbus uses a green line for displaying the flight plan. Incidentally, Airbus calls the CDU an MCDU (Multi-Function Control and Display Unit).

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Data is entered into the FMC via the CDU. Line select keys (LSK) on each side of the screen act like shortcuts. These are numbered 1L (top left) to 6L bottom left and 1R (top right) to 6R (bottom right).

Navigation database

An integral part of an FMC is a navigation database called an Aeronautical Information Regulation And Control (AIRAC) database. This is updated every 28 days and contains information on waypoints/intersections, airways, navigation aids including DME, VOR, NDBs and ILS as well as airports, runways and Standard Instrument Departure (SID) and Standard Terminal Arrival (STAR), holding patterns and Instrument Approach Procedure (IAP). Most high-fidelity addon aircraft come with an old version of the database, although it is possible to purchase a subscription from Navigraph, which enables you to update to the latest version.

And ending on that note, next time we will get to grips with flight planning and SID/ STARS and find out what packages are available to enhance our experience.