Chapter 6: Advanced Features of X-Plane for iPad/X-Plane HDEF 4G

From X-Plane Wiki

Note: This chapter assumes prior familiarity with the workings of the view options and the Settings menu, as well as with the standard flight instruments. All of this is described in Chapter 2: Getting Acquainted with the iPad/iPhone 4G Simulator.

Flying an Approach Using the Instrument Panel

Nearly all of the aircraft in X-Plane for iPad/X-Plane HDEF 4G have basic navigation radios and instruments built into them, and all of these are used in more or less the same way. We will go through an example for flying an ILS approach (that is, an approach using an instrument landing system) in the Southern California region, but similar steps can be used for any airport.

Note that instrument navigation is not for the faint of heart. X-Plane is as realistic a flight simulator as possible, and navigation is no exception. This section is by no means a complete guide to airplane navigation (there are plenty of 400-page books available that claim that), but it will go into quite a bit of detail. We will discuss a great deal of side information needed to fly all approaches, but we will always come back and relate it to flying the example approach into San Bernardino International (again, found in the Southern California region).

To fly an instrument approach, users will first need to know the local navigational aid (NAVAID) frequencies. To find this, tap the center of the screen to make the various menu options appear, then open the Settings menu.

The map in the window that appears shows the ILS, LOC, VOR, and VORTAC frequencies for the area. Zoom in and out of the map by placing two fingers on the screen and dragging them farther apart (to zoom in) or closer together (to zoom out). To pan the map, place one finger on the map and drag it, and to rotate it, place two fingers onto the map and twist them in a circular motion.

Let's discuss the specifics of each of these types of navigational aids (NAVAIDs)

Types of NAVAIDs

The earliest type of navigation modeled in X-Plane for iPad/X-Plane HDEF 4G is based on VOR signals (that is, signals from a very high frequency omnidirectional range transmitter). VOR transmitters work by sending a series of 360 discrete little carrier tones on a main frequency. Each of these carriers is oriented along a different radial from the station, one of 360 just like on a compass rose. Thus, when one is flying along and tunes in the main VOR frequency, one then fine tunes the navigation display to tell which of the 360 radials the aircraft is flying and also whether the transmitter station is in front of or behind the plane.

In X-Plane for iPad/X-Plane HDEF 4G, a VOR beacon is labeled as in the following image.

A specific type of VOR, a VOR-DME, combines the lateral guidance (that is, guidance left and right) of a VOR with the distance guidance of a DME (distance measuring equipment). In X-Plane, this is labeled as in the following image.

Another type of VOR beacon, a VORTAC, is also found throughout the X-Plane maps. This is a transmitter that combines both VOR and TACAN features. TACAN (or tactical air navigation) provides special information to military pilots similar to a civilian VOR. However, for our purposes, this is functionally identical to a VOR-DME. A VORTAC in X-Plane is labeled as in the following image.

A LOC (or localizer) transmitter provides guidance to the centerline of a runway. It works by sending out two signals on the same channel, one of which modulates at 90 Hz and the other of which modulates at 150 Hz. One of these signals is sent out slightly to the left of the runway, while the other sent out slightly to the right of it. If an aircraft is picking up more of the tone modulated at 150 Hz, it is off to the left. If it is picking up more of the tone modulated at 90 Hz, it is off to the right. The course deviation indicator (or CDI) in the instrument panel then indicates this so that the pilot can correct it. When both tones are being received in equal amounts, the craft is lined up with the physical centerline of the runway. In X-Plane, a LOC transmitter is marked as in the following image.

An ILS (or instrument landing system) combines the functionality of a localizer, which provides lateral guidance, with a glideslope transmitter, which provides vertical guidance to the runway. The glideslope beacon functions similarly to the localizer, sending out two tones that have the same frequency, but different modulations. The difference is that the glideslope tells the plane that it is either too high or too low for its distance from the runway. The pilot uses this information to push the craft's nose up or down as needed. The ILS will allow a pilot to fly on instruments only to a point that is a half mile from the end of the runway at 200 feet (depending on the category of the ILS) above the ground. If the runway cannot be clearly seen at that point the pilot is prevented from executing a normal landing. If this happens, the pilot in real life is required to fly a "missed approach" and climb back to altitude in order to try again or go somewhere else.

In X-Plane, an ILS transmitter is marked as in the following image.

For our example approach, we’ll be flying into San Bernardino International Airport (KSBD, found in the Southern California region). Zooming into the map screen near this airport shows that the ILS signal is coming from runway 06 (as seen in the following image). Not coincidentally, there is a button here in the map screen to put the aircraft on a final approach to this runway. As seen in the following screenshot, the frequency we need to tune for KSBD's runway 06 ILS is 109.30.

Navigation Instruments

Before we begin the approach, let’s review the instruments used in navigation. This section assumes familiarity with the panel view as described in Chapter 2: Getting Acquainted with the iPad/iPhone 4G Simulator.

Instruments in the Steam Gauge Panel

The image above is the panel view in the Cessna 172. The course deviation indicator (or CDI—the most important instrument in navigating approaches like this) is seen in the following image.

The vertical line in the instrument displays the aircraft's lateral position relative to the tuned signal, and the horizontal line represents its position relative to the transmitted glidepath (where available).

To navigate using any of the previously listed NAVAIDs (VOR, LOC, ILS, etc.), that NAVAID's frequency must first be tuned in to one of the navigation radios. The two knobs on each radio are used to tune them. The knob on the left is used to tune the integer (or "counting number") portion of the frequency. The knob on the right is used to tune the decimal portion of the frequency.

For instance, let's pretend we want to fly the ILS into San Bernardino International airport using the radio below.

We found above that the KSBD ILS is transmitting at 109.30 Hz.

To tune the radio down to 109.30 Hz, first touch the left knob and slowly move your finger counter-clockwise until the radio reads 109.10. From here, touch the right knob and move your finger clockwise around it, bringing the frequency up to the required 109.30. At this point, we are all set to fly San Bernardino International's ILS.

Note that it doesn’t matter which NAV radio is used, so long as you follow the proper radio when flying. In aircraft with a source select switch, the CDI will be driven with the signal from the radio indicated by the switch. For instance, if the source select switch was set as in the following image, the NAV 1 radio would drive the CDI. In aircraft without a source select switch, the NAV 1 radio drives the top CDI, while the NAV 2 radio drives the bottom CDI; following the right radio is a matter of following the right CDI.

With the navigation radio set, assuming we are on an approach to the ILS we just tuned (which can be done using the KSBD 06 Final button found on the Map screen), the CDI should begin to move.

For instance, in the following image, the vertical bar of the CDI instrument is a bit to the right of center. This indicates that the aircraft has moved to the left of the localizer course (recall that the localizer portion of the ILS is responsible for guiding the craft left and right). To get back on course, the aircraft needs to turn right—in other words, it needs to follow the line on the CDI.

Also note the horizontal bar in the instrument. This is the glideslope indicator. In the image above, it is a bit above the center of its range. In order to stay on the glideslope, the aircraft will need to pull its nose up just a bit—in other words, it needs to follow the glideslope indicator. When the horizontal line is in the center of the instrument, the craft is right on course.

Instruments in the Glass Cockpit Panel

The image above shows the relevant portion of the panel found in the Cirrus Vision. Recall that the LCD panel on the left, the primary flight display, indicates the craft's pitch and roll attitude. In addition, it combines in functionality from the horizontal situation indicator, or HSI. For our purposes, the HSI serves the same function as the CDI in the steam gauge panel; it simply displays the information differently. Let's look at this screen closer.

The course deviation indicator (CDI) portion of the HSI is represented by the vertical purple line in the image above. It is in the center of the artificial horizon, meaning that the aircraft is lined up almost perfectly with the physical centerline of the runway. The glideslope indicator portion of the HSI is represented by the horizontal purple line. In the previous image, this is lined up almost perfectly with the aircraft's attitude indicator. Follow these purple lines just like the white lines in the steam gauge CDI. If the horizontal line is above the craft attitude indicator, pull up to meet it, and if the vertical line is to the left of the artificial horizon center, turn left to meet it, and so on.

Below the attitude indicator is the directional gyro. This, like the CDI and glideslope indicator, is normally a part of the HSI.

The directional gyro works like a compass in that it indicates the aircraft's heading. For instance, in the previous image, the craft has a heading of 058 (notice that the arrow is pointing just a little to the left of the six, representing a heading of 060).

If we looked at a navigational chart for San Bernardino International Airport (or use an airport database like AirNav), we would see that runway 06 that we're flying into has a magnetic heading of 057. This means that, according to the previous image, we are pointed one degree to the right of the runway.

Now let's look at the moving map.

In the image above, the omni-bearing selector, which serves the same function as the OBS in the mechanical CDI instrument, is marked with a 1. In this case, it will rotate the green CDI found in the moving map to line up with whatever heading the pilot specifies—for our example approach to San Bernardino International, we would want it pointing a little to the left of the 6 found at the top of the map (for a heading of 057).

To the right of that is the navigation source select switch (marked with a 2 in the previous image), which switches between using the NAV 1 and NAV 2 radios. Data from the radio selected here gets sent to the EFIS. Tap this switch to change its position.

To the right of the source select switch is the zoom dial for the moving map, marked with a 3 in the image above. To move this, touch it and move your finger in a circle around it. Turn it clockwise to zoom out, and counter-clockwise to zoom in.

In the previous screenshot, the panel's moving map is marked with a 4. The green bar on this map indicates the aircraft's lateral position relative to the localizer's transmitted path. When the broken center portion of the bar is moved to the left, the aircraft needs to turn left in order to stay on the path, and when it is moved to the right, the craft needs to turn right.

Important to note are the light blue airports indicated in this map (for example, KSBD, CL95, and 74CA from the previous image). The locations of these airports are shown relative to the aircraft, which is represented as the white triangle in the center of the map.

Localizers are represented on the moving map as purple triangles for pilots to fly down. Recall from prior in this chapter that a localizer provides the lateral (left and right) guidance in an instrument landing system (ILS).

When flying a localizer, the pilot starts at the widest part of these purple triangles. The center line of the triangle is the desired course and the right and left edges correspond to full scale right and left deflections of the course deviation indicator. This means that the triangle’s edges represent the width that one could fly to either side of the CDI's center line and still get accurate guidance. The path comes to a point at the end of the approach (corresponding to the end of the runway). Consequently, it gets much more difficult to stay on course at the end of the approach because a very small deviation off course will give the pilot a full scale deflection on the CDI. So, pilots fly into the fat part of the arrow and, hopefully, right down the center line, keeping the CDI centered the whole time by making progressively smaller and smaller corrections left and right to keep the needle centered.

As the navigation radios work identically in all the instrument panels, we will not describe them again here.

Flying the Approach

Now that we've discussed the different types of NAVAIDs in X-Plane, as well as how to use the navigation instruments in all the aircraft, let's begin flying the actual approach.

For our example instrument approach, we'll be flying into San Bernardino International Airport (KSBD), which is found in the northern half of the Southern California region. According to the map (shown in the following image), KSBD has an ILS navigation system. This means that an instrument approach to the airport can take advantage of both horizontal (left and right) and vertical (up and down) guidance, thanks to the ILS's localizer and glideslope beacon, respectively. The map shows that the ILS frequency for runway 06 is 109.30.

For simplicity's sake, rather than taking off from one airport and flying to San Bernardino, press the Final button for KSBD runway 06 (marked with a red box in the image above).

Now that we're on the approach, select the instrument panel view. Tune one of the navigation radios to the desired ILS frequency (in this case, 109.30). Make sure that the radio that was tuned is also selected with the navigation source selector switch. For instance, if the NAV 1 radio is tuned to 109.30, the source selector also needs to be pointing to NAV 1.

In the real world, we would look at a approach plate to determine what heading we should be flying to get to the runway. As not everyone has a set of California approach plates, the AirNav database can be consulted for the heading. Scrolling down on that web page to the Runway Information section reveals that Runway 06 has a magnetic heading of 057. Additionally, the page lists the runway's elevation as 1084.6 feet above sea level. This information will be important when we get close to the runway, for obvious reasons!

At this point, the vertical bar in the CDI will begin to wander left or right to indicate which direction the craft needs to move in order to point down the centerline of the runway. Aim toward the deflection to intercept the localizer course; when the CDI wanders right, point the aircraft's nose right, and so on.

Additionally, the glideslope indicator (the horizontal bar in the CDI or EFIS) will begin to move. If its needles are above the center of the instrument then the craft needs to fly up, and if they are below the center of the instrument, it needs to fly down to intercept the glideslope. The goal is to keep the localizer bar in the CDI centered to stay on the localizer, and the glideslope bar centered to stay on the glideslope.

For example, in the following image, the CDI is deflected a little to the right (indicating the craft needs to turn to the right) and the glideslope indicators are a bit high (indicating that the aircraft needs to raise its nose a bit).

In the following image, the CDI is deflected to the right (indicating the aircraft needs to bank to the right) and the glideslope indicator is high (indicating the craft needs to raise its nose).

Follow the guidance of the localizer and glideslope until the craft reaches an altitude of about 300 feet above the runway. Remember from when we looked up the runway information on AirNav that its elevation is 1084.6 feet; therefore, our key altitude will be 1385 feet. When the aircraft's altimeter reads 1385, we should switch to visual navigation to land.

At this point, if everything was done correctly, the runway will be right in front of the aircraft. If the landing itself was managed properly, the aircraft will be at its stalling speed plus 30% with the gear and flaps down (remember that gear, flaps, and throttle are still visible in the panel view) as it comes in for a landing. In the Cirrus Vision, this is about 90 knots. In the Cessna 172, it's about 65 knots, and in the Boeing 747, it's about 140 knots.

Using the Autopilot

The autopilot is one of the most asked about features in X-Plane—indeed, in real world planes, too. The fact is that many real aircraft owners never take the time to learn to use their autopilots. The basic autopilot functions available in X-Plane for iPad/X-Plane HDEF 4G, however, are really not too difficult to understand once the user has taken the time to learn about them.

In a real aircraft, there are three levels of autopilot functionality:

Off, with no autopilot functions active,
On, where the autopilot servos take over the flight controls and fly the airplane, and
Flight Director, where the autopilot displays a set of "wings" on the attitude indicator to show the pilot where to fly.

If the pilot follows the flight director wings perfectly, the airplane will behave just like when it has the autopilot servos on. If the pilot does not follow the wings, it will be as if the autopilot were off completely.

X-Plane for iPad/X-Plane HDEF 4G does not have this flight director mode. Therefore, whenever the autopilot is switched on (using the switch at the top of the panel view, highlighted in the following image), it will automatically take control of the flight controls.

Aircraft with Autopilots

The following aircraft have autopilot functions:

Columbia 400
Cirrus SJ50 Vision
Eclipse 500
Boeing 747
Boeing 777
Airbus A380
Boeing 787
Boeing 737
Airbus A320
Boeing 757
B-2 Spirit

Available Autopilot Functions

The following autopilot functions are available in the aircraft listed above.

ROLL and PTCH

The first autopilot functions, ROLL and PTCH, are the roll and pitch hold modes, respectively. When the autopilot is switched on, these two are turned on automatically. They will hold the current roll and pitch attitudes of the aircraft. For example, if the craft has its nose pitched down ten degrees and is in a five degree left bank when the autopilot is switched on, ROLL and PTCH modes will hold this ten degree down, five degree left attitude. These modes are shown in the following image.

ATHR

The next autopilot function is the auto-throttle mode. When the ATHR button is pressed, the autopilot will attempt to maintain the craft's current airspeed by increasing or decreasing the throttle. It will not, however, attempt to control the craft's speed using any other method, such as pitching the nose up or down or adding or subtracting flaps. Therefore, the auto-throttle will be able to put the throttle anywhere between its maximum or minimum, but it will not be able to maintain an excessively high or low airspeed (such as one obtained by pitching the nose excessively low or high).

The ATHR is turned on (as indicated by its button being lit yellow) in the following image.

In the image above, the auto-throttle is set to hold 150 knots. Note that it is not uncommon for the auto-throttle to stay a few knots above or below the set speed like this.

With the ATHR button pressed, the other autopilot functions can be disengaged by turning the autopilot power switch to off. This allows the pilot to pitch and roll the craft freely while the auto-throttle maintains the same speed.

Also, note that when auto-throttle mode is engaged, it will start the throttle at its minimum, then slowly bring the throttle up to the point where it holds the selected airspeed. This results in a drop of around ten knots when the ATHR button is first pressed, but this drop in speed is not permanent.

HDG

The next autopilot function is the heading hold mode. Pressing the HDG button will set the autopilot to follow the heading currently displayed on the directional gyro (recall that the directional gyro is the partial circle found at the bottom of the left EFIS display). It will follow this heading by rolling the aircraft left and right. For this reason, when the HDG button is pressed, heading hold mode will replace roll hold mode.

For instance, in the following image, the HDG button was pressed when the craft was pointed at heading 043. Since a heading of 0 is due north, and a heading of 090 is due east, the autopilot will be flying the aircraft northeast.

HOLD

The final autopilot function is the altitude hold. Pressing the HOLD button will cause the autopilot to hold the current altitude by pitching the nose up or down. This mode automatically replaces pitch hold mode.

For instance, in the following screenshot, the HOLD button was pressed when the craft was at an altitude of 7,200 feet, so the autopilot will continue to maintain this altitude.

Taking Off from and Landing on a Carrier

Carrier operations are another challenging and fun feature of X-Plane for iPad and X-Plane HDEF 4G.

To take off from a carrier, a few things must be done in quick succession. First, the throttle slider must be dragged to the top of its range of motion. The flaps must be pulled down about half way, and the BRAKE button must be tapped to disengage the brakes and activate the catapult propelling the craft off the deck. From there, simply guide the craft down the flight deck and, once clear, pull the nose up sharply and bring the gear up.

(Note that information on the location of the these controls on the screen can be found in Chapter 2.)

Landing on the carrier is a bit more difficult. First, note that the ADF (the arrow in the middle of the direction gyro, which is highlighted in the following image) always points the way back to the carrier. This is invaluable in setting up an approach to the carrier.

To set up an approach to the WWII carrier used with the F4U (whose landing deck goes straight down the flight deck), a pilot should fly either a 90 or 45 degree intercept (depending on the aircraft's distance) in order to get behind the ship. If the ship is traveling north, and the aircraft is coming from the east with the ship to its north (as in the following diagram), the pilot will continue on his or her intercept trajectory until the ADF needle is pointing either 45 or 90 degrees to the right, at which point he or she will turn in toward the landing deck.

If the carrier is instead the John F. Kennedy-class ship used with the F-4, F-14, and F-18, the landing runway is angled 30 degrees to the port (left) side—it is not straight down the flight deck like in the older carriers. This change was made to prevent the all-too-common overruns that occurred in WWII when a landing plane crashed into the stacked line of planes at the far end of the carrier. A pilot landing on such a carrier must correct for this angling. Using the example and diagram above, the pilot would instead wait until the ADF was pointing either 15 or 60 degrees to the right before turning in for a landing.

When approaching the flight deck to land, a glidepath of about 3.5 degrees is standard. At this time, the tail hook should be lowered by tapping the HOOK button, turning it green. This will allow the tail of the aircraft to catch the arresting wires on the deck. These wires will accelerate the craft from well over 100 knots down to zero in little more than a second.

Unlike in a conventional landing, there should be no “flare” before touching down on the carrier. Whereas, say, an airliner would raise its nose up just before touching the runway (thereby ensuring a smooth landing), a carrier approach should maintain a constant glideslope until the craft hits the deck.

Also, rather counter-intuitively, a real fighter pilot must slam the throttle to full the instant that the aircraft touches the deck. This is because, even when the pilot has done everything right, the craft's tail hook can bounce over the arresting wires in what is called a “bolter.” When this happens, the pilot must be ready to get off the deck safely and come around for another try. Don't worry—even when the throttle revs up like this, the arresting wires will still pull the craft down to zero velocity.

To see how the pros do it, check out the following links:

Video: Carrier Landing—F-4J Phantom II in the Mediterranean Sea

Video: F-14 Carrier Landing

Walkthrough: How to land a jet plane on an aircraft carrier

Combat

Combat Basics

Of course, taking off and landing on the carrier are only means to an end. The real goal is the dogfight—shooting down the enemy. Each aircraft's weapons can be fired with the FIRE button (labeled 1 in the following image). Above and to the left of this button is the GUN button (labeled 2 in the following image), and beside this button is a number indicating the number of rounds left. In the MiG, F-4, F-14, and F-18, there is also an AIM9 button (labeled 3 in the following image) beneath the GUN button. Tapping this will switch from the guns to the guided missiles, and tapping the GUN button will switch back.

Using the Gun

When firing a gun, be sure to lead opponents (called deflection shooting)—fire at where they will be, not where they are. Mastering so-called “high deflection shooting” can make the difference between ending a fight quickly and losing it entirely. Whereas the surest shot will always come when a pilot is right on an enemy's tail, a high deflection shot comes from beside or in front of the enemy. In most cases, a pilot has only a split second in which the enemy will cross his or her path of fire, so timing is critical.

Using the Missiles

When firing the AIM-9 missiles, they will more or less lock on to an enemy automatically, even when fired from a good distance. While this makes it relatively easy to score a kill on an enemy, that enemy is equipped with the same missiles, so be prepared to jink (rapidly deflect the flight controls into turns in different directions) when the return fire comes.

Using the Targeting Reticle

The targeting reticle always follows the enemy's aircraft. If the enemy is visible on screen (as in the following image), it will appear as a thin green box around the opponent's craft.

If, however, the enemy is not visible on screen, the reticle will be “dragged” to the edge of the screen and will appear as a thick green bar on the edge of the screen. For instance, in the following image, the opponent is on the pilot's right side (the green bar is near the center on the right side of the screen).

The reticle breaks down, though, when the opponent's aircraft is very close to the user's, or when it is directly on the user's tail. In this case, the reticle will bounce around from full left deflection to full right deflection. This is simply a limitation associated with trying to point in three dimensions using a two dimensional display.

Strategy

The key to winning a dogfight lies in creating a situation where your aircraft's strengths are emphasized and an opponent's weaknesses are exploited. This means trying to force a tight, up-close battle when flying a more maneuverable fighter than the enemy, or aiming for dive-bombs and other tactics requiring speed and weight when flying a faster, larger craft.

Additionally, do not underestimate the value of quick combat maneuvers, such as:

corkscrews—rolling your craft left or right while continuously varying its pitch
feints—rolling to one side as though to go into a banked turn (i.e., a turn with the craft on its side, while pulling back on the controls in order to pull “in” to the turn), but pushing the nose forward instead
barrel rolls—often described as “a cross between a roll and a loop” (see the following image, released into the public domain by its creator MioUzaki).

For more information on combat tactics, see the Dicta Boelcke, a list of tactics developed by WWI ace Oswald Boelcke.

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