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One of the most-often asked questions in X-Plane are the same as one of the most often-asked questions in real planes: HOW DO I WORK THE AUTOPILOT? This is no surprise, as pilots don't know how to work
their autopilots all the time. I have even been on AIRLINER where the
plane was jerking abruptly left and light for 5 minutes or so as the
flight crew was clearly trying to figure out how to properly program
and engage their autopilot.
Well, for X-Plane, here are the autopilot functions available. Each of
these is a mode you can put your plane in simply by hitting that
button on the panel with the mouse.
Mode
(OFF, ENGAGED, ON) |
Function |
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WING-LEVELER. This will simply hold the wings level while you
figure out what to do next. |
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HEADING HOLD. This will simply follow the heading bug on the HSI or Direction Gyro. |
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Localizer. This will fly a VOR or ILS radial, or to a GPS destination... AND THE GPS CAN GET DATA FROM THE FMS IF THE GPS IS SET TO LISTEN TO THE FMS (explained soon). |
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This will HOLD the current or pre-selected ALTITUDE by pitching the nose up or down. |
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This will hold a constant VERTICAL SPEED by pitching the aircraft nose up or down. |
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This will hold the pre-selected AIRSPEED by pitching the nose up or down. (Leaving throttle alone) |
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Flight-Level Change. This will hold the pre-selected AIRSPEED
by pitching the nose up or down. (Leaving throttle alone) This is
commonly used to change altitude in Airliners by simply letting the
pilot add or take away power, while the airplane pitches the nose to
hold the most efficient speed. If the pilot adds power, the plane
climbs. If he takes it away, the plane descends. SPD and FLCH are
currently identical functions in X-Plane: They both pitch the nose up
or down to maintain a desired aircraft speed, so adding or taking
away power results in climbs or descents. |
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Pitch-Sync. Use this to cause the plane to hold it's nose at a
constant pitch attitude. Commonly used in King-Airs to just hold the
nose somewhere until the pilot decides what to do next. |
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Glideslope. This will fly the glideslope portion of the ILS. |
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Vertical Navigation: This will fly automatically load altitudes
from the FMS (Flight Management System) into the autopilot for you,
to follow route altitudes. (Explained soon). |
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Back Course. Every ILS on the planet has a LITTLE-KNOWN SECOND LOCALIZER THAT GOES IN THE OPPOSITE DIRECTION AS THE INBOUND LOCALIZER. THIS IS USED FOR THE MISSED APPROACH, ALLOWING YOU TO CONTINUE FLYING ALONG THE EXTENDED CENTERLINE OF THE RUNWAY, EVEN AFTER PASSING OVER AND BEYOND THE RUNWAY. To save money, some airports will NOT bother to install a new ILS at the airport to land on the same runway going the other direction, but instead let you fly this second localizer BACKWARDS to come into the runway from the opposite direction of the regular ILS! This is called a BACK COURSE ILS. Using the SAME ILS in BOTH directions has it's advantage (it's cheaper) but a drawback: The needle deflection on your instruments is BACKWARDS when going the WRONG WAY ON THE ILS! Hit the BC (back course) autopilot button if you are doing this. It causes the autopilot to realize that the needle deflection is BACKWARDS, and still fly the approach.
(Note: HSI's do NOT reverse the visible needle deflection in the back-
course because you turn the housing that the deflection needle is
mounted on around 180 degrees to fly the opposite direction... thus
reversing the reversal!) (NOTE: The glide-slope is NOT available on
the back-course, so you have to use the localizer part of the
procedure only). |
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Terrain Following. This will fly the aircraft at a low altitude, barely clearing the ground. |
OK, now you know what the various autopilot modes are... how do you use them?
First, you need to turn the autopilot ON!
The autopilot power is disguised as a 'Flight Director Mode' switch,
which has OFF, ON, AUTO.
- If the Flight director is OFF, then NOTHING will happen when you try to use the autopilot.
- If the Flight director is ON, then the autopilot will not physically move the airplane controls, but it will move little target wings on your artificial horizon that you can try to mimic as you fly.
- If the flight director is set to AUTO, then the autopilot will actually fly the airplane according to the autopilot mode you have selected.
Ok, so now that you know the various Flight Director Modes, how do you use them to control the autopilot?
When you first set the Flight Director Mode to AUTO, you will notice that the WLV and HOLD modes become activated. |
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