By Paul Mort

Keeping with the same image of the FMC (Figure 3), in order to simplify which of the twelve soft keys to press (six on the left and six on the right), refer to the following:

Figure 3

Firstly, by pressing key L1 over on the top left-hand corner, we are taken to the STATUS page (Figure 4) which gives details of the current state of the navaid database. This is not important to the route but is still shown nevertheless, for completeness.

Figure 4

>>>

Figure 5

Now for the first element of entering our data for the current route.

If you press the key R6 it will bring up the DATABASE page (Figure 5).

We enter our data, using the alpha numeric keys, into the area known as the scratchpad between the cyan square brackets. To clear the scratchpad of any previous data, press the CLR key on the bottom right-hand corner. Having entered our Departure ICAO (in this case it will be EGCC) into the scratchpad, we then transfer that into the IDENT position by pressing L1. What were originally four dashes, now change to our Departure ICAO and our starting airport data is displayed (top right).

Waypoints

Now it's time to enter our waypoints into the FMC which is done by clicking the FPLN key, outlined in red (Figure 6). We are presented with the ACT FLPN screen into which we can enter the origin airport, destination airport and navaids required, as our flight plan shows. As before, clear the scratchpad of any data and type in the departure airport (EGCC). L1 transfers it to the ORIGIN boxes. Notice that when a successful transfer occurs, the scratchpad becomes empty again. Now for the destination. Type our destination airport (EGGD) into the scratchpad and transfer it to DEST using R1.

CO ROUTE is optional and is the company route for fuel usage. It is not covered in this tutorial so we will leave it blank.

The FLT NO displayed below the destination data on the screen (Figure 7) is our flight number which can be anything you like, so we'll use XP737 and transfer it to R3. Our first waypoint is MONTY at 43 miles, 229 degrees, so input it into the scratchpad and transfer to R5. Doing this will show a direct route to the waypoint. We could also enter a designated airway name into L5, in which case the route would be via that airway to the waypoint, but we'll leave it blank this time in order to get a more direct route.

Figure 6

>>>

Figure 7

In Figure 7 you will notice that a cyan bar lights up above the EXEC button after we enter our data. This is asking for confirmation that our details are correct. Hit the EXEC button to confirm this and the light will go off again. Failure to do this whenever the EXEC button is lit will result in the aircraft not following the flight plan. Our first waypoint is entered, and to continue with more, we now need to view our ACT LEGS page (Figure 8), by clicking the LEGS button situated below the FPLN key.

Figure 8

>>>

Figure 9

We need to enter the next waypoint, RETSI, into L4 in the ACT LEGS page. Remember to hit that EXEC button too! Don't enter the destination airport as we have already specified that in the ACT FLPN page.

That's it for the waypoints.

Flight Data

Now for some important data about the flight. Press the CRZ button located next to FPLN to bring up the VNAV CRUISE page (Figure 10). A simple entry of our cruise speed of 250 knots and a cruise altitude of 5000ft, are in turn entered into the scratchpad, and again transferred to L1 and R1 respectively. If we now return to the LEGS page (Figure 11), we can see our speed and altitude references displayed in green on the right.

Figure 10

>>>

Figure 11

These references are used manually if flying LNAV or automatically if flying VNAV.

Departure / Arrival Data

The final task on the way to a fully programmed FMC is to input the details for the departure/arrival runways and any SIDS or STARS required in the route.

If you hit the DEP ARR key in red (Figure 12) it will then shows the DEP / ARR INDEX page. Here you will see your previously programmed departure and arrival airports in the center.

By pressing the key L1 it will bring up the options to input the departure runway (Figure 13). We have selected R3 for runway 23L. No SID is specified.

Figure 12

>>>

Figure 13

Once again, press the EXEC key to enter. L6 returns us to the DEP/ARR INDEX page where we can now select R2 for the arrival runway and STAR. No star is specified in our route plan so just the runway is required. We will choose R2 for runway ILS27 (Figure 14).

Figure 14

Discontinuity Errors

You may see the word 'Discontinuity' on the screen of the FMC. The explanation in a nutshell for this, is shown below (Figure 15).

Figure 15

The above image shows the flight plan of an aircraft with 4 waypoints programmed into the FMC. Marked in magenta is the route it will take from the first to the fourth waypoint. According to the arrival runway data we supplied, the FMC works the approach out shown in blue. Because the last waypoint, number 4 we entered, is not the same point as the first approach point, the FMC tells us there is discontinuity or dead space between waypoint 4 and approach point 1, which is not accounted for in the flight plan.

Figure 16

Figure 17

So, looking at pages 1 and 2 (Figure 16 and Figure 17) of the ACT LEGS, we have a discontinuity between our last waypoint of RETSI and our first approach waypoint of CI27. Fortunately, this is easy to correct. Just click button L1 on page 2 (CI27) which puts CI27 into the scratchpad. Now click on button L5 on page 1 (Discontinuity). This effectively removes the discontinuity and stitches the two parts of the flight plan together (Figure 18).

Figure 18

The easiest way to tell if your FMC has been successfully programmed, is to look at your screen, and if you are following a magenta line, then it is indeed correctly programmed (Figure 19). So following the standard autopilot procedure, we can get the aircraft to fly the complete route, and if we use VNAV, you can also observe the stated altitudes.

Figure 19

I hope you enjoyed this tutorial and by the end of it, feel clearer about getting the best out of the default FMC in X-Plane 11.