INS quick start guide

[Michael2 236]

I seem to recall promising this a while back, so here are a few tips to get to help understand it and get it working. 

 

When the aircraft loads, the engines are on, everything is powered and the INS is on and aligned.  You just need to load a standard flight plan using the sim interface.  After a few seconds it will go into the INS.  There are a number of ways to confirm it's loaded, but an easy on is to turn one of the CDU knobs to DIS/TIME to see if the distance to the first waypoint is shown correctly.  It might be best to start this way at first to gain confidence with the basic INS functions before starting from cold and dark and doing DME updates. During flight

 

The flight plan must be for IFR or high altitude airways.  You can see if it is designated this way in the P3D flight planner dialogue. VOR to VOR flighplans are used not for your waypoints, but as an easy way to load DME positions into the INS for DME updating of you position later on in your flight.  This raises a point that may at first be confusing.  The INS stores both your flight plan waypoints and DME station positions.  While both waypoints and DME positions both have number IDs from 1 to 9, they are not the same thing.  You have a list of waypoints and a list of DME positions - they are different lists.  You don't need to have any DME positions stored unless you think you will need them. If you do believe you will need DME updating for a long flight, you can enter them by constructing a VOR to VOR flight plan that consists of only DME positions and loading it with the Flight Planner dialogue. This has nothing to do with the flight plan you will fly, it's just a convenient way of getting the data into the INS.  Or, during your flight, you can at some point choose a DME that you are going to pass by and enter it's position as a DME station manually, and then start an update of the INS position when the DME comes into radio range. 

 

If you start from cold and dark, the INS will be powered down and you need to turn them both on and align each one.  Once the aircraft has electrical power, you can begin.  The process to get started is shown at figure 3 at page 19 of the manual but I will give only the essential steps here:

 

1.  Turn each MSU on the overhead to STBY (standby).  You can go directly to ALIGN if you wish, but it helps break down the steps to put in standby first. 

 

2.  Make sure each CDU knob is set to POS (position).  Each unit will display a latitude and longitude. Even though this will likely be the correct ramp position, you still must manually enter your ramp position or alignment will not complete. 

 

3. To enter the ramp position, you can use the coordinates displayed by P3D when you press shift-z.  These will have an extra digit; you will need to round off the minutes of longitude and latitude.  To enter latitude, press 2 or 4 on the INS keypad for North or South (the insert light comes on), and then the digits that correspond to the ramp latitude.  Press the insert key.  Then enter the longitude in the same way (but with 4 or 6 for West or East).  Press the insert key again, and the light will go off. 

 

4.

 

 

[Michael2 236]

I posted by mistake.  To continue:

 

4.  Repeat for the second unit.

 

5.  Begin alignment.  Turn the MSU knob for each unit to ALIGN.  You will have to pull the knob (right click) before turning. Then push it in again.

Turn the CDU knobs to DSRTK/STS.  This will display your alignment index (third digit showing in the right window). It will be 9 and over time decrease one integer at a time.  When it gets to 5 the READY NAV green light comes on on the overhead and you can switch to NAV, but it would be better to let it reach a lower number first. 

 

6.  Switch to NAV.  The green light goes out and you are now free to release the parking brake and pushback/taxi.  If the aircraft moves during the alignment process, you will get a warning and have to start over again. 

 

That should be enough to get you started.  Once you are in the air, setting the autopilot on and the turn mode knob to AUX will cause the INS to control your heading to follow the flight plan.  The CDU knobs can be used to display various data that you may find helpful from time to time such as ground speed, drift angle, wind, time and distance to the next waypoint and so on. 

 

Also there is an undocumented (not on purpose!) fast alignment available.  Instead of switching directly to ALIGN, turn the knob to NAV and then to ALIGN.  The alignment will go a lot quicker.