Flight file (MSFS)

Applicable
MSFS
MS Flight
LM P3D5
LM P3D4
LM P3D3
LM P3D2
LM P3D
FS World
FSXSE
FSXA
FSX
FS2004
FS2002
XP11
XP10
XP9

The documentation here is pretty complete: Documentation

Your flight file (.FLT) determines the state of the aircraft (location, switches), world (weather, time, assistance), ui (panels), and the sim in general (speed, traffic, multiplayer) at spawn. It also determines the type of mission (Tutorial, Landing Challenge, Bushtrip, Freeflight) and the briefing screen:

And loading screen:

Creating your flight file

To create your flight file, you start with loading your flightplan or the starting location in the world map.
Choose a plane, livery, etc. Choose a time and weather.
Then start your flight.
Move your plane to the position you want and change it to the configuration you want (switches etc.). If you want to spawn in the air you should stabilize the planes pitch and altitude so the plane is stable after spawn. You should use trim and throttle or autopilot for this. Keep in mind that changing the weather may change the conditions, so configure the weather first.
If you have the correct configuration, save the flight file with Escape>Save flight>save .FLT.
You now need to configure the .FLT:

Changes to make in the .FLT file.

[Main]
Add title (e.g. Airline emergency)
Add description/location (e.g. 'LIRN, Italy' or TT:Telluride.Description)
Change MissionType to whatever you want (e.g., BushTrip, LandingChallenge, Story Mission)
Delete: MissionLocation, OriginalFlight, FlightType, StartingCameraCategory

[ResourcePath] and [ObjectFile]
Change to the name you use for the .xml

Delete [FreeFlight]

If you use custom weather:
 Set UseWeatherFile=True
 And delete
  UseLiveWeather
  WeatherPresetFile
  WeatherCanBeLive

Set:  
[TrafficOptions]
AllowAbientVehicleTraffic=FALSE

Add:
[Multiplayer]
Status=0

[Airtraffic]
Status=0

[Assistance]
Preset=ASSISTANCE_PRESET_TRUE_TO_LIFE

Fix flightplan in [ATC_Aircraft.0], [ATC_ActiveFlightPlan.0], and [GPS_Engine] as shown in the documentation.

For [GPS_Engine]
Change: Filename= to the name of the .PLN file.

NOTE: You can use ChangeAssistanceItemAction to change specific assistance items.

Briefing, and loading screen

In the .FLT file you can add these lines:

[Briefing]
BriefingText=TT:MISSIONNAME.BRIEFING
BriefingImage0=./images/MissionName_Briefing.png

[Loading]
ImageName0=./images/MissionName_Loading0.png
Tips0=TT:LOADING.TIPS.MISSIONNAME_000
Tips1=TT:LOADING.TIPS.MISSIONNAME_001
Tips2=TT:LOADING.TIPS.MISSIONNAME_002

For the TT: explanation, see: Localisation (MSFS)

You will have to add pictures for the mission thumbnail, and the loading, briefing, and ending screens.

Mission Creation for MSFS

Pages relevant to mission creation for MSFS.

Mission structure

AirportLandingTrigger & AreaLandingTrigger · CounterTrigger · PropertyTrigger · ProximityTrigger · TimerTrigger

Actions