February 23rd, 2023 Development Update

Working Title

• MSFS Avionics Framework
  • We are still working to finalize the framework update for AAU_01 content, including plug-in documentation – stay tuned.
  • Remember you can find the MSFS Avionics Framework on GitHub here.
  • Upcoming framework updates:
    • Added new Aural Alert System to the framework that supports aural alerts for CAS and other messages, including managing the priority of alerts when multiple alerts are active. (AAU_02)
    • Updated the framework autopilot to support a default selected altitude (other than 0) value on avionics start. (AAU_02)
    • Updated the framework with a bug fix for calculating LPV glidepath angles when a flight plan error exists where more than one FAF or MAP are in the plan at the same time. (AAU_02)
    • Began work on a framework autopilot update adding more configurability to the directors and standardizing common logic. (AAU_02)

• Avionics Framework Feature Highlight: Subjects
  • What are Subjects:
    • Last week we covered the Event Bus, which enables avionics to be driven by events, rather than per-frame update loops. Another framework tool that assists us in this regard are Subjects. A Subject in the framework follows the software development observer pattern, meaning that a Subject is a container for a value that consumers can subscribe to and receive updates from whenever that value changes. We use this tool to drive logic within individual classes, or components, to perform some logic whenever a specific value (the Subject) changes.
  • Why use Subjects:
    • By using Subjects instead of simple class variables to hold values, you can avoid having to check those values in an update loop, and instead can actually trigger code execution directly to that value – whenever the value changes, the code is executed using the new value. This tends to improve sim performance by limiting code execution and changes to the rendered display. In addition, Subjects in the framework come in many varieties – here are a few examples:
      • A Consumer Subject is one that is directly tied to an event from the Event Bus and automatically updates when the subscribed Event changes.
      • A Mapped Subject is one that allows you to create a new value based on the value of one or more other Subjects, and automatically update when any of the input subject values change.
      • A Computed Subject is one that takes an input value, transforms it with some logic you specify and returns the desired value.
  • Simple examples:
    • Mapped Subject: Imagine you want to update a displayed target airspeed, but only if that option is enabled, only if the plane is in the air and only if the current airspeed is over the target airspeed. We could create a Mapped Subject that maps to those input values (target airspeed, show target airspeed option, plane is airborne and current airspeed) – by using a mapped subject when any of those four input values change, the output value will be re-evaluated and then published to it’s own subscriber.
    • Computed Subject: Image you want to display distance in nautical miles as a string with the units displayed and the value always padded to three digits, but your input value is simply a number in meters. By using a Computed Subject we can build that logic (the unit conversion and the display string formatting) into the subject, so that the input value is just a number in meters, and the output that consumers subscribe to is a string of distance in nautical miles, properly padded and with the units displayed/formatted as we want.

• Read more about Subjects here (many of the subject types have their own entries under Framework API Reference -> Classes)

Community Video

We know you’re excited to fly the Antonov An-225 in Microsoft Flight Simulator, and what better place to start or end your flights than the real Mriya’s home base, Hostomel Airport (ICAO: UKKM). Community member Oh_Gaz has spent the last year re-creating a bespoke version of UKKM, and its release date draws near. You can see a recently-uploaded preview video of this addon airport below.

You can submit your screenshot via Twitter with #MSFSchallenge or the Weekly Forum Post! This week’s screenshot challenge: New Zealand

This past month our Screenshot Challenge was “The Stratosphere“.

Screenshot by akysmile (Twitter)

Screenshot by Elevatorisbest (Forum)

Screenshot by IcemanAMD (Forum)

Screenshot by lassombra8785 (Forum)

Screenshot by pommes_l (Twitter)

Screenshot by snm0S0 (Twitter)

Screenshot by syokatunofu (Twitter)

Screenshot by tsujiKa_air (Twitter)

Screenshot by ukaka5656 (Twitter)

Screenshot by ZILLNIAZI17 (Forum)

 

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NEXT DEVELOPMENT BLOG UPDATE – March 2nd, 2023

Sincerely,

Microsoft Flight Simulator Team