RAD/ALT vs Barometric IRS

1st Official Post

    High altitude airports - Am thinking Radio altimeter would be better as a trigger for any low altitude stuff rather than using the inertial reference system. Barometric pressure might trigger instantly or too early. Haven't tested this yet.

    Is it possible to use the Radio altimeter?

    One more question regarding oil quantities for the XWB Engine, I have randomized it to simulate real-life fluctuations when the crew receives the aircraft. I only have real-world data for the 777. From engine data I found online, the oil levels can be between 15 & 24 quarts for safe limits, but the A350-1000 in the sim thinks anything above 20 quarts is bad. Not a huge deal, but was this taken from real-world data? It shows as amber when above 18 q in the sim


    • A350-900: 13 quarts
    • A350-1000:
      • Flights < 5 hours: 13 quarts
      • Flights 5-7 hours: 15 quarts
      • Flights > 7 hours: Full (typically 22-24 quarts)

    Maximum Oil Quantity

    • Full Indication: The maximum capacity is generally considered to be between 21 and 24 quarts, with typical servicing filling it to full before long-haul flights.

    Edited 3 times, last by 777Driver (February 19, 2026 at 9:57 PM).

    • Official Post

    Yes the radar altimeter can be used but the signal fluctuates because of the terrain shape. You can also use the integral of the IRS vertical velocity (yields height above takeoff, regardless of ground elevation changes). If a route departure runway is set you an also do difference between current baro and departure runway elevation. Not sure if the pressurization departure altitude is accessible but that also stores the takeoff elevation.

    I'd have to check the engine oil level indication, might not be correct.

    The numbers that you listed, are those the "amber caution" for low quantity or are those the expected oil consumption?

    Thank you, i'll take a look at the IRS vertical velocity


    The numbers listed are the optimal fill levels depending on the length of flight. The A350 oil indication turns amber above 18quarts in the sim, a real world longhaul flight should be topped up to 20+quarts before departure.

    • Official Post

    Something like this:

    Code
               <[integral][InertialReferenceHeightAboveStart][]
               <[string8][Input][InertialReferenceSystem.OutputVerticalVelocity]>
               <[float64][Value][0.0]>
           >

    You can also use events to reset the integral to zero or to some other value and you use an trigger event_edge_rising on InertialReferenceHeightAboveStart.Output for example if you want to fail engines above a certain height above ground.