code: public static long toFSUIPCAlititude(double altitude) {
          double meter = altitude * 0.0254 * 12D;
          long mUnit = (long)meter;
          long mFraction = (long)((meter - mUnit) * 1000000000);
          return mUnit << 32 | mFraction;
      }
docs: *
  Altitude, in metres and fractional metres. The units are in the high 32-bit integer (at 0574) and the fractional part is in the low 32-bit integer (at 0570).