Originally Posted by
itsnotthatbloodyhard
Not ‘back on the elevator’ - it’s always on the elevator in FLCH, regardless of what thrust happens to be set. (Leaving aside whatever might happen now in low speed reversion, which is after my time)
Yes sorry. So this does go in the same way as the end of my reply.
- If the target can be reached in less than 2min, AT will compute a given amount of thrust. This will definitely lead to an output VS.
Once the thrust is set, it won’t keep changing. In a perfect world, no elevator input would be required for a perfectly trimmed aircraft. The aircraft would climb at the MCP window speed at the target ROC set by thrust. But as we are not in a perfect world, elevator does pitch for speed once the thrust is set…as FLCH gives priority to speed. Our target VS (ROC/ROD) set by THR will change but the system disregards these changes…it’s just some initial math done to compute a given amount of thrust set for the climb.
THR sets a value below THR REF in order to command a ROC leading to our target altitude in less than 2min at MCP window speed. Once thrust is set, it doesn’t change. Speed is on elevator. I’d assume if target thrust is correctly computed (and we don’t change MCP speed), very few elevator input should be required.