Just playing devils advocate here - you're on ILS final at 90 knots, you've got the IAS climb default set to 100 knots, you go missed at the MAP and hit the AP to climb out. Because you're less than the target airspeed the autopilot will now nose down until achieving the target airspeed. Quick review - how much room below you do you have for safe descent???
let me think this through... the GA button only functions if the AP is in the VNAV mode; and when you press GA the vertical mode it uses is the default value for the VS. so if using the GA button I think VS is presumed, and a default IAS would not change the way the GA presently works. So I do not see the problem.
But I think the general AP pitch operation requires a bit more thought. Right now you set pitch mode by —
1) engage AP for VS hold
2) press VS for VS hold mode
3) press a nose up/down button and VS uses the bug (or default VS value)
4) pressing the IAS button and the AP goes into IAS hold
So that no retraining would be required, I would advocate adding a double press function to VS and IAS buttons. The first press functions as it does now to set the bug the current value. a SECOND press would set the the IAS bug to the default value.
Yep— for VS and IAS — Press once to set bug to present value, press twice to set bug to default value. That would be handy.