This old info may be of interest:
Semper Lightning: F-35 Flight Control System 09 Dec
2015 Dan “Dog” Canin
"...The ability to tailor the airplane’s response as a function of its configuration and flight regime is the beauty – and potential curse – of FBW. If control engineers get it right – if they define the modes properly, put the transitions in the right places, and give the pilot the right feedback – then control is intuitive. But if they make the various modes too complicated,
or the feedback (visual or tactile) isn’t compelling, then modal confusion can set in and bad things can happen.
Some mode changes occur without our knowing, which is fine as long as we don’t have to change our control strategy. An example is the blend from pitch rate command at low speed to g-command at high speed. This transition is seamless from the pilot’s perspective. Other changes require us to change our technique, which is okay if we command the changes ourselves and they’re accompanied by a compelling change in symbology. Examples are the transitions from gear-up (UA) to gear-down (PA), and from CTOL to STOVL.
There are few areas, though, where a mode change is important but not obvious, which is where pilot discipline and training come in. For example, the CV airplane has three different approach modes, easily selected using buttons on the stick and throttle. Two of these modes – APC and DFP[3] – are autothrottle modes, indicated by a three-letter label on the left side of the HUD.
The third mode – manual throttle – is indicated by the absence of a label…arguably not the most compelling indication that you’re responsible for the throttle. This interface will probably evolve; [yes sireebob] in the meantime, we need to be disciplined and to make
doubly sure we’ve got APC engaged before we turn throttle control over to George...."
https://www.codeonemagazine.com/arti...ml?item_id=187