Try quickly saying the colours not the words. It takes up to three seconds to change a complex cognitive task, such as switching from instrument flying to visual flying. The Big Airline pioneered monitored approaches (and otjers helped) so that P2 flies the instrument approach and potentially the instrument missed approach while P1 takes over if visual requirements are met in time, preventing the handling pilot from having to switch cognitive tasks.
It’s also a great tool to help force a stable approach as P1 can’t take control until the aircraft is past 1000 radio AND fully stable (speed/slope/config), helping crews with a maxed out rushed approach make the correct decision and go around.
Finally it’s a great tool to force a crew to come up with an agreed plan from TOD to 1000 radio meaning briefings are thorough assisting crew SA and allowing the other pilot to intervene if the agreed plan or gates aren’t met.
Im sure I’ve missed something but is that enough?
I know many here will roll their eyes at this, however would you rather sitting in 1A quaffing champagne behind a crew flying a monitored approach or one who’s briefing was “standard Mykonos*). *pick an airfield of your choice.
Now I’m not saying it’s the only way to do it and lots of very professional crews fly very safe approaches “unmonitored “, however it’s all about marginal gains. When it all unravels and the holes in the cheese line up, it might just be the monitored approach that puts a barrier between a crew and an accident. Ever read the report of a British registered A320 at Glasgow when the Captain suddenly announced “I’m going Visual” and the First Officer replied “are you sure?”. They were lucky they were in an A320 in normal law. It wasn’t necessarily a stability problem, however an agreed plan would certainly have helped.
I hope that makes sense? Not preaching, just saying why it’s done, and I’m sure many will disagree.
ATB
LD
Edited to add that the control handover is different for approaches planned to terminate with an autoland.