Originally Posted by Dg800
You're missing the fact that there can be no co-pilot on a plane certified only for single-pilot operations.
Nope, you can (and indeed must) operate certain single-pilot aircraft in multi-crew environment, if you want to fly commercially under IFR.
AMC1 FCL.050 Recording of flight time
...
(2) co-pilot flight time: the holder of a pilot licence occupying a pilot seat as co-pilot may log all flight time as co-pilot flight time on an aircraft on which more than one pilot is required under the type certification of the aircraft, or the regulations under which the flight is conducted;
The CAA may require a co-pilot for commercial IFR flights with DA42 (single-pilot aircraft) and the person acting as co-pilot can then log co-pilot time which counts towards ATPL, since it only requires 500h in
multi-pilot operation, not with multi-pilot aircraft. The skill test for it however has to be done on a multi-pilot aircraft.
While I agree that the legislation doesn't actually punctuate this, transfer of PIC in-flight isn't that problematic, you just have to note the time - and of course, you can only count times and landings when you were PIC, not the entire flight. There are some issues though - Germany (see AIP), insurance (check if it coveres right-seat PIC which is not an FI or the flight isn't part of flight instruction), common sense (can you takeoff, land and do all emergency from the right seat as good as from the left one?). I've done quite a number of flight from the right seat, but it wasn't done ad-hoc without previous consideration.
That being said, the reasons for PIC change-over in-flight could be: landing is expected at night and the left-seat pilot isn't night qualified/rated or the weather is becoming worse and the left-seat pilot isn't instrument rated - although flying IFR from right-seat in aircraft with steam gauges is
a really bad idea unless trained/qualified.