Night or IMC don't preclude asymmetric training. I have done it where it was considered acceptable.
Octas8,
A large body of well informed opinion would totally disagree with that statement. One large and very long standing Australian operator bars any engine shutdown ( and that would include mixture cuts), except in VMC, daylight, min. 3000 AGL.
As for asymmetric training ---- zero thrust only --- and the training manual mandatory requirements meant that night operations were severely limited. On pistons (a la FAA) "slowly retard the throttle".
All risk assessment based (although those were not the words used when the policy was established in the 1940s) with the assessment that night training hugely increased the risk --- hence the very tight night limitations.
Not surprisingly, this same operator was an early adopter, a pioneer even, of flight simulation --- long before a mandate for their use.
We kill more people asymmetric training than as a result of actual engine failures, but it is clear that the message is lost on "the survivors".
Tootle pip!!