Flight Duty Limitations

[Hulabaloo]

When operating on a split duty is it permissible to then if required extend the flight duty time further by the commander under his dicretion, or is the extension granted by the split duty final and subject to no extensions.
Also when does a rest period officially begin, when chocks are on and post flight duties complete?...or when you arrive at the HOTAC....or when you finally receive the keys to your HOTAC room?...many thanks

[FlapsOne]

A split duty, by definition, already increases the maximum duty day. You cannot extend it any further.

As to when the rest period starts, this must be a matter for common sense. You cannot use a standard time because you just don't know how long it will take to put the aircraft to bed - especially in the current environment of increased securutity checks etc.

Personally I start it upon arrival at the hotel.