Basically min rest is the length of the proceding duty period or 12 hours which ever is the greater.
Yes, but that clause of the AFTLS only applies in the event some kind of roster disruption occurs. Under normal circumstances flight crew must be given the minimum 'Physiological Rest' stated in the AFTLS. For a typical out and back ULR pattern from HKG, para 1 applies, ie the longest of:
- The length of the preceding duty period,
- 14 hours, or
- a period sufficient to allow a sleep opportunity (ie 8 consecutive hours) within the period 2200 to 0800 hours home base local time.
The minimum rest period is therefore the length of the preceding duty period or 14 hours, whichever is the greater,
provided that period allows a sleep opportunity of at least 8 hours between 2200-0800 local time for the flight crew member's home base.
In practice, the requirement to provide an 8-hour sleep opportunity at the flight crew member's normal home base 'sleep time' is often limiting.
For example, the current 840/841 New York pattern arrives JFK at 2125 local time (1025 HK time), the rest period starts at 2155 local time and the total duty period is 17:05. According to the rules, the next sleep opportunity doesn't occur until 2200 HK time, or 0900 local time - 8 hours later would be 1700 local time. The sleep opportunity doesn't include the 1 hour before leaving the hotel or the travelling time back to the airport, say 45 minutes. That makes the earliest sign-on time 1845 local, for a total rest period of 20:50.
The minimum rest required would therefore be the greater of:
- The length of the preceding duty period, ie 17:05
- 14 hours
- The period that allows an 8-hour sleep opportunity, ie 20:50
Having said all that, the normal layover for the 840/841 pattern is approximately 34 hours.