Hi Paula,
Accountants now run airlines, including FOP departments. They see LIMITATIONS as goalposts to MAX PRODUCTIVITY.
They hit those goalposts frequently then lobby the authority (HKCAD here) for extensions to those limits.
Prime example is the extension from CAD371 edition 1 to edition 2 allowing WOCL (window of circadian low) night flights to be extended from their previous limit of 8 hours to a new limit of 9 hours, plus allowing 3 crew Europe ops from the previous requirement of 4 crew. This was all done by CAD after requests made by CX and KA.
Excerpt from our HK CAD 371 (edition 2) document:
"3.6 Factors to be considered when constructing crew rosters should include:
3.6.1 The undesirability of alternating day/night duties.
3.6.2 Avoiding scheduling rest periods of between 18 and 30 hours, except when rest is physiologically based.
3.6.3 The effect of consecutive flights through, or ending within, the window of circadian low.
3.6.4 The effect of consecutive transmeridian flights ensuring that sufficient rest, and where applicable sufficient physiological rest, is provided.
3.6.5 The notification of crews well in advance of days off. "
Accountants now running FOP departments IGNORE the INTENT of the above governing paragraph in the FTL's (CAD371 excerpt edn 2) because they state it says "SHOULD avoid", not "SHALL avoid". They say rostering in contravention of the above is OK because "it's legal", they completely IGNORE the purpose and intent of the above, which is clearly to avoid fatigue in air crews.
As evidence, check any one of CX Middle East or India flights where EVERY SINGLE flight pairing to those cities (Airbus regional fleet now) is rostered in direct contravention of the above paragraph. Back to back WOCL sectors separated by rest within 18-30 hour period. The only exception is where the flight pairing to some cities is not daily, so crew by default gain an extra night's rest.