Q.Once recognised, how to deal with fatigue without upsetting the company with an outright refusal?
A1. Call in sick. Don't give details. Provide medical certificate if required, from own doctor
or
A2. Explain to company that you are OK for a regular duty period, but you are doubtful about continuing into a discretion period due to recent long back of the clock duties etc. You are more than willing to operate the duty, but if unable to complete it due to delays, would they prefer to roster another pilot or provide a heavy crew? Your only interest is completing the mission. If company calls your bluff, at the point where discretion is needed, re-assess situation. Even if you decide you can continue, the company will not want the stress of possible multiple disruptions due to their risky roster.
or
A3. A poor choice, but accept the flight. Call in sick at the point where discretion would have been required to continue
or
A4. Worst choice, accept the flight and use maximum discretion even when you know that this is illegal
and
A5. Be a paid up member of your pilot union.
and
A5. Be sure to have years of respectful co-operation with rostering staff, including offering solutions to "there is nobody else". If you have 998 hours of the yearly 1000 hours already, ask them if a 4 hour delay would be acceptable to depart at 22:00 and tick over to 1000 hours when airborne, right on midnight. Or if there is a 03:00 phone call for an unexpected 03:45 departure, do your best. If your departure is delayed, catch up as much of that time as reasonably possible with reduced flight and ground times to avoid need for discretion decision. Crew will be happy to be with a captain who can get them home on time and rostering will see you as a reliable and valuable asset. A nice tick in the box if you are ever called in for a cup of tea.
and
A6. Always try to have alternative employment, happy working wife, low living expenses and money in the bank.
and
A7. Remember that you are taking your co-pilot and cabin crew along with you on this challenge. Every instance of discretion must include consultation with all of the crew. One time when you sign off from a partially completed mission, they will be more likely to remain in good humour.
The above is exactly how I manage illegal or suspect rostering attempts during my career. If you do none of the above, the discretion refusal challenge is a much more difficult.