B757 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Fatigue
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Illness / Injury
General Work Refused
Human Factors
I reported for pairing at approx. XA:00 ET on day 1. It would later be modified before I decided that a fatigue call was warranted. It started with one leg to ZZZ. Duty out time was XE:00 ET day 1. I was scheduled the next day to fly from ZZZ to ZZZ1. We had an XA:00 ET Day 2 duty in and left on time. In ZZZ1; approx. 2 hours after landing; our schedule was modified the first time. We originally were schedule to have 24 hours off in ZZZ1 and fly to ZZZ2 the following day. Instead of an XH:00 PST on Day 3 duty in; we were looking at another early morning. Schedule pick up time would now be XA:00 PST Day 3. We were rescheduled to fly on the 3rd day from ZZZ1 to ZZZ3 and then DH to ZZZ4. Enroute to ZZZ3; a customer; 20 year old boy; started having convulsions and lost control of his body functions. The physician on board informed us that the boy needed immediate attention. We [advised ATC] and diverted to ZZZ5. The divert was successful and the boy was reported in stable condition hours later. However; during our time on the ground; we ran into a serious problems that were out of our control.  Medical equipment; such as the O2 bottle used by our customer; was a required piece of equipment that could evidently not be deferred. The contract maintenance personnel where finally able to refill the bottle. However; they were not certified to do so and we now had an unknown gas that was onboard the aircraft. This issue was finally corrected and we made an attempt to push back and Maintenance Control discovered that the maintenance contract with these mechanics after many years had been canceled the day prior. We returned to the gate and waited. During this time; we had to do a great deal of face time with our customers. The station manager; station personnel; captain; and flight attendants; and our customers; all did very well considering the circumstances we were all in. We even walked a customer's dog for her; while she looked on in relief. The 4 hour ground delay in ZZZ5 put us into ZZZ3 at XL:00 PST Day 3. After helping the customers deplane and insuring all that had questions were taken care of; especially the customer with the dog; we missed our connection to ZZZ4. At this point we contacted scheduling. Scheduling reassigned us to DH at XA:00 CST Day 4 to ZZZ4 and arrive at XD:00 EST Day 4. The Captain was finished at that point. I; however; was scheduled to complete the ZZZ turn that showed at XD:40 EST Day 4. This turn is where my question of safety arose. On the last day of a pairing; with already two wake up times before dawn; and now a third. Total block time for the 4th day was approx. 11.52 minutes. I was truly concerned that I would not be fit enough to fly our customers safely after having spent that much time on an aircraft with minimal downtime between legs.
A B757 First Officer called in fatigued and unable to complete his pairing. This happened after a number of schedule modifications; a lengthy diversion; and three early morning show times and minimal downtime between legs.