Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Distraction; Situational Awareness
Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Flight Crew Returned To Clearance
Human Factors; Environment - Non Weather Related
At approximately XA:15Z the pilot flying noticed we were about 500 feet above our assigned block altitude FLX50-X70 and climbing at 200 FPM. This was brought to my attention; pilot flying quickly corrected the error; and we resumed cruise flight at FLX70. No other aircraft were around us and nothing was said to us by the Center Controller. Flight continued uneventfully.Ultimately both the pilot flying and I were distracted and tired. Both of us had reported in a tiredness the night before after several long tough days. Neither one of us got the amount of quality of sleep we wanted for that day. In addition; we were in an in depth discussion on current events and I believe that added to the distraction. We were in the block FLX50-FLX70 but level at FLX60 when the pilot flying communicated and decided to climb to FLX70. I acknowledged that; but failed to realize that the altitude selector was never reset from FLX60 to FLX70. Under normal circumstances I would have trapped that error; but I believe the aforementioned factors contributed to me missing this detail.This was a breakdown of SOP. Both of us are to blame for letting our guard down and not remaining diligent despite the fact that we had now flown together enough to trust each other. Sometimes it creates more errors when you trust the other person too much; it makes it easier to deviate from SOP. I believe this error was caused by a multitude of factors which have been mentioned above and to prevent that in the future requires more diligence on my part and the part of the pilot flying.
While in the block FLX50-X70; we were level at FLX60. We had become light enough to climb to FLX70 so I notified the FO that I was doing so. For whatever reason; this time I selected the climb mode without resetting the Altitude Selector first. We'd had a couple challenging days with schedules and passengers and were also distracted by a sensitive conversation about COVID-19. We agreed afterward that we were more tired than we realized. I caught the error as we approached FLX75 doing 200 FPM. The last altitude I remember seeing in my scan was FLX68; when I made a subtle mental note that we should be level in a minute. The total deviation was 500 feet and ATC never said anything to us as I descended back down to FLX70. I checked the TCAS both Above and Below on the 50 nm scale and didn't see any aircraft anywhere on the map. Fortunately we were in relatively empty airspace controlled by Center. I don't know why I didn't set the altitude first. That is certainly not normal practice for me so I guess it was the cumulative effect of being tired and being distracted by a conversation about a sensitive subject.Both crew members being more tired than we realized. Being distracted by a sensitive conversation about COVID-19. My deviation from SOP and the FO's failure to monitor the SOP.If any one of the factors of SOP deviation; conversation distraction; or fatigue is removed; it wouldn't have happened. All we can do is try to minimize these threats. Most important is the adherence to SOP; but it's the cumulative effect that got us in this case. Obviously my attention has been refocused on SOP adherence going forward.
Flight crew reported climbing 500 feet above assigned block altitudes and cited COVID-19 conversation distractions and fatigue as contributing factors.