Date: 202103
Local time of day: 1201-1800
Location: ZAB.ARTCC, NM
Flight conditions: Mixed
Aircraft: Small Aircraft
Operator: Personal
Operating under: Part 91
Flight plan: IFR
Mission: Personal
Flight phase: Cruise
Airspace: Class E ZAB
ATC / advisory: Center ZAB
Reporter organization: Government
Reporter function: Enroute
Human factors: Situational Awareness; Human-Machine Interface; Distraction; Confusion; Communication Breakdown; Time Pressure; Workload; Training / Qualification
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors; ATC Equipment / Nav Facility / Buildings; Manuals; Staffing; Procedure
Primary problem: ATC Equipment / Nav Facility / Buildings

Narrative: The sector had been very busy. I had earlier dealt with the breakup of an ALTRAV (Altitude Reservation Flight Plan) where almost all of the original information was incorrect and the breakup required coordination with multiple sectors. I had a Radar Assist trainee training on position next to me with approximately 15 hours of training time on that position in the last two months during the flight breakup; and he had left to go assist another sector with the same flight breakup. While the training team was gone; I took the handoff from the adjacent Center sector on Aircraft X. He was level at 6;000 feet and needed a beacon code change.I lost radar contact with him around the boundary; which is not uncommon in that area. He did not check on; but radio coverage is not normally an issue in that area. I don't remember what I was doing; but I was talking to aircraft and looking at the south area of my scope for a while. When I realized Aircraft X had not checked on I tried him on multiple transmitter sites. I then dealt with some other aircraft requests before returning to Aircraft X. At this point; Aircraft X position was identified by ADS-B. The data block was still in coast track because he had never gotten the beacon code change. I had another aircraft near him at 12;000 feet and asked him to relay. I was off line coordinating during the relay. When I returned to the frequency; I dealt with aircraft checking on and their requests before asking the 2nd aircraft if he had gotten a response on the relay. He did not. I called the adjacent sector and asked them if Aircraft X had returned to them or if they had issued any lost communication procedures. The sector said they would reattempt the aircraft and call back. They called and said they were able to get Aircraft X via relay and that he would be coming to me. Aircraft X checked on; and I issued the new beacon code. The data block paired and I radar identified the aircraft and issued an altimeter. As this was happening; the Assist training team returned to my sector.I had an IR (instrument training route) for Aircraft Y that I was blocking for with an exit time of XA44Z; but I had not written down that the aircraft would be exiting at a point which is is my airspace. There is currently a radar outage at one of the radar sites and we are unable to see aircraft southeast of Approach's airspace below 7;500 feet. For the past week; when I have had aircraft come out of an IR route; I instruct them to maintain a VFR climb to 9;000 feet and issue their clearance once I can radar identify the aircraft. When I did that procedure with Aircraft Y; the pilot stated she was in IFR conditions and could not maintain a VFR climb. I was trying to get my Assist to coordinate a block altitude with another sector so I could issue a non-radar clearance; but I was also asking the Assist side trainer if there was a correct way to do this. I had no idea what the correct procedure was.The trainer was not paying attention to the scope and thought it was a hypothetical question; while the trainee had no idea who or what I was talking about. I was very focused on getting Aircraft Y her clearance because she was non radar in IFR conditions with icing in the area. At some point I noticed that Aircraft X was flashing an MSAW (Minimum Safe Altitude Warning) alert. I pulled up the IFR altitude chart; saw that Aircraft X was still at 6;000 feet and entering a block of 6400 feet and issued a climb. I issued 'Aircraft X climb and maintain 7;000 for a low altitude alert' but did not actually issue the low altitude alert. Aircraft X climbed quickly; but I believe they did violate the 6;400 foot block.We should have written procedures for non-radar IR exits. If there is one; I am unaware of it and should receive more training in that area. Since the radar site outage is a daily occurrence right now; and the IR routes are very frequent in this sector I feel like I should know exactly what to do instead of coming up with something that could be completely incorrect and continuing that procedure until it didn't work. I believe my focus on that event is what led me to miss the altitude until the MSAW alert went off. I have had specialized training in MSAW alerts and the issuance of a low altitude alert; but this is my first time ever actually seeing it and I failed to issue it.




Synopsis: A Center Controller reported an aircraft below radar coverage was late in communication due to not switching over from the previous sectors frequency. The reporter was distracted while dealing with a military aircraft on a military training route.