Date: 202008
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Light: Daylight
Aircraft: Small Transport; Low Wing; 2 Turboprop Eng
Operator: Personal
Operating under: Part 91
Mission: Personal
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Personal
Reporter function: Pilot Flying; Captain; Single Pilot
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Communication Breakdown; Distraction; Situational Awareness; Workload
Anomaly: ATC Issue All Types
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Airspace Structure; Company Policy; Staffing; Human Factors
Primary problem: Staffing

Narrative: I was enroute from ZZZ1 to ZZZ2. I was with ZZZ on frequency for at least 30 minutes; including cruise at FL280 until about 10;000 feet when I was handed off to ZZZ2 Tower at about XA:00 local. I was Aircraft X. The Center Controller was overwhelmed with workload: military; corporate planes; airliners; IFR departures and arrivals; and requests for deviations around numerous scattered thunderstorms. I live in [State X] so I am accustomed to busy ATC frequencies; but this Controller was buried by the workload. There was another plane on frequency who requested a weather deviation. The Controller said he had to stay on his route unless he descended from the flight levels to 16;000 feet. Other than 'military airspace;' the Controller did not offer any information on the vertical or horizontal dimensions of this airspace. In my case; I was issued vectors around this airspace at least twice - but was not provided any information on how long I would be on the vector. Normally; I would have inquired about this - but the Controller was so busy and the off-route vector was not creating any operational issues for me - so I silently endured to provide time to others who might need the Controller's help more than I did.Additionally; the Controller seemed to be working a large swath of northern [State Y]. I would hear airplanes responding to his transmissions; but I couldn't hear many of the transmissions. Another pilot finally asked about this and the Controller explained that he was using several different transmitter locations for frequency - and planes couldn't hear the faraway ground transmissions - but could hear the airborne replies.I am not faulting the Controller. He was a competent; hard-working gentleman. But I am faulting ZZZ Center for being understaffed and assigning such a large sector to one Controller. In fact; after I landed at ZZZ2; I asked the Ground Controller for a phone for ZZZ. I called the Supervisor at ZZZ Center and told him his frequency Controller was overwhelmed. The Supervisor said he was aware of it; but was out of bodies.The Controller's high workload and stress level was obvious - to the point that I felt safety was being compromised. If I had needed a greater level of ATC service or assistance; I am not confident that I would have received that help. And I don't know how much fuel pressure was created for the pilot who was forced to descend to 16;000 feet because the Controller was too busy to explain his options or to create other options.




Synopsis: Pilot reported Controller was overworked and unable to respond to many frequency transmissions.