Date: 202010
Local time of day: 0601-1200
Location: ZZZ.ARTCC, US
Light: Daylight
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Time Pressure; Communication Breakdown; Workload
Second reporter function: Captain; Pilot Not Flying
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Environment - Non Weather Related; Human Factors; Staffing
Primary problem: Ambiguous

Narrative: ATC held the flight high.  Were given clearance to descend to lower altitude. Aircraft was 7;000 feet high on path.  Began expedited descent to catch up to path; ATC then gave level off of FL290.  Around FL320; Pilot Flying noticed traffic appear on TCAS below at FL280 and started to adjust vertical descent rate.  TCAS RA was triggered for level off.  Crew disconnected autopilot and autothrottles and leveled off until traffic was clear; and then continued descent to FL290.  Reported RA to ATC.  Crew was then notified of aircraft at FL280.ATC was overwhelmed. Perhaps more Controllers are needed in that sector. At the very least; a heads up for aircraft at FL280 would have helped. Crew could have ignored the high on path profile and also descended slower; but that would have caused problems down the road.


Second narrative: Switched to a frequency that was very busy. The Controller was overwhelmed; we were getting high on the arrival but couldn't get a word in. Finally cleared to descend; the FO who was Pilot Flying started down with the boards out; but weather ahead didn't allow us to speed up to get down. We were 9;000 feet above profile and coming down when we got a TCAS Alert caused by the descent rate. The FO got busy to alleviate it but by the time he pushed a few buttons; it started saying 'Level Off!' So he disconnected everything and leveled the aircraft off. I told the Controller we were leveling off due to a TCAS conflict; but never got an acknowledgment; because [the Controller] was still constantly talking. After the traffic passed we went to our assigned FL290 and [the Controller] asked '(Call sign) verify your level at FL290.' [Controller] didn't have a clue what just happened. I confirmed we were at FL290 and gave us '...cross ZZZZZ at 9;000 feet…' I said we'd do our best but we'd never make ZZZZZ at 9;000 feet. [The Controller] didn't even acknowledge; so we started hurrying down. When we got switched to Approach frequency I told [the Controller] we'd be high at ZZZZZ and the Controller said 'I know; just do your best and descend to 6;000 feet.'With so many aircraft parked; with so many fewer aircraft flying; why is ATC so min-staffed? It seems the new normal is too few Controllers to handle the traffic that's there.


Synopsis: Air carrier flight crew reported ATC was difficult to communicate with and suggested that staffing is a contributing factor.