Air carrier flight crew reported an altitude deviation during arrival. Captain stated rustiness due ...

Attributes
ACN	1745174
Time
Date	202006
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 35 Flight Crew Type 35
Person 2
Function	Captain Pilot Not Flying
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance

Narrative:

On the zzzzz arrival we were at 6;000 feet and the radios were busy. There were numerous aircraft with similar call signs. We were given clearance off the STAR and cleared direct ZZZZZ1 for ILS xr. We both thought the controller also cleared us to 4;000 feet. I asked the capitan; pm; if we were cleared to 4;000 feet; and he said; 'yes.' I also thought I heard the controller clear us to 4;000 feet. I started down in vertical speed mode 1;000 FPM; and when we approached 5;000 feet; ATC queried why we were descending; and to just level off at 5;000 feet. The pm told ATC that we understood that we were given a descend clearance but ATC said; 'nope.'

Original NASA ASRS Text

Title: Air carrier flight crew reported an altitude deviation during arrival. Captain stated rustiness due to lack of flying was a contributing factor.

Narrative: On the ZZZZZ Arrival we were at 6;000 feet and the radios were busy. There were numerous aircraft with similar call signs. We were given clearance off the STAR and cleared direct ZZZZZ1 for ILS XR. We both thought the Controller also cleared us to 4;000 feet. I asked the Capitan; PM; if we were cleared to 4;000 feet; and he said; 'Yes.' I also thought I heard the Controller clear us to 4;000 feet. I started down in Vertical Speed mode 1;000 FPM; and when we approached 5;000 feet; ATC queried why we were descending; and to just level off at 5;000 feet. The PM told ATC that we understood that we were given a descend clearance but ATC said; 'NOPE.'

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.