Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Training / Qualification; Situational Awareness; Communication Breakdown
Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented
Environment - Non Weather Related; Human Factors
While descending to FL240 we were cleared to descended via the ZZZZZ X RNAV Arrival.  I selected 11;000 feet.  Approaching ZZZZZ Intersection I noticed that we were in open descent.  I disconnected the autopilot and leveled off at FL238 and then started a climb back to FL240.  Cause- While level at FL350 ATC cleared us to FL240 with a restriction to descend below FL310.  I selected open descent to meet the restriction.  After being cleared to descend via the arrival I did not select the managed mode.I need to increase vigilance when flying with people coming back from leaves for both PF and PM roles.
Air carrier flying pilot reported an altitude deviation during arrival and cited lack of flying as a contributing factor.