Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Communication Breakdown; Human-Machine Interface; Situational Awareness; Training / Qualification
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; Staffing
Assigned to descend via. Inside ZZZZZ assigned 300 knots. Captain used the speed window to adjust speed. Approaching ZZZZZ1; realized he was crossing low. He attempted to correct but still crossed low by what I estimate to be 500-800 feet low. I looked and realized he did not use Speed Intervention but instead had used LVL Change. ATC did not query us about the error nor was there traffic in the area.Captain new to aircraft and seat with limited recency of experience confused speed/descent modes. FO (PM) limited recency of experience involved with approach programming and communications did not notice the error.For our part better announcement and verification of MCP changes. Better monitoring during busy descent.
Air Carrier First Officer reported an altitude deviation and cited the Captain being new to the aircraft and both pilots' lack of flying contributed to the event.