Citation II S2/Bravo (C550)
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Engineer; Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 60; Flight Crew Total 23039; Flight Crew Type 254
Distraction; Human-Machine Interface; Fatigue
Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Flight Crew Became Reoriented; Flight Crew Returned To Clearance; Flight Crew FLC Overrode Automation
Aircraft; Human Factors; Weather
I was the co-pilot and flying pilot with no passengers. This was the third mission in this airplane and unlike the usual aircraft I fly this one has a glass cockpit with the Mode Control Panel in front of the Captain. We had worked together very well as a crew with excellent CRM. We were descending to land at RNO where the weather was about 1200 overcast with tops about 8000 ft and because of the temperature; icing was expected; level unknown. The autopilot was engaged. I had briefed the approach and we completed the appropriate checklists. We were getting step down descents and when we were cleared from 10000 to 9000 ft. I saw the captain select 9000 in the altitude preselect window but failed to notice the arm button was not pushed. I had just called for engine anti-ice to be turned on and we were discussing when to turn on the wing anti-ice. Then I noticed the airplane going through 8700 ft. I immediately disconnected the autopilot and started a climb back to 9000. Just as the airplane started climbing ATC announced 'stop your descent.'  We received further vectors and descents and accomplished the approach; landing in RNO.Contributing factors were I had little time on this glass panel airplane; night flight; IFR weather ahead with possible icing and busy time of flight. We lost situational awareness and my inaction was not confirming autopilot status and reliance on automation.
Prior to descent; all appropriate checklists/briefs were complete in accordance with SOPs. PF was descending to assigned altitude of 10;000 ft. Pilots entered brief conversation about cloud deck; thickness and potential icing. Decision was made to turn anti-ice on (anti-ice switches accessed from left seat) PNF moved to select AI switches 'ON.' Concurrently; ATC directed a descent from 10;000 to 9;000 just prior to PF reaching 10;000 (SOP calls for PNF to select/reset alt preselect controller to new alt (9;000) and select ALT ARM -- this is to be announced and subsequently acknowledge by PF). Upon receipt of ATC instructions; PNF selected 9;000 in Alt pre-select window. Announced 'Pilot; cleared to 9;000.' PNF failed to select ARM as attention went back to verifying proper anti-ice controls were in place. Acknowledgment of 'preselects' did not occur. Passing through 8800; PF recognized AP failed to capture preselected altitude of 9;000. PF interrupted AP and started a smooth climb (night IMC conditions at this time) back to 9;000. In process of maneuvering; the aircraft descended to 8700. During climb back to 9;000 ATC directed 'Stop descent.' During climb back to altitude; ATC directed subsequent vector and descent to intercept the LOC with clearance for approach. Subsequent approach was uneventful.ROOT CAUSE: Failure to follow SOP.CAUSAL FACTORS: Distraction due to environmental factors; Crew fatigue; early morning hours; PF completed early morning sortie the day prior. Although it was the fourth leg of mission the PNF had not flown in 17 days.
C550 pilots reported incorrectly setting their altitude during a descent to RNO resulting in overshooting their assigned altitude.