Falcon 2000 flight crew reported that during descent the autopilot failed to capture the preselected...

Attributes
ACN	1569446
Time
Date	201808
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Falcon 2000
Flight Phase	Descent
Flight Plan	IFR
Component
Aircraft Component	Altitude Hold/Capture
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Overshoot Deviation - Procedural Published Material / Policy

Narrative:

Enroute to ZZZ. Was level at 16000 ft and direct to zzzzz when event started. ATC cleared us to descend via ZZZZZ1 arrival. I identified [the] lowest altitude 9000 ft at ZZZZZ2. Dialed in 9000 ft and engaged VNAV.the descent cue came down shortly and autopilot captured VNAV and started its descent. Everything looked normal to me. Crossing altitude at zzzzz is 15000 ft. And we had the pink 15000 displayed on pfd (primary flight display) as a restriction. However we crossed below 15000 ft prior to zzzzz without me noticing. The PIC called out stop. By the time I realized what was happening we were 700-800 feet low. I disconnected the autopilot and corrected back to 15000 ft. ATC told us to check our altitude the minimum vector altitude he said was 14400 ft. Rest of flight was uneventful.I have flown the falcon for years. I feel totally comfortable with using the VNAV function. I have never seen the autopilot do this before. During our debrief of the event we agreed everything was set up correctly and we had the right indications. However I know my faith in the automation caused me to let my guard down. I should have caught the descent below 15000 ft immediately. This was completely my mistake. The PIC was off getting the latest ATIS as I set it up.

Original NASA ASRS Text

Title: Falcon 2000 flight crew reported that during descent the autopilot failed to capture the preselected altitude.

Narrative: Enroute to ZZZ. Was level at 16000 ft and direct to ZZZZZ when event started. ATC cleared us to descend via ZZZZZ1 arrival. I identified [the] lowest altitude 9000 ft at ZZZZZ2. Dialed in 9000 ft and engaged VNAV.The descent cue came down shortly and autopilot captured VNAV and started its descent. Everything looked normal to me. Crossing altitude at ZZZZZ is 15000 ft. And we had the pink 15000 displayed on PFD (Primary Flight Display) as a restriction. However we crossed below 15000 ft prior to ZZZZZ without me noticing. The PIC called out STOP. By the time I realized what was happening we were 700-800 feet low. I disconnected the autopilot and corrected back to 15000 ft. ATC told us to check our altitude the Minimum Vector Altitude he said was 14400 ft. Rest of flight was uneventful.I have flown the Falcon for years. I feel totally comfortable with using the VNAV function. I have never seen the autopilot do this before. During our debrief of the event we agreed everything was set up correctly and we had the right indications. However I know my faith in the automation caused me to let my guard down. I should have caught the descent below 15000 ft immediately. This was completely my mistake. The PIC was off getting the latest ATIS as I set it up.

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.