A be-400XP FMS with VNAV engaged dropped the 13;000 ft constraint and descended 200 ft before ATC an...

Attributes
ACN	1043049
Time
Date	201210
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	Beechjet 400
Operating Under FAR Part	Part 91
Flight Phase	Descent
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Pilot Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Narrative:

[We were] cleared to descend via the STAR by approach. Pilot not flying dialed in 7;000 ft. I noticed altitudes were missing from the FMS and began to pull up the STAR from the ipad to review the altitudes. As I was doing so; the aircraft descended below 13;000 ft prior to the fix. We reached approximately 12;800 ft and ATC advised we were not supposed to descend below 13 before the fix then further cleared us to descend to 11;000 ft and continue the arrival. Nothing further occurred. We were confused by the missing altitudes on the FMS and were distracted and failed to catch the gradual descent. Altitudes/fixes were all confirmed prior to departure. Better vigilance to the current FMS may have reduced the likelihood of this event.

Original NASA ASRS Text

Title: A BE-400XP FMS with VNAV engaged dropped the 13;000 FT constraint and descended 200 FT before ATC and crew saw the descent to 7;000 FT begin which was set in the altitude alerter.

Narrative: [We were] cleared to descend via the STAR by Approach. Pilot not flying dialed in 7;000 FT. I noticed altitudes were missing from the FMS and began to pull up the STAR from the iPad to review the altitudes. As I was doing so; the aircraft descended below 13;000 FT prior to the fix. We reached approximately 12;800 FT and ATC advised we were not supposed to descend below 13 before the fix then further cleared us to descend to 11;000 FT and continue the arrival. Nothing further occurred. We were confused by the missing altitudes on the FMS and were distracted and failed to catch the gradual descent. Altitudes/fixes were all confirmed prior to departure. Better vigilance to the current FMS may have reduced the likelihood of this event.

Data retrieved from NASA's ASRS site as of July 2013 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.

A be-400XP FMS with VNAV engaged dropped the 13;000 ft constraint and descended 200 ft before ATC and crew saw the descent to 7;000 ft begin which was set in the altitude alerter.