Citation X flight crew descended below assigned crossing altitude.

Attributes
ACN	1074129
Time
Date	201303
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.TRACON
State Reference	US
Aircraft 1
Make Model Name	Citation X (C750)
Operating Under FAR Part	Part 91
Flight Phase	Descent
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Pilot Flying Captain
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Narrative:

During descent we went 400 ft below a crossing altitude. The pilot flying caught the error as it was happening; disconnected the autopilot; and returned to the assigned altitude. At about the same time; ATC called to let us know that he noticed and let us know that there was no traffic/conflict noted. Background: we had loaded and double checked the altitudes in the FMS and were using the VNAV function. I had just put in the runway in use and was in the process of checking the FMS/ipad to confirm the altitudes again when the error occurred. Upon further checking; we found that all the crossing altitudes (even the hard programmed ones) had been dropped from the FMS.

Original NASA ASRS Text

Title: Citation X flight crew descended below assigned crossing altitude.

Narrative: During descent we went 400 FT below a crossing altitude. The pilot flying caught the error as it was happening; disconnected the autopilot; and returned to the assigned altitude. At about the same time; ATC called to let us know that he noticed and let us know that there was no traffic/conflict noted. Background: we had loaded and double checked the altitudes in the FMS and were using the VNAV function. I had just put in the runway in use and was in the process of checking the FMS/IPAD to confirm the altitudes again when the error occurred. Upon further checking; we found that all the crossing altitudes (even the hard programmed ones) had been dropped from the FMS.

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.