An A319 crew monitoring the FMGC in the desc mode failed to see that the aircraft did not remain lev...

Narrative:

This was the first flight of a four day trip. It is ironic that the captain and I had a lengthy discussion about the threat of complacency just prior to this flight. Kepec arrival las; assigned to cross clarr at 13;000 ft; 210 KTS. Altitude of 13;000 ft captured before clarr and all altitude constraints checked prior to the arrival. Assigned to descend via kepec arrival; I set 8;000 ft as the lowest altitude on the descent. After passing clarr the captain initiated a managed descent; a magenta 11;000 ft altitude constraint was displayed and desc was boxed as the descent mode. Upon descent mode initiation; the aircraft started descending out of 13;000 ft. All appeared normal. Unfortunately; there is a 13;000 ft altitude constraint at kepec; approximately 20 miles or so from clarr; we should have been in level flight. I didn't determine that we should be in level flight; not descending; until we were already at 11;800 ft or so. I had my range scale in either 10 or 20 NM (to de-clutter the upcoming restraints) and didn't see the 13;000 ft restriction at kepec initially; although I should have known having just verified the altitude constraints. It took me a bit to recheck the approach plate; then the map display and verbalize to the pilot flying that we were below our kepec altitude. L30 approach queried us; then gave us direct to ipumy (which has an 11;000 ft constraint) and we proceeded with the approach and landing. As the pilot not flying; I should have caught the descent much sooner. I was lured into a flight myth versus flight reality by seemingly normal managed descent indications. I didn't cross check fast enough; I took too much time trying to reconcile what looked ok as a managed descent with the approach criteria. I admit I am puzzled by the aircraft's managed descent below a clearly indicated altitude constraint on the map display and with all seemingly normal managed descent indications. We do this procedure many times during any given trip. From a systems perspective; I really have no answers as to why our managed descent deviation occurred; although I'm sure there is a simple explanation.

Original NASA ASRS Text

Title: An A319 crew monitoring the FMGC in the DESC Mode failed to see that the aircraft did not remain level to the KEPEC 13;000 FT constraint even though the system was in the Managed Descent Mode with next constraint illuminated magenta.

Narrative: This was the first flight of a four day trip. It is ironic that the Captain and I had a lengthy discussion about the threat of complacency just prior to this flight. KEPEC arrival LAS; assigned to cross CLARR at 13;000 FT; 210 KTS. Altitude of 13;000 FT captured before CLARR and all altitude constraints checked prior to the arrival. Assigned to descend via KEPEC arrival; I set 8;000 FT as the lowest altitude on the descent. After passing CLARR the Captain initiated a managed descent; a magenta 11;000 FT altitude constraint was displayed and DESC was boxed as the descent mode. Upon descent mode initiation; the aircraft started descending out of 13;000 FT. All appeared normal. Unfortunately; there is a 13;000 FT altitude constraint at KEPEC; approximately 20 miles or so from CLARR; we should have been in level flight. I didn't determine that we should be in level flight; not descending; until we were already at 11;800 FT or so. I had my range scale in either 10 or 20 NM (to de-clutter the upcoming restraints) and didn't see the 13;000 FT restriction at KEPEC initially; although I should have known having just verified the altitude constraints. It took me a bit to recheck the approach plate; then the map display and verbalize to the pilot flying that we were below our KEPEC altitude. L30 Approach queried us; then gave us direct to IPUMY (which has an 11;000 FT constraint) and we proceeded with the approach and landing. As the pilot not flying; I should have caught the descent much sooner. I was lured into a flight myth versus flight reality by seemingly normal managed descent indications. I didn't cross check fast enough; I took too much time trying to reconcile what looked OK as a managed descent with the approach criteria. I admit I am puzzled by the aircraft's managed descent below a clearly indicated altitude constraint on the map display and with all seemingly normal managed descent indications. We do this procedure many times during any given trip. From a systems perspective; I really have no answers as to why our managed descent deviation occurred; although I'm sure there is a simple explanation.

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.

Attributes
ACN	1157306
Time
Date	201403
Local Time Of Day	0601-1200
Place
Locale Reference	LAS.Airport
State Reference	NV
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	Descent Initial Approach
Route In Use	STAR KEPEC
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	First Officer Pilot Not Flying
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 10000 Flight Crew Type 8000
Person 2
Function	Pilot Flying Captain
Experience	Flight Crew Last 90 Days 120 Flight Crew Type 5500
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

An A319 crew monitoring the FMGC in the desc mode failed to see that the aircraft did not remain level to the kepec 13;000 ft constraint even though the system was in the managed descent mode with next constraint illuminated magenta.