A319 flight crew reports descending below the ltown crossing restriction on the ltown 6 RNAV arrival...

Narrative:

Enroute to mem we did the ltown 6 arrival verification and approach brief. The captain {flying pilot} said we are starting to get high; ask for lower. Before I could ask; approach gave us 'descend to 240'. The captain selected operation des and we started down. While in the descent we were given 'direct ltown; descend via the ltown 6 arrival north transition'. The captain entered 3;000 in the altitude alert window and we confirmed '3;000'. The aircraft was in the managed descent mode and speed and I remember seeing the magenta dot showing us below profile and descending at 1;000 FPM. This is normal until the aircraft gets back on profile or hits an altitude constraint. I got distracted {explained below} and approach called and asked what altitude we were descending through and I told them 7;600 feet. I immediately looked up and saw that we had not reached ltown and the altitude window was 10;000 feet to 16;000 feet. Approach advised us to maintain 7;000 feet. Somehow we ended up in the operation des or V/south mode and the aircraft was descending to 3;000 feet and ignoring the constraints.while on the arrival my efb generated a message 'software failure'. This had happened on the ground earlier and while trying to fix the problem I found a note saying to try turning the efb off and then back on. It worked and required all the data to be downloaded back into the efb. On the ltown arrival I was doing the same procedure to restore the efb when approach called to check our altitude. This had taken me out of the loop. I had the paper charts out for mem and should have left the efb alone so I could better monitor the arrival. We had the aircraft for 5 legs that day and it continued to fail numerous times and I left it alone. I also feel that situational awareness is lessened when we are taken off the full published arrival since it is briefed as a full procedure. There are also airbus software anomalies that occur when the arrival is changed yet I don't know if that was a problem in this case.

Original NASA ASRS Text

Title: A319 Flight Crew reports descending below the LTOWN crossing restriction on the LTOWN 6 RNAV arrival to MEM. The crew had been cleared direct LTOWN but for unknown reasons the managed descent was lost after selection or was never selected.

Narrative: Enroute to MEM we did the LTOWN 6 Arrival verification and approach brief. The Captain {Flying Pilot} said we are starting to get high; ask for lower. Before I could ask; Approach gave us 'descend to 240'. The Captain selected OP DES and we started down. While in the descent we were given 'direct LTOWN; descend via the LTOWN 6 Arrival north transition'. The Captain entered 3;000 in the altitude alert window and we confirmed '3;000'. The aircraft was in the managed descent mode and speed and I remember seeing the magenta dot showing us below profile and descending at 1;000 FPM. This is normal until the aircraft gets back on profile or hits an altitude constraint. I got distracted {explained below} and Approach called and asked what altitude we were descending through and I told them 7;600 feet. I immediately looked up and saw that we had not reached LTOWN and the altitude window was 10;000 feet to 16;000 feet. Approach advised us to maintain 7;000 feet. Somehow we ended up in the OP DES or V/S mode and the aircraft was descending to 3;000 feet and ignoring the constraints.While on the arrival my EFB generated a message 'software failure'. This had happened on the ground earlier and while trying to fix the problem I found a note saying to try turning the EFB off and then back on. It worked and required all the data to be downloaded back into the EFB. On the LTOWN arrival I was doing the same procedure to restore the EFB when Approach called to check our altitude. This had taken me out of the loop. I had the paper charts out for MEM and should have left the EFB alone so I could better monitor the Arrival. We had the aircraft for 5 legs that day and it continued to fail numerous times and I left it alone. I also feel that situational awareness is lessened when we are taken off the full published arrival since it is briefed as a full procedure. There are also Airbus software anomalies that occur when the arrival is changed yet I don't know if that was a problem in this case.

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.

Attributes
ACN	1121700
Time
Date	201310
Local Time Of Day	1201-1800
Place
Locale Reference	MEM.TRACON
State Reference	TN
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR LTOWN 6
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	First Officer Pilot Not Flying
Person 2
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Overshoot Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

A319 flight crew reports descending below the ltown crossing restriction on the ltown 6 RNAV arrival to mem. The crew had been cleared direct ltown but for unknown reasons the managed descent was lost after selection or was never selected.