Date: 201310
Local time of day: 1201-1800
Location: MEM.TRACON, TN
Flight conditions: VMC
Light: Daylight
Aircraft: A319
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class E MEM
ATC / advisory: TRACON MEM
Aircraft component: FMS/FMC
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Human factors: Human-Machine Interface; Distraction
Second reporter function: Captain; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Contributing factors: Human Factors; Aircraft; Procedure
Primary problem: Human Factors

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.


Second narrative: I was the Captain flying the aircraft on the LTOWN 6 RNAV Arrival to MEM. Arrival verification complete. ATC had us a little high and asked for descent; given FL240. Started open descent to catch up on profile. Then ATC gave us Direct LTOWN and cleared LTOWN 6 RNAV. Set altitude to 3;000 feet which was the final altitude fix DINKE. The aircraft had been on profile but it got off profile and we did not catch that fact. The aircraft descended to approximately 7;800 feet MSL. ATC called us and asked what arrival we were on and then cleared us to 7;000 feet.I think being high on the profile and having to ask for the initial descent was the beginning of the event; then being cleared on the descent profile direct to another fix; LTOWN; compounded the error that as a crew we did not catch. I feel that any and all of these RNAV arrivals should have one fixed crossing altitude at each fix and ATC should leave the aircraft on the ENTIRE ARRIVAL. All of the problems that are happening I believe are due to the multiple altitudes over a fix instead of one hard altitude over the fix and also ATC vectoring the aircraft off the RNAV approach and then rejoining the RNAV arrivals.


Synopsis: 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.