Date: 201501
Local time of day: 1201-1800
Location: ZFW.ARTCC, TX
Flight conditions: VMC
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class E ZFW
ATC / advisory: Center ZFW
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Workload; Human-Machine Interface; Distraction; Confusion
Second reporter function: First Officer; Pilot Flying
Anomaly: ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew FLC Overrode Automation
Contributing factors: Aircraft; Chart Or Publication; Procedure; Human Factors
Primary problem: Ambiguous

Narrative: Cleared to descend on the BRDJE ONE arrival. ATC issued an instruction to maintain FL240 and a speed of 290 KIAS. (I am not positive of these numbers but I am sure there was a modification to the arrival). Subsequent clearance was to descend via the arrival and normal speed. The next fix we were coming up on was SEEVR to cross below 23000 but above 20000. We set 8000 in the altitude select window and managed the speed and the altitude. This I am sure of. At this point we checked the FMS against the chart and both pilots verified the restrictions would be met. I then got busy with talking to the passengers to update arrival time and thank them for flying with us and such. Also called operations to get a gate assignment. When I finished with that I got back in the loop and noticed the airplane altitude was 17000 feet. I noticed we were not yet at SEEVR but the airplane had descended to the next fix after SEEVR altitude (BRDJE between 19000 and 17000). The altitude was constrained at 17000 at this point. We selected a level of at 17000 with a push of the VSI selector until we could figure out what happened. I immediately contacted center and told him we were 3000 feet too low at 17000 feet. He asked me if we were on the BRDJE arrival and if I was familiar with it to which I replied 'yes'. He said maintain 17000 and descend via the BRDJE arrival. There was no mention of a deviation and no traffic conflict of any kind. The remainder of the trip went without incident.I am not sure of what I can add to help resolve the problems associated with these arrivals other than to beat the same horse about monitor; monitor; monitor. I do not want it to be an excuse for my failure to fly the airplane at the proper altitude; but these arrivals have problems with our airplanes as well as other operators. I have a 30 year record with no altitude deviations other than the last month or so; and now I have two. Both of them on these new arrivals. I have lost confidence in the automation and how it works on these arrivals. I think that I will start flying them all in selected mode and just meet all the lower altitudes. I have observed this on several [other] Airline flights that I have jump seated to work on. Also; these arrivals may (probably would) work just fine if the controllers would not make modifications to the altitudes or the speeds. It defeats the purpose and intent of the arrival when it has to be adjusted manually to meet the requirements of ATC.


Second narrative: While enroute starting our initial descent into DFW we were given vectors off course for spacing. I believe it was 20 to the right of course. At the time we had just finished a restroom break. I was informed of the vector when I got back into the cockpit. ATC issued an instruction to maintain FL 240 and a speed of 290 KIAS. We were then instructed to proceed direct SEEVR. I was reviewing the arrival procedure and the approach plates for both 35C and 36L; and the airport diagram chart in case we got a late switch in runways. We were both then putting on our shoulder harnesses; putting our headsets on and getting ready for the approach checklist procedures. Before I realized it we were descending through 17200 feet still several miles from SEEVR. I immediately pressed the VSI selector to level the airplane off as I knew the altitude was not correct for our location. I am still fairly new to the airbus and the managed concept with the automation from the MCDU. I had put my confidence in this concept and it makes sense when you can see the constraints on the MCDU and the airplane is managed that it will follow the programming. I think that I will start flying them all in selected mode to meet all speeds and altitudes. I am not sure if being vectored off course for spacing and then direct to a fix on the arrival made the automation fail to capture the altitudes or not. The speed seems to not change; however on other arrivals I have noticed with the large speed window tolerance the aircraft allows it is easy to get slow on speed for some arrivals. I have been selecting speed when this occurs. It defeats the purpose and intent of the arrival when it has to be adjusted manually to meet the requirements of ATC.


Synopsis: After having been vectored off the BRDJE RNAV STAR to DFW and descend to FL240 an A320 flight crew was cleared direct to intercept the STAR at SEEVR; and cleared to descend via the arrival. Believing they had assured the arrival was properly programmed both pilots undertook other required preparations for the arrival. Shortly; they noticed that they had descended well beyond the minimum SEEVR crossing of FL200 although they had not yet reached that fix. They advised ATC who re-cleared them and the balance of the flight was uneventful. Both airmen expressed skepticism about the ability of their aircraft to successfully navigate the complex procedures; especially when any ATC alteration to the line selectable procedure is required by ATC.