A320
Flight Crew Air Transport Pilot (ATP)
Workload; Human-Machine Interface; Distraction; Confusion
Deviation - Altitude Overshoot; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Air Traffic Control Issued New Clearance
Aircraft; Human Factors; Procedure
I failed to cross HIMOM on the arrival at the prescribed 11;000 FT. I was flying the aircraft on autopilot in the select speed and V/S modes. As I approached HIMOM I pushed the 'PUSH TO LEVEL OFF' button and then dialed my speed down to 210 KTS. As I immediately went from the V/S knob to the speed knob; I failed to check the PFD to ensure that I had entered 'V/S zero' mode. My speed was not slowing as I thought it should so I employed the speedbrakes; further focusing on making my speed restriction. At this point the First Officer; who had been heads down inserting a runway assignment change; caught the deviation in my altitude and brought it to my attention. Before I could take corrective action Approach Control (who I learned later had noticed the deviation at this time) issued me a lower altitude. I continued to landing with no further incident.I have had a personal problem with these new RNAV approach procedures from the beginning. With the Airbus' frequent +/- 20 KIAS and 200 FT airspeed and altitude tolerances; I have yet to fly one of these arrivals fully managed where I have not had to intercede (or should have) to make an acceptable crossing restriction. Even during the portions of the arrival that were flown fully managed; it was like riding a roller coaster as the airplane pitched up and down to meet the seemingly arbitrary altitudes it had chosen to cross each waypoint. The engines spool up and down between 0% and 60% and that is just to stay within the [system's wide open] 40 KTS window. It makes for a very poor ride for the passengers and should be an affront to any professional pilot. On previous arrivals I had tried using 'selected speed' to stabilize the engines while allowing the autopilot to descend in the managed mode. The pitching was even worse as now I'd taken away its 40 KTS window. This leg I tried for the first time to fly the arrival with V/S and Selected Speed selected. The descent was very pleasant and only required occasional tweaking of the V/S to stay on profile. The engines stayed steady to hold speed. If I had managed to actually activate the push-to-level-off function at HIMOM the arrival would have been perfect and would be my preferred way of doing the arrivals from now on. Since I didn't; all I really managed to do was substitute the imperfections of the autopilot with my own. I have only flown a few of these arrivals where Approach Control has not vectored me off for 'spacing'. I have never flown one where the throttles go to idle at the top of descent only to spool up at the final approach fix; as we were told would be the case during training. Before [the implementation of OPD RNAV STARS]; I only had to sweat making one crossing restriction at either TOMSN or DANDD. Now I have to sweat a dozen on each arrival into DEN. And I can now blow the restriction in either selected or managed mode! That's called progress I suppose. I suggest that we give the guy who thought of these arrivals a pat on the back; a promotion with a big fat bonus check and a corner office as far away as possible from anything important that may be going on in aviation. Then [trash] can these arrivals and let's get back to flying airplanes instead of generating deviation reports. I want to add the First Officer was doing his job and there was nothing procedurally he could have done to prevent this; given the duties he was performing at the time. This incident was entirely my fault.
The Captain was flying the aircraft on autopilot using 'vertical speed mode' as we were 'descending via' the MOLTN1 RNAV arrival into Denver. The use of 'Managed Descent' mode of the autopilot could have prevented the deviation. Better monitoring of the approach during periods of high workload/task saturation on my part should have caught the error in time to level off.
The Captain of an A320; 'descending via' the MOLTN RNAV STAR to DEN; utilizing Vertical Speed and Selected Speed modes vice Managed Descent; failed to comply with the 'intermediate' crossing restriction at HIMOM when he failed to ensure the jet was leveling at the prescribed 11;000 MSL. The First Officer alerted the deviation at 10;700 and ATC issued a timely further descent.