Narrative:

While on the MAIRS2 arrival into phx; we were told to keep 300 KTS and cross brusr at 12000 ft at 250 KTS. I was in selected speed and vertical descent (1500 FPM) because the controller asked us to keep the speed up as long as possible. Approach then asked us approximately 18 mi prior to brusr to increase to 310 KTS till brusr. I declined and told them we couldn't comply. Approximately 8 mi prior to brusr; we were told to descend via the MAIRS2 arrival. I was sure my altitude was at 12000 ft and I was in the process of slowing to 250 KTS so I reset my altitude to 6000 ft which is the lowest altitude for the FMC arrival. I then went to engage the speed so the aircraft would meet the speed restrs on the arrival (I neglected to engage managed descent.) it was shortly thereafter that I realized we were descending below 12000 ft (approximately 11700 ft) prior to brusr. I immediately realized that the 12000 ft altitude had not captured when I reset the altitude to 6000 ft and we were still in the vertical speed mode and I immediately engaged managed descent. Unfortunately; we were descending at 1500 FPM and I went to vertical speed hold to arrest the descent and started to climb back to 12000 ft when ATC questioned our altitude. We had reached approximately 11200 ft during the recovery and approach had us maintain 11000 ft and issued another descent clearance after brusr. I tried to recover as expeditiously as possible without overly aggressive maneuvers. I also realized that we were cleared for the descent in only 3-4 mi that I did not make any rash aggressive movements to climb back to 12000 ft when we would be starting back down in 3-4 mi. There were no aircraft near us on TCAS. I believe the event occurred for a variety of reasons. We were in a high workload environment at a busy airport where the controller had asked a number of times to keep our speed up to make some metering times. In order to hold 300 KTS and cross brusr at 12000 ft at 250 KTS; I had to use selected speed and vertical speed because managed speed would have been 290 KTS give or take 10-15 KTS. I planned the descent to level approximately 8 mi to brusr in order to slow to 250 KTS by brusr. The controllers nowadays always seem to issue further dscnts very close to capturing altitudes during dscnts which can cause the aircraft to go or in our case stay in a vertical speed mode. The limitations of the airbus software and the constant changing of speed requests and sometimes heading deviations and altitude revisions are not compatible with FMC approachs that have numerous controller altitude and aircraft speed changes from the FMC arrs. It is very difficult to do a hands off managed descent in today's rushed ATC environment. You are either asked to keep the speed up; slow down; maintain altitude or turned off the arrival altogether. I believe the pressures to controllers and pilots alike of trying to make an inadequate ATC system appear adequate these days has made me realize that both controllers and pilots need to slow down. We are an accident waiting to happen. We are human beings and we all occasionally make errors. I will no longer accept speed requests and high turns to final just to increase arrival traffic. The airbus limitations need to be made known to controllers. Dscnts at 250 KTS in the clean confign only give you a descent rate of approximately 1000 FPM. Use of the speed brake should be used to correct mistakes not be the normal mode of descent. All aircraft should be level and at approach speed at least 3 mi prior to intercepting the GS or 3 degree glidepath to the runway. Further dscnts during the descent phase should be issued by ATC at approximately 1000 ft prior to level or at level altitude. This would help alleviate the airbus limitations of reverting to another mode. Making every attempt by controllers to not change speeds from the airbus normal descent speed of 290 KTS in the descent mode would allow pilots to actually fly the airbus in the managed mode it was meant to fly. But barring software changes by airbus to actually maintain a speed in the descent rather than a 30 KT spread or allowing a pilot to make changes to speed in the FMC during the phase of flight they are in (similar to B737); better vigilance on my part is all I can offer.

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Original NASA ASRS Text

Title: A319 CAPT DESCENDS BELOW CROSSING RESTRICTION WHILE ATTEMPTING TO COMPLY WITH ATC ASSIGNED AIRSPEEDS.

Narrative: WHILE ON THE MAIRS2 ARR INTO PHX; WE WERE TOLD TO KEEP 300 KTS AND CROSS BRUSR AT 12000 FT AT 250 KTS. I WAS IN SELECTED SPD AND VERT DSCNT (1500 FPM) BECAUSE THE CTLR ASKED US TO KEEP THE SPD UP AS LONG AS POSSIBLE. APCH THEN ASKED US APPROX 18 MI PRIOR TO BRUSR TO INCREASE TO 310 KTS TILL BRUSR. I DECLINED AND TOLD THEM WE COULDN'T COMPLY. APPROX 8 MI PRIOR TO BRUSR; WE WERE TOLD TO DSND VIA THE MAIRS2 ARR. I WAS SURE MY ALT WAS AT 12000 FT AND I WAS IN THE PROCESS OF SLOWING TO 250 KTS SO I RESET MY ALT TO 6000 FT WHICH IS THE LOWEST ALT FOR THE FMC ARR. I THEN WENT TO ENGAGE THE SPD SO THE ACFT WOULD MEET THE SPD RESTRS ON THE ARR (I NEGLECTED TO ENGAGE MANAGED DSCNT.) IT WAS SHORTLY THEREAFTER THAT I REALIZED WE WERE DSNDING BELOW 12000 FT (APPROX 11700 FT) PRIOR TO BRUSR. I IMMEDIATELY REALIZED THAT THE 12000 FT ALT HAD NOT CAPTURED WHEN I RESET THE ALT TO 6000 FT AND WE WERE STILL IN THE VERT SPD MODE AND I IMMEDIATELY ENGAGED MANAGED DSCNT. UNFORTUNATELY; WE WERE DSNDING AT 1500 FPM AND I WENT TO VERT SPD HOLD TO ARREST THE DSCNT AND STARTED TO CLB BACK TO 12000 FT WHEN ATC QUESTIONED OUR ALT. WE HAD REACHED APPROX 11200 FT DURING THE RECOVERY AND APCH HAD US MAINTAIN 11000 FT AND ISSUED ANOTHER DSCNT CLRNC AFTER BRUSR. I TRIED TO RECOVER AS EXPEDITIOUSLY AS POSSIBLE WITHOUT OVERLY AGGRESSIVE MANEUVERS. I ALSO REALIZED THAT WE WERE CLRED FOR THE DSCNT IN ONLY 3-4 MI THAT I DID NOT MAKE ANY RASH AGGRESSIVE MOVEMENTS TO CLB BACK TO 12000 FT WHEN WE WOULD BE STARTING BACK DOWN IN 3-4 MI. THERE WERE NO ACFT NEAR US ON TCAS. I BELIEVE THE EVENT OCCURRED FOR A VARIETY OF REASONS. WE WERE IN A HIGH WORKLOAD ENVIRONMENT AT A BUSY ARPT WHERE THE CTLR HAD ASKED A NUMBER OF TIMES TO KEEP OUR SPD UP TO MAKE SOME METERING TIMES. IN ORDER TO HOLD 300 KTS AND CROSS BRUSR AT 12000 FT AT 250 KTS; I HAD TO USE SELECTED SPD AND VERT SPD BECAUSE MANAGED SPD WOULD HAVE BEEN 290 KTS GIVE OR TAKE 10-15 KTS. I PLANNED THE DSCNT TO LEVEL APPROX 8 MI TO BRUSR IN ORDER TO SLOW TO 250 KTS BY BRUSR. THE CTLRS NOWADAYS ALWAYS SEEM TO ISSUE FURTHER DSCNTS VERY CLOSE TO CAPTURING ALTS DURING DSCNTS WHICH CAN CAUSE THE ACFT TO GO OR IN OUR CASE STAY IN A VERT SPD MODE. THE LIMITATIONS OF THE AIRBUS SOFTWARE AND THE CONSTANT CHANGING OF SPD REQUESTS AND SOMETIMES HDG DEVS AND ALT REVISIONS ARE NOT COMPATIBLE WITH FMC APCHS THAT HAVE NUMEROUS CTLR ALT AND ACFT SPD CHANGES FROM THE FMC ARRS. IT IS VERY DIFFICULT TO DO A HANDS OFF MANAGED DSCNT IN TODAY'S RUSHED ATC ENVIRONMENT. YOU ARE EITHER ASKED TO KEEP THE SPD UP; SLOW DOWN; MAINTAIN ALT OR TURNED OFF THE ARR ALTOGETHER. I BELIEVE THE PRESSURES TO CTLRS AND PLTS ALIKE OF TRYING TO MAKE AN INADEQUATE ATC SYS APPEAR ADEQUATE THESE DAYS HAS MADE ME REALIZE THAT BOTH CTLRS AND PLTS NEED TO SLOW DOWN. WE ARE AN ACCIDENT WAITING TO HAPPEN. WE ARE HUMAN BEINGS AND WE ALL OCCASIONALLY MAKE ERRORS. I WILL NO LONGER ACCEPT SPD REQUESTS AND HIGH TURNS TO FINAL JUST TO INCREASE ARR TFC. THE AIRBUS LIMITATIONS NEED TO BE MADE KNOWN TO CTLRS. DSCNTS AT 250 KTS IN THE CLEAN CONFIGN ONLY GIVE YOU A DSCNT RATE OF APPROX 1000 FPM. USE OF THE SPD BRAKE SHOULD BE USED TO CORRECT MISTAKES NOT BE THE NORMAL MODE OF DSCNT. ALL ACFT SHOULD BE LEVEL AND AT APCH SPD AT LEAST 3 MI PRIOR TO INTERCEPTING THE GS OR 3 DEG GLIDEPATH TO THE RWY. FURTHER DSCNTS DURING THE DSCNT PHASE SHOULD BE ISSUED BY ATC AT APPROX 1000 FT PRIOR TO LEVEL OR AT LEVEL ALT. THIS WOULD HELP ALLEVIATE THE AIRBUS LIMITATIONS OF REVERTING TO ANOTHER MODE. MAKING EVERY ATTEMPT BY CTLRS TO NOT CHANGE SPDS FROM THE AIRBUS NORMAL DSCNT SPD OF 290 KTS IN THE DSCNT MODE WOULD ALLOW PLTS TO ACTUALLY FLY THE AIRBUS IN THE MANAGED MODE IT WAS MEANT TO FLY. BUT BARRING SOFTWARE CHANGES BY AIRBUS TO ACTUALLY MAINTAIN A SPD IN THE DSCNT RATHER THAN A 30 KT SPREAD OR ALLOWING A PLT TO MAKE CHANGES TO SPD IN THE FMC DURING THE PHASE OF FLT THEY ARE IN (SIMILAR TO B737); BETTER VIGILANCE ON MY PART IS ALL I CAN OFFER.

Data retrieved from NASA's ASRS site as of January 2009 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.