Narrative:

This was a far 91 cpr flight from ege to sfo. It was the second flight of the day for this crew that had spent the night in denver. The aircraft had a crew of 2 pilots and 1 flight attendant. We had 4 passenger on board. I was the PIC and was flying the aircraft from the left seat. All the navigation, autoplt, FMC, TCASII, and radio communication system were operating normally. The WX was clear and we had a tailwind, which was unusual for our direction of flight (west) and altitude (FL350). Our routing was confirmed as direct to oak with a modesto 2 arrival to sfo. This route is very familiar to me, as I have flown it hundreds of times over 9 yrs as an sfo based pilot. We were flying at our assigned altitude of FL350. About 150 mi east of oak, ATC requested we slow the aircraft to .82 mach. The sic acknowledged and I complied immediately. This was our first indication of ATC sequencing problems along our route. Additional speed reductions were requested to 280 KTS, then 270 KTS, then as we were decreasing through 265 KTS, ATC requested 260 KTS. Later, ATC requested 250 KTS. Each speed reduction was acknowledged by the sic and I immediately complied. At about 50 mi earlier than normal, ATC requested a descent to FL310 for traffic conflict problems. The sic acknowledged and he reset the altitude preselect to FL310. During the descent, ATC began giving us numerous heading changes, first north of course and then south of our west course. I disconnected the autoplt and began to make all the numerous heading changes manually because I felt I could comply with the numerous ATC requests with more rapid response time and with less discomfort to the passenger. At this point in our route, ATC normally clears our aircraft to FL240. As we passed through FL320, the altitude alert aural tone sounded and the sic called the alert and I responded. I called for the descent checklist and the sic began obtaining the ATIS, computing the V reference speed, setting the pressure controller, etc. I was descending at a rate of about 1500 FPM. The sic called my attention to the lower than assigned altitude and I immediately began aggressive pitch and power changes consistent with safe operating procedures. After I began the correction, ATC called about our altitude which the sic acknowledged. The lowest altitude indication I saw was about FL297. There were no warnings issued by the TCASII either as TA's or RA's. The flight continued to sfo without incident. The WX at sfo airport was VFR and we flew the usual visual approach to runway 28R. Chain of events: it started with the unusual tailwind and heavy inbound and outbound high altitude traffic to and from the san francisco bay area airports. The problem was compounded by the numerous speed and heading changes requested by ATC. The aircraft may have been vectored outside the normal airspace reserved for inbound aircraft. Contributing factor occurred as the PIC disconnected the autoplt to more rapidly comply with those numerous requests. There was a lack of crew coordination in the cockpit. Crew: the crew must emphasize CRM and rethink the process that led to this incident. Perhaps additional visual cues such as hand movements -- pointing to the altitude preselect, the altimeter, and the vertical speed indicators should be instituted. All distracting factors should be prohibited during a phase of flight such as descent. The PIC should notify the sic when the autoplt is disconnected to alert the crew that a higher level of awareness is required. The crew should visit ZOA to gain a new awareness of the multitude of traffic factors that a controller must handle. The crew is scheduled to attend routine 6 month recurrent training within 30 days. This incident could be duplicated in the simulator to coordinate new cockpit procedures.

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Original NASA ASRS Text

Title: FLC OF A CPR DA50 HAS ALTDEV ON DSCNT.

Narrative: THIS WAS A FAR 91 CPR FLT FROM EGE TO SFO. IT WAS THE SECOND FLT OF THE DAY FOR THIS CREW THAT HAD SPENT THE NIGHT IN DENVER. THE ACFT HAD A CREW OF 2 PLTS AND 1 FLT ATTENDANT. WE HAD 4 PAX ON BOARD. I WAS THE PIC AND WAS FLYING THE ACFT FROM THE L SEAT. ALL THE NAV, AUTOPLT, FMC, TCASII, AND RADIO COM SYS WERE OPERATING NORMALLY. THE WX WAS CLR AND WE HAD A TAILWIND, WHICH WAS UNUSUAL FOR OUR DIRECTION OF FLT (W) AND ALT (FL350). OUR ROUTING WAS CONFIRMED AS DIRECT TO OAK WITH A MODESTO 2 ARR TO SFO. THIS RTE IS VERY FAMILIAR TO ME, AS I HAVE FLOWN IT HUNDREDS OF TIMES OVER 9 YRS AS AN SFO BASED PLT. WE WERE FLYING AT OUR ASSIGNED ALT OF FL350. ABOUT 150 MI E OF OAK, ATC REQUESTED WE SLOW THE ACFT TO .82 MACH. THE SIC ACKNOWLEDGED AND I COMPLIED IMMEDIATELY. THIS WAS OUR FIRST INDICATION OF ATC SEQUENCING PROBS ALONG OUR RTE. ADDITIONAL SPD REDUCTIONS WERE REQUESTED TO 280 KTS, THEN 270 KTS, THEN AS WE WERE DECREASING THROUGH 265 KTS, ATC REQUESTED 260 KTS. LATER, ATC REQUESTED 250 KTS. EACH SPD REDUCTION WAS ACKNOWLEDGED BY THE SIC AND I IMMEDIATELY COMPLIED. AT ABOUT 50 MI EARLIER THAN NORMAL, ATC REQUESTED A DSCNT TO FL310 FOR TFC CONFLICT PROBS. THE SIC ACKNOWLEDGED AND HE RESET THE ALT PRESELECT TO FL310. DURING THE DSCNT, ATC BEGAN GIVING US NUMEROUS HDG CHANGES, FIRST N OF COURSE AND THEN S OF OUR W COURSE. I DISCONNECTED THE AUTOPLT AND BEGAN TO MAKE ALL THE NUMEROUS HDG CHANGES MANUALLY BECAUSE I FELT I COULD COMPLY WITH THE NUMEROUS ATC REQUESTS WITH MORE RAPID RESPONSE TIME AND WITH LESS DISCOMFORT TO THE PAX. AT THIS POINT IN OUR RTE, ATC NORMALLY CLRS OUR ACFT TO FL240. AS WE PASSED THROUGH FL320, THE ALT ALERT AURAL TONE SOUNDED AND THE SIC CALLED THE ALERT AND I RESPONDED. I CALLED FOR THE DSCNT CHKLIST AND THE SIC BEGAN OBTAINING THE ATIS, COMPUTING THE V REF SPD, SETTING THE PRESSURE CTLR, ETC. I WAS DSNDING AT A RATE OF ABOUT 1500 FPM. THE SIC CALLED MY ATTN TO THE LOWER THAN ASSIGNED ALT AND I IMMEDIATELY BEGAN AGGRESSIVE PITCH AND PWR CHANGES CONSISTENT WITH SAFE OPERATING PROCS. AFTER I BEGAN THE CORRECTION, ATC CALLED ABOUT OUR ALT WHICH THE SIC ACKNOWLEDGED. THE LOWEST ALT INDICATION I SAW WAS ABOUT FL297. THERE WERE NO WARNINGS ISSUED BY THE TCASII EITHER AS TA'S OR RA'S. THE FLT CONTINUED TO SFO WITHOUT INCIDENT. THE WX AT SFO ARPT WAS VFR AND WE FLEW THE USUAL VISUAL APCH TO RWY 28R. CHAIN OF EVENTS: IT STARTED WITH THE UNUSUAL TAILWIND AND HVY INBOUND AND OUTBOUND HIGH ALT TFC TO AND FROM THE SAN FRANCISCO BAY AREA ARPTS. THE PROB WAS COMPOUNDED BY THE NUMEROUS SPD AND HDG CHANGES REQUESTED BY ATC. THE ACFT MAY HAVE BEEN VECTORED OUTSIDE THE NORMAL AIRSPACE RESERVED FOR INBOUND ACFT. CONTRIBUTING FACTOR OCCURRED AS THE PIC DISCONNECTED THE AUTOPLT TO MORE RAPIDLY COMPLY WITH THOSE NUMEROUS REQUESTS. THERE WAS A LACK OF CREW COORD IN THE COCKPIT. CREW: THE CREW MUST EMPHASIZE CRM AND RETHINK THE PROCESS THAT LED TO THIS INCIDENT. PERHAPS ADDITIONAL VISUAL CUES SUCH AS HAND MOVEMENTS -- POINTING TO THE ALT PRESELECT, THE ALTIMETER, AND THE VERT SPD INDICATORS SHOULD BE INSTITUTED. ALL DISTRACTING FACTORS SHOULD BE PROHIBITED DURING A PHASE OF FLT SUCH AS DSCNT. THE PIC SHOULD NOTIFY THE SIC WHEN THE AUTOPLT IS DISCONNECTED TO ALERT THE CREW THAT A HIGHER LEVEL OF AWARENESS IS REQUIRED. THE CREW SHOULD VISIT ZOA TO GAIN A NEW AWARENESS OF THE MULTITUDE OF TFC FACTORS THAT A CTLR MUST HANDLE. THE CREW IS SCHEDULED TO ATTEND ROUTINE 6 MONTH RECURRENT TRAINING WITHIN 30 DAYS. THIS INCIDENT COULD BE DUPLICATED IN THE SIMULATOR TO COORDINATE NEW COCKPIT PROCS.

Data retrieved from NASA's ASRS site as of July 2007 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.