Narrative:

The first officer was flying a descent profile (coatt 1 arrival, coatt.coatt 1) to dulles. At approximately 20 mi on the 214 degree right of broke VOR (brv 114.5), we were cleared from 15000 to 11000'. Shortly thereafter the first officer descended momentarily to 10600' and immediately recovered to 11000'. Neither pilot saw nor heard the altitude alert. To reduce cockpit workload to fly this aircraft with 2 pilots, the company and the pilot agreed that among other things there would always be a fully operational automatic pressure controller. A recent FAA directive, in effect, prohibits using the automatic pressure controller. Instead we must use the standby pressure controller which requires almost constant attention of the first officer (particularly during descent). The /first officer was distracted by monitoring and adjusting the pressure controller and maintaining a visibility lookout. The normal clearance at that point is to 10000' as per the published profile. The captain was distracted with attempting to establish contact on a new communications frequency, completing the approach descent checklist and watching for traffic. The FAA directive and its additional operational requirements increases the cockpit workload, on occasion, beyond acceptable safety margins.

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Original NASA ASRS Text

Title: ACR MLG ALT DEVIATION OVERSHOT DURING DESCENT. FLT CREW CLAIMS FAA DIRECTIVE FOR OPERATING ACFT PRESSURIZATION CONTROL WAS A DISTRACTION.

Narrative: THE F/O WAS FLYING A DSCNT PROFILE (COATT 1 ARR, COATT.COATT 1) TO DULLES. AT APPROX 20 MI ON THE 214 DEG R OF BROKE VOR (BRV 114.5), WE WERE CLRED FROM 15000 TO 11000'. SHORTLY THEREAFTER THE F/O DSNDED MOMENTARILY TO 10600' AND IMMEDIATELY RECOVERED TO 11000'. NEITHER PLT SAW NOR HEARD THE ALT ALERT. TO REDUCE COCKPIT WORKLOAD TO FLY THIS ACFT WITH 2 PLTS, THE COMPANY AND THE PLT AGREED THAT AMONG OTHER THINGS THERE WOULD ALWAYS BE A FULLY OPERATIONAL AUTOMATIC PRESSURE CTLR. A RECENT FAA DIRECTIVE, IN EFFECT, PROHIBITS USING THE AUTOMATIC PRESSURE CTLR. INSTEAD WE MUST USE THE STANDBY PRESSURE CTLR WHICH REQUIRES ALMOST CONSTANT ATTN OF THE F/O (PARTICULARLY DURING DSCNT). THE /FO WAS DISTRACTED BY MONITORING AND ADJUSTING THE PRESSURE CTLR AND MAINTAINING A VIS LOOKOUT. THE NORMAL CLRNC AT THAT POINT IS TO 10000' AS PER THE PUBLISHED PROFILE. THE CAPT WAS DISTRACTED WITH ATTEMPTING TO ESTABLISH CONTACT ON A NEW COMS FREQ, COMPLETING THE APCH DSCNT CHKLIST AND WATCHING FOR TFC. THE FAA DIRECTIVE AND ITS ADDITIONAL OPERATIONAL REQUIREMENTS INCREASES THE COCKPIT WORKLOAD, ON OCCASION, BEYOND ACCEPTABLE SAFETY MARGINS.

Data retrieved from NASA's ASRS site as of August 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.