Narrative:

I was the captain on a scheduled air carrier flight from ontario, ca to seattle, wa, on nov/sun/89. Our arrival time was approximately XA15 pm. The sun was low on the horizon, and directly in front effecting forward vision, but conditions were basically VFR. We were attempting a CAT III/autoland practice approach at seatac runway 16R using CAT III ILS navigational aids. Autoland practice apches are required by my company in order to complete line check rides, and maintain crew proficiency. In addition, testing of the autoland system is required in order to maintain certification for low visibility actual CAT III/autoland apches. The autoland system operated normally throughout the approach until approximately 30' radar altimeter. At 50' radar altimeter the autoplt went into flare mode flaring the aircraft normally, and the autothrottle system went into retard reducing the power or pulling the throttles back. The aircraft descended to approximately 30', and appeared to be unusually nose high, and leveling off. The aircraft's airspeed was approximately vref at this point. I felt this situation was abnormal, and could become dangerous if continued. I disconnected the autoplt, and autothrottles and rapidly advanced the power. We weighed approximately 116,000 pounds (moderate landing weight for medium large transport) on landing. By the time the engines spooled up we had already touched down. The result was a bounced, but safe landing. In order to prevent a recurrence more stable autoland systems, or higher power setting for faster engine spool ups are my only suggestions.

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Original NASA ASRS Text

Title: FLT CREW DISCONNECTS AUTOPLT AT VERY LOW ALT DURING AUTOLAND RESULTING IN CONTROLLED LNDG BOUNCE.

Narrative: I WAS THE CAPT ON A SCHEDULED AIR CARRIER FLT FROM ONTARIO, CA TO SEATTLE, WA, ON NOV/SUN/89. OUR ARR TIME WAS APPROX XA15 PM. THE SUN WAS LOW ON THE HORIZON, AND DIRECTLY IN FRONT EFFECTING FORWARD VISION, BUT CONDITIONS WERE BASICALLY VFR. WE WERE ATTEMPTING A CAT III/AUTOLAND PRACTICE APCH AT SEATAC RWY 16R USING CAT III ILS NAVIGATIONAL AIDS. AUTOLAND PRACTICE APCHES ARE REQUIRED BY MY COMPANY IN ORDER TO COMPLETE LINE CHECK RIDES, AND MAINTAIN CREW PROFICIENCY. IN ADDITION, TESTING OF THE AUTOLAND SYSTEM IS REQUIRED IN ORDER TO MAINTAIN CERTIFICATION FOR LOW VISIBILITY ACTUAL CAT III/AUTOLAND APCHES. THE AUTOLAND SYSTEM OPERATED NORMALLY THROUGHOUT THE APCH UNTIL APPROX 30' RADAR ALTIMETER. AT 50' RADAR ALTIMETER THE AUTOPLT WENT INTO FLARE MODE FLARING THE ACFT NORMALLY, AND THE AUTOTHROTTLE SYSTEM WENT INTO RETARD REDUCING THE POWER OR PULLING THE THROTTLES BACK. THE ACFT DESCENDED TO APPROX 30', AND APPEARED TO BE UNUSUALLY NOSE HIGH, AND LEVELING OFF. THE ACFT'S AIRSPEED WAS APPROX VREF AT THIS POINT. I FELT THIS SITUATION WAS ABNORMAL, AND COULD BECOME DANGEROUS IF CONTINUED. I DISCONNECTED THE AUTOPLT, AND AUTOTHROTTLES AND RAPIDLY ADVANCED THE POWER. WE WEIGHED APPROX 116,000 LBS (MODERATE LNDG WEIGHT FOR MLG) ON LNDG. BY THE TIME THE ENGINES SPOOLED UP WE HAD ALREADY TOUCHED DOWN. THE RESULT WAS A BOUNCED, BUT SAFE LNDG. IN ORDER TO PREVENT A RECURRENCE MORE STABLE AUTOLAND SYSTEMS, OR HIGHER POWER SETTING FOR FASTER ENGINE SPOOL UPS ARE MY ONLY SUGGESTIONS.

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.