Narrative:

Flight departed sfo. The flight was normal in all phases. WX en route and at first stop, stl was excellent. First officer was flying the leg. Approaching stl, ATIS reported clear 7 77/54 120/08 30.24 visibility runway 12 right&left. Landing weight of aircraft 324,000 pounds, bug setting for approach 136 KTS. Aircraft vectored for runway 12R. A normal and routine ILS runway 12R approach was flown. All normal callouts were made. Several comments were made on final approach as to the wind direction and speed. Stl tower reported wind 'calm', later followed by wind '190/12 KTS.' at approximately 50' I (first officer) closed the throttles and began a flare. At this point bob (captain), called out '10 attitude' and then I relaxed some back pressure on the control to lower the nose (approximately 8-9 degrees). My attention focused outside the aircraft, it appeared we may have floated for a second followed by a sink. Reacting to the sink, I began to apply back pressure to stop the sink, but at this point we contacted the runway. The landing was firm, but by no means excessive or hard. Rollout was normal and exit was made at taxiway H. No indications were given by F/a or passenger that anything was out of the ordinary. Aircraft parked, and normal shutdown. Post-flight inspection indicated that the tailskid contacted the runway. A later inspection (approximately 40 mins later), indicated that the APU/lav drain masts could have also struck the runway.

Related reports:

Google
 

Original NASA ASRS Text

Title: FO FLYING WDB STRIKES TAIL SKID UPON LNDG.

Narrative: FLT DEPARTED SFO. THE FLT WAS NORMAL IN ALL PHASES. WX ENRTE AND AT FIRST STOP, STL WAS EXCELLENT. F/O WAS FLYING THE LEG. APCHING STL, ATIS REPORTED CLR 7 77/54 120/08 30.24 VIS RWY 12 R&L. LNDG WEIGHT OF ACFT 324,000 LBS, BUG SETTING FOR APCH 136 KTS. ACFT VECTORED FOR RWY 12R. A NORMAL AND ROUTINE ILS RWY 12R APCH WAS FLOWN. ALL NORMAL CALLOUTS WERE MADE. SEVERAL COMMENTS WERE MADE ON FINAL APCH AS TO THE WIND DIRECTION AND SPEED. STL TWR REPORTED WIND 'CALM', LATER FOLLOWED BY WIND '190/12 KTS.' AT APPROX 50' I (F/O) CLOSED THE THROTTLES AND BEGAN A FLARE. AT THIS POINT BOB (CAPT), CALLED OUT '10 ATTITUDE' AND THEN I RELAXED SOME BACK PRESSURE ON THE CTL TO LOWER THE NOSE (APPROX 8-9 DEGS). MY ATTN FOCUSED OUTSIDE THE ACFT, IT APPEARED WE MAY HAVE FLOATED FOR A SECOND FOLLOWED BY A SINK. REACTING TO THE SINK, I BEGAN TO APPLY BACK PRESSURE TO STOP THE SINK, BUT AT THIS POINT WE CONTACTED THE RWY. THE LNDG WAS FIRM, BUT BY NO MEANS EXCESSIVE OR HARD. ROLLOUT WAS NORMAL AND EXIT WAS MADE AT TXWY H. NO INDICATIONS WERE GIVEN BY F/A OR PAX THAT ANYTHING WAS OUT OF THE ORDINARY. ACFT PARKED, AND NORMAL SHUTDOWN. POST-FLT INSPECTION INDICATED THAT THE TAILSKID CONTACTED THE RWY. A LATER INSPECTION (APPROX 40 MINS LATER), INDICATED THAT THE APU/LAV DRAIN MASTS COULD HAVE ALSO STRUCK THE RWY.

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.