B757 FLT CREW LWOC AT DEN.

Narrative

THIS EVENT OCCURRED AT THE END OF A FLT SEQUENCE THAT BEGAN THE NIGHT BEFORE IN OAK; CA. THE FLT DEPARTED OAK AT XB05 AND FLEW TO CANCUN; MEXICO (MMUN); SPENT APPROX 2 HRS ON THE GND UNLOADING PAX; FUELING AND LOADING PAX; THEN WENT ON TO DEN; CO. SCHEDULED BLOCK TIME WAS 9 HRS 10 MINS; ACTUAL BLOCK TIME WAS 8 HRS 45 MINS. THE FLT SEQUENCE WAS 'HVY CREWED' (CAPT; FO AND IRO) DUE TO SCHEDULED BLOCK TIME EXCEEDING 8 HRS AND THE INTL NATURE OF THE OP. I WAS ASSIGNED TO THE FLT AS THE INFLT RELIEF OFFICER AND WAS OCCUPYING THE R SEAT AND PERFORMING PNF DUTIES AT THE TIME OF THE EVENT. THE CAPT WAS IN THE L SEAT PERFORMING PF DUTIES AND THE FO WAS ON THE JUMPSEAT. THE EVENT OCCURRED ON APCH AND LNDG TO DEN. DURING OUR ARR INTO THE DEN APCH CTL AIRSPACE; WE WERE ASSIGNED AND VECTORED FOR 3 DIFFERENT RWYS -- FIRST RWY 17R; THEN RWY 35R; THEN RWY 35L (THE RWY WE ACTUALLY LANDED ON). AFTER APCH CTL CLRED US FOR THE VISUAL TO RWY 35L AND WE JOINED THE FINAL APCH COURSE; WE WERE BUSY; STILL COMPLETING OUR APCH AND LNDG CHKLISTS. COMING DOWN FINAL APCH; WE EXPERIENCED MODERATE TURB; WHICH HAD BEEN RPTED; A SIGNIFICANT L XWIND (APPROX 15 KTS) AND SOME MINOR SHEAR (APPROX 10-15 KTS AIRSPD CHANGE). SURFACE WINDS WERE RPTED OUT OF THE SW AT APPROX 8 KTS. WE LANDED UNEVENTFULLY. HOWEVER; UPON ROLLOUT; I REALIZED AS I SWITCHED FREQS TO CALL GND CTL; THAT THE COM RADIO WAS STILL TUNED TO APCH CTL AND THAT WE HAD NEVER TALKED TO TWR; AND THUS NEVER RECEIVED A LNDG CLRNC. AT THAT TIME I SWITCHED TO TWR FREQ; STATED OUR POS AS 'EXITING RWY 35L;' AND WAS CLRED BY TWR TO THE RAMP. THERE WERE NO FURTHER COMS WITH ATC. HERE ARE THE FACTORS THAT I BELIEVE WERE CAUSAL TO THIS EVENT: 1) FATIGUE. WE LEFT THE HOTEL IN OAK AT XA00 PM PST AND LANDED AT XA00 AM MST AND DURING THAT TIME FLEW ALMOST 9 HRS. WE ALL ADMITTED THAT WE WERE FUNCTIONING AT SIGNIFICANTLY REDUCED MENTAL CAPACITY DURING APCH TO DEN. 2) CONTRIBUTING TO THE FATIGUE OF THE TRIP ITSELF IS A LONGER-TERM FATIGUE THAT COMES FROM THE WAY OUR TRIP SEQUENCES ARE SCHEDULED. IN A TYPICAL WK OF FLYING; WE MAY HAVE A 'RED-EYE' OVERNIGHT TRIP; FOLLOWED BY A TRIP WITH AN EARLY MORNING DEP; FOLLOWED BY A TRIP WITH AN AFTERNOON OR EVENING DEP. I PERSONALLY FIND IT IMPOSSIBLE FOR MY BODY CLOCK TO ADAPT AT ALL WHEN THERE IS NO CONSISTENCY IN TRIP DEP TIMES WITHIN A WK OF FLYING (WE FLY A WK ON/WK OFF SCHEDULE TYPICALLY). 3) WE WERE RUNNING BEHIND IN PERFORMING CHKLISTS. WE WERE STILL PERFORMING OUR APCH CHKLIST AS WE WERE BEING VECTORED FOR FINAL. THIS CHKLIST IS NORMALLY DONE AT FL180 DURING DSCNT. ADDITIONALLY; THE CAPT DECIDED TO DELAY EXTENSION OF LNDG GEAR DUE TO FOLLOWING TFC IN ORDER TO MAINTAIN HIGHER AIRSPD. THIS MEANT WE WERE PERFORMING OUR LNDG CHKLIST LATER DURING FINAL APCH THAN USUAL. 4) ENVIRONMENTAL FACTORS (L QUARTERING XWIND; TURB; SHEAR); COMBINED WITH 3) ABOVE; PLUS THE 3 SUCCESSIVE RWY ASSIGNMENTS; CAUSED A 'COMPRESSION OF EVENTS' INTO THE LIMITED TIME-FRAME OF THE FINAL APCH; AS WE DEALT WITH TUNING NAV RADIOS; COMMUNICATING; CHKLISTS; AND THE PHYSICAL MANEUVERING OF THE AIRPLANE.