Narrative:

ATIS reported that winds at rno were out of the north at 9 KTS and visual approachs to runway 34R were in use. The ILS and back course localizer were OTS and runway 16R/34L was closed. There are no instrument approachs published for runway 34R so a visual approach was required. Visibility was not restr by WX; but approach would be made in dusk lighting conditions under an overcast layer at around 17000 ft MSL. I had not landed to the north at rno previously so I wanted to use all available aids. I was aware of the high terrain at this airport and wanted to be prepared. I discussed the arrival with the captain and I studied the 19-06 page and the back course localizer approach to runway 34L even though it would not be used. We built an FMC visual approach with a 5 mi runway extension point. I assigned an altitude of 6000 ft MSL to this waypoint to assist with vertical guidance. I chose 6000 ft MSL for 2 reasons: 1) it provided a normal 3 degree glide path to the runway threshold at 4408 ft MSL; and 2) it was compatible with the stepdown altitudes on the adjacent back course localizer runway 34L approach; which allows a descent out of 6800 ft MSL to 6000 ft MSL at a distance of 6.3 NM from the threshold of that runway. I flew approach with the autoplt engaged and coupled to the LNAV course with the intent to disconnect the autoplt just prior to the runway extension point. I used vertical speed to match the FMC-computed descent rate. At approximately 10 mi from the field; I noted the PAPI's were visible in the distance but showing mostly red. At approximately 7000 ft MSL; I received a GPWS caution of 'terrain; terrain; pull up; pull up!' I did not get any GPWS warnings first (ie; 'caution terrain') and this struck me as odd. Outside; I could see finger of a ridge line extending across our flight path; left to right. I had seen this terrain already; but had projected our flight path to be far enough above it that it would not be a concern. Perhaps in the dusk lighting conditions; I had misjudged the proximity? Upon receipt of the caution; I thought about executing the GPWS caution terrain avoidance maneuver. But I thought that this would certainly lead to us having to abandon the approach; and I did not want to do that from a visual approach in mountainous terrain with darkness approaching; especially since none of the navaids required to fly the published missed approach for the adjacent runway 34L back course localizer would be available. In addition; I was in day; VMC with a visual on the terrain that caused the caution and I felt that I could safely avoid it and continue. As a result; I elected to disconnect the autoplt; increase power; and increase pitch as required to silence the caution. This seemed to be the least risky course of action at the time; but I realize in retrospect that I did not follow company procedure as outlined in the fom and probably should have. I could see we were clear of the ridge line and I thought it was ok to resume descent; so I relaxed back pressure on the stick and started a descent; only to get a second caution ('pull up'). Apparently; we were still in the computer's caution envelope; even though we had nothing but the valley floor between us and the runway now. I again increased power and pitch to climb until the caution silenced. After climbing and leveling off; I resumed the approach using PAPI guidance and landed uneventfully on runway 34R. Contributing factors: my unfamiliarity with north approachs at rno was a factor. My choice of 6000 ft MSL may have been too low for the runway extension point at 5 mi. My poor xchk led to dipping below the FMC-computed flight path. My premature descent after the first recovery led to another caution. My decision not to abandon the approach after the first caution subjected me to a second one. Prevention: obviously; I could have done things better on this approach. I did not strictly adhere to the vertical profile I had planned in the FMC; and a better xchk will prevent that in the future. Better aircraft equipment would allow use of the charted RNAV (GPS) approach to runway 34R. The -300's avionics are not compatible with RNAV (GPS) approachs; and while the -700's avionics are probably capable; we are prohibited by opsspecs from flying these kinds of approachs.

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Original NASA ASRS Text

Title: A B737-300 RECEIVED A GPWS CAUTION APCHING RNO RWY 34R LOW ON A MANUALLY BUILT FMS APCH.

Narrative: ATIS RPTED THAT WINDS AT RNO WERE OUT OF THE N AT 9 KTS AND VISUAL APCHS TO RWY 34R WERE IN USE. THE ILS AND BACK COURSE LOC WERE OTS AND RWY 16R/34L WAS CLOSED. THERE ARE NO INST APCHS PUBLISHED FOR RWY 34R SO A VISUAL APCH WAS REQUIRED. VISIBILITY WAS NOT RESTR BY WX; BUT APCH WOULD BE MADE IN DUSK LIGHTING CONDITIONS UNDER AN OVCST LAYER AT AROUND 17000 FT MSL. I HAD NOT LANDED TO THE N AT RNO PREVIOUSLY SO I WANTED TO USE ALL AVAILABLE AIDS. I WAS AWARE OF THE HIGH TERRAIN AT THIS ARPT AND WANTED TO BE PREPARED. I DISCUSSED THE ARR WITH THE CAPT AND I STUDIED THE 19-06 PAGE AND THE BACK COURSE LOC APCH TO RWY 34L EVEN THOUGH IT WOULD NOT BE USED. WE BUILT AN FMC VISUAL APCH WITH A 5 MI RWY EXTENSION POINT. I ASSIGNED AN ALT OF 6000 FT MSL TO THIS WAYPOINT TO ASSIST WITH VERT GUIDANCE. I CHOSE 6000 FT MSL FOR 2 REASONS: 1) IT PROVIDED A NORMAL 3 DEG GLIDE PATH TO THE RWY THRESHOLD AT 4408 FT MSL; AND 2) IT WAS COMPATIBLE WITH THE STEPDOWN ALTS ON THE ADJACENT BACK COURSE LOC RWY 34L APCH; WHICH ALLOWS A DSCNT OUT OF 6800 FT MSL TO 6000 FT MSL AT A DISTANCE OF 6.3 NM FROM THE THRESHOLD OF THAT RWY. I FLEW APCH WITH THE AUTOPLT ENGAGED AND COUPLED TO THE LNAV COURSE WITH THE INTENT TO DISCONNECT THE AUTOPLT JUST PRIOR TO THE RWY EXTENSION POINT. I USED VERT SPD TO MATCH THE FMC-COMPUTED DSCNT RATE. AT APPROX 10 MI FROM THE FIELD; I NOTED THE PAPI'S WERE VISIBLE IN THE DISTANCE BUT SHOWING MOSTLY RED. AT APPROX 7000 FT MSL; I RECEIVED A GPWS CAUTION OF 'TERRAIN; TERRAIN; PULL UP; PULL UP!' I DID NOT GET ANY GPWS WARNINGS FIRST (IE; 'CAUTION TERRAIN') AND THIS STRUCK ME AS ODD. OUTSIDE; I COULD SEE FINGER OF A RIDGE LINE EXTENDING ACROSS OUR FLT PATH; L TO R. I HAD SEEN THIS TERRAIN ALREADY; BUT HAD PROJECTED OUR FLT PATH TO BE FAR ENOUGH ABOVE IT THAT IT WOULD NOT BE A CONCERN. PERHAPS IN THE DUSK LIGHTING CONDITIONS; I HAD MISJUDGED THE PROX? UPON RECEIPT OF THE CAUTION; I THOUGHT ABOUT EXECUTING THE GPWS CAUTION TERRAIN AVOIDANCE MANEUVER. BUT I THOUGHT THAT THIS WOULD CERTAINLY LEAD TO US HAVING TO ABANDON THE APCH; AND I DID NOT WANT TO DO THAT FROM A VISUAL APCH IN MOUNTAINOUS TERRAIN WITH DARKNESS APCHING; ESPECIALLY SINCE NONE OF THE NAVAIDS REQUIRED TO FLY THE PUBLISHED MISSED APCH FOR THE ADJACENT RWY 34L BACK COURSE LOC WOULD BE AVAILABLE. IN ADDITION; I WAS IN DAY; VMC WITH A VISUAL ON THE TERRAIN THAT CAUSED THE CAUTION AND I FELT THAT I COULD SAFELY AVOID IT AND CONTINUE. AS A RESULT; I ELECTED TO DISCONNECT THE AUTOPLT; INCREASE PWR; AND INCREASE PITCH AS REQUIRED TO SILENCE THE CAUTION. THIS SEEMED TO BE THE LEAST RISKY COURSE OF ACTION AT THE TIME; BUT I REALIZE IN RETROSPECT THAT I DID NOT FOLLOW COMPANY PROC AS OUTLINED IN THE FOM AND PROBABLY SHOULD HAVE. I COULD SEE WE WERE CLR OF THE RIDGE LINE AND I THOUGHT IT WAS OK TO RESUME DSCNT; SO I RELAXED BACK PRESSURE ON THE STICK AND STARTED A DSCNT; ONLY TO GET A SECOND CAUTION ('PULL UP'). APPARENTLY; WE WERE STILL IN THE COMPUTER'S CAUTION ENVELOPE; EVEN THOUGH WE HAD NOTHING BUT THE VALLEY FLOOR BTWN US AND THE RWY NOW. I AGAIN INCREASED PWR AND PITCH TO CLB UNTIL THE CAUTION SILENCED. AFTER CLBING AND LEVELING OFF; I RESUMED THE APCH USING PAPI GUIDANCE AND LANDED UNEVENTFULLY ON RWY 34R. CONTRIBUTING FACTORS: MY UNFAMILIARITY WITH N APCHS AT RNO WAS A FACTOR. MY CHOICE OF 6000 FT MSL MAY HAVE BEEN TOO LOW FOR THE RWY EXTENSION POINT AT 5 MI. MY POOR XCHK LED TO DIPPING BELOW THE FMC-COMPUTED FLT PATH. MY PREMATURE DSCNT AFTER THE FIRST RECOVERY LED TO ANOTHER CAUTION. MY DECISION NOT TO ABANDON THE APCH AFTER THE FIRST CAUTION SUBJECTED ME TO A SECOND ONE. PREVENTION: OBVIOUSLY; I COULD HAVE DONE THINGS BETTER ON THIS APCH. I DID NOT STRICTLY ADHERE TO THE VERT PROFILE I HAD PLANNED IN THE FMC; AND A BETTER XCHK WILL PREVENT THAT IN THE FUTURE. BETTER ACFT EQUIP WOULD ALLOW USE OF THE CHARTED RNAV (GPS) APCH TO RWY 34R. THE -300'S AVIONICS ARE NOT COMPATIBLE WITH RNAV (GPS) APCHS; AND WHILE THE -700'S AVIONICS ARE PROBABLY CAPABLE; WE ARE PROHIBITED BY OPSSPECS FROM FLYING THESE KINDS OF APCHS.

Data retrieved from NASA's ASRS site as of January 2009 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.