Narrative:

En route lax-las, navigating cresco 3 STAR. Approximately 30 mi south of las, received clearance for visual approach runway 1R, VASI OTS. Discussed with first officer implications of descending visually in mountainous terrain off published route, plus no GS information. We were lulled into a false sense of security by familiarity of area, good visibility, and terrain being well lit by full moon. Approximately 10 mi south of las on the 180 degree radial, controller issued a 'below MVA' alert. We were at 4100 ft MSL. Seconds later, a GPWS warning 'terrain, terrain' only sounded with terrain in sight. An immediate climb was initiated per company procedure. We proceeded to the airport (las) and landed. I relied too heavily on experience and the terrain data on the VOR runway approach plate only. I feel there was a lack of depth perception caused by contributing factors, ie, good WX, experience, both pilots 'outside' with terrain in sight. A decrease in ability to perceive our actual AGL altitude resulted. Corrective action: no visual approachs at night in designated mountainous terrain, or at the very least, training emphasis on factors contributing to controled flight into terrain. Supplemental information from acn 351266: corrective action: night visual approachs in mountainous terrain with no GS information is not an every day procedure and an emphasis should be placed on following an approach procedure's ground track and altitude restrs or at least staying above the base of the class B airspace. Also, consider nighttime visual acuity and visual illusions. Callback conversation with reporter acn #351150 revealed the following information: reporter states that it was quite a surprise and very startling to have the GPWS activate when they could see the terrain and felt they were clear. There was a very high level of consternation and he remembers saying, 'this is making me nervous, let's get out of here.' reporter states that seeing the cftt videos in training makes one think, how could anyone fly into the terrain in VFR conditions? But this experience has made a believer out of him. The next day this same flight crew flew the same route in daylight and received the same clearance. They took particular note of the terrain in that same area and even received the same GPWS alert. Reporter feels it is partially a problem of the sensitivity of the GPWS itself and secondly a factor of the terrain rising. The radar altimeter had not activated so they know they were more than 2500 ft above terrain. On the daylight flight they were well past the last bump in the terrain and the GPWS still was set off. It is not uncommon to get an alert in mountainous terrain, but when one can see so clearly and feel comfortable with the clearance from terrain it really scares one to hear the alarm.

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Original NASA ASRS Text

Title: FLC ON NIGHT FLT IN MOUNTAINOUS TERRAIN IS ASSIGNED A VISUAL APCH. BRIGHT MOONLIGHT NIGHT GOOD VISIBILITY BUT THEY RECEIVE A GPWS WARNING. ATC ALSO GAVE A MVA ALERT. FLT CREW CLIMBED PER COMPANY PROC.

Narrative: ENRTE LAX-LAS, NAVING CRESCO 3 STAR. APPROX 30 MI S OF LAS, RECEIVED CLRNC FOR VISUAL APCH RWY 1R, VASI OTS. DISCUSSED WITH FO IMPLICATIONS OF DSNDING VISUALLY IN MOUNTAINOUS TERRAIN OFF PUBLISHED RTE, PLUS NO GS INFO. WE WERE LULLED INTO A FALSE SENSE OF SECURITY BY FAMILIARITY OF AREA, GOOD VISIBILITY, AND TERRAIN BEING WELL LIT BY FULL MOON. APPROX 10 MI S OF LAS ON THE 180 DEG RADIAL, CTLR ISSUED A 'BELOW MVA' ALERT. WE WERE AT 4100 FT MSL. SECONDS LATER, A GPWS WARNING 'TERRAIN, TERRAIN' ONLY SOUNDED WITH TERRAIN IN SIGHT. AN IMMEDIATE CLB WAS INITIATED PER COMPANY PROC. WE PROCEEDED TO THE ARPT (LAS) AND LANDED. I RELIED TOO HEAVILY ON EXPERIENCE AND THE TERRAIN DATA ON THE VOR RWY APCH PLATE ONLY. I FEEL THERE WAS A LACK OF DEPTH PERCEPTION CAUSED BY CONTRIBUTING FACTORS, IE, GOOD WX, EXPERIENCE, BOTH PLTS 'OUTSIDE' WITH TERRAIN IN SIGHT. A DECREASE IN ABILITY TO PERCEIVE OUR ACTUAL AGL ALT RESULTED. CORRECTIVE ACTION: NO VISUAL APCHS AT NIGHT IN DESIGNATED MOUNTAINOUS TERRAIN, OR AT THE VERY LEAST, TRAINING EMPHASIS ON FACTORS CONTRIBUTING TO CTLED FLT INTO TERRAIN. SUPPLEMENTAL INFO FROM ACN 351266: CORRECTIVE ACTION: NIGHT VISUAL APCHS IN MOUNTAINOUS TERRAIN WITH NO GS INFO IS NOT AN EVERY DAY PROC AND AN EMPHASIS SHOULD BE PLACED ON FOLLOWING AN APCH PROC'S GND TRACK AND ALT RESTRS OR AT LEAST STAYING ABOVE THE BASE OF THE CLASS B AIRSPACE. ALSO, CONSIDER NIGHTTIME VISUAL ACUITY AND VISUAL ILLUSIONS. CALLBACK CONVERSATION WITH RPTR ACN #351150 REVEALED THE FOLLOWING INFO: RPTR STATES THAT IT WAS QUITE A SURPRISE AND VERY STARTLING TO HAVE THE GPWS ACTIVATE WHEN THEY COULD SEE THE TERRAIN AND FELT THEY WERE CLR. THERE WAS A VERY HIGH LEVEL OF CONSTERNATION AND HE REMEMBERS SAYING, 'THIS IS MAKING ME NERVOUS, LET'S GET OUT OF HERE.' RPTR STATES THAT SEEING THE CFTT VIDEOS IN TRAINING MAKES ONE THINK, HOW COULD ANYONE FLY INTO THE TERRAIN IN VFR CONDITIONS? BUT THIS EXPERIENCE HAS MADE A BELIEVER OUT OF HIM. THE NEXT DAY THIS SAME FLC FLEW THE SAME RTE IN DAYLIGHT AND RECEIVED THE SAME CLRNC. THEY TOOK PARTICULAR NOTE OF THE TERRAIN IN THAT SAME AREA AND EVEN RECEIVED THE SAME GPWS ALERT. RPTR FEELS IT IS PARTIALLY A PROB OF THE SENSITIVITY OF THE GPWS ITSELF AND SECONDLY A FACTOR OF THE TERRAIN RISING. THE RADAR ALTIMETER HAD NOT ACTIVATED SO THEY KNOW THEY WERE MORE THAN 2500 FT ABOVE TERRAIN. ON THE DAYLIGHT FLT THEY WERE WELL PAST THE LAST BUMP IN THE TERRAIN AND THE GPWS STILL WAS SET OFF. IT IS NOT UNCOMMON TO GET AN ALERT IN MOUNTAINOUS TERRAIN, BUT WHEN ONE CAN SEE SO CLRLY AND FEEL COMFORTABLE WITH THE CLRNC FROM TERRAIN IT REALLY SCARES ONE TO HEAR THE ALARM.

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