Narrative:

During the descent, in night VFR conditions on a flight from lax-las approach control issued vectors off of the (creso 3 arrival) and speed 210 KTS. A visual approach for runway 25L was to be expected. A clearance was issued to descend to 8000 ft, while on downwind. Terrain and airport in sight, a heading of 030 degrees was assigned and another descend clearance to 6100 ft was issued. The autoplt and autothrottle were still engaged. The descend was initiated using (level change mode). At approximately 6400 ft the GPWS warning 'terrain, terrain' sounded. I immediately disengaged the autoplt and autothrottle and initiated the immediate action procedure (which calls for in addition to disconnecting the autoplt and autothrottle, calls for maximum thrust and initial pitch of 15 degrees anu). At approximately the same time ATC was advised of the climb. The GPWS warning stopped at approximately 7500 ft. ATC said that the MVA was 6100 ft and asked how high we needed to climb. At that point he was advised that the GPWS warning had stopped and we can maintain present altitude (7800 ft). ATC approved and assigned us a heading of 010 degrees and pointed out the traffic we were to follow to the airport, once traffic was in sight we called it and the airport in sight and we were cleared for the visual runway 25L approach. The approach and landing was uneventful. I contacted approach control supervisor and was told that the altitude they normally issue is 6500 ft for the traffic in that sector. I explained that we had to follow our procedure for a GPWS warning. He said no further action is required, I thanked him for his time and he thanked me for calling. We hung up. I think that a heading with more easterly direction may have prevented the GPWS warning, and of course a higher altitude on downwind (higher than 6100 ft) would've helped also. Traffic conflict with traffic overhead could have resulted during our climb to escape the warning. Luckily the area above was clear of traffic. I am sure that the rate of descent was a factor in this situation, but the airplane was on a normal (level change) descent. We had the terrain in sight the whole time. But it was nighttime and our procedure calls for the type of recovery we used during this situation. Maybe our partners at approach control should have the GPWS warnings and what triggers them explained in more details.

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Original NASA ASRS Text

Title: MLG ACFT ON VECTORS AND DSCNT CLRNCS RECEIVED GPWS 'TERRAIN' WARNING AND COMPLIED WITH PROCS OF APPLYING MAX THRUST AND PITCH UP 15 DEGS UNTIL WARNING CEASES. FLC ADVISED ATC OF MANEUVER AND CONTACTED THEM AFTER LNDG.

Narrative: DURING THE DSCNT, IN NIGHT VFR CONDITIONS ON A FLT FROM LAX-LAS APCH CTL ISSUED VECTORS OFF OF THE (CRESO 3 ARR) AND SPD 210 KTS. A VISUAL APCH FOR RWY 25L WAS TO BE EXPECTED. A CLRNC WAS ISSUED TO DSND TO 8000 FT, WHILE ON DOWNWIND. TERRAIN AND ARPT IN SIGHT, A HDG OF 030 DEGS WAS ASSIGNED AND ANOTHER DSND CLRNC TO 6100 FT WAS ISSUED. THE AUTOPLT AND AUTOTHROTTLE WERE STILL ENGAGED. THE DSND WAS INITIATED USING (LEVEL CHANGE MODE). AT APPROX 6400 FT THE GPWS WARNING 'TERRAIN, TERRAIN' SOUNDED. I IMMEDIATELY DISENGAGED THE AUTOPLT AND AUTOTHROTTLE AND INITIATED THE IMMEDIATE ACTION PROC (WHICH CALLS FOR IN ADDITION TO DISCONNECTING THE AUTOPLT AND AUTOTHROTTLE, CALLS FOR MAX THRUST AND INITIAL PITCH OF 15 DEGS ANU). AT APPROX THE SAME TIME ATC WAS ADVISED OF THE CLB. THE GPWS WARNING STOPPED AT APPROX 7500 FT. ATC SAID THAT THE MVA WAS 6100 FT AND ASKED HOW HIGH WE NEEDED TO CLB. AT THAT POINT HE WAS ADVISED THAT THE GPWS WARNING HAD STOPPED AND WE CAN MAINTAIN PRESENT ALT (7800 FT). ATC APPROVED AND ASSIGNED US A HDG OF 010 DEGS AND POINTED OUT THE TFC WE WERE TO FOLLOW TO THE ARPT, ONCE TFC WAS IN SIGHT WE CALLED IT AND THE ARPT IN SIGHT AND WE WERE CLRED FOR THE VISUAL RWY 25L APCH. THE APCH AND LNDG WAS UNEVENTFUL. I CONTACTED APCH CTL SUPVR AND WAS TOLD THAT THE ALT THEY NORMALLY ISSUE IS 6500 FT FOR THE TFC IN THAT SECTOR. I EXPLAINED THAT WE HAD TO FOLLOW OUR PROC FOR A GPWS WARNING. HE SAID NO FURTHER ACTION IS REQUIRED, I THANKED HIM FOR HIS TIME AND HE THANKED ME FOR CALLING. WE HUNG UP. I THINK THAT A HEADING WITH MORE EASTERLY DIRECTION MAY HAVE PREVENTED THE GPWS WARNING, AND OF COURSE A HIGHER ALT ON DOWNWIND (HIGHER THAN 6100 FT) WOULD'VE HELPED ALSO. TFC CONFLICT WITH TFC OVERHEAD COULD HAVE RESULTED DURING OUR CLB TO ESCAPE THE WARNING. LUCKILY THE AREA ABOVE WAS CLR OF TFC. I AM SURE THAT THE RATE OF DSCNT WAS A FACTOR IN THIS SIT, BUT THE AIRPLANE WAS ON A NORMAL (LEVEL CHANGE) DSCNT. WE HAD THE TERRAIN IN SIGHT THE WHOLE TIME. BUT IT WAS NIGHTTIME AND OUR PROC CALLS FOR THE TYPE OF RECOVERY WE USED DURING THIS SIT. MAYBE OUR PARTNERS AT APCH CTL SHOULD HAVE THE GPWS WARNINGS AND WHAT TRIGGERS THEM EXPLAINED IN MORE DETAILS.

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.