Narrative:

Near midair collision/exceeded 30 degree bank angle. Departing las on OASYS2 departure, near oasys intersection, climbing through 7000 ft for 8000 ft we were given clearance to 15000 ft. Frequency 125.9. Aircraft ahead was at 8500 ft. We saw him descend through 8500 ft to 8100 ft and knew he did not intend (or was cleared to descend) below VFR separation and the controller should not have given us clearance to 15000 ft. We had decided to delay the climb until passed traffic, but now had a lethal conflict. The RA sounded descend, but I elected not to descend into rapidly rising terrain. The cessna was slightly to our right, passing through 100 ft above us, less than 1/4 mi. I elected to break hard left. Using 60 degree bank turn we cleared the traffic.

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Original NASA ASRS Text

Title: B737-300 CREW TOOK EVASIVE ACTION TO AVOID A CESSNA WHILE FLYING ON THE OASYS 2 DEPARTING LAS.

Narrative: NMAC/EXCEEDED 30 DEG BANK ANGLE. DEPARTING LAS ON OASYS2 DEP, NEAR OASYS INTXN, CLBING THROUGH 7000 FT FOR 8000 FT WE WERE GIVEN CLRNC TO 15000 FT. FREQ 125.9. ACFT AHEAD WAS AT 8500 FT. WE SAW HIM DSND THROUGH 8500 FT TO 8100 FT AND KNEW HE DID NOT INTEND (OR WAS CLRED TO DSND) BELOW VFR SEPARATION AND THE CTLR SHOULD NOT HAVE GIVEN US CLRNC TO 15000 FT. WE HAD DECIDED TO DELAY THE CLB UNTIL PASSED TFC, BUT NOW HAD A LETHAL CONFLICT. THE RA SOUNDED DSND, BUT I ELECTED NOT TO DSND INTO RAPIDLY RISING TERRAIN. THE CESSNA WAS SLIGHTLY TO OUR R, PASSING THROUGH 100 FT ABOVE US, LESS THAN 1/4 MI. I ELECTED TO BREAK HARD L. USING 60 DEG BANK TURN WE CLRED THE TFC.

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.