Narrative:

Climbing through 12000 ft to assigned altitude of 15000 ft, las vegas departure (133.95) had us on an assigned heading of 070 degrees for vectors for the oveto departure/bcf transition and handed us off to ZLA on 124.2. As soon as we switched over, lax started to advise us of a flight of 4 aircraft at our 1 O'clock position when the TCASII advised 'monitor vertical speed' followed immediately by 'descend, descend now' which I complied with and the first officer advised ATC. I glanced out the window and saw 4 F15 or F14 (twin tail fighters) headed straight for us. While descending they continued their descent towards us. We nosed over at 12800 ft and were 'clear of conflict' at approximately 11700 ft and resumed our climb. I asked ZLA about the traffic and was told that nobody was in contact with the aircraft. I assume the aircraft were going to nellis AFB but don't know for sure. Notes: 1) prior to handoff, las departure said nothing about the traffic. 2) if we did not have TCASII, I am 99% sure we would have had a midair collision. (Lax was trying to tell us but it would have been too late.) 3) reason for deviation from an ATC clearance: avoid midair collision. The TCASII was correct, the traffic was there. 4) I did not note the radial and distance from the las VOR but I did note the latitude/longitude approximately 1-2 mins after event.

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Original NASA ASRS Text

Title: A B757-200 CLBING NE OF LAS ENCOUNTERS A FLT OF 4 F15'S DSNDING, OPPOSITE DIRECTION TFC. TCASII SAVES THE DAY WHEN TA NOT GIVEN BY DEP CTLR AT LAS.

Narrative: CLBING THROUGH 12000 FT TO ASSIGNED ALT OF 15000 FT, LAS VEGAS DEP (133.95) HAD US ON AN ASSIGNED HDG OF 070 DEGS FOR VECTORS FOR THE OVETO DEP/BCF TRANSITION AND HANDED US OFF TO ZLA ON 124.2. AS SOON AS WE SWITCHED OVER, LAX STARTED TO ADVISE US OF A FLT OF 4 ACFT AT OUR 1 O'CLOCK POS WHEN THE TCASII ADVISED 'MONITOR VERT SPD' FOLLOWED IMMEDIATELY BY 'DSND, DSND NOW' WHICH I COMPLIED WITH AND THE FO ADVISED ATC. I GLANCED OUT THE WINDOW AND SAW 4 F15 OR F14 (TWIN TAIL FIGHTERS) HEADED STRAIGHT FOR US. WHILE DSNDING THEY CONTINUED THEIR DSCNT TOWARDS US. WE NOSED OVER AT 12800 FT AND WERE 'CLR OF CONFLICT' AT APPROX 11700 FT AND RESUMED OUR CLB. I ASKED ZLA ABOUT THE TFC AND WAS TOLD THAT NOBODY WAS IN CONTACT WITH THE ACFT. I ASSUME THE ACFT WERE GOING TO NELLIS AFB BUT DON'T KNOW FOR SURE. NOTES: 1) PRIOR TO HDOF, LAS DEP SAID NOTHING ABOUT THE TFC. 2) IF WE DID NOT HAVE TCASII, I AM 99% SURE WE WOULD HAVE HAD A MIDAIR COLLISION. (LAX WAS TRYING TO TELL US BUT IT WOULD HAVE BEEN TOO LATE.) 3) REASON FOR DEV FROM AN ATC CLRNC: AVOID MIDAIR COLLISION. THE TCASII WAS CORRECT, THE TFC WAS THERE. 4) I DID NOT NOTE THE RADIAL AND DISTANCE FROM THE LAS VOR BUT I DID NOTE THE LATITUDE/LONGITUDE APPROX 1-2 MINS AFTER EVENT.

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.