Narrative:

Departed sna on musel departure; daggett transition. I was the PF. We were cleared to 8000 ft; on radar vectors. We were in a climbing right turn; passing 7000 ft; when the TCAS advised; 'traffic.' I glanced down at the screen and saw a yellow target showing '+9.' the TCAS then advised 'reduce vertical speed;' followed immediately by 'descend; descend;' followed immediately by 'increase descent.' during the advisories; I clicked off the autoplt and autothrottles and aggressively pushed the nose over. We peaked at about 7500 ft. The light twin went directly overhead about 400-500 away. We advised ATC that we were complying with a TCAS RA. The controller said 'I show traffic behind you at 8000 ft.' we said; 'yes; that's the guy -- you cleared us to 8000 ft.' the controller said; 'roger.' I called the socal TRACON after we landed and the operations manager had reviewed the incident. He said the aircraft was not in class B airspace; was not talking to socal (not required); and had an intermittent mode C readout. We had a captain on the jumpseat; and all 3 of us agreed that had it not been for TCAS and the corrective action; we would have collided with the light twin. I credit 2 things for saving us from colliding. 1) TCAS; 2) the training I have received and the constant reminders from my airline's safety department about instantly complying with RA's. 'Don't think -- fly the jet' is the message when it comes to RA's; and in this case it saved us.

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Original NASA ASRS Text

Title: AN MD90 PILOT DEPARTING SNA REPORTS AN NMAC WITH A LIGHT TWIN AS IT RESPONDED TO A TCAS AT 8000 FT.

Narrative: DEPARTED SNA ON MUSEL DEP; DAGGETT TRANSITION. I WAS THE PF. WE WERE CLRED TO 8000 FT; ON RADAR VECTORS. WE WERE IN A CLBING R TURN; PASSING 7000 FT; WHEN THE TCAS ADVISED; 'TFC.' I GLANCED DOWN AT THE SCREEN AND SAW A YELLOW TARGET SHOWING '+9.' THE TCAS THEN ADVISED 'REDUCE VERT SPD;' FOLLOWED IMMEDIATELY BY 'DSND; DSND;' FOLLOWED IMMEDIATELY BY 'INCREASE DSCNT.' DURING THE ADVISORIES; I CLICKED OFF THE AUTOPLT AND AUTOTHROTTLES AND AGGRESSIVELY PUSHED THE NOSE OVER. WE PEAKED AT ABOUT 7500 FT. THE LIGHT TWIN WENT DIRECTLY OVERHEAD ABOUT 400-500 AWAY. WE ADVISED ATC THAT WE WERE COMPLYING WITH A TCAS RA. THE CTLR SAID 'I SHOW TFC BEHIND YOU AT 8000 FT.' WE SAID; 'YES; THAT'S THE GUY -- YOU CLRED US TO 8000 FT.' THE CTLR SAID; 'ROGER.' I CALLED THE SOCAL TRACON AFTER WE LANDED AND THE OPS MGR HAD REVIEWED THE INCIDENT. HE SAID THE ACFT WAS NOT IN CLASS B AIRSPACE; WAS NOT TALKING TO SOCAL (NOT REQUIRED); AND HAD AN INTERMITTENT MODE C READOUT. WE HAD A CAPT ON THE JUMPSEAT; AND ALL 3 OF US AGREED THAT HAD IT NOT BEEN FOR TCAS AND THE CORRECTIVE ACTION; WE WOULD HAVE COLLIDED WITH THE LIGHT TWIN. I CREDIT 2 THINGS FOR SAVING US FROM COLLIDING. 1) TCAS; 2) THE TRAINING I HAVE RECEIVED AND THE CONSTANT REMINDERS FROM MY AIRLINE'S SAFETY DEPT ABOUT INSTANTLY COMPLYING WITH RA'S. 'DON'T THINK -- FLY THE JET' IS THE MESSAGE WHEN IT COMES TO RA'S; AND IN THIS CASE IT SAVED US.

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.