Narrative:

We were asked to expedite a descent clearance from 4000 ft to 2500 ft which I (PNF) accepted, but the PF (first officer), felt this would put us in the wake of the aircraft that preceded us. He had a better vantage point and the TCASII confirmed their altitude, so I agreed and told the controller that 'we would like to stay high for wake turbulence.' this upset her and she vectored us out of the sequence for our descent. We didn't mind this, it was much safer, but she was still upset. Later they (socal) asked us to call them and we did. He explained to me that she needed me at 2500 ft MSL to turn us onto base leg. I said I realize this, but the preceding 2 aircraft were well above that altitude at the point we would have reached 2500 ft. We know this would have put us very close to wake turbulence. We were following a B737 who was staying high because of a B747 ahead of him. The B747 was a little high which made the B737 even higher and me, being the little guy, needed to stay even higher. The only way we (pilots) can stay close to other aircraft on visual (3-5 mi spacing) approachs is if we can stay above the other aircraft's flight paths. I had a hard time explaining this to the controller, and that spacing is not the only factor to consider for wake turbulence. The other aircraft's size, altitude, time-and-point in space, and wind conditions are also factors we must consider. He disagreed with me! And said that I was wrong for not complying. This upset me very much and prompted this letter. My life, my crew, my passenger, and every aircraft they handle depends on their judgement of 'safe' separation from other aircraft.

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Original NASA ASRS Text

Title: FLC OF AN LTT REFUSED AN EXPEDITED DSCNT CLRNC. THE APCH CTLR NEEDED THEM TO DSND FOR A BASE LEG AND VISUAL APCH, AND THE REFUSAL LED TO A DISCUSSION ON THE TELEPHONE AFTERWARDS. THE RPTR CLAIMS THAT THE CLRNC WOULD HAVE PUT THEM IN THE WAKE OF OTHER ACFT.

Narrative: WE WERE ASKED TO EXPEDITE A DSCNT CLRNC FROM 4000 FT TO 2500 FT WHICH I (PNF) ACCEPTED, BUT THE PF (FO), FELT THIS WOULD PUT US IN THE WAKE OF THE ACFT THAT PRECEDED US. HE HAD A BETTER VANTAGE POINT AND THE TCASII CONFIRMED THEIR ALT, SO I AGREED AND TOLD THE CTLR THAT 'WE WOULD LIKE TO STAY HIGH FOR WAKE TURB.' THIS UPSET HER AND SHE VECTORED US OUT OF THE SEQUENCE FOR OUR DSCNT. WE DIDN'T MIND THIS, IT WAS MUCH SAFER, BUT SHE WAS STILL UPSET. LATER THEY (SOCAL) ASKED US TO CALL THEM AND WE DID. HE EXPLAINED TO ME THAT SHE NEEDED ME AT 2500 FT MSL TO TURN US ONTO BASE LEG. I SAID I REALIZE THIS, BUT THE PRECEDING 2 ACFT WERE WELL ABOVE THAT ALT AT THE POINT WE WOULD HAVE REACHED 2500 FT. WE KNOW THIS WOULD HAVE PUT US VERY CLOSE TO WAKE TURB. WE WERE FOLLOWING A B737 WHO WAS STAYING HIGH BECAUSE OF A B747 AHEAD OF HIM. THE B747 WAS A LITTLE HIGH WHICH MADE THE B737 EVEN HIGHER AND ME, BEING THE LITTLE GUY, NEEDED TO STAY EVEN HIGHER. THE ONLY WAY WE (PLTS) CAN STAY CLOSE TO OTHER ACFT ON VISUAL (3-5 MI SPACING) APCHS IS IF WE CAN STAY ABOVE THE OTHER ACFT'S FLT PATHS. I HAD A HARD TIME EXPLAINING THIS TO THE CTLR, AND THAT SPACING IS NOT THE ONLY FACTOR TO CONSIDER FOR WAKE TURB. THE OTHER ACFT'S SIZE, ALT, TIME-AND-POINT IN SPACE, AND WIND CONDITIONS ARE ALSO FACTORS WE MUST CONSIDER. HE DISAGREED WITH ME! AND SAID THAT I WAS WRONG FOR NOT COMPLYING. THIS UPSET ME VERY MUCH AND PROMPTED THIS LETTER. MY LIFE, MY CREW, MY PAX, AND EVERY ACFT THEY HANDLE DEPENDS ON THEIR JUDGEMENT OF 'SAFE' SEPARATION FROM OTHER ACFT.

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.