Narrative:

On radar vectors for bay visual approach runway 16R sea, cleared bay visual 'inside' sea 320 degree radial, 10 DME, at approximately 3000 ft with a speed restr of 170 KTS till boeing field. A descent for landing was started with a turn toward the final approach course. At approximately 2400 ft, the controller commanded a climb to 3000 ft, pointing out VFR traffic, and then stated we were supposed to be at 3000 ft. The VFR traffic was sighted and no conflict was noted. The subsequent approach and landing was uneventful. Approach control was contacted by phone. A supervisor stated that the controller expects a base leg (90 degrees to intercept to final) and to maintain 3000 ft until intercepting final -- presumably to prevent conflicts with boeing field traffic. There are no altitude restrs on the bay visual to reflect this, nor did it appear that our aircraft came in conflict with TCA limits. If a true conflict with boeing VFR traffic is possible, I suggest the altitude restrs be displayed and the course depicted to show a 90 degree intercept angle. Callback conversation with reporter revealed the following information: reporter states that there has been no further follow-up. Since the flight was under radar vectors, there was no way to make a 90 degree intercept to the final approach. The crew did see the boeing field traffic below and about 1 mi to the right. They felt comfortable with the separation. Reporter said that the visual approachs for traffic from the south do have altitude restrs indicated. He feels more guidance in writing is needed if controllers 'expect' certain altitudes to be used. There are visual approachs where one can descend below the class B airspace when on a visual. Las is one of these, and if expected to remain above the class B, it is so stated. Supplemental information from acn 432603: approximately 9 NM from sea VORTAC, descended to 2400 ft MSL. At approximately 7 DME, controller pointed out VFR traffic at 1 O'clock and 1500 ft. Then he stated we should have been at 3000 ft MSL. We climbed to 3000 ft MSL, the made normal visual approach/landing at sea. During a phone conversation with the controller, he stated that approach 'expects' a base turn to final and 'expects' aircraft to maintain 3000 ft until intercepting final. The sea bay visual approach to runway 16R has no altitude restrs, and approach should not clear an aircraft based on expectations contrary to requirements.

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Original NASA ASRS Text

Title: A B757 FLC FLYING A CHARTED VISUAL APCH ON RADAR VECTORS IS TOLD THEY HAVE DSNDED BELOW THE PROPER ALT AND TO CLB TO 3000 FT. THEY COMPLY.

Narrative: ON RADAR VECTORS FOR BAY VISUAL APCH RWY 16R SEA, CLRED BAY VISUAL 'INSIDE' SEA 320 DEG RADIAL, 10 DME, AT APPROX 3000 FT WITH A SPD RESTR OF 170 KTS TILL BOEING FIELD. A DSCNT FOR LNDG WAS STARTED WITH A TURN TOWARD THE FINAL APCH COURSE. AT APPROX 2400 FT, THE CTLR COMMANDED A CLB TO 3000 FT, POINTING OUT VFR TFC, AND THEN STATED WE WERE SUPPOSED TO BE AT 3000 FT. THE VFR TFC WAS SIGHTED AND NO CONFLICT WAS NOTED. THE SUBSEQUENT APCH AND LNDG WAS UNEVENTFUL. APCH CTL WAS CONTACTED BY PHONE. A SUPVR STATED THAT THE CTLR EXPECTS A BASE LEG (90 DEGS TO INTERCEPT TO FINAL) AND TO MAINTAIN 3000 FT UNTIL INTERCEPTING FINAL -- PRESUMABLY TO PREVENT CONFLICTS WITH BOEING FIELD TFC. THERE ARE NO ALT RESTRS ON THE BAY VISUAL TO REFLECT THIS, NOR DID IT APPEAR THAT OUR ACFT CAME IN CONFLICT WITH TCA LIMITS. IF A TRUE CONFLICT WITH BOEING VFR TFC IS POSSIBLE, I SUGGEST THE ALT RESTRS BE DISPLAYED AND THE COURSE DEPICTED TO SHOW A 90 DEG INTERCEPT ANGLE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT THERE HAS BEEN NO FURTHER FOLLOW-UP. SINCE THE FLT WAS UNDER RADAR VECTORS, THERE WAS NO WAY TO MAKE A 90 DEG INTERCEPT TO THE FINAL APCH. THE CREW DID SEE THE BOEING FIELD TFC BELOW AND ABOUT 1 MI TO THE R. THEY FELT COMFORTABLE WITH THE SEPARATION. RPTR SAID THAT THE VISUAL APCHS FOR TFC FROM THE S DO HAVE ALT RESTRS INDICATED. HE FEELS MORE GUIDANCE IN WRITING IS NEEDED IF CTLRS 'EXPECT' CERTAIN ALTS TO BE USED. THERE ARE VISUAL APCHS WHERE ONE CAN DSND BELOW THE CLASS B AIRSPACE WHEN ON A VISUAL. LAS IS ONE OF THESE, AND IF EXPECTED TO REMAIN ABOVE THE CLASS B, IT IS SO STATED. SUPPLEMENTAL INFO FROM ACN 432603: APPROX 9 NM FROM SEA VORTAC, DSNDED TO 2400 FT MSL. AT APPROX 7 DME, CTLR POINTED OUT VFR TFC AT 1 O'CLOCK AND 1500 FT. THEN HE STATED WE SHOULD HAVE BEEN AT 3000 FT MSL. WE CLBED TO 3000 FT MSL, THE MADE NORMAL VISUAL APCH/LNDG AT SEA. DURING A PHONE CONVERSATION WITH THE CTLR, HE STATED THAT APCH 'EXPECTS' A BASE TURN TO FINAL AND 'EXPECTS' ACFT TO MAINTAIN 3000 FT UNTIL INTERCEPTING FINAL. THE SEA BAY VISUAL APCH TO RWY 16R HAS NO ALT RESTRS, AND APCH SHOULD NOT CLR AN ACFT BASED ON EXPECTATIONS CONTRARY TO REQUIREMENTS.

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.