Narrative:

First officer was flying. We were cleared to 5000 ft MSL and to turn right to a heading of 180 degrees (approximately) and look for traffic roughly 5 mi at our 1 - 2 O'clock position, going for runway 3OL at stl. (We were on vectors for lda 30R at stl.) on these approachs you must visually callout the other traffic to ATC or often times they break you off the approach. So while my first officer and myself mightily looked for our traffic we were turned to roughly a 270 degree heading and descended through 5000 ft MSL to 4000 ft MSL. I noticed this in 2 ways: 1) the aircraft we sighted 3-4 mi ahead appeared visually to be at our altitude. 2) TCASII confirmed a 0 ft altitude difference but offered no visual or aural warning. As we were constantly talking to the controller he neither noticed nor said anything. There was no collision hazard as he was ahead of us and faster. The controller cleared us for the visual for runway 30R and nothing further out of the ordinary transpired. How did it happen? 1) both captain and first officer looking for traffic with neither monitoring altitude. 2) rapid fire set of instructions by ATC which overloaded us both. 3) knowledge that if we didn't visually acquire traffic soon we would be 'broken off' the approach, thus our concentrating more on the target aircraft than altitude. How to prevent a recurrence? 1) ATC give only 1 or 2 instructions per radio call so as not to overload crew. 2) crews need to divide tasks of looking primarily to PNF and PF fly the plane but make sure PNF and PF xchk one another. 3) build a new larger airport in stl so these oddball approachs and their rules are a thing of the past.

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Original NASA ASRS Text

Title: FO OF A JETSTREAM 32 ALLOWED ACFT TO DRIFT DOWN OFF OF ASSIGNED ALT AND DEVIATED FROM ASSIGNED VECTOR HDG WHILE LOOKING FOR OTHER TFC THEY WERE ASSIGNED TO FOLLOW. CAPT WAS ALSO LOOKING FOR THE OTHER TFC. (NO ONE WAS WATCHING THE STORE.)

Narrative: FO WAS FLYING. WE WERE CLRED TO 5000 FT MSL AND TO TURN R TO A HDG OF 180 DEGS (APPROX) AND LOOK FOR TFC ROUGHLY 5 MI AT OUR 1 - 2 O'CLOCK POS, GOING FOR RWY 3OL AT STL. (WE WERE ON VECTORS FOR LDA 30R AT STL.) ON THESE APCHS YOU MUST VISUALLY CALLOUT THE OTHER TFC TO ATC OR OFTEN TIMES THEY BREAK YOU OFF THE APCH. SO WHILE MY FO AND MYSELF MIGHTILY LOOKED FOR OUR TFC WE WERE TURNED TO ROUGHLY A 270 DEG HDG AND DSNDED THROUGH 5000 FT MSL TO 4000 FT MSL. I NOTICED THIS IN 2 WAYS: 1) THE ACFT WE SIGHTED 3-4 MI AHEAD APPEARED VISUALLY TO BE AT OUR ALT. 2) TCASII CONFIRMED A 0 FT ALT DIFFERENCE BUT OFFERED NO VISUAL OR AURAL WARNING. AS WE WERE CONSTANTLY TALKING TO THE CTLR HE NEITHER NOTICED NOR SAID ANYTHING. THERE WAS NO COLLISION HAZARD AS HE WAS AHEAD OF US AND FASTER. THE CTLR CLRED US FOR THE VISUAL FOR RWY 30R AND NOTHING FURTHER OUT OF THE ORDINARY TRANSPIRED. HOW DID IT HAPPEN? 1) BOTH CAPT AND FO LOOKING FOR TFC WITH NEITHER MONITORING ALT. 2) RAPID FIRE SET OF INSTRUCTIONS BY ATC WHICH OVERLOADED US BOTH. 3) KNOWLEDGE THAT IF WE DIDN'T VISUALLY ACQUIRE TFC SOON WE WOULD BE 'BROKEN OFF' THE APCH, THUS OUR CONCENTRATING MORE ON THE TARGET ACFT THAN ALT. HOW TO PREVENT A RECURRENCE? 1) ATC GIVE ONLY 1 OR 2 INSTRUCTIONS PER RADIO CALL SO AS NOT TO OVERLOAD CREW. 2) CREWS NEED TO DIVIDE TASKS OF LOOKING PRIMARILY TO PNF AND PF FLY THE PLANE BUT MAKE SURE PNF AND PF XCHK ONE ANOTHER. 3) BUILD A NEW LARGER ARPT IN STL SO THESE ODDBALL APCHS AND THEIR RULES ARE A THING OF THE PAST.

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.