Narrative:

We were assigned 4000 ft while on the localizer for runway 24 outside class B airspace. Airspeed was requested by ATC at approximately 22 NM. We reported our speed as 230 KTS while decelerating. We continued at 4000 ft below class B 'step' (15-20 NM, 5000 ft). My concern for report is this is a very common practice at stl of vectoring and assigning altitudes below class B lateral limits. The bae 4100 is a large turbine pwred aircraft, and as this is an approved procedure under the FARS for atl, this also places (I feel) an unnecessary burden on the air crew of observing speed restrs in and under class B airspace. In an environment where ATC is asking us to give maximum forward speed the majority of the time, assigning an altitude within class B would permit an additional 50 KTS and most importantly, reduce the risk of flight crew violation. Callback conversation with reporter revealed the following information: reporter advised that ATC frequently placed turbojets beneath class B, asking for 'maximum forward speed,' without the understanding of the far requirement of reduced speed, 200-210 KTS, when operating beneath the floors of class B. The reporter also had concerns of being set up by approach control to one runway, then changed on initial contact by the tower to the other parallel runway or to runway 13/31 -- a converted taxiway to a runway. The reporter advised that frequently there were concerns of wake turbulence that he perceived that ATC was not taking into account.

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Original NASA ASRS Text

Title: BA41 PIC CONCERNED WITH ATC HANDLING WHILE ON APCH TO STL ARPT. ALT AND SPD ASSIGNMENT APPEARS TO CONFLICT WITH FARS, SPECIFIC TO TURBOPROP OP.

Narrative: WE WERE ASSIGNED 4000 FT WHILE ON THE LOC FOR RWY 24 OUTSIDE CLASS B AIRSPACE. AIRSPD WAS REQUESTED BY ATC AT APPROX 22 NM. WE RPTED OUR SPD AS 230 KTS WHILE DECELERATING. WE CONTINUED AT 4000 FT BELOW CLASS B 'STEP' (15-20 NM, 5000 FT). MY CONCERN FOR RPT IS THIS IS A VERY COMMON PRACTICE AT STL OF VECTORING AND ASSIGNING ALTS BELOW CLASS B LATERAL LIMITS. THE BAE 4100 IS A LARGE TURBINE PWRED ACFT, AND AS THIS IS AN APPROVED PROC UNDER THE FARS FOR ATL, THIS ALSO PLACES (I FEEL) AN UNNECESSARY BURDEN ON THE AIR CREW OF OBSERVING SPD RESTRS IN AND UNDER CLASS B AIRSPACE. IN AN ENVIRONMENT WHERE ATC IS ASKING US TO GIVE MAX FORWARD SPD THE MAJORITY OF THE TIME, ASSIGNING AN ALT WITHIN CLASS B WOULD PERMIT AN ADDITIONAL 50 KTS AND MOST IMPORTANTLY, REDUCE THE RISK OF FLC VIOLATION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ADVISED THAT ATC FREQUENTLY PLACED TURBOJETS BENEATH CLASS B, ASKING FOR 'MAX FORWARD SPD,' WITHOUT THE UNDERSTANDING OF THE FAR REQUIREMENT OF REDUCED SPD, 200-210 KTS, WHEN OPERATING BENEATH THE FLOORS OF CLASS B. THE RPTR ALSO HAD CONCERNS OF BEING SET UP BY APCH CTL TO ONE RWY, THEN CHANGED ON INITIAL CONTACT BY THE TWR TO THE OTHER PARALLEL RWY OR TO RWY 13/31 -- A CONVERTED TXWY TO A RWY. THE RPTR ADVISED THAT FREQUENTLY THERE WERE CONCERNS OF WAKE TURB THAT HE PERCEIVED THAT ATC WAS NOT TAKING INTO ACCOUNT.

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.