Date: 201206
Local time of day: 1201-1800
Location: A80.TRACON, GA
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Flight phase: Descent
Airspace: Class B ATL
ATC / advisory: TRACON A80
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Commercial
Human factors: Situational Awareness
Anomaly: Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
Result: General None Reported / Taken
Contributing factors: Airspace Structure; Human Factors; Procedure
Primary problem: Human Factors

Narrative: I was First Officer (pilot not flying). On CANUK arrival; approximately 2 miles inside of HUSKY; we had just leveled off at 8;000 FT MSL. The controller issued us a heading of 020 and descend to 5;000 FT; and contact Approach. Then he said that we would 'be out of the Bravo for one mile.' In my mind I was picturing us leaving the lateral limits of the shelf of the Class B we were in when we made a turn to the northeast. I quickly looked at my Class B chart for Atlanta and cross checked our position with the chart. In my mind; I was concerned that we were still at 250 KIAS and a turn would eventually put us under a different shelf of the Bravo; breaking the 200 KIAS speed limit. After looking at the chart for a moment; I was pretty certain that the turn would not have us leave the Bravo. Even after a few more minutes of analyzing the situation; I was almost sure that we hadn't left the Class B. It was only after we finished the flight; and I had more time to analyze the chart; that I realized the descent momentarily put us below the 8;000 FT shelf for maybe 10 seconds until we entered the next shelf with a floor of 5;000 FT. We were doing 250 KIAS the whole time; so we broke the 200 KIAS speed limit under the Class B for that short time. ATC never said anything about the speed. Cause; the main threats were high workload and some fatigue. This was the fifth leg of the day and approaching 12 hours on duty. I always have my Class B chart available; but it took me a moment to identify our exact position. Obviously; better situational awareness would have helped. By the time I had crosschecked my chart in any detail; we had already gone below the Class B and were actually back into the next shelf; this plus changing frequencies; verifying the altitude selector and changing headings contributed. After the controller advised us that we'd leave the Bravo at one point; I should have said something to keep us from changing heading or altitude until we knew where we'd be leaving the Bravo. The error was breaking the speed limit for about 10 seconds. That would also be the undesired state. Suggestions; even when tired; I am always aware of major safety issues and obvious 'traps' in the operation. I flat out missed this one by having a poor picture in my head of our position. I needed to maintain better situational awareness.




Synopsis: ATL Air Carrier arrival reported a 'below Class B speed infraction' when failing to correctly identify his/her position relative to the airspace.