Date: 201207
Local time of day: 0601-1200
Location: MEM.Airport, TN
Flight conditions: VMC
Light: Daylight
Aircraft: A300
Operator: Air Carrier
Operating under: Part 125
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Descent
Airspace: Class B MEM
ATC / advisory: TRACON M03
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Flight Engineer; Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor
Human factors: Communication Breakdown; Confusion
Anomaly: ATC Issue All Types; Deviation - Track / Heading All Types
Detector: Person Flight Crew; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Contributing factors: Airport; Chart Or Publication; Human Factors; Weather; Procedure
Primary problem: Ambiguous

Narrative: Optimum Performance Descent/Arrival Procedures in MEM are brand new to both ATC and flight crews. We were flying the LTOWNE6 RNAV arrival for the first time. The flight crew and ATC encountered confusion at or near LTWONE Intersection. Operations at MEM switched from landing south to landing north right about the time we crossed LTOWNE Intersection. Two different track options exist after LTOWNE Intersection.This crew understood from ATC that we should continue on the North option (track) after LTOWNE despite the fact that MEM was now landing north. The Controller used the phrase 'North transition' which is nowhere to be found in writing on the STAR chart.This situation became a non-issue when the Controller helped clarify what was expected of us by clearing us direct to a point south of LTWONE to rejoin the arrival. We complied exactly as we understood the instructions; discussed together; and received clarification/asked questions as needed.MEM ATC and our company have been working together to reduce confusion; clarify controller phraseology; and maximize efficiency with the use of these new 'OPD' arrivals. A great example of this relates to our flight/situation. On AUG2012 a clarifying 'vital' message was received entitled 'OPD Update' that clarified the meaning of the Controller used term 'north transition.' It was also mentioned in this message that an Aerodrome (AD) change bulletin would be forthcoming.In the future; to reduce confusion; I think that ATC 'phraseology' should be limited to options on an arrival/procedure that are printed on the procedure or given in a change bulletin (especially on newly implemented 'trial procedures'). Seeking clarification from ATC is always best; but sometimes not immediately possible and things occur at just the 'wrong time' (such as the airport 'turning around').




Synopsis: Confusion reigned at MEM when an A300 flight crew crossed LTOWN Intersection just as the airport was turning around to land to the north. When told to fly the 'North transition' the crew interpreted that to mean 'take the Northerly' track from LTOWN. ATC recognized the error and provided a clearance back to the 'Southerly' track appropriate for flights landing 'to' the north.