Date: 201208
Local time of day: 0601-1200
Location: BTR.Airport, LA
Flight conditions: VMC
Light: Daylight
Aircraft: Medium Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground BTR
Aircraft component: Aero Charts
Component problem: Design
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; First Officer
Human factors: Situational Awareness; Communication Breakdown; Confusion
Second reporter function: Captain; Pilot Flying
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Detector: Person Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert
Contributing factors: Airport; Chart Or Publication; Procedure; Human Factors; Environment - Non Weather Related
Primary problem: Ambiguous

Narrative: We were instructed to 'taxi to 4L via Alpha; behind the 727.' Alpha does not connect to ramp; took most direct route to Alpha (via Delta). It appeared all other connections between ramp and Alpha toward 4L were blocked by construction. On Delta; Ground Control advised we were going wrong direction. He wanted us to pass behind the parked 727 on the ramp behind us; then on an unnamed taxiway that we could not see behind the parked 727. We were given new taxi clearance; and we continued with out further delay. Misunderstanding between what was said by ATC and what was understood by the flight crew; also poor airport diagram and lack of special directions. There were no special directions issued for the construction. NOTAMs mentioned Alpha being closed at Taxiway Charlie; but Charlie is not labeled on the Commercial Charts Airport Diagram. Nothing was mentioned on the ATIS. Both of these would have helped situational awareness. More specific directions from ATC stating 'there is an unmarked taxiway behind the parked 727 on the ramp; pass to the right of the 727; proceed on unmarked; unnamed taxiway; then join Alpha to 4L.

Callback: The Reporter stated that this event occurred on his first trip into BTR and that after the fact the taxi route clearance made sense. What was confusing was Taxiway C; which was part of the route clearance; was not defined on the BTR Airport diagram and so the crew; believing construction blocked the ramp Taxiway H; took the most direct route to Taxiway A which was via D. After passing the parked B727 it became clear what Ground Control wanted; but not knowing where Taxiway C was; the crew simply went on what appeared to be the shortest route to A. The BTR NACO Chart description of the Ramp area looks nothing like it actually exists and it also does not define Taxiway C.

Second narrative: The event occurred due to the fact ATIS did not present the taxiway closure. I feel the taxi instructions seemed vague. There was a NOTAM in the crew messages that explained the taxiway closure; but Taxiway Charlie is not depicted on the Commercial Chart.


Synopsis: BTR ramp construction appeared to block south ramp taxiways to Runway 4L so a crew taxied from the ramp on Taxiway D to Taxiway A south. Taxiway C is not defined on any airport diagrams event though it was part of the taxi clearance.