Date: 201302
Local time of day: 0601-1200
Location: ZID.ARTCC, IN
Aircraft: A300
Operator: Air Carrier
Operating under: Part 121
Mission: Cargo / Freight / Delivery
Flight phase: Cruise
Airspace: Class A ZID
ATC / advisory: Center ZID
Aircraft component: FMS/FMC
Component problem: Design
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Human-Machine Interface; Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: We were approximately 140 miles east of MIE VORTAC at FL340 proceeding direct to MIE with NAV engaged. We were given a clearance to cross 110 miles east of MIE at FL300. I was performing pilot monitoring duties at the time. We created a Place/Distance waypoint in the FMS based off of MIE. The FMS inserted the waypoint at the proper distance; but as is often the case with the Airbus; the 'direct' line to MIE showed a slight bend after the PD waypoint. Because this is very common; I double checked the mileage and was satisfied that the point was inserted correctly. After a minute or so; the Controller asked us if we were still going direct to MIE. We responded 'Affirmative.' After another minute passed; the Controller indicated that he was showing that we needed to turn 10 degrees right for direct MIE. Knowing what was causing the difference; we elected to just select direct MIE again (deleting the PD waypoint) and perform the vertical calculation manually. After selecting direct to MIE (we remained engaged in NAV during this whole sequence) the airplane turned slightly back to the right. I explained to the Controller that sometimes when we insert Place/Distance way points; the FMS creates a slight bend explaining our turn from 'Direct'. He then made a comment that was something to the effect of 'Yeah; that issue was just brought up at a meeting we had last week.' But he never indicated whether he considered what we had done as acceptable or not. Because we needed to devote our attention to initiating our descent to comply with the altitude crossing restriction clearance; I did not ask him for additional clarification. We complied with the altitude crossing restriction and were subsequently turned over to another frequency. Our insertion of the point in the FMS was procedurally correct; but I am not clear as to whether this limitation (or method) of the Airbus FMS creating the waypoint are acceptable to ATC in terms of complying with a clearance. This situation can be prevented by clarifying our procedure with ATC and communicating that to the flight crews.




Synopsis: Attempting to create a way point to comply with an ATC crossing restriction; the waypoint created using place/bearing/distance does not fall precisely on the direct route but is accepted by the crew.  ATC questions the deviation and the crew proceeds direct.