B767-300 and 300 ER
Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 12000
Training / Qualification; Situational Awareness; Human-Machine Interface
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Aircraft; Chart Or Publication
Our flight was cleared from LFPG as filed via EVX2A Departure; Runway 27L; FL100 assigned as per RNAV SID. During initial climb Paris Departure Control assigned us a heading of 265 degrees and shortly thereafter informed us that we had deviated south of the departure course. EVX2A Departure was issued to our flight on two separate occasions. The departure was loaded into the FMC and was checked against Commercial Chart for accuracy. Aircraft symbol was within runway parameters. All flight deck indications showed the departure to be properly flown. The Captain (pilot flying) was in 5 mile scale map mode. The First Officer (pilot not flying) was monitoring raw data and progress page 2. Departure was flown as per Company procedures; LNAV 400 FT/left autopilot 500 FT/VNAV 1;900 FT. This aircraft is a B767-300 equipped with FMC navigation. The inherent drift in the ring laser gyro system make these aircraft unsuitable for RNAV departures. All procedures were diligently followed and all flight deck indications were well within operating parameters leading the crew to believe that the aircraft was accurately tracking the departure course. In this instance the weather was clear and visibility unrestricted. An impending conflict would have been easily detected visually. In IMC conditions; the same southerly deviation from Runway 27L could be disastrous with aircraft operating from Runways 26L/R.
[Narrative #2 contained no additional information.]
A crew flying non GPS B767-300 on the LFPG EVX2A RNAV was notified about a track deviation while the FMS indicated on track from taxi through the entire departure.