B737-800
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 192; Flight Crew Type 192
Communication Breakdown
ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance
Human Factors
Washington Center cleared us direct to STEVY (pronounced STEE-VEE by the Controller) waypoint along our filed route; but there was some static/background noise that made interpreting the fix name a little ambiguous. We both consulted the LEGS page of the FMC to see if there was a waypoint that looked like what we thought we heard. Seeing the waypoint GBEES further down the LEGS page (which we assumed is pronounced GEE-BEE-ZZZ); we concluded this was the fix ATC was referring to. I read back cleared direct GEE-BEE-ZZZ; with extra effort to articulate it clearly; and the Controller did not issue a correction. We brought GBEES to the top of the LEGS page and executed the route change. Approximately five minutes later the Controller asked us if we are still proceeding to STEVY waypoint (it was clearer that time); and we replied that we understood and read back direct to GBEES. The Controller said the original clearance was for STEVY; but that we were now cleared direct HNN VOR; further down our route.
I don't know if the miscommunication was between the first Controller and us; or if it was between the two Controllers.
B737-800 flight crew reported they misunderstood the Controller's clearance and a track deviation resulted.