B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 198; Flight Crew Type 18000
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Equipment / Tooling
During preflight briefing; the Crew noted that the route in the FMC defaulted to and loaded a Runway for a particular RNAV Departure. The active runway was different. If uncorrected; this could have resulted in a huge problem on departure. I inquired of the FO whether he often sees the runway pre-load to a default runway on our 01 routes. He stated that he thought that about 20% of our routes pre-load a runway. I was shocked to learn this. I believe that this is a bad idea; especially on RNAV routings and even more especially at locations where the wrong runway loaded could result in a major course deviation. It would be fine if the departure was just limited for use from that runway. I realize that our procedures and briefings are designed to catch wrong runway loading errors (which they did in this case) but feel we are setting ourselves up for navigation errors by pre-loading runways in the 01 routes. Chief Pilot on Call was notified of my concerns.
Captain discovered that FMC's are designed to sometimes auto load a runway with a particular RNAV departure.