B737-800
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Situational Awareness; Communication Breakdown
ATC Issue All Types; Aircraft Equipment Problem Critical
Flight Crew Diverted; General Declared Emergency; General Maintenance Action
Aircraft; Procedure
While enroute the Master Caution and FLT CONT light illuminated. We discovered the FLT CONT SYS B low press light on the overhead panel. We followed the QRH. After completion of QRH procedure we were left with System B flight controls un-powered. A System A loss would have put us in manual reversion. After having done that in the simulator I didn't want to expose myself or my passengers to that risk. I made the decision to divert. Prior to the diversion I notified Dispatch and talked to Maintenance Control to confirm systems status. Diversion was coordinated with ATC and was uneventful until talking to Approach. We were assigned Runway 35R I told them I would require a longer runway due to the degradation in flight controls. I was then assigned Runway 31R than runway gave us a direct crosswind and I didn't want that with the loss of the yaw damper. I told them I needed Runway 35C for operational reasons. Controller said 'understand you are declaring an emergency?' I said if that is the only way to get [Runway] 35C then yes. We were then cleared for [Runway] 35C and landing was uneventful.Pilots in general don't ask for things they don't need. So when I asked for a long N-S runway a little more consideration from ATC could have been given.
A storm was over the area; lots of circuit breakers and moderate chop so we descended to improve the ride and better control. We asked for [Runway] 35C for operational reasons but were then assigned [Runway] 31R - that would have been a decent crosswind with no yaw damper; some inoperative spoilers and the R reverser powered by the standby system. We elected to declare an emergency to get the longer runway (this was the only way Approach was going to give it to us). Normal landing and taxi to gate.
A B737NG flight crew elected to divert to a nearby airport when the B Hydrualic System failed thus eliminating one of two sources for multiple flight controls. The crew declared an emergency in order to land on the longest available runway and into the prevailing wind.