B737-800
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Aircraft Equipment Problem Less Severe
Flight Crew Overcame Equipment Problem
Aircraft
I'm writing to voice a concern I have with the 737 FMCs. I've had three major; and many minor; lock up problems in the past year.Each time in the past; I was in VMC weather and went to raw data. I completed the arrival/approach with nothing more than higher workload. This past [event] I encountered wind shear and confusion in the cockpit because the FMCs again went into a mode rendering them inoperative at the worst possible time (magenta line going away; flight directors unusable; FMC key pads locking up; nav data unusable either from blanking or simply not functioning). I've written two of these up and found no satisfaction that the problem would be fixed. I brought this up in recurrent [training] and the instructor found [someone] to explain what was going on. He said it was a software problem and it would be fixed in two months. Six months later; same problems.The so-called momentary blanking; for me and others in the classroom; is a puzzle. It might be 2-3 seconds or 30-40 seconds --you never can tell. This has always happened in high work load areas; not allowing me to troubleshoot the system -- if it's even possible.I have 31 years of FMC aircraft experience and never found it this bad. To say I'm having trust issues with the FMCs is an understatement.
A B737-800 Captain reported that the FMCs are blanking and locking-up.