Date: 202102
Local time of day: 1201-1800
Location: ZZZZ.TRACON, FO
Flight conditions: VMC
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Hydraulic Main System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Troubleshooting
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed As Precaution; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Normal takeoff and climb out. We went to FL400 for cruise altitude. We got to cruise; made our PA turned off the seatbelt sign. I was Pilot Monitoring. FO (First Officer) said;'uh oh we have a light on the HYD overhead.' I looked up and ENG2 engine driven pump said low pressure. I canceled the master caution and got out the QRH. Simple checklist; select the HYD pump switch to off. End of checklist. We pulled up the hydraulic display on the center screen. B system 106%; normal pressure. We started a what if dialogue. We agreed it was OK to continue with present condition. We looked up Loss of System B in QRH; and discussed it. We looked at flight plan divert circles and discussed scenarios. After 5-10 min the system B quantity started to decrease; slowly at first. I asked ATC for a descent to FL 320. Now the System B started to decrease rapidly. We knew we were about to loose Hyd Sys B. We selected Autopilot A to fly the aircraft; still descending; we were now over Location X but before ZZZZZ fix. We texted Dispatch we were going to lose System B and wanted to confer if we should divert or continue; Note-Loss of SYS B checklist did not say land at nearest suitable airport. We were almost to FL 320 and the ELEC 1 low pressure light illuminated; as the system quantity reached 0 and system pressure was 0;pump switch off per checklist. We got a few more lights and confirmed we had a complete loss of system B. Unbelievably we now got an ENG 1 hyd low pressure light illuminate; pump switch off per checklist. ELEC 2 HYD pump only hydraulic pump now functioning. It held autopilot A. We looked at each other and said lets head to ZZZ1; we had previously talked about divert points and where to go if the situation had gotten worse which it did. During this time we noticed A HYD quantity decreasing from 90+% to low 80's(we thought we might loose A too)I requested a descent and a turn direct to ZZZ1 from Center for a hydraulic loss. He gave us a different heading and said to expect to hold for sequence. We were now clearer to the controller and requested priority handling. The lead FA dinged us and asked if everything was OK; I told her no; type of situation; and to prepare the cabin for a divert to ZZZ1; I asked her to have the cabin ready in 10 minutes; no evac prep necessary. We got direct from ZZZZ Center; reprogramed the FMC and let dispatch know we were diverting. We started in on the loss of System B checklist as we were making a dive for ZZZ1. We ended up taking a vector to lose altitude. We completed the loss of system B to the ALT Flap extension. I then called back to the FA confirmed TEST; no evac; trucks would be standing by; we might seem like we were landing faster. I made a PA to the passengers. The FO did an excellent job of flying the airplane first; great CRM working with me on the checklists; with ATC ; keeping me in the loop where we were when we were being pulled from so many directions (We were getting pulled from ATC; Dispatch; FA; PAX; checklists...). We completed the ALT Flap extension and then landing checklist. The landing was normal for a flaps 15 landing.After the parking checklist; we debriefed. ZZZ1 station manager entered the aircraft and said they might have an aircraft swap if we could fly to ZZZ2. Sent Maintenance report. I talked to the FO and cabin crew and they all wanted to continue and fly to ZZZ2. We called dispatch and he elaborated on the possibility of us flying to ZZZ2. All the crew members wanted to finish the flight to ZZZ2; so we started in on this plan. I spoke with the Operations Manager and the ZZZ2 Chief Pilot for clearance for all of us to continue to ZZZ2. We did have to also fill out a simple report and give copies of our licensed to the [local] authorities. We informed the passengers. The plan did come together and we did an aircraft swap and an uneventful continuation to ZZZ2.


Second narrative: In cruise; the System B Engine Pump 'Low Pressure' light illuminated. The Captain (non-flying pilot) accomplished the QRH checklist and the pump switch was deselected. Hydraulic quantity in the 'B' system was over 100%. Approximately 5 minutes later the 'B' system quantity starts to rapidly drop to zero. After reaching zero; the 'B' system Electric Hydraulic Pump unexpectedly illuminates 'Low Pressure.' We also receive the associated caution light for the flight control system. While the Captain was completing 'Loss of System B' checklist and we were discussing our options (ZZZ1 vs ZZZ2); we received another caution light for System 'A' Engine Pump 'Low Pressure.'We immediately decide to divert to ZZZ1. The Captain advised ATC; and notified the Dispatcher over ACARS. We completed the checklists; notified the Flight Attendants; and informed the passengers. There was a very clear division in the flight deck workload. The Captain worked the problems; communications with the company; and in cabin communications. I flew the aircraft and communicated with ATC. This workload division not only works well in the simulator but also in real life.We completed the 'Loss of System B' deferred items and Alternate Flap Extension procedure. We shot the ILS in ZZZ1 and landed without incident. Clearing the runway we taxied to the gate. The System 'A' Electric Pump continued to function and we fortunately had no other problems.This whole situation was extremely similar a recurrent training scenario that we had not that long ago. Having 'seen it before' was strangely reassuring.


Synopsis: B737 flight crew reported a loss of B system hydraulic fluid; followed by the loss of multiple hydraulic pumps resulted in a diversion.