Date: 201708
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Night
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: Oil Pressure Indication
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Troubleshooting; Time Pressure
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Landed in Emergency Condition; Flight Crew Inflight Shutdown; Flight Crew Diverted; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: Climbing northbound out through FL240 we noticed Engine 1 Oil Qty slowly declining. Upon level off at FL360 the Qty was indicating 0%. No checklist/procedure for Low Oil Qty in B737 Quick Reference Handbook (QRH); but we continued to monitor all engine parameters specifically the Engine 1 Pressure and Temperature. We had just finished an ACARS message to [maintenance control] informing them of this indication when we notice the Oil Pressure fluctuating and begin a declining trend. Messages sent to [maintenance] and Dispatch with our concern this is a real problem with the Engine 1 Engine Oil System. At this point I transferred control of the aircraft to the First Officer. I Contacted Dispatch via VHF radio and we agreed that ZZZ 80 miles behind us was the best and safest option with excellent weather; 13000 foot runways and Company Maintenance. By this time the Pressure was in the Yellow Caution Zone; still fluctuating and still dropping. Now the First Officer was flying and communicating with ATC while I monitored and coordinated the situation. Under my direction the First Officer [advised ATC] with Center and requested a course reversal for an emergency descent and divert to ZZZ. Flight Attendants were advised of the situation via 'TEST' (Time available; Emergency; Signal; Transmit additional instructions) and passenger were given a PA informing them of an Engine Problem; a Diversion and that our ETA was about 20 minutes from now. By the time we were heading for ZZZ and descending through FL240 the Oil Pressure was in the Red (single digits); the QRH was used starting with Engine Low Oil Pressure checklist which directed us to the Engine Shutdown Check List. Engine 1 was shutdown using the checklist and all items up to the Landing portion were completed by 10000 feet. Requested a straight-in approach instead of landing to the north which was the airports configuration at the time. Called Flight Attendants on inter-phone for a 5 minute warning and also assured passenger via PA that all checklists were complete; Engine on left side had to be shut down and that all would be well. At 3000 ft and a 10 mile final I took control of the aircraft for the single engine approach and landing which was uneventful. Stopped about halfway down runway for an Aircraft inspection by Airport Fire Rescue. We were cleared of any leakage or aircraft damage which allowed us to continue to the assigned gate. Maintenance personnel confirmed that we had a serious oil leak somewhere in the accessory drive/starter section of the engine confirming our cockpit indications were correct.My first officer did a tremendous job of flying and communicating with ATC while I managed the problem; ran all of the QRH checklists meanwhile communicating with FA's and passenger. Threat and Error Management (TEM) and Crew Resource Management (CRM) procedures were used throughout the event. The flight attendants were cool; calm and collected on the inter-phone and did a great job of keeping the passenger calm and safe during this event. I was able to greet all passengers as they left the airplane and all seemed relieved and happy with the crew and very happy with the outcome. Was able to debrief all crew members and we all agreed that the event went very well and that all of our years of training and experience had paid off.


Second narrative: [Report narrative contained no additional information.]


Synopsis: B737 flight crew reported a decreasing oil quantity indication on the Number 1 engine; followed by a subsequent loss of oil pressure. The engine was shut down and a successful diversion was accomplished.