B737 captain reported loss of hydraulic system a during cruise.

Attributes
ACN	1764026
Time
Date	202009
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Hydraulic Main System
Person 1
Function	Captain
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument
Experience	Flight Crew Last 90 Days 151 Flight Crew Total 10195 Flight Crew Type 10195
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy

Narrative:

Leaving ZZZ an engine hydraulic system (hydraulic system) a loss light illuminated. A system hydraulic quantity at that time was normal. After approximately 2 hours into the flight a system hydraulic quantity fell to 16%. Although the a system hydraulic electric pump was providing pressure for the a system; I believed that there was potential that we might experience a total loss of the a system hydraulics once the landing gear was extended. I [requested priority handling] and contacted dispatch. We extended the landing gear early and it extended normally. On approach; the gear and all other systems functioned normally. Landing was normal and uneventful. We taxied to the gate and discovered that we had a major hydraulic leak in the a system pump.

Original NASA ASRS Text

Title: B737 Captain reported loss of Hydraulic System A during cruise.

Narrative: Leaving ZZZ an engine HYD SYS (Hydraulic System) A loss light illuminated. A SYS HYD Quantity at that time was normal. After approximately 2 hours into the flight A SYS HYD quantity fell to 16%. Although the A SYS HYD electric pump was providing pressure for the A SYS; I believed that there was potential that we might experience a total loss of the A SYS hydraulics once the landing gear was extended. I [requested priority handling] and contacted Dispatch. We extended the landing gear early and it extended normally. On approach; the gear and all other systems functioned normally. Landing was normal and uneventful. We taxied to the gate and discovered that we had a major HYD leak in the A SYS pump.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.