B737 pilot reported a complete loss of system a hydraulic fluid.

Attributes
ACN	1571510
Time
Date	201808
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZZ.ARTCC
State Reference	FO
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Hydraulic Fluid
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Total 3500
Events
Anomaly	Aircraft Equipment Problem Less Severe

Narrative:

The aircraft indicated we lost all our system a quantity hydraulic fluid. We ran the checklist. I felt the safest course of action was to return to [the airport]. We landed with no further issues.

Original NASA ASRS Text

Title: B737 pilot reported a complete loss of System A hydraulic fluid.

Narrative: The aircraft indicated we lost all our system A quantity hydraulic fluid. We ran the checklist. I felt the safest course of action was to return to [the airport]. We landed with no further issues.

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.