B767 captain reported hydraulic system malfunction during cruise.

Attributes
ACN	1612996
Time
Date	201901
Local Time Of Day	0001-0600
Place
Locale Reference	ZMP.ARTCC
State Reference	MN
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	Hydraulic System
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 30 Flight Crew Total 11000 Flight Crew Type 3300
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

Encounter at 30;000 feet we received a 'C hydraulic qty' EICAS message. Center hydraulic quantity was at 0.48 and decreasing. Contacted flight control and decided to divert. We decided to try to land while we still had center hydraulic pressure. We kept our speed up and received an artr (amended release to read) for change of destination. It began to appear that we would not land prior to losing all center hydraulic fluid; so we descended about 50 NM early and extended the landing gear with 0.13 in the center reservoir. The gear extended normally; but when we selected flaps 1 we lost all center hydraulic pressure. We followed aom procedures for lost C hydraulic pressure; [advised ATC] and landed. We had a 757 captain jump seating with us and we use him to aid the first officer (first officer) as pm (pilot monitoring) in executing the non-normal checklist and procedures.

Original NASA ASRS Text

Title: B767 Captain reported hydraulic system malfunction during cruise.

Narrative: Encounter at 30;000 feet we received a 'C HYD QTY' EICAS message. Center hydraulic quantity was at 0.48 and decreasing. Contacted Flight Control and decided to divert. We decided to try to land while we still had center hydraulic pressure. We kept our speed up and received an ARTR (Amended Release to Read) for change of destination. It began to appear that we would not land prior to losing all center hydraulic fluid; so we descended about 50 NM early and extended the landing gear with 0.13 in the center reservoir. The gear extended normally; but when we selected Flaps 1 we lost all center hydraulic pressure. We followed AOM procedures for lost C HYD pressure; [advised ATC] and landed. We had a 757 Captain jump seating with us and we use him to aid the FO (First Officer) as PM (Pilot Monitoring) in executing the non-normal checklist and procedures.

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.