Ce-560EP flight crew reported loss of pressurization at FL260. Flight descended and diverted.

Attributes
ACN	1283565
Time
Date	201507
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Citation V/Ultra/Encore (C560)
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Component
Aircraft Component	Pressurization System
Person 1
Function	Pilot Not Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical

Narrative:

At FL260 in cruise flight we both suddenly heard and felt a difference in the cabin atmosphere and noise level. We both scanned the instruments and found the cabin alt was climbing and the differential pressure was descending. We [responded to the situation] and were given a small descent to FL210 due to traffic. Before we got to FL210 ATC gave us 10;000 ft. We both donned our O2 masks and ran the quick reference checklist. We leveled at 10;000 ft. And contacted our company about our issue and when they got back to us they requested we [divert] to [a nearby airport] instead of continuing to [destination]. [We] landed without further incident.

Original NASA ASRS Text

Title: CE-560EP flight crew reported loss of pressurization at FL260. Flight descended and diverted.

Narrative: At FL260 in cruise flight we both suddenly heard and felt a difference in the cabin atmosphere and noise level. We both scanned the instruments and found the Cabin Alt was climbing and the differential pressure was descending. We [responded to the situation] and were given a small descent to FL210 due to traffic. Before we got to FL210 ATC gave us 10;000 ft. We both donned our O2 masks and ran the Quick Reference Checklist. We leveled at 10;000 ft. and contacted our company about our issue and when they got back to us they requested we [divert] to [a nearby airport] instead of continuing to [destination]. [We] landed without further incident.

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.