Date: 201708
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 145 ER/LR
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: Pressurization Control System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: First Officer; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; Flight Crew Diverted; Flight Crew Landed As Precaution
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: We got a step up climb to FL360 and we were only at that altitude for about 5 minutes when I felt my ears pop. I looked down about the same time the Captain did and I pointed out that the cabin pressurization went from 7700 FT to 8100 FT and started rising rapidly. We both said we needed to don our oxygen masks; so we did and established communication with each other. We then got the 'CABIN CABIN' aural warning message and the cabin pressure went up to 10;100 feet and was flashing red. I immediately said we need to descend and put 10;000 feet in the altimeter and speed hold 240. As I did that I opened up the speed brakes and called for the gear to be lowered. I made sure the seat belt sign was on and told the Captain we need to notify the FA. The captain notified ATC of our rapid descent and told them that we were going to 10;000 ft. ATC acknowledged and asked us if we were going to divert; the Captain told them yes but we will get back with them on the location. Then the Captain called the FA and told her what was going on and if everything was okay. The FA said everything was okay in the back. While in the descent; the Captain backed up our configuration with the checklists and the QRH. As far as I know; the cabin pressure never exceeded 10;100 feet so the oxygen masks in the back of the plane never fell down. When we leveled off at 10;000 ft; we slowed down and retracted the gear and speed brakes and flew 200 kts and we started coordinating with Dispatch about our divert situation. We were trying to figure out where we should divert when ATC gave us a heading for [a nearby airport]. We told Dispatch where we were going and to give station operations a heads up that we were coming in. We flew a normal approach and had the fire trucks waiting for us. Threats were potential hypoxia; loudness of cockpit (gear down at 240 kias); and time to get down to 10000 feet. Possible errors could have been rushing procedures. We reacted quickly probably because adrenaline kicked in. We knew that hypoxia is very dangerous because of the limited amount of time to react. While I feel that I stayed relatively calm and flew the airplane; my reactions were quick and I probably could have slowed down some after we donned our O2 masks. Everything felt like it happened very fast.




Synopsis: EMB-145 First Officer reported executing a rapid descent and diverting to an alternate after losing cabin pressurization.