Regional Jet 900 (CRJ900)
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Situational Awareness; Troubleshooting
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Illness / Injury; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Provided Assistance; Aircraft Equipment Problem Dissipated; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; General Maintenance Action
Aircraft; Human Factors; Environment - Non Weather Related
While at cruise altitude; about 100 nm northeast of ZZZ; I felt a faint burning sensation in my eyes and smelled a faint sharp odor. It was a condition I had not ever noticed before. I asked [copilot] if he noticed the same. He said no. I said I would talk to the flight attendants because sometimes they overheat things in the oven; she said that they had not used the oven. [Copilot] turned off the recirculation fan. The burning and odor had subsided. We went to the QRH and reviewed the Smoke and Fumes section. We discussed the need to divert in length and for me the overlying detail was 'to continue to the destination; the crew must acknowledge that the threat has been positively identified.' In my mind; we had not; so we both agreed to divert and ZZZ was about 80 nm away with all the services. After landing in ZZZ; CFR [Crew Fire Rescue] met us on RWY XXL and confirmed no fire; [and] we continued to gate. After deplaning the passengers; Maintenance came on board; we explained the condition. They later came back and said that there is a hydraulic leak and the fluid was dripping on to the PAC and those fumes were what caused the odor.
CRJ-900 First Officer reported smelling an odor during flight accompanied by health issues resulting in a diversion.