Large Transport; Low Wing; 2 Turbojet Eng
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Situational Awareness
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Maintenance Action
Aircraft
During climb to FL380 started getting fumes of unknown origin in cockpit; smelled like something electrical burning or overheating. Asked the Captain if he smelled something; which he did. While investigating instruments and lights for 2-3 minutes; [the] smell started to dissipate. We started discussing possible causes and plan of action. Closest airports were ZZZ1; ZZZ2; and ZZZ. Got weather for ZZZ2 and ZZZ. After level off at FL380; the smell started to come back. Once the smell came back; [we] swapped roles and [requested priority handling]; requesting a divert to ZZZ due to familiarity and less traffic congestion. While I talked to ATC and started flying forward ZZZ; PM (Pilot Monitoring) started setting us up for ZZZ. After setting up approach notified [Operations Control]. Landed in ZZZ uneventfully; taxied off runway and got inspected by fire crews which didn't see anything on thermal scan. Taxied to ramp to have Maintenance check the aircraft.
During the climb phase; both of us started to smell a burning; electrical smell. It came very strong at first and then started to dissipate almost immediately. It was almost gone after 2-3 minutes. During that time we tried to troubleshoot what it might be. There were no indications of a problem. When we leveled off at FL380 the smell returned; not as strong as before but was definitely there and was constant. We had already looked at ZZZ2 and ZZZ weather by this point and [we] made a decision to divert to ZZZ. Once we were on the ground; we had CFR (Crash Fire Rescue) inspect the airplane. They couldn't find anything wrong; so we taxied to the gate and Maintenance took the airplane.
Large Transport aircraft flight crew reported intermittent burning electrical fumes during cruise. After troubleshooting the problem; the flight crew decided to divert.