Date: 202006
Local time of day: 1201-1800
Location: ZZZZ.ARTCC, FO
Aircraft: B767-300 and 300 ER
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Cruise
ATC / advisory: Center ZZZZ
Aircraft component: Cargo Compartment Fire/Overheat Warning
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Situational Awareness
Second reporter function: Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: After crossing the northern shore of Country X we got a main cargo deck fire warning. The checklist was started and the decision to return to ZZZ was made. Crew coordination and checklist usage went really well. I computed the non normal landing distances and it was decided to land Runway XX as it was the most expeditious. On final we received a left engine fire indication for one second; and then the indication extinguished. We landed without issue and rolled to the end of the runway to clear. ATC and crash fire rescue said no indication of fire. It was decided to taxi into the gate. On taxi in we got multiple left engine fire warnings. After block in 4 tire fuse plugs blew.All facets worked well together; inside and outside the cockpit. Some issues we faced; the EICAS message for main cargo deck fire/smoke did not match the QRH message. We never train main cargo deck fire in the sim because the sim doesn't have that panel. The lithium batteries on board were scattered throughout the cargo compartment; and would not have been accessible if we needed to. Although I'm not sure we could've done anything even if we could've gotten to their location. Crew scheduling assigned us to another flight after we returned; we were legal for it; but no one bothered to ask if we were okay; and if we felt safe to do another flight. We are humans; that was scary; have some empathy.


Second narrative: Departed ZZZ climbed to FL350. Over the north shore of Country X the aircraft MAIN CARGO warning alarm sounded with the corresponding MAIN Warning Light and CARGO FIRE EICAS message. The smoke detectors remained 'green for the entire flight. Referred to the QRH for MAIN CARGO FIRE and accomplished the checklist. A visual inspection through the main cargo compartment portal indicated no observable fire or smoke indications. The crew advised ATC with Country X Control. It was decided a return to ZZZ was the best immediate option and the forwarding controllers were notified.  An eventual descent to 10;000 MSL was made and we arranged for a landing to Runway XX. We broke out of the weather for a visual arrival at approximately 2000 MSL. Due to excessive aircraft speed; the crew elected to abort the landing and circle to the north for a subsequent approach to Runway XX. The next approach and landing were successful; but was a planned overweight landing to a full stop off the runway on Taxiway XX. The rescue crews performed a thermal and visual inspection and there was no indication of smoke or fire. The aircraft continued taxiing to the ramp and while doing so we experienced a left engine fire indication. It was visually verified that there was no left engine fire. once in the chocks with the brakes released; the latent heat in the brakes caused 4 fuse plugs to blow. No further incidences were involved.


Synopsis: B767-300 flight crew reported a cargo fire warning and returning to departure airport.