Date: 201603
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: Mixed
Light: Night
Aircraft: A300
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Cargo Compartment Fire/Overheat Warning
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Human factors: Distraction; Confusion; Situational Awareness
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; 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 As Precaution; Flight Crew Returned To Departure Airport; Flight Crew Landed in Emergency Condition; General Flight Cancelled / Delayed
Contributing factors: Human Factors; Aircraft
Primary problem: Aircraft

Narrative: The aircraft was thoroughly covered in de-icing fluid for our flight. We were loaded with Dangerous Goods listed; but not limited to: Toluene; Adhesives; Compressed Gas; Resin; Flammable Aerosols; Environmentally Hazardous Liquids; Dry Ice; and other. The First Officer (FO) and I have flown together in the past on the A300; but this was the first leg of the first day together. The FO was called out on reserve for the flight. During climb out through approximately 16;000 feet we had a momentary AFT LOOP B warning on the ECAM for the MAIN DECK CARGO SMOKE DET SYSTEM. It reoccurred shortly thereafter. Since the panel and system was closer to him on his overhead; we transferred controls and I asked him to run the procedure while I worked ATC and flew. ATC swapped us to a new frequency as we approached 18;000. We were cleared to FL230. We elected to stop earlier at FL 210. While I got us started in a turn back to ZZZ; the FO ran the checklist more than once and ended at the same spot. I tried to remain in the loop best I could and provide support while assessing all the variables. We agreed that a return would be the most prudent. At around 267;000 pounds we expedited our descent and approach while trying to brief and coordinate with each other and ATC. Approach; landing; and rollout were without incident. At no time did we experience any smoke; fire or fumes. Crash Fire and Rescue (CFR) confirmed no fire. ATC; CFR and OPS coordinated with us on the ground.


Second narrative: I hand flew the takeoff and departure. Sometime during climb out; we got indications that main cargo deck aft loop B was faulting. I immediately asked for the autopilot to be engaged. The Captain engaged the autopilot; opened the checklist; and changed ATC frequencies in a very short period of time. As we continued to climb out; the Captain then took the aircraft and radios and directed me to run the checklist. I ran the checklist starting on the page that he gave me. Shortly thereafter; we passed transition altitude and we asked for an early level-off. We stopped our climb at FL210. I read the checklist out loud and accomplished the steps. I found the wording a bit confusing; so I re-read it several times. In accordance with the checklist; I deactivated the suspected faulty loop; and tested the other loop. I did not see the AFT smoke light illuminate when the test was run. The ECAM did display smoke warning messages when the test was run; but I did not see any text that included the word 'AFT' in them; and that is what I was expecting to see. In the meantime we had already made a turn back towards the departure airport. I asked the Captain to go over the steps with me while I read them aloud. I ran through the steps again and came to the same conclusion; that LOOP A was faulty; and that loop B was actually picking up something. In accordance with the checklist; I deactivated LOOP A. So now; LOOP B would cause a correct smoke indication. Compounding the issue was the fact that the loop B fault was intermittent; and at the time that was also making me somewhat question the validity of the test. In hindsight; that intermittency really does not change anything; but at the time it did induce an additional degree of uncertainty. Neither of us was certain that there was actually smoke or not; so we took the safest course of action and landed the aircraft as soon as possible. We prepared for the arrival. I ran the normal checklists and backed the Captain up on the approach. I missed my standard 1;000 and 500 foot calls. We were met on the ground by emergency responders. After coordinating with them; we headed to parking. I do not believe that they found any evidence of fire.


Synopsis: A300 flight crew experienced an intermittent smoke indication; so they returned to the departure airport.