Date: 201707
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: Q400
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class E ZZZ
ATC / advisory: Center ZZZ
Reporter organization: Air Carrier
Reporter function: Flight Attendant (On Duty)
Reporter qualification: Flight Attendant Current
Human factors: Situational Awareness
Anomaly: Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Other / Unknown
Detector: Person Flight Crew; Person Flight Attendant
When detected: In-flight
Result: Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; Flight Crew Landed As Precaution; General Evacuated
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: As we took off from ZZZ this morning we received the after takeoff chime and as we started setting up the cart to start the inflight service we heard a loud noise that sounded like a decompression; as if a tire had blown and all of the air was being released and the sound was coming from the cargo compartment. I immediately called our CA and he said that he was just about to call us and that the flight deck warning light indicated that a fire in the cargo compartment could be a possibility. The FO asked if we could see smoke and I replied no. I felt the back galley wall to see if I could feel heat; which I did not. The CA said that we would be going back to ZZZ and that he would make a PA. We quickly put away the cart and made the announcement to prepare the cabin for landing. The CA told us that we would be doing an expeditious deplaning of passengers and I repeated the instructions back to him. I did my silent review preparing that we could have a fire in the cargo compartment going over in my head; donning the oxygen equipment; fire extinguishers; evacuating the aircraft. When we landed I could see the fire truck but was still unsure if we had a fire or not. Our CA made a PA remain seated; we taxied to the gate and did an expeditious deplaning of the passenger. I made an announcement to leave all personal belongings behind; to exit out of the main cabin door only. The CA instructed the passengers to congregate by the stop sign. After we got all of the passengers off I made sure that there we did not have any passengers still on the aircraft. The crew exited the plane.The CA spoke with the fire department and what bothers me is that the fire department had stated to the CA that if we were on the taxiway we should not have deplaned the passengers immediately after opening the cabin door. I don't understand this thought process at all. Shouldn't our priority be to get the passengers off of the plane in the event that we did have a fire regardless of where we deplane the passengers? The fire department verified that there was not a fire and one of the firemen checked with a heat sensor. After being on the tarmac with the passengers we asked the ground crew if they would direct the passengers inside. The passengers did follow our instructions and they did leave all personal belongings on board. After discussing what to do to return the personal belongings to the passengers originally the ground crew thought that they would collect all belongings and put them on the cart; which I spoke up and said I didn't feel comfortable with that and I did not want to be responsible for collecting all personal belongings. After discussing it we decided that the best alternative would be to have 5 passengers at a time come back onto the plane and collect their own personal items which worked out well. As the passengers came back on board I asked each one if I could help in any way; if they needed anything. During this the duty officer had called. A fire is a very serious situation and in our training we know how quickly a fire can spread. I am thankful that we did not actually have a fire; I am thankful for flying with a crew that communicated well as a crew and that we talked about what happened. We debriefed and we took the time to debrief. I appreciate that the FO took the time to show us the checklist. I now know what it sounds like to have the pilots oxygen donned. I feel that in a situation like this that you should automatically be taken off of your trip to decompress. You shouldn't have to decide if you want to continue to fly or not. We each handle situations differently but to take myself off of the trip was the absolute best choice for myself. We deadheaded to ZZZ1 and when we landed our supervisor entered the back of the aircraft. I thought that he was there to discuss what had happened but did not.




Synopsis: Q400 Flight Attendant reported that as they started service they heard a loud noise that sounded like decompression that came from the cargo compartment.