Narrative:

We departed runway xyr at ZZZ. On climb out prior to sterile cockpit light being selected off; the flight attendants called us and informed us they were concerned about a loud bumping or banging noise coming from below the forward part of first class; possibly from the forward cargo pit 'like someone was banging on the aircraft flooring' they asked the first class passengers if someone was stomping on the floor; or kicking the sidewall for some reason; and no one was. The flight attendants were experienced; and have flown frequently on the 737 series aircraft. We leveled off at 14;000 feet and were eastbound now on the departure from ZZZ. We decided to go back to ZZZ and have the aircraft inspected. The forward cargo pit cargo loading system was deferred inoperative. We were also concerned about the possibility of a ground crewman left in the cargo pit due to the late night departure. Or possibly a panel flapping in the air. The weather was good; traffic was very light; we were able to land under structural landing weight; and ATC was not busy. We coordinated with ATC; dispatch was sent a quick message; the station was notified; and we coordinated with the flight attendants about our return to ZZZ. The passengers were briefed. A log item was placed in the logbook. When we landed; the station did a head count and no one was missing. We inspected the cargo pits; and maintenance inspected cargo pits; cargo loading system; nose wheel well; east and east compartments amount other things; and did not find anything obvious. We then coordinated for a continuation with the company. In the flight deck; we never heard any unusual noises. Also; we notified the operations manager on our arrival. He said he supported our decision to return and have things checked out.

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Original NASA ASRS Text

Title: B737 Captain reported returning to departure airport when the flight attendants reported hearing noises from the forward cargo pit area.

Narrative: We departed Runway XYR at ZZZ. On climb out prior to sterile cockpit light being selected off; the flight attendants called us and informed us they were concerned about a loud bumping or banging noise coming from below the forward part of first class; possibly from the forward cargo pit 'like someone was banging on the aircraft flooring' They asked the first class passengers if someone was stomping on the floor; or kicking the sidewall for some reason; and no one was. The flight attendants were experienced; and have flown frequently on the 737 series aircraft. We leveled off at 14;000 feet and were eastbound now on the departure from ZZZ. We decided to go back to ZZZ and have the aircraft inspected. The forward cargo pit cargo loading system was deferred inoperative. We were also concerned about the possibility of a ground crewman left in the cargo pit due to the late night departure. Or possibly a panel flapping in the air. The weather was good; traffic was very light; we were able to land under structural landing weight; and ATC was not busy. We coordinated with ATC; dispatch was sent a quick message; the station was notified; and we coordinated with the flight attendants about our return to ZZZ. The passengers were briefed. A log item was placed in the logbook. When we landed; the station did a head count and no one was missing. We inspected the cargo pits; and maintenance inspected cargo pits; cargo loading system; nose wheel well; E and E compartments amount other things; and did not find anything obvious. We then coordinated for a continuation with the company. In the flight deck; we never heard any unusual noises. Also; we notified the Operations Manager on our arrival. He said he supported our decision to return and have things checked out.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.