B737-700
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 384
Time Pressure; Distraction; Human-Machine Interface; Troubleshooting
Aircraft Equipment Problem Critical; Flight Deck / Cabin / Aircraft Event Other / Unknown
Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Diverted; Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem
Aircraft; Human Factors
Cruising at FL400 we heard a loud bang that sounded like it came from the galley. A couple minutes later; the Flight Attendant called and asked us about the noise. At that time; we noticed the cabin altitude climbing. The altitude warning horn sounded shortly thereafter. I told the Flight Attendant we would be landing soon. We proceeded with our immediate action items and notified ATC. Once we were given a clearance to descend; we began an emergency descent. I ran the Cabin Altitude Warning checklist. That checklist led us to the Emergency Descent checklist. We descended the aircraft to below 10;000 ft before taking off our oxygen masks.After descending through 10;000 ft I got a status update from the Flight Attendant. I also briefed them about our diversion and time until landing. I then briefed the Passengers and notified them that they could remove their masks. The First Officer remained the Pilot Flying and did a great job flying and preparing for the landing. We briefed the approach and ran appropriate checklists. As time permitted; we notified Ops. After clearing the runway; we had CFR (Crash Fire Rescue) inspect the aircraft for damage. No visible damage was noted. We taxied to the gate. When we arrived; we had a cabin altitude of approximately 3000 ft. So; I manually depressurized the plane so we could open the door. The aircraft was further inspected by CFR and was deemed secure.
Boeing 737-700 Captain reported loss of pressurization.