B737 flight crew reported loss of cabin pressure control during descent and the need for oxygen masks. The flight crew requested priority handling and made an immediate descent and landing at destination airport.
Synopsis
B737 flight crew reported loss of cabin pressure control during descent and the need for oxygen masks. The flight crew requested priority handling and made an immediate descent and landing at destination airport.
Narrative
As the pilot flying on Aircraft X from ZZZ to ZZZ1. I started the initial descent from 38;000 feet; shortly after starting the descent the Master Caution Light illuminated with the corresponding 'Auto Fail' Light illuminating on the pressurization panel. At that time I also noticed that the Cruise Altitude and Landing Altitude displays were blanked. I called out the abnormality and the Captain stated that it was 'Your Aircraft'. At that time I verified that I was in control of the aircraft 'My Aircraft' and continued the descent. Continuing the descent I also worked the radios while the captain proceeded to run the 'Auto Fail' light checklist in the QRH (Quick Reference Handbook). Initially it looked as though the captain was able to control the pressurization but around 22 thousand feet the captain directed me to put on my O2 mask. After donning the O2 masks and establishing crew communications the Captain told me to request priority handling and he then manually deployed the Passengers O2 masks. Once we were below 10;000 feet the Captain directed me to remove my O2 mask at that time we completed all normal checklists and landed safely.During the Auto Fail light checklist I noticed that the 'Auto Fail' light stayed illuminated and the 'ALT' and 'MAN' light never illuminated during the checklist. During the descent a slower rate of descent may have helped with controlling the pressurization of the Aircraft. After Landing maintenance informed us that the aircraft had previous pressurization issues with this aircraft. (9 write ups on Pressurization Problems was mentioned). I believe a slower rate of descent and smaller thrust reductions may have helped with manually controlling the pressurization after the initial pressurization failure. I also believe with multiple write ups on the pressurization system their may have been an issue that maintenance might not have caught.
Second reporter narrative
Just after starting our descent into ZZZ from FL380; we got a Master Caution Light and 'AUTO FAIL' light on pressurization panel. No other lights on. Both cruise altitude window and landing altitude window had dashes '- - - -'. Checked cabin altitude and deferential pressure; both ok at this time. Cabin vertical speed indicator began moving between 330 FPM down to near 1;000 FPM down. Initiated 'Auto Fail' checklist on iPad QRH. When directed to go to manual control; manual light did not come on. Was able to control cabin vertical speed between 300 FPM to 800 FPM with momentary switch movements open/close. FO was pilot flying so I gave him aircraft and radios while I worked the manual valve. Descending thru approximately FL220 cabin started to climb and cabin deferential started going down at steady but rapid rate. Looked like we were loosing control of the cabin. Directed FO to put on O2 masks and request priority handling. I elected to manually deploy the cabin O2 before the cabin went above 10;000 feet. Initiated loss of cabin pressure checklist. Made a PA instructing the passengers to put on mask and follow crew member instructions. Called the Flight Attendants to let the know where we were at and notified the company thru ACARS. Did not complete emergency descent checklist as we were approaching 10;000 feet. Below 10;000 feet I made a PA. We were at a safe altitude and everyone could remove the O2 masks. Looking at the cabin altitude indicator showed basically our current altitude with differential pressure gauge at the upper limits. We could feel the pressure changes in our ears. At that point I check with the flight attendants to see if any was going to need medical assistance on the ground. They told my everyone was fine. Gave them my game plan for a normal landing and taxi to the gate. Let ATC know we were not going to need assistance on the ground and would land and taxi to the gate. After arriving at the gate and had deplaned; two passengers were complaining of ear pain and customer service people had called paramedics to have the checked out. 9 prior write-ups referencing pressurization problems. 2. Possible option- While in the descent ATC gave us the next crossing restriction. Thinking now the FO may have reduced the power more and the change in engine power may have cause the cabin to climb. With all the other erratic indications I didn't recognize this and called for the O2 masks. Recommend adding a caution note just after step 4 or 5 in the 'Auto Fail' checklist recommending manual throttles and small coordinated movements of the throttles while doing manual pressurization and to coordinate with ATC for an easy descent if able.
More incidents for this aircraft family →
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.