Narrative:

As PF in an aircraft which I just got checked out in, in february, I was given the radios while the captain was making a PA. The aircraft automatic pressurization control was deferred and we were operating the pressure manually. I noticed that the cabin pressure was climbing higher than normal for our altitude so I dialed the pressurization manual control lever forward causing the cabin to descend at 500-600 FPM. The captain, still making his PA, irritatedly asked me what I was doing and said that he 'had it' (the cabin pressure). I said 'ok' and continued to fly and handle the radios. Center called a few seconds later and remarked that we were 'several mi' off course. Our instruments showed us on course and I immediately began to investigate the problem. The 'cabin altitude' light illuminated (indicating that the cabin altitude was between 9500-10000 ft). The captain saw the light and hastily pulled the manual pressure control in the wrong direction, bumping the cabin up to 10500 ft. At this point the senior flight attendant entered the cockpit, but the captain said, 'not now, we're busy!' (at which point she left.) I said to the captain that he was moving the controller the wrong way. He moved it in the other direction and a few seconds later called the senior flight attendant up to the cockpit. She told us that the passenger oxygen masks had dropped. The captain made a PA and announced that there was no need to wear the oxygen masks. At this point the cabin pressure was below 10000 ft and descending. The captain wanted to know how to shut off the oxygen and I told him that I did not know of any way. After quickly looking through the system manual, we descended the cabin to 6000 ft which shut off the oxygen flow. I told him the oxygen bottles still indicated full. I asked him what 'the plan' was. He said that this was not an emergency and that he saw no reason to go back to dfw. We leveled at approximately FL260 and continued to pie. In the future, in similar sits, I will be more aggressive in suggesting the captain wait to do his PA if I am as busy as I was. I will also be more aggressive in stating my desire to return for corrective maintenance rather than continue the flight. Callback conversation with reporter revealed the following information: the reporter flies 3 different models of the dc-9 and md-80 for a charter air carrier. His previous experience was A-10's in the USAF and light transport's with a commuter air carrier. The captain realized that he had fouled up the pressurization system and did not attempt to cover up or blame the first officer. The captain wrote a letter to the air carrier which was not upset with the captain. Everyone put on their masks as the flight attendants did their bit on this incident. As this was gaseous oxygen, very little was used. The first officer suggested that the trip return to dfw, but the captain decided to go on. The captain is the type to get excited. He has a 'flawed way to run the cockpit' and his 'prioritization of tasks is really crazy.' the captain 'got in a hurry and made a mistake.' in this model aircraft, the oxygen supply is automatically shut off when the cabin altitude goes below 6000 ft. This meant that the crew would have to use the PA system if another need for oxygen arose. The reporter believes that the captain did not trust him. The first officer was new to the aircraft and the air carrier.

Related reports:

Google
 

Original NASA ASRS Text

Title: OXYGEN MASK DROP.

Narrative: AS PF IN AN ACFT WHICH I JUST GOT CHKED OUT IN, IN FEBRUARY, I WAS GIVEN THE RADIOS WHILE THE CAPT WAS MAKING A PA. THE ACFT AUTO PRESSURIZATION CTL WAS DEFERRED AND WE WERE OPERATING THE PRESSURE MANUALLY. I NOTICED THAT THE CABIN PRESSURE WAS CLBING HIGHER THAN NORMAL FOR OUR ALT SO I DIALED THE PRESSURIZATION MANUAL CTL LEVER FORWARD CAUSING THE CABIN TO DSND AT 500-600 FPM. THE CAPT, STILL MAKING HIS PA, IRRITATEDLY ASKED ME WHAT I WAS DOING AND SAID THAT HE 'HAD IT' (THE CABIN PRESSURE). I SAID 'OK' AND CONTINUED TO FLY AND HANDLE THE RADIOS. CTR CALLED A FEW SECONDS LATER AND REMARKED THAT WE WERE 'SEVERAL MI' OFF COURSE. OUR INSTS SHOWED US ON COURSE AND I IMMEDIATELY BEGAN TO INVESTIGATE THE PROB. THE 'CABIN ALT' LIGHT ILLUMINATED (INDICATING THAT THE CABIN ALT WAS BTWN 9500-10000 FT). THE CAPT SAW THE LIGHT AND HASTILY PULLED THE MANUAL PRESSURE CTL IN THE WRONG DIRECTION, BUMPING THE CABIN UP TO 10500 FT. AT THIS POINT THE SENIOR FLT ATTENDANT ENTERED THE COCKPIT, BUT THE CAPT SAID, 'NOT NOW, WE'RE BUSY!' (AT WHICH POINT SHE LEFT.) I SAID TO THE CAPT THAT HE WAS MOVING THE CTLR THE WRONG WAY. HE MOVED IT IN THE OTHER DIRECTION AND A FEW SECONDS LATER CALLED THE SENIOR FLT ATTENDANT UP TO THE COCKPIT. SHE TOLD US THAT THE PAX OXYGEN MASKS HAD DROPPED. THE CAPT MADE A PA AND ANNOUNCED THAT THERE WAS NO NEED TO WEAR THE OXYGEN MASKS. AT THIS POINT THE CABIN PRESSURE WAS BELOW 10000 FT AND DSNDING. THE CAPT WANTED TO KNOW HOW TO SHUT OFF THE OXYGEN AND I TOLD HIM THAT I DID NOT KNOW OF ANY WAY. AFTER QUICKLY LOOKING THROUGH THE SYS MANUAL, WE DSNDED THE CABIN TO 6000 FT WHICH SHUT OFF THE OXYGEN FLOW. I TOLD HIM THE OXYGEN BOTTLES STILL INDICATED FULL. I ASKED HIM WHAT 'THE PLAN' WAS. HE SAID THAT THIS WAS NOT AN EMER AND THAT HE SAW NO REASON TO GO BACK TO DFW. WE LEVELED AT APPROX FL260 AND CONTINUED TO PIE. IN THE FUTURE, IN SIMILAR SITS, I WILL BE MORE AGGRESSIVE IN SUGGESTING THE CAPT WAIT TO DO HIS PA IF I AM AS BUSY AS I WAS. I WILL ALSO BE MORE AGGRESSIVE IN STATING MY DESIRE TO RETURN FOR CORRECTIVE MAINT RATHER THAN CONTINUE THE FLT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES 3 DIFFERENT MODELS OF THE DC-9 AND MD-80 FOR A CHARTER ACR. HIS PREVIOUS EXPERIENCE WAS A-10'S IN THE USAF AND LTT'S WITH A COMMUTER ACR. THE CAPT REALIZED THAT HE HAD FOULED UP THE PRESSURIZATION SYS AND DID NOT ATTEMPT TO COVER UP OR BLAME THE FO. THE CAPT WROTE A LETTER TO THE ACR WHICH WAS NOT UPSET WITH THE CAPT. EVERYONE PUT ON THEIR MASKS AS THE FLT ATTENDANTS DID THEIR BIT ON THIS INCIDENT. AS THIS WAS GASEOUS OXYGEN, VERY LITTLE WAS USED. THE FO SUGGESTED THAT THE TRIP RETURN TO DFW, BUT THE CAPT DECIDED TO GO ON. THE CAPT IS THE TYPE TO GET EXCITED. HE HAS A 'FLAWED WAY TO RUN THE COCKPIT' AND HIS 'PRIORITIZATION OF TASKS IS REALLY CRAZY.' THE CAPT 'GOT IN A HURRY AND MADE A MISTAKE.' IN THIS MODEL ACFT, THE OXYGEN SUPPLY IS AUTOMATICALLY SHUT OFF WHEN THE CABIN ALT GOES BELOW 6000 FT. THIS MEANT THAT THE CREW WOULD HAVE TO USE THE PA SYS IF ANOTHER NEED FOR OXYGEN AROSE. THE RPTR BELIEVES THAT THE CAPT DID NOT TRUST HIM. THE FO WAS NEW TO THE ACFT AND THE ACR.

Data retrieved from NASA's ASRS site as of July 2007 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.