Q400
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown; Distraction; Human-Machine Interface; Time Pressure; Training / Qualification; Workload
Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented; Flight Crew FLC complied w / Automation / Advisory
Human Factors; Environment - Non Weather Related; Company Policy; Procedure
Departed out of [a high altitude airport]; clear day; smooth air; at 12;000 ft got a Cabin Press warning light. On the ground my FO and I had talked about doing a [normal] TOP (Takeoff Performance) vs [maximum] TOP takeoff. We decided on NTOP and I had missed that both procedures were with bleeds off. Immediately knowing I had forgotten to turn on the bleeds; I quickly turned them on. I pulled out the emergency action card and proceeded to read through the Cabin Press emergency procedure. Cabin altitude was stable at 9.8 and not rising (nor was it descending). We slowed our rate of climb hoping the cabin controller would catch up while I continued with the Pressurization Fail Checklist. This led us to the Manual Pressurization checklist. I manually controlled the pressurization and was able to bring the cabin alt back down to 8;000 feet before switching it back to auto mode and allowing the cabin controller to do the work for us. There were some decisions I did not make due to the knowledge of the system and that the event was due to pilot error. The first was not calling Oxygen/Don Masks. My reasoning was that the cabin was stable at 9.8 and not climbing any more once the bleeds were turned on and I did not want the extra distraction of masks while trying to get the pressurization under control. The second was not declaring an emergency with ATC. My reasoning was once again I realized that the cabin press warning was due to pilot error. Since I had flown the aircraft the whole day; I figured I could get the cabin pressure under control. I also did not want to take the people back to the out station we just departed and the subsequent delays with maintenance that would happen there. Both oxygen/Don masks and declaring an emergency were in my back pocket and I was prepared to execute them but had felt that doing so at that time was jumping the gun. There was a bit of distraction for me in making those decisions. I was confused as to why the cabin controller wasn't automatically bringing the cabin altitude back down once the bleeds were turned on (past experience this had not happened). There was a part of me that yelled to follow our emergency memory items and yet the other part that rationalized following our checklists would alleviate my mistake to declare an emergency and declaring an emergency would add more complications. Due to the conflict in my mind I did miss a few radio calls from ATC and instead of requesting a lower altitude to run checklists; I accepted a climb to a higher altitude. My decisions were based on the observation of the cabin not further climbing; eventually getting the pressurization under control manually; the social impact of forgetting the bleeds; passenger inconvenience; and knowing I could declare an emergency if I noticed the cabin getting out of control.For bleeds off takeoff; I need to come up with a better way to remind myself that the bleeds were turned off for takeoff and to turn them on at 400 feet. The cause was doing something that is not a normal procedure. During winter it is easier to remember turning the bleeds back on due to icing conditions and our deice equipment being ALL ON. On a clear day it is easier to get distracted. There is no normal procedure to verify that the bleeds are ON at 400 ft. We do have the after takeoff checklist which I will now physically touch the bleeds and ensure they are on; but it's easy sitting in the left seat to look up and assume they are on (since they always are; right?). I also noted during the climb that the pressurization did not look correct. The altitude indicated 8;000; the rate was climbing at 500 ft per minute; and the differential was low; not climbing at all (usually it's the other way around). I stared at this for a while trying to figure it out but determined that it was at 8;000 feet because we took off at an airport at 7;000 feet elevation. Had I verified bleeds were ON physically while accomplishing the after takeoff checklistor if I had further investigated the abnormality with the pressurization (maybe even bringing my FO in the loop and my concern); we would not have had a cabin press warning light.
Q400 Captain reported departing a high altitude airport using a bleeds off procedure; but did not reselect the bleeds on until observing the cabin altitude warning light as the cabin climbed to 9;800 feet.