EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Distraction; Human-Machine Interface; Situational Awareness; Workload
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Aircraft; Human Factors; Procedure
The cause of this event was high pilot workload due to deferred on-board equipment and distraction. We had a deferred ACARS and FMS system. As a result; we were unable to use the normal RNAV procedures in the Houston area. Instead we were navigating point-to-point using VOR's. This caused some confusion for controllers and we dealt with multiple re-routes throughout the day. Communicating our situation to ATC; finding correct frequencies for new navaids; and determining appropriate radials was very distracting.Additionally; before; during and after the 10;000 foot flow we received multiple radio calls from Center. These included speed; heading; and altitude changes. As pilot monitoring; I was answering the radio during the 10;000 foot flow and missed the change from APU bleed to engine bleed air supply to the packs. I accept full responsibility for my part in this event. In the future I intend to always double check my flow patterns. As we were climbing through 16;500 feet to FL230 we received a 'CABIN' aural warning due to the cabin altitude increasing over 10;000 feet. We immediately deployed oxygen masks and informed ATC we had a pressurization issue and needed to descend to 10;000 feet. Upon reaching 10;000 we ran the QRH and discovered we had not changed from APU bleed to engine bleeds. We changed to the engine bleeds; determined that the pressurization system was fully functional; and continued to our destination after climbing to 320.
[Report narrative contained no additional information].
When an EMB-145 was dispatched with both the FMS and ACARS inoperative the resulting increased workload contributed to their failure to switch pressurization from APU to engine bleeds.  They received a cabin altitude warning climbing through about 16;000 and descended to 10;000 where they discovered their error.  After reconfiguring the bleeds they continued to their destination.