Narrative:

The flight was an early morning departure. Everything was normal up until holding short of the runway for departure. We detected a slight electrical fume in the cockpit but could not identify the source. All instrument and engine indications were in the normal and acceptable parameters. We considered that we could have a pack smell (pack overheat) but dismissed it as a different type of smell. Because all indications were normal we elected to continue the flight as briefed and planned. An exception was made while holding short of the departure runway to review the cabin fire smoke memory items as a precaution with returning to land should conditions worsen right after departure. The smell appeared to dissipate after departure and everything was normal until established in cruise flight. We noticed the cabin altitude beginning to climb in cruise flight; more so than the pressurization was able to handle. Upon the altitude in the pressurization [controller] turning amber around 8;500 ft; we elected to start a descent. I believe the altitude the descent started was around FL250. At the same time the descent began we noticed the electrical fumes begin again; only much stronger. We noticed that at a lower altitude; the pressurization was able to descend inside the aircraft. However; because of the increasing smell of the electrical fumes we thought that problem was increasing in intensity. We called the flight attendant who came to the front of the aircraft and also noticed the smell. She mentioned the jump seating captain; and we asked him to join us in the jump seat to help manage the situation and provide insight if necessary. Upon the captain joining us; all three of us elected to divert because of the deteriorating situation. We had the oxygen masks sitting on our laps should we need them if a fire began. We told ATC of our problem; did not declare an emergency; and made a non eventful landing. We had an MEL with the number 2 pack causing a reliance on one pack for the entire pressurization of the aircraft. Another threat was the electrical fumes and its unknown source. Diversion was a threat as it caused an increase in the workload of all crew members. Pressurization failure also increased the workload. Having two problems occur almost simultaneously put a strain on our ability to focus and fix the problems. There are two things that I believe we might have done differently; although I believe the outcome would have been the same. We could have declared an emergency and had priority handling; however once the decision was made to divert; ATC let us have anything that we asked for without bothering us; or having us declare an emergency. If we needed lower we got it; if we needed slower speeds we got it; we received priority handling from the time we advised them of our situation. There were no delaying vectors or anything that added more time for us to divert. The other item we might have considered was to start the APU and have it help the remaining pack at pressurizing the aircraft. While this might have helped the first problem; the electrical fumes turned out to be independent of the packs so diversion would still have been necessary. We made good decisions that were backed by sound planning and judgment. Many different avenues of possibility were discussed between the flight crew and the now jump seating captain. All gave inputs; listened; and then acted on the information that was presented.

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Original NASA ASRS Text

Title: EMB145 First Officer describes an electrical fume event with a pressurization anomaly at FL250 requiring descent and diversion to the nearest suitable airport.

Narrative: The flight was an early morning departure. Everything was normal up until holding short of the runway for departure. We detected a slight electrical fume in the cockpit but could not identify the source. All instrument and engine indications were in the normal and acceptable parameters. We considered that we could have a pack smell (pack overheat) but dismissed it as a different type of smell. Because all indications were normal we elected to continue the flight as briefed and planned. An exception was made while holding short of the departure runway to review the cabin fire smoke memory items as a precaution with returning to land should conditions worsen right after departure. The smell appeared to dissipate after departure and everything was normal until established in cruise flight. We noticed the cabin altitude beginning to climb in cruise flight; more so than the pressurization was able to handle. Upon the altitude in the pressurization [controller] turning amber around 8;500 FT; we elected to start a descent. I believe the altitude the descent started was around FL250. At the same time the descent began we noticed the electrical fumes begin again; only much stronger. We noticed that at a lower altitude; the pressurization was able to descend inside the aircraft. However; because of the increasing smell of the electrical fumes we thought that problem was increasing in intensity. We called the Flight Attendant who came to the front of the aircraft and also noticed the smell. She mentioned the jump seating Captain; and we asked him to join us in the jump seat to help manage the situation and provide insight if necessary. Upon the Captain joining us; all three of us elected to divert because of the deteriorating situation. We had the oxygen masks sitting on our laps should we need them if a fire began. We told ATC of our problem; did not declare an emergency; and made a non eventful landing. We had an MEL with the Number 2 Pack causing a reliance on one pack for the entire pressurization of the aircraft. Another threat was the electrical fumes and its unknown source. Diversion was a threat as it caused an increase in the workload of all crew members. Pressurization failure also increased the workload. Having two problems occur almost simultaneously put a strain on our ability to focus and fix the problems. There are two things that I believe we might have done differently; although I believe the outcome would have been the same. We could have declared an emergency and had priority handling; however once the decision was made to divert; ATC let us have anything that we asked for without bothering us; or having us declare an emergency. If we needed lower we got it; if we needed slower speeds we got it; we received priority handling from the time we advised them of our situation. There were no delaying vectors or anything that added more time for us to divert. The other item we might have considered was to start the APU and have it help the remaining pack at pressurizing the aircraft. While this might have helped the first problem; the electrical fumes turned out to be independent of the Packs so diversion would still have been necessary. We made good decisions that were backed by sound planning and judgment. Many different avenues of possibility were discussed between the flight crew and the now jump seating captain. All gave inputs; listened; and then acted on the information that was presented.

Data retrieved from NASA's ASRS site as of July 2013 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.