Date: 201605
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Air Conditioning and Pressurization Pack
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness; Time Pressure; Workload
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Observer
When detected: In-flight
Result: Flight Crew Took Evasive Action; Flight Crew Returned To Departure Airport; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Became Reoriented; General Maintenance Action
Contributing factors: Aircraft; Environment - Non Weather Related
Primary problem: Aircraft

Narrative: When we showed up to the airplane there was an FAA inspector that requested to ride in the jump seat to our destination. He took our medical; and license and asked a few questions in regards to the flight. I gave him the flight time; discussed with him the MEL that was on our paper work regarding PACK 2 being inop (21-51-00-3 AIR COND PACK WITH ISIS [Integrated Standby Instrument System]) and continued to brief him in regards to him being in the jump seat. I did take out the briefing card and continued to brief him. He told us that he was very familiar with the EMB-145 and that he was qualified on the aircraft. I told him even though he was observing us that he was still an additional crew member in case of an emergency. My First Officer (FO) and I had also discussed the MEL and noted some of the threats that go along with that MEL. This was the first leg of a day trip that was assigned to us and we were just starting out our day. I had flown with my FO in the past and was happy to see a familiar face. We essentially briefed; and set up the aircraft for departure without anything out of the ordinary other than the FAA being in the jump seat. We had an on time departure; we pushed back and started engine number 2 on the push. Once taxiing to the runway we started the other engine; ran the required checklists and took off. The takeoff was normal and everything seemed to be going as planned. At some point during the climb we were given instructions to climb to FL240. This was our cruise altitude due to the MEL. At about FL220 we were given a direct to our destination airport. We set that up in the FMS and at that point I started to pull up my destination charts as to try and plan ahead as much as possible. At about FL230 the FAA inspector tapped me on the shoulder and pointed at a cyan message on the EICAS and suggested to eliminate the climb. The message indicated that we had lost PACK 1 and I realized at that point we were not pressurizing anymore. Initially; I asked my FO to pull out the QRH; while at the same time I slowed our climb to 500 FPM. Somehow I had hoped that recycling the PACK it would just take care of our problem but after doing just that and no luck; I quickly realized this was going to be a huge problem. I immediately got on the radio and requested a lower altitude and told ATC we had a pressurization problem. They gave us 10;000 feet. We immediately started down and I was trying to monitor the pressurization. I noticed it was climbing quite rapidly so I tried to increase our rate of descent and at that point I [advised ATC] with the request to go back to the departure airport. Our descent reached 5000 FPM at one point. During our descent I called the Flight Attendant and told him we had a problem pressurizing and that we were descending to a safe altitude and going back. I instructed him to prepare the cabin for arrival. During the descent my FO ran the QRH and I flew the airplane. I remember asking my FO to send a message via ACARS to company regarding our air return/emergency but he had already sent the message and was on his A game. At about 16000 feet we got the cabin alert and the cabin was at over 10;000 feet. I don't remember how fast my airspeed was but I do remember thinking I needed to drop the gear to transition from a fast descent to an emergency descent. I slowed to 250 knots; dropped the gear and transitioned into an emergency descent. We never put on our oxygen masks during the descent; but I didn't think we were at risk simply because the aircraft was already below FL180 and knew we would be leveling off soon. The cabin altitude reached 11900 if I can remember correctly; before dropping back down once we leveled off. Once level; my FO and I started discussing our overweight situation. My FO suggested turning on the APU and we did. We also started creating drag in order to burn more fuel. We were 70 miles or so from landing and needed to burn 2500 LBS. We asked ATC for a 20 mile vector. Luckily;the airport was completely VFR and we were able to quickly brief a visual to 36L. We ran all appropriate checklists and eventually were cleared for a visual approach. On an 8 mile final the FMS had us landing roughly at 43550 and we knew it would be close but felt comfortable continuing. As we got closer; at about a 4-5 mile final; I realized that we would be landing overweight by approximately 100 LBS. I briefed my FO and jump seater that we would continue to land since we were so close. On landing we were exactly 80 LBS too heavy. On the ground we simply exited the runway; and held short of the other runway until instructed to cross. Once on the other side my FO coordinated our parking gate and we went to the gate. I'm sure there were several errors made during our flight but I felt that we dealt with the situation safely and reacted appropriately. Thankfully my FO and I had flown together in the past and it made dealing with this situation easier since we work well together. The existing MEL was a threat since we already had one of our PACKS on MEL.Identifying the problem and acting quickly was another threat.Our overweight situation was another threat that we had to deal with during our return to the departure airport.The FAA jump seater also helped to catch the altitude setting on the pressurization for landing. We had set filed destination and we needed to return it to the departure airport. Granted we were not pressurized; it was still an error on my part to not catch that.FAA jump seater told me that while cleared to intercept the LOC I mistakenly hit the APR mode instead of the LOC. I didn't realize this until we were on the ground and he brought it up to my attention.Again; several errors were made but I felt that the safety and integrity of the flight were never compromised.I learned that it is vital to have a good scan in the cockpit particularly when you are already working with something broken on the airplane. I am thankful for our training department for preparing us for this situation. I believe that even though we both made mistakes we were able to land safely back because of our good training and CRM. I felt the extra stress of having the FAA on board but at the same time I am glad that I had another pair of eyes in the flight deck to help identify the problem quickly. This goes to show that an emergency can happen anytime. Complacency is something that we have to fight every day we show up for work.


Second narrative: I learned a lot from this event. To prioritize thing[s] first; to take a deep breath and not rush things to be as much efficient as possible. Communication and CRM [are] really important. Deal with one issue at a time. I think we did a fairly good job on this event but of course could have done better and can still improve our CRM and decision making. Also of course keeping [a] scan [of] the instruments and EICAS is always very important.


Synopsis: EMB-145 flight crew reported the loss of pressurization during climb to FL240 with the other PACK already MEL'd.