Date: 201909
Local time of day: 0001-0600
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Dawn
Aircraft: Regional Jet 900 (CRJ900)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class B ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Exterior Pax/Crew Door
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Second reporter function: First Officer; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Illness / Injury
Detector: Person Flight Attendant
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Landed in Emergency Condition
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Upon passing about 20;000 feet to 21;000 feet in the vicinity of ZZZ VOR; both the FO (First Officer) and I heard an unusual 'popping' sound coming from behind the door; then a steady loud 'hissing' sound. Before we finished asking each other what was that; one of the FAs (Flight Attendant) called; saying the noise is coming from the main passenger door. I had immediately said to the effect; for them to sit down and get buckled just in case there is a door failure; and we will be descending to a lower altitude. My FO must have heard me say about the descent; as he appeared to hit the ALT button on the flight control panel; and scrolling 10;000 feet. Just to be clear; I said to the FO; emergency decent and I'm requesting priority handling with ATC. I called Center; [Requesting Priority Handling] for a probable pressurization and main door issue; initially needing 10;000 feet as our safe altitude. Center gave it to us. The FO; PF (Pilot Flying); performed the rapid descent.A few moments into the descent; I noticed the cabin pressure was increasing; but not rapidly. I checked the Doors page; and all doors indicated 'Green;' including the main passenger door; but without being more certain about any damage yet; we descended at our current airspeed.  Around 16;000 feet; I gave Center the souls on board count; asked direct to ZZZ; and would get back with them. The FO continued PF duties; while I was talking with Center; talking with FAs about their status; pulling out the QRH for Passenger Door with No-EICAS message (none; with closest being Passenger Door Warning); and ACARS Dispatch being a [priority] aircraft for the Passenger Door. In my peripherals while doing these things; the average decent rate was about 2;500/minute holding current airspeed; pressure was stabilized; going lower; with less possibility of masks deploying or sudden loss of pressure.During the initial ACARS messages; I informed Dispatch we were an [priority] aircraft; descending to 10;000 feet with passenger door issue; pressure was stable/stabilizing; doors are indicating 'green' and we could continue to ZZZ. In hind-sight while writing this; I should have asked Dispatch if to continue to ZZZ; or divert somewhere closer and suitable. I learned later with a call from on-duty pilot in [Dispatch]; I had not included [Maintenance Control] with the initial couple ACARS; and this could have also aided in the decision-making process to continue as we did; or divert.While cruising at 10;000 feet direct to ZZZ; I continued to write ACARS; talk to FAs as needed; and Center as needed. Talking with the FA's was difficult for us to understand each other with the continuous hissing sounds. I had informed the FAs; that we are continuing to ZZZ and expecting a normal landing; therefore it's a Yellow Level; they seemed to verbalize a confirmation understanding Yellow Level and continuing to ZZZ.Shortly after talking with the FAs about the Yellow Level; I proceeded to make a PA to all the passengers. I informed them; we had descended to a lower altitude for an abundance of caution; at that time we were continuing to ZZZ; expecting a normal landing there along with the expected time of arrival; and apologized for the discomfort the sounds may be causing.Approaching ZZZ; I gave the standard in-range PA to the passengers; with gate information; arrival time; and again stated expecting a normal landing at this time.During the final approach and landing; the hissing sound stopped at about 2;000 feet. Upon landing; we double check the doors page; asked the FAs if the door was physically normal; and if they knew anyone needing special assistance. Once they gave a hurried yes indication; I notified Tower we would terminate the emergency. We taxied to the gate as normal. At the gate; I learned the forward FA; was complaining of terrible headache; and difficulty hearing. I asked her directly; if she needed medical attention. After a couple times asking; she said she should get checked out by medical personnel. I asked the FO; to call operations as our forward FA needs to be checked by medical personnel. No other passengers or crew needed medical attention. Because I was completing the discrepancy log; talking with Maintenance; and then phone call from on-duty pilot; I am uncertain if she received medical attention near the gate; in the jet-bridge; or anywhere else in the airport. What I can say; is she was talking on the phone with likely Dispatch saying about needing to be checked out; and the same with the gate agent. Myself; the FO; and aft FA continued on to the [next leg]; with a new FA taking the other's place.Maintenance met aircraft at the gate; and discovered approximately 4-6 inch area of the door seal had separated from the door. The seal itself was still serviceable from what the mechanics said when they had invited me down to see for myself.


Second narrative: I was the PF (Pilot Flying) and the Captain was the Pilot Observing. Climbing through approximately 22;000 feet. I heard a loud almost popping like sound then a constant loud hissing like sound coming from the other side of the flight deck door. When that happened the Captain and I looked at each other instantaneously with big eyes and at the same time the call button rang from the forward FA (Flight Attendant). I overheard the Captain tell the FA to sit down and buckle up. When he hung up I quickly asked him something to the effect 'do we need to descend to 10;000 feet?' (I suspected main cabin door seal) The Captain said yes so I stopped our climb immediately while the Captain was [Requesting Priority Handling] and requested a descent to 10;000 feet. We got immediate clearance to do so; so I put 10;000 feet in the altitude pre-select; the thrust levers to idle; full speed breaks and selected vertical speed and initially set rate of about 4;000 FPM and pulled my oxygen mask out; and I did not put it on. The autopilot was engaged the whole time.Once we were established in the descent I had a second to look at the cabin altitude. From my recollection it was showing about 2;100 feet and I believe a cabin rate increase of about 600 feet. At that point it did not appear that we were having a rapid decompression; I pointed out the cabin pressure to the Captain and did not feel a descent as aggressive as I was doing was necessary so I slowed the rate down to 2;500 FPM. Leveled off at 10;000 feet and continued to ZZZ. I continued to fly the aircraft as the Captain communicated with Dispatch; [Maintenance Control]; ran checklists and made a PA to the passengers. At some point a Controller asked us if we wanted to turn back to ZZZ1 or continue to ZZZ; we had good door indications so we elected to continue to ZZZ. We had several Controller changes enroute to ZZZ and we never [retracted priority handling]. I only said that because the Dispatcher kept asking if we were going to [Request Priority Handling] with approach? We got priority handling to ZZZ; we were greeted by ZZZ's [Aircraft Rescue and Fire Fighting]. We taxied off the runway without incident and stopped on the taxiway for a few minutes to asses everything then we continued to the gate without further incident. I stayed in the flight deck while the passengers were getting off the airplane and the Captain stood at the door. I only heard one lady say something like 'I didn't understand why we were descending that quickly at first.' That is the only comment I heard. The forward FA was complaining about having a headache and that their ears hear so the Captain asked me to contact operations and have them send medics to the airplane to check out the FA. After all the passengers were off I gathered my things and hurried across the terminal to our next flight. Nobody met us at our plane; like from management; to check on the Captain and I. There were a couple people there for the FA's but I couldn't tell you who you were.A 4-6 inch piece of the main cabin door seal dislodged from what holds it to the airplane is what I hear caused all the noise. Could have looked at the cabin altitude and rate before being so aggressive with the descent but wanted to get the aircraft descending first because of what could be a time critical situation.


Synopsis: CRJ-900 flight crew reported entry door seal failure inflight; resulting in a diversion.