Crj-200 flight crew reported a pack failure that resulted in a cabin decompression and a diversion.

Attributes
ACN	1692556
Time
Date	201910
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Regional Jet 200 ER/LR (CRJ200)
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Air Conditioning and Pressurization Pack
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Critical Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor

Narrative:

We were climbing through FL200 when the left pack seemed to fail (the right pack was currently deferred and inoperative). There was a depressurization followed by an immediate descent to 10;000 ft. Appropriate checklists were run which entailed the passenger oxygen masks would drop down. The decision to return to ZZZ was made shortly after and then unfortunately; fumes and smoke were detected next and a diversion to ZZZ1 was safely executed. Checklists were done appropriately; a [diversion] brief was made; passengers briefed to the situation; and an aircraft deplaning through the main cabin door in a walking manner was made with everyone. An expedited deplaning checklist was run and the aircraft shut down and secured after everyone had left.the cause was suspected to be a remaining pack failure.this was unexpected and the only thing that may have prevented this was having a shorter time period for the MEL for the right pack deferral.

Original NASA ASRS Text

Title: CRJ-200 flight crew reported a pack failure that resulted in a cabin decompression and a diversion.

Narrative: We were climbing through FL200 when the Left Pack seemed to fail (the right pack was currently deferred and inoperative). There was a depressurization followed by an immediate descent to 10;000 ft. Appropriate checklists were run which entailed the passenger oxygen masks would drop down. The decision to return to ZZZ was made shortly after and then unfortunately; fumes and smoke were detected next and a diversion to ZZZ1 was safely executed. Checklists were done appropriately; a [diversion] brief was made; passengers briefed to the situation; and an aircraft deplaning through the main cabin door in a walking manner was made with everyone. An expedited deplaning checklist was run and the aircraft shut down and secured after everyone had left.The cause was suspected to be a remaining PACK failure.This was unexpected and the only thing that may have prevented this was having a shorter time period for the MEL for the R PACK deferral.

Data retrieved from NASA's ASRS site 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.