Date: 202010
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Aircraft: A320
Operator: Air Carrier
Operating under: Part 121
Mission: Ferry / Re-Positioning
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Communication Breakdown; Time Pressure; Confusion
Second reporter function: Captain
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Maintenance
When detected: Aircraft In Service At Gate
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: On Sunday; (date) I was called off reserve to fly Aircraft X under Ops Spec XXXX; with a ferry permit; from ZZZ1 to ZZZ. As far as I knew the flight went smoothly and according to plan; but I got a call on Tuesday; (date); informing me that the R1 slide had deployed when maintenance personnel opened the door later that day. I am not positive what happened; but here is what I recall: being that no flight attendants were on board; it was up to the flight crew to disarm the doors. During our approach briefing; the Captain had briefed me about disarming the doors prior to maintenance personnel opening the L1 door. I understood the Captain to be saying 'it is critical that we disarm the L1 door quickly upon arrival; before personnel open it from outside.' Upon shutdown I reiterated to the Captain that I would disarm the L1 door right away; which I did. I can not remember exactly the captain's response when I read the 'cabin doors' item on the parking checklist; but I was under the impression that we were only worried about the L1 door; and that we were turning it over to Maintenance; so they would handle the rest. If I remember correctly; I only disarmed the L1 door. My recommendation would be to not perform the parking checklist until all doors were disarmed. As a brand new First Officer with 3 trips under my belt since consolidation; I should not have assumed anything; instead of assuming there must have been an exception to the '6 disarmed' response on the parking checklist; or assuming that the Captain had done this before and knew a procedure that I did not know.


Second narrative: At the conclusion of a maintenance flight from ZZZ1 to ZZZ; the disarming of the doors was not verified. During approach brief; I briefed that the L1 door needed to be disarmed before anyone tried to open the door from the outside. We parked the aircraft; shut down the engines and did the parking checklist. Upon reaching the door verification; I stated 'to go' because we had to disarm the doors ourselves. We got up and I went to the back and disarmed L2 and R2; leaving the front doors to the First Officer. As I returned to the flight deck; I double checked L1 to make sure it was disarmed. I then returned to the flight deck and shut down the aircraft. I did not re-verify that the parking checklist was completed. I was informed yesterday that a slide had deployed after our flight. I did not verify the doors disarmed; to finish the parking checklist. I also should have double checked both front doors; after disarming the back.


Synopsis: Flight Crew reported an evacuation slide deployed after parking aircraft.