Date: 201710
Local time of day: 0001-0600
Location: MMAS.Airport, FO
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Escape Slide
Component problem: Improperly Operated
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting; Distraction
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: Flight Crew Overcame Equipment Problem; General Maintenance Action
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Upon parking; I set the parking brake and continued with the parking flow which includes shutting down Engine 1. Gave the brake set signal to the ground crew. Ground crew gave me the chock signal. I monitored the status page on Display Unit 2 and first observed the Forward Cargo door indicate Red. Waited several seconds more and then observed the Main Passenger Door indicate red. At that point called for the Parking Checklist. First Officer and I completed the checklist and then I removed my headset and unlocked the cockpit door. At about the same time the Number 1 Flight Attendant called on the cabin call line. The First Officer answered her call and was told there was a 'serious problem' with the door.I was already pushing open the cockpit door and then she told me as well there was a problem with the Passenger door. I stood up to take a look and saw that the girt bar was still attached to the floor assembly and the slide was partially protruding from its casing. It appeared to be lodged between the aircraft and the station stairs which prevented it from inflating. The door was about half open. I directed the ramp agents to stay off and clear of the stairs. I asked the Flight Attendant what happened. She told me while she was attempting to disarm the door someone opened it from the outside. Contract maintenance was already on the scene which I assume is normal in Mexico for all arriving flights. I contacted MOC borrowing a phone from contract Maintenance. We first attempted to deplane the Passenger through the Aft Passenger Door; but the spare stairs was not tall enough. We then resorted to deplaning through the Forward Service door with the First Officer and Number 1 Flight Attendant blocking the Main Door as passengers passed by. Contract Maintenance successfully disconnected the bottle and removed the slide; casing and all. I made an entry in the [logbooks] and we terminated the aircraft for the night. I did not witness the event first hand so I can only relay what Flight Attendant 1 told me. It sounds like two individuals were handling the Main door at the same time. The Flight Attendant on the inside and ground personnel employee on the outside. Unless there was a mechanical malfunction; the event sounds like either a miscommunication or misinterpretation between the two parties.


Second narrative: [Report narrative contained no additional information.]


Synopsis: A regional jet flight crew and flight attendant reported a partial slide deployment due to miscommunication between flight attendants and ground personnel at a foreign airport.