Date: 201504
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B737-900
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
ATC / advisory: Ramp ZZZ
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Time Pressure; Distraction; Confusion; Communication Breakdown; Workload
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew; Person Dispatch
When detected: Aircraft In Service At Gate; In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Aircraft; Company Policy; Procedure; Manuals
Primary problem: Company Policy

Narrative: We got a message from Dispatch that when we got to Airport ZZZ we needed to keep everyone in their seats because we were in a 900ER and we may have the 'tipping aircraft' issue. We let the FAs know about it enroute. FO backed it up by asking dispatch if we still need to do the procedure since it did not show up on our 'In Range' reply. We were told yes. The FAs talked about the procedure with each other. None of us on the plane had done this procedure before. The FO and I had a discussion ourselves on what we needed to do. My only question was (as was the FA's) who and how were we going to be told to let the people up. In our pilot discussion; I wondered 'if' I shutdown and had the seat belt light turned off; would the passengers get up as they are conditioned to do. So I elected to do the safest thing and leave the seat belt sign on until we heard from ZZZ ops to let everyone up. So that is what we did. After we got to the gate; we shut everything down; the jetway came up which is fine; I still had the seatbelt sign on so no problem. After a very short wait; I get a call from the back saying that it was okay to let them leave the airplane. I asked her how did she know that and she told me the gate agent told her so. Confused; I asked how she talked to the gate agent; she said through the front door. We looked up and the 'FWD ENTRY' light was on. I jumped up and went to the back and sure enough; the front door was open with the agent looking in. I told them the seat belts lights were still on and they are not to open the doors when that light is on. The FAs seemed surprised as they simply heard the gate agent knock on the door and opened it. After a short discussion; we let the passengers de-plane. As a side note; while the FO was doing his exterior preflight; he noted that the nose gear strut was fully extended and felt the jetway canopy was holding the aircraft down; but we talked to maintenance and they assured us that was normal for this situation and had checked that the nose gear were fully in contact with the ground and did not rotate.Everyone but the pilots seem to be more worried about the measuring 'matrix' than safety. It ALWAYS rush; rush; rush; rush no matter what! Everyone is more concerned about 'protecting their six' then having any sort of situational awareness. As pilots we have to be EVERYONE'S safety 'thinker' and slow them down or override them. Then we immediately become the bad guys! We have also conditioned the Flight Attendants to open the door as soon as possible; and they are conditioned to react to any sound; knock; noise; whatever to rush; rush; rush even when we are EARLY; so sometimes things happen. I am not saying the measuring 'matrix' is bad; it is not; it serves a good purpose. BUT everyone needs to know that when things are 'NOT NORMAL' use common sense; the 'matrix' is a 'goal' and not an absolute! We may have not done the procedure as the station thought we should have; but no one on the crew had done this before so we decided to do what we thought was the SAFEST way to do it (keep the seat belt on so that we could be sure the PAX would remain seated). As a note; other than bringing the jetway up and knocking on the door; the gate agent did what she was told; she did not open the door in any way.




Synopsis: A B737-900 Captain reported a Dispatch alert not to deplane passengers at the destination until advised because of a potential 'tipping aircraft.' No one seemed to have details about the issue.