Date: 201511
Local time of day: 0601-1200
Location: ZZZZ.Airport, FO
Aircraft: B757-200
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Flight Attendant In Charge; Flight Attendant (On Duty)
Reporter qualification: Flight Attendant Current
Human factors: Confusion
Second reporter function: Flight Attendant (On Duty)
Anomaly: Deviation / Discrepancy - Procedural Security; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
Detector: Person Flight Attendant
When detected: Aircraft In Service At Gate
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Yesterday at XA:58 was going thru security when a passenger behind me stated; 'why were we late since they are boarding'; in which I replied impossible he must have mistaken us for the cancelled flight from the previous night and they sent the passengers to an unscheduled flight for XA:30 departure. I stated that he must have been slightly delayed since our flight has a XC:00 departure with an XB:00 sign in. When my crew and I arrived at the gate we noticed few people in gate area and many boarding our flight! We were in disbelief since it was not even XB:00 and boarding time was not till XB:15! When we approached the agents they were in shock and did not know how to respond to us. We told them that this was a huge security breach and refused to board until they deplaned all passengers and do another security sweep. They did as requested and we boarded; did our equipment check and were able to board and depart on time.


Second narrative: We arrived at the gate approximately XA:57 and [are] met by the Ground Manager informing us they allowed passengers to board without the entire flight crew (pilots and flight attendants). I was shocked and told her that was a serious breach of security. Our Lead Flight Attendant and the rest of the crew refused to step on board the plane till proper security procedure be corrected. We were looking for the Captain; not aware he boarded the plane. After a few minutes the Captain deplaned and came back to the gate where he basically wanted us to go ahead and continue the rest of the boarding process. He said majority of the passengers are already on board and he wanted us to continue. I told him I did not want to violate security procedure with another violation because he said so. We tried to explain to him we also need few minutes to check our emergency equipment and other security procedure. Moreover we are not sure those passengers that boarded had been security cleared. Our Lead FA and the other 2 FAs explained to Captain as well to please do it right. We told him we need to deplane everybody and do another security sweep. If we do it right immediately we can manage to board all and still leave on time.At the end it was corrected and security sweep was accomplished after deplaning all the passengers.I honestly have no idea why it happened. This was my first experience of a security violation in my many years of flying. Gate agents and ground crew need to be retrained on security procedures. Most importantly Captain must be on top of these and have it corrected as soon as possible instead of persuading flight attendants to continue a serious security violation that can easily be corrected in the first place.


Synopsis: Three flight attendants reported arriving at their B757 aircraft; at the scheduled check in time; to find boarding nearly complete with no flight attendants on board. It is not clear how this occurred; but the passengers are deplaned and a security sweep accomplished before reboarding and departing on time.