When traveling yesterday BWI-ATL, a man moved seats 3-times in First Class as seat holders began to board and then settled in the first row of coach. When I asked a flight attendant to verify authenticity of the traveler during the boarding period, I received no response. I asked another flight attendant... again, no action. I got up and spoke to the pilot about the situation. He called the gate agent, who came on the plane. The traveler in question, who was now seated in the bulkhead row of coach, just behind me, had a ticket for 33C. The gate agent did not move the passenger. I asked that the passenger be moved to his assigned seat, for at this point, I was not comfortable with this large man being right behind me. The gate agent did not comply with my request. During taxi, I noticed the traveler in question to be on the phone so I called for the flight attendant. The attendant did not ask the man to hang up the phone. He stayed on the phone through takeoff. To me this is just another example of DL staff not being observant and proactive of the situation. In the end, I am probably more disappointed in the FA's response and not proactively addressing the situation on their own than I was about my true safety. However, I do feel the flight staff should have more appropriately responded to my concern, when it was brought to their attention. I am used to being blown off by DL plan staff, but when it potentially affects my safety as I feel this situation did, it makes me mad. I spoke with a service member upon landing at ATL about the situation. She told me all concerns must be communicated via delta.com. I just feel this security concern is worth more than a "push & pray" internet submission, from which I will never receive a true response... any ideas on how I can actually speak to DL about this situation?

Call, do not write, the FAA Inspector General. The phone during takeoff, esp. that close to the cockpit, is a safety (not a security) issue. Make clear that you reported the violation and that the FA did nothing.

As to where the guy sits, that's not your concern and if you didn't want him sitting behind you, you could have moved to 33C which was presumably empty.

I presume but do not know that based on your prior interchange regarding your comfort level with the guy in a bulkhead, the FA ignored you. That's too bad, it's human nature and bad flight safety.

Sort of boy who cried wold -- in the end, he really was eaten by a wolf.

I apologize in advance, but no one will believe the story.

If you had a concern about your safety then perhaps you should have deplaned.