Hmm
Something is off here . The visual resolution for human eye is 3-4 arcmins . And this is when are looking hard at the object in cause , not glancing it from the sky . 4 arcmins equals aproximatively 3.5 meters at 2 miles . I think what you have seen wasn't the drone , but the police helicopter. As for the "drone" a party ballon blown by the slow wind inside the airport would fit the scenario nicely .