Abstract: In an aircraft having a pressure window mounted in the hull, an interior window assembly is removably mounted in an interior wall spaced from the hull. The interior window assembly is in register with the pressure window to enable occupants of the aircraft to view the outside. The interior wall has an opening formed therein to accept the interior window assembly and the portions of the wall surrounding the opening are biased toward the interior of the aircraft. The interior window assembly includes a windowpane mounted in a frame. The frame includes a flange that overlies the inboard surface of the portions of the wall surrounding the opening, and the bias of the wall portions is exerted on the flange. A constraint means is affixed to the hull of the aircraft and releasably engages the frame to constrain the frame from inboard movement. The bias force of the wall portions and the constraint means cooperate to hold the window in place.