SatoriEnd said:
"In the pipe" = in the correct parameters to enter atmosphere without burning up and will arrive on target (in the movie there's a display with purple rectangles showing the calculated flight path, hence "pipe").
"Five-by-five" = is an old signal strength check used by radio operators, it was a measure of signal strength and quality both rated on a scale of 1 - 5 with 1 being the weakest / poorest and 5 being the strongest / clearest. In theory you could wind up with a signal that was weak but clear 1x5 or strong but garbled 5x1 or any combination in between. In essence she's reconfirming that she's in really good shape for her entry.