Use the following command
ffmpeg -vframes 200 -f image2 -i airport1%03d.bmp -f avi -vcodec rawvideo -pix_fmt bgr24 -acodec pcm_s16le airport.avi
This will convert all the files airport1000.bmp to airport1200.bmp to an avi file.
Using mencoder will allow you to chose the framerate:
mencoder "mf://*.bmp" -mf fps=12 -o out.avi -ovc lavc -lavcopts vcodec=msmpeg4v2:vbitrate=800