Short answer: don't.
Assuming that the id is the primary key of the wp_flr_planes, there is never any reason to carry the plane_name into a different table. You can simply join the records and look up the plane_name from the wp_flr_planes table. All you need to store is the primary key of the wp_flr_planes in order to look up any corresponding information.
If this is a composite key, then you do require both to be provided as the option value. The only way to do this in a select control is by using a method that allows you to pass both of the keys. An array of the two serialized would allow you to pass it as the option value, and you can unserialize it on the receiving side.