BTW The "NW" tacked on to the "N" number - tells us that this aircraft was originally in the Northwest fleet - before they were gobbled up by Delta. Delta still uses them on the same runs that Northwest did. This is a common practice with other mergers as well. For example - American uses the A330's that they inherited from US Air - on transatlantic routes - that were previously operated by US Air. It is a common practice to tag the airline's code letters on the tail end of the "N" numbers assigned to newly purchased aircraft. And these numbers are perpetuated during the life of the aircraft. Occasionally, one will see an "AW" tacked on to the "N" number of certain AA aircraft. These were originally assigned to America West aircraft - which then became US Air aircraft - which then became AA aircraft. I've even recognized the unique appearance of cabin partition dividers - part of the original design in the cabins of America West aircraft - now clashing with the decor on certain AA runs!

Thank you Art. Good info !