# How did NASA Langley end up with the first 737?

This answer shows N515NA, CN/MSN: 19437 as an early 737, and mentions that it may be the first one.

Was this a special design built for NASA, or perhaps a prototype that nobody wanted for commercial use?

The Boeing 737 was Langley's number one choice, however, since it had a slightly wider fuselage and an advanced, high-lift flap system. Money however, was extremely tight. The market value of a used 737 in 1972 was about $3.5 million, but the Boeing Company had one particular 737 that its sales people said they might be willing to sell for substantially less." ... Boeing had designated the prototype as PA-099: PA for Lufthansa, and 099 as the last one in a block of 100 aircraft numbers Boeing had reserved for the airline. The prototype was never sold, however, because it was only certified for experimental use. With all the holes, wiring and other modifications that were made to the airplane for certification tests, bringing it up to the standards of a commercial transport airplane would have been too expensive. Boeing used the airplane for a few additional flight tests and then simply set it aside. ' In short, it was cheap, couldn't be used for commercial flight, and just what NASA needed. Chapter 2 in the above linked document covers the history in more depth and explains more of the nuances of the deal. To keep from copying the whole text I'll end it here. • This will make for some very enjoyable reading; thank you for such a thorough answer! – uhoh May 21 '19 at 2:23 • Ch. 2 pg. 11, or pg. 22 in the linked document. May 23 '19 at 10:00 • Other interesting characteristics about this 737: it ending up costing NASA "only"$2.2 million, and it also included all of the technology that Boeing had created during its work on the USA's cancelled SST (supersonic transport) aircraft. May 23 '19 at 10:06