Marska: There is no bus within the Pamplona Airport itself (though you could walk to bus connections 1 - 2 kilometers away, as Google Maps outlines -- see below). If you go to the airport website, you will see that the only way to get there directly is by car or by taxi.
https://www.aena.es/en/pamplona.html.
(Many reviewers also comment on the lack of buses: Click on this link, then on "Reviews", then on "Buses":
https://www.google.com/gasearch?q=Pamplona Airport (PNA), Carr. del Aeropuerto, 31110 Noáin, Navarra, Spain&source=sh/x/gs/m2/5#lkt=LocalPoiReviews&lpg=cid:CgIgAQ==&topic=mid:/m/01bjv).
But If you don't want to take a taxi, and you don't want to walk all the way to Tiebas following the track that
@trecile outlined, Google maps describes bus options that start 1 to 2 kilometers away from the airport, and will get you to Tiebas in 45-60 minutes. For specifics, simply input Pamplona Airport and Tiebas using the public transit option for Google maps. In brief, this route involves a walk of approximately 1 k from the airport to a roundabout, where you pick up the L16 bus to Noian, where you then change for the Lerin bus to Tiebas. You could also walk directly to Noian from the airport (approx. 2k), and pick up the Lerin bus, thus avoiding the transfer. Google maps also includes links to the websites of the relevant bus companies.
(If I were doing this, though, I'd simply avoid the hassle and jump in a taxi at the taxi stand. But
chacun a son gout).
As others have commented, Tiebas is a cute (and quiet) little town, with a comfortable modern albergue and a lively bar / restaurant, and on the way to Puente La Reina the next day, you get to stop at the gorgeous chapel at Santa Maria de Eunate. Not a bad starting point at all, especially if you want to avoid the crowds out of Pamplona and the climb up to Alto del Perdon.
. Your post led to the finding of the missing InterBus schedule.
