The ATC tape I've heard start with him saying he's on a "Vi...RNAV GPS approach 19L". So it sounds like he was officially on an IFR approach but was actually on a visual. If they had entered the approach in the FMC and it was displayed on the Nav Display, one wonders how they got it wrong. After landing the pilot talks to McConnel tower to try and figure out where they are. From the level of confusion in the pilots voice, fatigue seems like a likely culprit here.

Here is the tape: https://soundcloud.com/producermatth...-4241-lands-at