B737-300 crew overshot the localizer on runway 11L at TUS after the captain did not arm the localizer for an autopilot capture.

Narrative

Rewritten in plain English from NASA’s original all-caps telegraphic report — facts, figures, and terminology preserved.

I was PNF and we were on the DINGO 5 arrival to TUS. It was VFR. The captain flew the beginning of the arrival properly, but did not arm the 'LOC' button and flew through final. On the DINGO 5, a 75 degree heading from MAVVA puts you on the ILS approach course.

After flying through the final approach course he said, 'There are 2 airports out here; ask her if we're cleared for the approach.' I then realized that he was heading toward Davis-Monthan AFB and hadn't transitioned. I asked approach if we were cleared for the approach and she remarked, 'If you call the airport in sight.' I asked the captain if he had the airport in sight and he replied, 'Yes.'

We then turned 90 degrees to about a 170 degree heading and rejoined the approach close to the airport. The captain said, 'She was supposed to clear us for the approach!' I tried to explain that we were expected to join final from the heading, but I didn't convince him.

Looking back, I believe he was reading the instructions for runway 29R (not the active, runway 11L) where one gets vectors from MAVVA and is most often flown. I also believe he was heading for the MIL base, since it was very well lit. I didn't have TUS in sight; I was expecting to see it once we were established. I do not believe he had it in sight until after we were well past course. We were certainly misidentified off our arrival; I can't even estimate how many since we remained on the 075 degree heading through full-scale deflection on the ILS and continued.

I felt we were very close to the AFB by the time we turned; but it was a clear night and hopefully I was wrong. Neither approach nor tower mentioned anything, so perhaps no harm no foul. I learned that just because I understand an arrival doesn't mean the guy sitting next to me does, and I have to keep a vigilant eye on what is selected/not selected (in this case, the 'LOC' button) and the CDI, even in perfectly clear, VFR weather. I did not have the airport in sight; I was trusting that if we remained on the arrival, I would see it. Had we remained on the arrival, I imagine I would have been correct. But I should have caught the mistake.

To top off a perfect day, at the gate (we were using 'gate services' where we don't start the APU, but leave an engine running until ground power is connected) the captain, through habit, cut both engines before waiting for ground power, plunging the airplane into emergency lighting confusion/darkness for about 20 seconds.