Air carrier flight crew reported a track deviation on arrival into sat after missing a runway change...

Attributes
ACN	1606562
Time
Date	201812
Local Time Of Day	1201-1800
Place
Locale Reference	SAT.Airport
State Reference	TX
Environment
Light	Daylight
Aircraft 1
Make Model Name	Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Descent
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 515 Flight Crew Type 15000
Person 2
Function	Pilot Flying First Officer
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument
Experience	Flight Crew Last 90 Days 590
Events
Anomaly	Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Narrative:

Flight to san antonio. We were filed on a SID to a STAR and thus briefed the entire flight at the departure gate. I looked at the weather packet and assumed that sat was landing on 31L. We programmed 31L into the FMC and briefed the STAR. Approaching marks in the descent; we were given off course vectors and several speed changes to follow traffic. We were distracted from reading the current ATIS and verifying the landing runway on the legs page. We flew part of the 31L transition until queried by ATC. We were on the wrong transition and were given clearance direct to a fix on the correct transition. The remainder of the approach was uneventful.the transition needs to be briefed and verified again regardless of the previous briefing at the departure gate.

Original NASA ASRS Text

Title: Air Carrier flight crew reported a track deviation on arrival into SAT after missing a runway change.

Narrative: Flight to San Antonio. We were filed on a SID to a STAR and thus briefed the entire flight at the departure gate. I looked at the weather packet and assumed that SAT was landing on 31L. We programmed 31L into the FMC and briefed the STAR. Approaching MARKS in the descent; we were given off course vectors and several speed changes to follow traffic. We were distracted from reading the current ATIS and verifying the landing runway on the LEGS page. We flew part of the 31L transition until queried by ATC. We were on the wrong transition and were given clearance direct to a fix on the correct transition. The remainder of the approach was uneventful.The transition needs to be briefed and verified again regardless of the previous briefing at the departure gate.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.