An MD83 flight crew experience an anomaly in the FMS system.

Attributes
ACN	519600
Time
Date	200107
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : mwa.vor
State Reference	IL
Altitude	msl single value : 27000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	tracon : phl.tracon
Operator	common carrier : air carrier
Make Model Name	MD-83
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : qball
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : cfi pilot : atp
Experience	flight time last 90 days : 80 flight time total : 12424 flight time type : 900
ASRS Report	519600
Events
Anomaly	aircraft equipment problem : less severe non adherence : clearance other anomaly other other spatial deviation
Resolutory Action	flight crew : overcame equipment problem
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance ATC Human Performance
Primary Problem	Aircraft

Narrative:

En route from XXX to stl, we were reclred direct dxv (pocket city) then the qball arrival to stl. Workload was moderate due to thunderstorm deviations. We had planned on a runway 30L arrival. En route, the stl ATIS indicated runway 12R at stl. I went to the arrival and departure page and changed the selected runway to runway 12R. I had the first officer verify the change. We then noticed the qball arrival had dropped out. So then I re-entered the correct flavor of qball arrival. (We have about 6 different qballs depending on runway or approach in use.) I closed the en route discontinuity and entered the appropriate crossing restr for qball, ie, 15000 ft. The first officer verified the correct arrival and also my executing the crossing restr on the legs page. What both my first officer and myself failed to notice was that the marion transition dropped out. Routing is hard to see as you approach the 320 NM range. After pocket city, the aircraft was flying direct to qball rather than towards marion VOR. The controller then asked if we were on a heading and I said no. He then cleared us direct to qball. Just because an arrival gate is entered and being flown to and the proper arrival entered, doesn't mean the transition between that fix and arrival is entered. I will watch for this trap.

Original NASA ASRS Text

Title: AN MD83 FLT CREW EXPERIENCE AN ANOMALY IN THE FMS SYS.

Narrative: ENRTE FROM XXX TO STL, WE WERE RECLRED DIRECT DXV (POCKET CITY) THEN THE QBALL ARR TO STL. WORKLOAD WAS MODERATE DUE TO TSTM DEVS. WE HAD PLANNED ON A RWY 30L ARR. ENRTE, THE STL ATIS INDICATED RWY 12R AT STL. I WENT TO THE ARR AND DEP PAGE AND CHANGED THE SELECTED RWY TO RWY 12R. I HAD THE FO VERIFY THE CHANGE. WE THEN NOTICED THE QBALL ARR HAD DROPPED OUT. SO THEN I RE-ENTERED THE CORRECT FLAVOR OF QBALL ARR. (WE HAVE ABOUT 6 DIFFERENT QBALLS DEPENDING ON RWY OR APCH IN USE.) I CLOSED THE ENRTE DISCONTINUITY AND ENTERED THE APPROPRIATE XING RESTR FOR QBALL, IE, 15000 FT. THE FO VERIFIED THE CORRECT ARR AND ALSO MY EXECUTING THE XING RESTR ON THE LEGS PAGE. WHAT BOTH MY FO AND MYSELF FAILED TO NOTICE WAS THAT THE MARION TRANSITION DROPPED OUT. ROUTING IS HARD TO SEE AS YOU APCH THE 320 NM RANGE. AFTER POCKET CITY, THE ACFT WAS FLYING DIRECT TO QBALL RATHER THAN TOWARDS MARION VOR. THE CTLR THEN ASKED IF WE WERE ON A HDG AND I SAID NO. HE THEN CLRED US DIRECT TO QBALL. JUST BECAUSE AN ARR GATE IS ENTERED AND BEING FLOWN TO AND THE PROPER ARR ENTERED, DOESN'T MEAN THE TRANSITION BTWN THAT FIX AND ARR IS ENTERED. I WILL WATCH FOR THIS TRAP.

Data retrieved from NASA's ASRS site as of July 2007 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.