A319 repeatedly rejects programming of runway 35L; reverting back to 35R uncommanded.

Attributes
ACN	780522
Time
Date	200803
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : den.airport
State Reference	CO
Altitude	msl single value : 11000
Environment
Flight Conditions	IMC
Light	Daylight Night
Aircraft 1
Controlling Facilities	tracon : d01.tracon
Operator	common carrier : air carrier
Make Model Name	A319
Operating Under FAR Part	Part 121
Navigation In Use	ils localizer only : 35l other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 230
ASRS Report	780522
Person 2
Affiliation	government : faa
Function	controller : approach
Events
Anomaly	aircraft equipment problem : critical non adherence : clearance other spatial deviation
Independent Detector	other controllera other flight crewa
Resolutory Action	aircraft : equipment problem dissipated controller : issued advisory controller : issued new clearance flight crew : overrode automation flight crew : executed go around
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft ATC Human Performance
Primary Problem	Aircraft

Narrative:

Inbound to den we briefed and loaded runway 35L into the mcdu. On descent; we noticed that the runway in the mcdu changed to runway 35R. The first officer changed the runway back to runway 35L and reloaded the approach performance data. About 5 mins later; 'enter destination data' popped up on the mcdu. The captain entered the destination data again for runway 35L. We activated the approach and were given vectors to intercept runway 35L localizer and cleared for the approach. As we turned onto the final; we noticed it was a tight vector and then noticed that the box again had runway 35R in it. Just as we noticed; the controller noticed as well and asked us if we were joining runway 35L. I informed him that we were on runway 35R localizer and that the mcdu malfunctioned. We were given vectors off the approach and re-sequenced for another runway 35L approach. We recycled the box again and monitored carefully. The intercept then proceeded normally except for a temporary CAT ii downgrade. Careful doublechking that the aircraft is intercepting the correct localizer.

Original NASA ASRS Text

Title: A319 REPEATEDLY REJECTS PROGRAMMING OF RWY 35L; REVERTING BACK TO 35R UNCOMMANDED.

Narrative: INBOUND TO DEN WE BRIEFED AND LOADED RWY 35L INTO THE MCDU. ON DSCNT; WE NOTICED THAT THE RWY IN THE MCDU CHANGED TO RWY 35R. THE FO CHANGED THE RWY BACK TO RWY 35L AND RELOADED THE APCH PERFORMANCE DATA. ABOUT 5 MINS LATER; 'ENTER DEST DATA' POPPED UP ON THE MCDU. THE CAPT ENTERED THE DEST DATA AGAIN FOR RWY 35L. WE ACTIVATED THE APCH AND WERE GIVEN VECTORS TO INTERCEPT RWY 35L LOC AND CLRED FOR THE APCH. AS WE TURNED ONTO THE FINAL; WE NOTICED IT WAS A TIGHT VECTOR AND THEN NOTICED THAT THE BOX AGAIN HAD RWY 35R IN IT. JUST AS WE NOTICED; THE CTLR NOTICED AS WELL AND ASKED US IF WE WERE JOINING RWY 35L. I INFORMED HIM THAT WE WERE ON RWY 35R LOC AND THAT THE MCDU MALFUNCTIONED. WE WERE GIVEN VECTORS OFF THE APCH AND RE-SEQUENCED FOR ANOTHER RWY 35L APCH. WE RECYCLED THE BOX AGAIN AND MONITORED CAREFULLY. THE INTERCEPT THEN PROCEEDED NORMALLY EXCEPT FOR A TEMPORARY CAT II DOWNGRADE. CAREFUL DOUBLECHKING THAT THE ACFT IS INTERCEPTING THE CORRECT LOC.

Data retrieved from NASA's ASRS site as of May 2009 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.