An A320 climbing through FL180 returned to the departure airport due to a dual FMS failure and ECAM ...

Attributes
ACN	694450
Time
Date	200604
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 18000
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 175 flight time total : 15000 flight time type : 2800
ASRS Report	694450
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : ecam other flight crewa other flight crewb
Resolutory Action	flight crew : landed as precaution other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Climbing through FL180; both navigation displays indicated 'map not available' along with a 'please wait' message in both FMGC's. Several moments later we received an ECAM for the pressurization system stating 'landing elevation not set.' the navigation displays and the ECAM reset themselves and shortly thereafter the entire sequence repeated itself. The autoplt disconnected and the autothrottles disarmed. We contacted center and told them we were having a navigation system problem and would like to return to ZZZ. The FMGC's remained locked out with no map displayed for several mins; followed by the FMGC's returning with all information deleted/empty. We returned to ZZZ and landed in the rose-ILS mode without event. Callback conversation with reporter revealed the following information: the reporter stated that what happened was a dual FMS computer failure. The pressurization ECAM warning was also caused by the computer failures; as the pressurization system has a 'landing elevation input' from the FMS computers.

Original NASA ASRS Text

Title: AN A320 CLBING THROUGH FL180 RETURNED TO THE DEP ARPT DUE TO A DUAL FMS FAILURE AND ECAM PRESSURIZATION WARNING.

Narrative: CLBING THROUGH FL180; BOTH NAV DISPLAYS INDICATED 'MAP NOT AVAILABLE' ALONG WITH A 'PLEASE WAIT' MESSAGE IN BOTH FMGC'S. SEVERAL MOMENTS LATER WE RECEIVED AN ECAM FOR THE PRESSURIZATION SYS STATING 'LNDG ELEVATION NOT SET.' THE NAV DISPLAYS AND THE ECAM RESET THEMSELVES AND SHORTLY THEREAFTER THE ENTIRE SEQUENCE REPEATED ITSELF. THE AUTOPLT DISCONNECTED AND THE AUTOTHROTTLES DISARMED. WE CONTACTED CTR AND TOLD THEM WE WERE HAVING A NAV SYS PROB AND WOULD LIKE TO RETURN TO ZZZ. THE FMGC'S REMAINED LOCKED OUT WITH NO MAP DISPLAYED FOR SEVERAL MINS; FOLLOWED BY THE FMGC'S RETURNING WITH ALL INFO DELETED/EMPTY. WE RETURNED TO ZZZ AND LANDED IN THE ROSE-ILS MODE WITHOUT EVENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT WHAT HAPPENED WAS A DUAL FMS COMPUTER FAILURE. THE PRESSURIZATION ECAM WARNING WAS ALSO CAUSED BY THE COMPUTER FAILURES; AS THE PRESSURIZATION SYS HAS A 'LNDG ELEVATION INPUT' FROM THE FMS COMPUTERS.

Data retrieved from NASA's ASRS site as of January 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.

An A320 climbing through FL180 returned to the departure airport due to a dual FMS failure and ECAM pressurization warning.