Both B737-700 FMC's blanked out in flight as FL370 was entered as the next expected cruise altitude ...

Narrative:

Cruise at FL330 autopilot; LNAV; VNAV; autothrottles engaged; we entered FL370 in the CDU for our next expected cruise altitude (FL350 was in at the time). FL330 was in the MCP. Optimum was FL37.6. Upon line selecting L1; both CDU's blanked out and the amber vtk was displayed on both pilots' EFIS panels. We also had the FMC P/rst caution light on the forward panel. All data dumped and then came back. We notified ATC that we would like to proceed direct XXX.VOR since we were receiving it raw data and it was next on our route. After re-attempting to enter FL370 on the CDU; it dumped again. We disengaged the VNAV and autothrottles; re-entered all route and performance data and everything returned to normal. This whole process took just a few minutes. We notified ATC that we could continue via RNAV on our route and were cleared to do so. The entire remainder of the flight went normally with use of all equipment. I am assuming it was a temporary software glitch of some sort.

Original NASA ASRS Text

Title: Both B737-700 FMC's blanked out in flight as FL370 was entered as the next expected cruise altitude with FL350 the current FMC altitude and FL330 was set in the MCP. VTK annunciated on both EFIS panel and FMC P/RST caution light on the forward panel.

Narrative: Cruise at FL330 autopilot; LNAV; VNAV; autothrottles engaged; we entered FL370 in the CDU for our next expected cruise altitude (FL350 was in at the time). FL330 was in the MCP. Optimum was FL37.6. Upon line selecting L1; both CDU's blanked out and the amber VTK was displayed on both pilots' EFIS panels. We also had the FMC P/RST caution light on the forward panel. All data dumped and then came back. We notified ATC that we would like to proceed direct XXX.VOR since we were receiving it raw data and it was next on our route. After re-attempting to enter FL370 on the CDU; it dumped again. We disengaged the VNAV and autothrottles; re-entered all route and performance data and everything returned to normal. This whole process took just a few minutes. We notified ATC that we could continue via RNAV on our route and were cleared to do so. The entire remainder of the flight went normally with use of all equipment. I am assuming it was a temporary software glitch of some sort.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	824413
Time
Date	200902
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.VOR
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain Pilot Not Flying
Experience	Flight Crew Last 90 Days 211
Events
Anomaly	Aircraft Equipment Problem Less Severe

Both B737-700 FMC's blanked out in flight as FL370 was entered as the next expected cruise altitude with FL350 the current FMC altitude and FL330 was set in the MCP. Vtk annunciated on both EFIS panel and FMC P/rst caution light on the forward panel.