<< >> NASA ASRS Report 1175026, May 2014

After selecting altitude intv to initiate a descent to the mdw PANGG1 RNAV sailz waypoint; a B737-800 leveled at 3;300 ft with the FMA indicating altitude hld but 3;000 ft set in both the MCP and FMC. ATC alerted the crew about the error.

Attributes
ACN	1175026
Time
Date	201405
Local Time Of Day	0601-1200
Place
Locale Reference	MDW.Airport
State Reference	IL
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737 Next Generation Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Route In Use	STAR PANGG 1 RNAV
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain
Experience	Flight Crew Last 90 Days 372
Person 2
Function	First Officer
Experience	Flight Crew Last 90 Days 401 Flight Crew Type 7000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Undershoot Deviation - Procedural Clearance

Narrative:

We were cleared direct sailz and to descend and maintain 3;000 ft. We were LNAV/VNAV established and had 3;000 ft set in altitude window and 3;000 ft restriction set in CDU for sailz. We initiated a descent to 3;000 ft and the pilot not flying verified it. We did not notice the aircraft level off at 3;300 ft. ATC queried our altitude we admitted 3;300 ft and descended to 3;000 ft and were established prior to the fix. After landing; the captain of another flight came over to us. He was following us in an -800 with the same clearance and reported to us his aircraft level led off at 3;300 ft too. We suspect an -800 software issue.

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Original NASA ASRS Text

Title: After selecting ALT INTV to initiate a descent to the MDW PANGG1 RNAV SAILZ waypoint; a B737-800 leveled at 3;300 FT with the FMA indicating ALT HLD but 3;000 FT set in both the MCP and FMC. ATC alerted the crew about the error.

Narrative: We were cleared direct SAILZ and to descend and maintain 3;000 FT. We were LNAV/VNAV established and had 3;000 FT set in Altitude window and 3;000 FT restriction set in CDU for SAILZ. We initiated a descent to 3;000 FT and the pilot not flying verified it. We did not notice the aircraft level off at 3;300 FT. ATC queried our altitude we admitted 3;300 FT and descended to 3;000 FT and were established prior to the fix. After landing; the Captain of another flight came over to us. He was following us in an -800 with the same clearance and reported to us his aircraft level led off at 3;300 FT too. We suspect an -800 software issue.

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.