An A319 FMGC failed to command appropriate power and airspeed parameters to comply with the crossing...

Narrative:

During dandd arrival on descent into den we were instructed to cross dandd at FL190 250 KTS. This was entered into the FMGC and descent begun at least 10 NM prior to TOD point. Airplane was descending at 273 KTS and 1;000 FPM until intercepting descent path. At the intercept point FMGC commanded thrust idle and increased descent rate to stay on the path. The engines did not retard to true idle (approximately 1;200 pounds fuel flow). Then a message appeared in FMGC stating speed error at dandd. FMGC indicated it would cross dandd at 273 KTS. We watched the aircraft stay on the descent path; accelerate to 293 KTS; and then retard to true idle. The speed error message remained (actually speed predicted at dandd increased to over 280) and passing about FL220 we had to extend speed brakes to make the speed portion of the restriction. The fault appears to be a software error. I have experienced at least five other instances of similar speed errors at crossing restrictions with new FMGC. This was the most deviation and worst response from the aircraft I have seen.

Original NASA ASRS Text

Title: An A319 FMGC failed to command appropriate power and airspeed parameters to comply with the crossing restriction at DANDD waypoint on the RNAV STAR to DEN. The reporter stated he had experienced previous failures with the 'new' FMGC.

Narrative: During DANDD arrival on descent into DEN we were instructed to cross DANDD at FL190 250 KTS. This was entered into the FMGC and descent begun at least 10 NM prior to TOD point. Airplane was descending at 273 KTS and 1;000 FPM until intercepting descent path. At the intercept point FMGC commanded thrust idle and increased descent rate to stay on the path. The engines did not retard to true idle (approximately 1;200 LBS fuel flow). Then a message appeared in FMGC stating SPEED ERROR at DANDD. FMGC indicated it would cross DANDD at 273 KTS. We watched the aircraft stay on the descent path; accelerate to 293 KTS; and then retard to true idle. The SPEED ERROR message remained (actually speed predicted at DANDD increased to over 280) and passing about FL220 we had to extend speed brakes to make the speed portion of the restriction. The fault appears to be a software error. I have experienced at least five other instances of similar speed errors at crossing restrictions with new FMGC. This was the most deviation and worst response from the aircraft I have seen.

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	919978
Time
Date	201011
Local Time Of Day	0601-1200
Place
Locale Reference	DEN.Airport
State Reference	CO
Aircraft 1
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR DANND
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Speed All Types

An A319 FMGC failed to command appropriate power and airspeed parameters to comply with the crossing restriction at dandd waypoint on the RNAV STAR to den. The reporter stated he had experienced previous failures with the 'new' FMGC.