Narrative:

The perf init (FMS page) was routinely programmed with a vmo/mmo/3.0 descent; the standard configuration. Upon descent we were cleared to cross wynde at 10;000 [ft]. I verified the correct TOD with the information in the FMS progress page as well as the vn (vertical navigation) data page; and began an early descent. Throughout; the descent I monitored our progress on the vn data page which consistently showed around -2;000 ft; as well as the pfd v-path indicator (showing below the required path for wynde). These (incorrect) indications continued all the way until we crossed wynde at 12;000 [ft]; which is 2;000 ft above the requirement. By the time the crew realized both indications; the vn data page and the pfd vpi; were false; there was insufficient time to make complete corrections; and we crossed at 12;000 [ft]. With increased use of opds and other heavily FMS dependent descents; I must seriously question the reliability of our equipment. The FMS is supposed to help manage the flight; it is now becoming a threat. Fmss have lied to the crews before. If this continues; flight crews will be forced to advise ATC that they are unable RNAV descents; because of FMS unreliability.

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Original NASA ASRS Text

Title: Despite having insured proper FMS programming and monitoring available vertical path guidance; an E-145 flight crew failed to comply with the 10;000 FT crossing restriction at WYNDE waypoint while flying the WYNDE RNAV STAR to ORD.

Narrative: The Perf Init (FMS page) was routinely programmed with a Vmo/Mmo/3.0 descent; the standard configuration. Upon descent we were cleared to cross WYNDE at 10;000 [FT]. I verified the correct TOD with the information in the FMS progress page as well as the VN (Vertical Navigation) Data page; and began an early descent. Throughout; the descent I monitored our progress on the VN Data page which consistently showed around -2;000 FT; as well as the PFD V-path indicator (showing below the required path for WYNDE). These (incorrect) indications continued all the way until we crossed WYNDE at 12;000 [FT]; which is 2;000 FT above the requirement. By the time the crew realized both indications; the VN Data page and the PFD VPI; were false; there was insufficient time to make complete corrections; and we crossed at 12;000 [FT]. With increased use of OPDs and other heavily FMS dependent descents; I must seriously question the reliability of our equipment. The FMS is supposed to help manage the flight; it is now becoming a threat. FMSs have lied to the crews before. If this continues; flight crews will be forced to advise ATC that they are unable RNAV descents; because of FMS unreliability.

Data retrieved from NASA's ASRS site as of July 2013 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.