A300
Flight Crew Air Transport Pilot (ATP)
Workload; Confusion; Human-Machine Interface
Aircraft Equipment Problem Critical; Deviation - Speed All Types; Deviation / Discrepancy - Procedural FAR
Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Aircraft; Chart Or Publication; Human Factors; Procedure
During descent on the FNCHR arrival to MEM; the aircraft didn't seem to be descending enough to meet the programmed restrictions so the First Officer elected to use Level Change and extend speed brakes to get on the proper profile. After this; he reselected Profile to let the jet fly the profile but; once again; it didn't seem to be slowing at the programmed rate to meet the next restriction so the he again selected Level Change in order to slow. At the same time we needed to descend after FNCHR for LOONR. We both focused on the beginning of descent and didn't realize as we passed 10;000 MSL that we were still at 290 KIAS. As soon as we noticed it; we slowed immediately to 250 KIAS for JESTI; then 210 KIAS for LOONR. We made all the altitude restrictions and slowed to 250 KIAS below 10;000 as soon as we noticed our error.One of our conclusions was that if we needed to revert to Level Change for any reason; we should perhaps leave it there for the remainder of the arrival to avoid confusing ourselves or the jet. I've noticed that; on more than one occasion; the jet doesn't want to slow to the programmed speeds in a timely manner on the MEM arrivals. At other times it works fine. Perhaps the arrivals could also be revised to be a little straighter forward in their design for smoothness of operation.
[No substantive additional information was included in the secondary narrative.]
Distracted by the failure of their autoflight system to comply with the constraints of the FNCHR RNAV STAR into MEM; the flight crew of an A300 descended below 10;000 MSL prior to reducing to 250 KIAS.