B757-200
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Communication Breakdown; Distraction; Time Pressure; Workload
ATC Issue All Types; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Human Factors; Aircraft; Chart Or Publication; Procedure
We were cleared to descend via FNCHR1 [North Transition] RNAV STAR; landing Runway 36L at MEM. As we approached STANI on the VNAV computed vertical path; ATC assigned speed of 250 KTS. Speed intervene mode was initially utilized until the FMC could be reprogrammed. As the aircraft slowed; it went above path even though we utilized drag devices. The aircraft could not cross STANI at the charted altitude restriction (FL230B) due to the speed assignment and; thus; crossed at approximately 23;800 FT (800 FT high)The OPD (Optimized Profile Descent) RNAV STARs into MEM are a work in progress as everyone gains experience. As such; all parties should be aware that airspeed clearances that vary from the OPD as published (and reflected in the FMS)--especially if given in the proximity of an approaching waypoint with constraints--will prevent these constraints from being met without very aggressive maneuvering of the aircraft. If speed reductions are necessary; ATC should remove the higher altitude constraints on the OPD as a part of the speed clearance / assignment.
No substantive additional information was provided in the secondary narrative.
A B757-200 established on a 'descend via the FNCHR RNAV STAR' clearance was directed to reduce speed to 250 KTS outside of STANI which caused them to be unable to cross STANI at or below FL230 as charted.