A B757-200 established on a 'descend via the fnchr RNAV STAR' clearance was directed to reduce speed...

Narrative:

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.

Original NASA ASRS Text

Title: 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.

Narrative: 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.

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.

Attributes
ACN	1048957
Time
Date	201211
Local Time Of Day	1801-2400
Place
Locale Reference	MEM.Airport
State Reference	TN
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR FNCHR1
Flight Plan	IFR
Person 1
Function	Captain Pilot Flying Check Pilot
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	ATC Issue All Types Deviation - Altitude Crossing Restriction Not Met Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

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.