A B757 crew in descent were 700 ft high at an assigned crossing restr.

Attributes
ACN	520665
Time
Date	200108
Day	Tue
Local Time Of Day	1801 To 2400
Place
Locale Reference	navaid : hnk.vor
State Reference	NY
Altitude	msl bound lower : 29000 msl bound upper : 29700
Environment
Flight Conditions	VMC
Weather Elements	Thunderstorm
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zbw.artcc
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 150 flight time total : 25000 flight time type : 3501
ASRS Report	520665
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	altitude deviation : undershoot altitude deviation : crossing restriction not met non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : detected after the fact
Supplementary
Problem Areas	Weather Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Clearance issued just after passing hnk VOR to cross 45 mi north hnk at FL290. Cruise altitude was FL370. About 40 KTS tailwind. FMS programming required mental calculation of restr from active waypoint, as FMS cannot place a fix beyond a waypoint that is passed. A simple miscalculation of the distance resulted (4 mi off). So we actually crossed 49 mi north of hnk at FL290. We had tuned the hnk VOR manually and noticed the discrepancy, but too late to correct the 4 mi error. We crossed the 45 mi fix about 700 ft high. This is a simple human factors mistake with an automation limitation (can't program fix as cleared by controller). Tailwind also made restr difficult as FMS does not handle crossing restrs well in tailwind situation.

Original NASA ASRS Text

Title: A B757 CREW IN DSCNT WERE 700 FT HIGH AT AN ASSIGNED XING RESTR.

Narrative: CLRNC ISSUED JUST AFTER PASSING HNK VOR TO CROSS 45 MI N HNK AT FL290. CRUISE ALT WAS FL370. ABOUT 40 KTS TAILWIND. FMS PROGRAMMING REQUIRED MENTAL CALCULATION OF RESTR FROM ACTIVE WAYPOINT, AS FMS CANNOT PLACE A FIX BEYOND A WAYPOINT THAT IS PASSED. A SIMPLE MISCALCULATION OF THE DISTANCE RESULTED (4 MI OFF). SO WE ACTUALLY CROSSED 49 MI N OF HNK AT FL290. WE HAD TUNED THE HNK VOR MANUALLY AND NOTICED THE DISCREPANCY, BUT TOO LATE TO CORRECT THE 4 MI ERROR. WE CROSSED THE 45 MI FIX ABOUT 700 FT HIGH. THIS IS A SIMPLE HUMAN FACTORS MISTAKE WITH AN AUTOMATION LIMITATION (CAN'T PROGRAM FIX AS CLRED BY CTLR). TAILWIND ALSO MADE RESTR DIFFICULT AS FMS DOES NOT HANDLE XING RESTRS WELL IN TAILWIND SIT.

Data retrieved from NASA's ASRS site as of July 2007 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.