Narrative:

On descent into jfk via the lendy 5 arrival; the current ATIS was received and an approach to runway 22L was briefed and set up. A clearance to cross harty at FL230 was given and the aircraft began a VNAV descent to cross the fix at the given altitude. Prior to reaching harty; a new ATIS was given and a runway change necessitating a new approach set-up and briefing was required. As the PNF; I accomplished the set-up. Just after the approach briefing was complete; it was observed that the aircraft was no longer in VNAV path but had defaulted to VNAV speed. It was (aircraft) high on its profile descent to cross harty at FL230. Aggressive means were used to make the crossing restr. However; the aircraft was 400 ft high when crossing the actual fix. On review; it was noted that the controllers had wanted an increased speed on the arrival. That increased speed was placed into the FMC on the cruise page. When the actual descent began; the commanded speed dropped by more than 60 KTS due to the fact that a low cost index was placed into the FMC during preflight. This is a company directed procedure to save fuel during this era of high energy prices we live in. A speed decrease of 60-70 KTS from cruise to descent is 99% of the time not appreciated by any center or approach controller. We are then required to pull out the low cost index derived speed and manually insert the practical speed required not to disrupt flow on the arrival. If workload is increased and this change is not made; a shift from VNAV path to VNAV speed is a real possibility and an identical result will happen.

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Original NASA ASRS Text

Title: HIGH ASSIGNED CRUISE MACH AND PROGRAMMED LOW COST INDEX DESCENT SPEED RESULT IN FAILURE TO MAKE CROSSING RESTRICTION. A DISTRACTION DUE TO REPROGRAMMING A RWY CHANGE CONTRIBUTED TO LATE RECOGNITION OF THE PROBLEM.

Narrative: ON DSCNT INTO JFK VIA THE LENDY 5 ARR; THE CURRENT ATIS WAS RECEIVED AND AN APCH TO RWY 22L WAS BRIEFED AND SET UP. A CLRNC TO CROSS HARTY AT FL230 WAS GIVEN AND THE ACFT BEGAN A VNAV DSCNT TO CROSS THE FIX AT THE GIVEN ALT. PRIOR TO REACHING HARTY; A NEW ATIS WAS GIVEN AND A RWY CHANGE NECESSITATING A NEW APCH SET-UP AND BRIEFING WAS REQUIRED. AS THE PNF; I ACCOMPLISHED THE SET-UP. JUST AFTER THE APCH BRIEFING WAS COMPLETE; IT WAS OBSERVED THAT THE ACFT WAS NO LONGER IN VNAV PATH BUT HAD DEFAULTED TO VNAV SPD. IT WAS (ACFT) HIGH ON ITS PROFILE DSCNT TO CROSS HARTY AT FL230. AGGRESSIVE MEANS WERE USED TO MAKE THE XING RESTR. HOWEVER; THE ACFT WAS 400 FT HIGH WHEN XING THE ACTUAL FIX. ON REVIEW; IT WAS NOTED THAT THE CTLRS HAD WANTED AN INCREASED SPD ON THE ARR. THAT INCREASED SPD WAS PLACED INTO THE FMC ON THE CRUISE PAGE. WHEN THE ACTUAL DSCNT BEGAN; THE COMMANDED SPD DROPPED BY MORE THAN 60 KTS DUE TO THE FACT THAT A LOW COST INDEX WAS PLACED INTO THE FMC DURING PREFLT. THIS IS A COMPANY DIRECTED PROC TO SAVE FUEL DURING THIS ERA OF HIGH ENERGY PRICES WE LIVE IN. A SPD DECREASE OF 60-70 KTS FROM CRUISE TO DSCNT IS 99% OF THE TIME NOT APPRECIATED BY ANY CTR OR APCH CTLR. WE ARE THEN REQUIRED TO PULL OUT THE LOW COST INDEX DERIVED SPD AND MANUALLY INSERT THE PRACTICAL SPD REQUIRED NOT TO DISRUPT FLOW ON THE ARR. IF WORKLOAD IS INCREASED AND THIS CHANGE IS NOT MADE; A SHIFT FROM VNAV PATH TO VNAV SPD IS A REAL POSSIBILITY AND AN IDENTICAL RESULT WILL HAPPEN.

Data retrieved from NASA's ASRS site as of January 2009 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.