A B757-200 PIC is dissatisfied with the aircraft's FMC VNAV performance related to autothrottle responses in conjunction with a noise abatement procedure out of sna, ca.

Home

Browse by month

Random

Latest

About

Contact

Attributes
ACN	508306
Time
Date	200104
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sna.airport
State Reference	CA
Altitude	msl single value : 800
Aircraft 1
Controlling Facilities	tower : sna.tower tracon : d10.tracon
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : initial
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : undershoot non adherence : published procedure other anomaly other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : overrode automation flight crew : regained aircraft control flight crew : overcame equipment problem flight crew : returned to original clearance
Supplementary
Problem Areas	Aircraft Airport Airspace Structure Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

On departure from sna runway 19R when we selected VNAV at 800 ft, the power came back to .20 less than climb 2 EPR bug. I pushed up the throttles when speed fell below 150 KTS and rate of climb went to zero. But the autothrottles reduced again. Disconnected autothrottle and advanced power manually to continue climb. This departure is a hazard to aircraft doing it and would be considered unsafe anywhere else. Noise is not worth crashing the aircraft. This malfunction only adds to the danger. Next time, I'll use flight level change. VNAV is unreliable here.

Original NASA ASRS Text

Title: A B757-200 PIC IS DISSATISFIED WITH THE ACFT'S FMC VNAV PERFORMANCE RELATED TO AUTOTHROTTLE RESPONSES IN CONJUNCTION WITH A NOISE ABATEMENT PROC OUT OF SNA, CA.

Narrative: ON DEP FROM SNA RWY 19R WHEN WE SELECTED VNAV AT 800 FT, THE PWR CAME BACK TO .20 LESS THAN CLB 2 EPR BUG. I PUSHED UP THE THROTTLES WHEN SPD FELL BELOW 150 KTS AND RATE OF CLB WENT TO ZERO. BUT THE AUTOTHROTTLES REDUCED AGAIN. DISCONNECTED AUTOTHROTTLE AND ADVANCED PWR MANUALLY TO CONTINUE CLB. THIS DEP IS A HAZARD TO ACFT DOING IT AND WOULD BE CONSIDERED UNSAFE ANYWHERE ELSE. NOISE IS NOT WORTH CRASHING THE ACFT. THIS MALFUNCTION ONLY ADDS TO THE DANGER. NEXT TIME, I'LL USE FLT LEVEL CHANGE. VNAV IS UNRELIABLE HERE.

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.