Takeoff acceleration stopped approaching vr speed.

Attributes
ACN	99546
Time
Date	198811
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : ewr
State Reference	NJ
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : takeoff
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 220 flight time total : 23000 flight time type : 10000
ASRS Report	99546
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	inflight encounter : weather other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : exited adverse environment
Consequence	Other
Supplementary
Primary Problem	Weather
Air Traffic Incident	other

Narrative:

Taxi out near maximum gnt for takeoff runway 5L ewr. Note on our company flight plan asked us to avoid takeoff on runway 4R due bumpy conditions and to use runway 4L, weight permitting. Wind was almost exactly crosschecked fast prior to takeoff. Takeoff roll acceleration stopped at 130. Rotation being 139. It then increased to 139 and I rotated at the beginning of the red runway edge length warning lights, meaning last 3000' left. At rotation 10 degrees nothing happened so I rotated to 15 degrees deck angle. Aircraft flew. I really thought we had it. Rechked weight. Callback conversation with reporter revealed the following: weight checked out. Aircraft flew absolutely normally rest of flight. The most logical explanation seems that a sudden gust (explaining hesitation in acceleration) of tailwind occurred just prior to rotation. Other factors, company and tower not readily allowing use of other runway, but putting final responsibility on pilot. Perhaps lack of accurate wind reporting.

Original NASA ASRS Text

Title: TKOF ACCELERATION STOPPED APCHING VR SPEED.

Narrative: TAXI OUT NEAR MAX GNT FOR TKOF RWY 5L EWR. NOTE ON OUR COMPANY FLT PLAN ASKED US TO AVOID TKOF ON RWY 4R DUE BUMPY CONDITIONS AND TO USE RWY 4L, WT PERMITTING. WIND WAS ALMOST EXACTLY XCHKED FAST PRIOR TO TKOF. TKOF ROLL ACCELERATION STOPPED AT 130. ROTATION BEING 139. IT THEN INCREASED TO 139 AND I ROTATED AT THE BEGINNING OF THE RED RWY EDGE LENGTH WARNING LIGHTS, MEANING LAST 3000' LEFT. AT ROTATION 10 DEGS NOTHING HAPPENED SO I ROTATED TO 15 DEGS DECK ANGLE. ACFT FLEW. I REALLY THOUGHT WE HAD IT. RECHKED WT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: WT CHKED OUT. ACFT FLEW ABSOLUTELY NORMALLY REST OF FLT. THE MOST LOGICAL EXPLANATION SEEMS THAT A SUDDEN GUST (EXPLAINING HESITATION IN ACCELERATION) OF TAILWIND OCCURRED JUST PRIOR TO ROTATION. OTHER FACTORS, COMPANY AND TWR NOT READILY ALLOWING USE OF OTHER RWY, BUT PUTTING FINAL RESPONSIBILITY ON PLT. PERHAPS LACK OF ACCURATE WIND RPTING.

Data retrieved from NASA's ASRS site as of August 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.