A tower controller claims that the ASOS was giving erroneous wind direction and velocity while a C17...

Attributes
ACN	378178
Time
Date	199708
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bgm
State Reference	NY
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : ord
Operator	general aviation : instructional
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	landing other
Flight Plan	VFR
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar pilot : instrument
Experience	controller radar : 10 flight time total : 300
ASRS Report	378178
Person 2
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : private
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other
Situations
Navigational Aid	Unspecified

Narrative:

Cessna had just turned base to final to runway 16 having been cleared to land on downwind issued wind 100 degrees, 8 KTS. ASOS WX was 100 degrees 8 KTS 10 SM few 17 19/16, altimeter 29.74. In actuality no portion of sky visible through clouds, all estimated at less than 12000 ft. Thunderstorm about 3 mi west of field. Felt tower buffeted by wind. Issued to pilot based on observation of ASOS and parking lot 'ASOS wind variable at 4 KTS, in reality it's bending trees.' aircraft required 3200 ft of runway to land. On touchdown ASOS still read variable at 4 KTS. As aircraft exited runway ASOS updated to 250 degrees 9 KTS gusting to 16 KTS, 200v280, and then to 270 degrees 15 KTS gusting to 21 KTS. Note that the originally issued wind was 170 degrees different from the actual wind at time of landing and at 2.5 times the velocity and approaching the aircraft's demonstrated crosswind landing capability, not to mention with a tailwind component rather than the expected headwind component. I believe that the inability to issue real time information created a hazardous situation. The only valid information the pilot had in this case was my notably unauthorized remark.

Original NASA ASRS Text

Title: A TWR CTLR CLAIMS THAT THE ASOS WAS GIVING ERRONEOUS WIND DIRECTION AND VELOCITY WHILE A C172 WAS LNDG. THE RPTR ISSUED NEW WX TO THE C172 BASED UPON HIS OBSERVATIONS.

Narrative: CESSNA HAD JUST TURNED BASE TO FINAL TO RWY 16 HAVING BEEN CLRED TO LAND ON DOWNWIND ISSUED WIND 100 DEGS, 8 KTS. ASOS WX WAS 100 DEGS 8 KTS 10 SM FEW 17 19/16, ALTIMETER 29.74. IN ACTUALITY NO PORTION OF SKY VISIBLE THROUGH CLOUDS, ALL ESTIMATED AT LESS THAN 12000 FT. TSTM ABOUT 3 MI W OF FIELD. FELT TWR BUFFETED BY WIND. ISSUED TO PLT BASED ON OBSERVATION OF ASOS AND PARKING LOT 'ASOS WIND VARIABLE AT 4 KTS, IN REALITY IT'S BENDING TREES.' ACFT REQUIRED 3200 FT OF RWY TO LAND. ON TOUCHDOWN ASOS STILL READ VARIABLE AT 4 KTS. AS ACFT EXITED RWY ASOS UPDATED TO 250 DEGS 9 KTS GUSTING TO 16 KTS, 200V280, AND THEN TO 270 DEGS 15 KTS GUSTING TO 21 KTS. NOTE THAT THE ORIGINALLY ISSUED WIND WAS 170 DEGS DIFFERENT FROM THE ACTUAL WIND AT TIME OF LNDG AND AT 2.5 TIMES THE VELOCITY AND APCHING THE ACFT'S DEMONSTRATED XWIND LNDG CAPABILITY, NOT TO MENTION WITH A TAILWIND COMPONENT RATHER THAN THE EXPECTED HEADWIND COMPONENT. I BELIEVE THAT THE INABILITY TO ISSUE REAL TIME INFO CREATED A HAZARDOUS SIT. THE ONLY VALID INFO THE PLT HAD IN THIS CASE WAS MY NOTABLY UNAUTH REMARK.

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.

A tower controller claims that the ASOS was giving erroneous wind direction and velocity while a C172 was landing. The reporter issued new WX to the C172 based upon his observations.