<< >> NASA ASRS Report 341770, July 1996

Inaccurate ASOS reporting.

Attributes
ACN	341770
Time
Date	199607
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : pia
State Reference	IL
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	Mixed
Light	Daylight
Person 1
Affiliation	government : faa
Function	controller : local
Experience	controller military : 3 controller radar : 6
ASRS Report	341770
Person 2
Affiliation	government : faa
Function	oversight : supervisor
Qualification	controller : radar
Events
Anomaly	other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : unable
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

ASOS reporting '10 SM' as real visibility had decreased to less than 3 mi (from tower). After about 20 mins and tower visibility 2 being sent, ASOS was finally below 3 mi. ASOS is not representative of conditions beyond its limited sensors, and therefore dangerous. The design short coming of ASOS, when combined with the time delay in augmenting observations, releasing observations, and making an ATIS, have the effect of making WX available 5- 30 mins after it develops. I believe this system will eventually cause/contribute to fatal aviation accidents.

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Original NASA ASRS Text

Title: INACCURATE ASOS RPTING.

Narrative: ASOS RPTING '10 SM' AS REAL VISIBILITY HAD DECREASED TO LESS THAN 3 MI (FROM TWR). AFTER ABOUT 20 MINS AND TWR VISIBILITY 2 BEING SENT, ASOS WAS FINALLY BELOW 3 MI. ASOS IS NOT REPRESENTATIVE OF CONDITIONS BEYOND ITS LIMITED SENSORS, AND THEREFORE DANGEROUS. THE DESIGN SHORT COMING OF ASOS, WHEN COMBINED WITH THE TIME DELAY IN AUGMENTING OBSERVATIONS, RELEASING OBSERVATIONS, AND MAKING AN ATIS, HAVE THE EFFECT OF MAKING WX AVAILABLE 5- 30 MINS AFTER IT DEVELOPS. I BELIEVE THIS SYS WILL EVENTUALLY CAUSE/CONTRIBUTE TO FATAL AVIATION ACCIDENTS.

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.