Flight crew of E120 transponder erroneously indicated 300 ft high at assigned flight lvl near okw.

Attributes
ACN	426120
Time
Date	199901
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : okw
State Reference	AL
Altitude	msl bound lower : 19000 msl bound upper : 19000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : tvc
Operator	common carrier : air carrier
Make Model Name	Brasilia EMB-120 All Series
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : instrument
Experience	flight time last 90 days : 115 flight time total : 3900 flight time type : 410
ASRS Report	426120
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	atc equipment other atc equipment : unspecified
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Air Traffic Incident	other

Narrative:

While leveling at FL190 on a flight from gtr to atl, ZTL queried us about our altitude. We reported level at FL190. I then switched to transponder #2 and asked center what it was reporting. He said FL190 and told us that #1 reported 300 ft high. There was no conflict and safety of flight was not an issue. The discrepancy was reported to maintenance.

Original NASA ASRS Text

Title: FLC OF E120 XPONDER ERRONEOUSLY INDICATED 300 FT HIGH AT ASSIGNED FLT LVL NEAR OKW.

Narrative: WHILE LEVELING AT FL190 ON A FLT FROM GTR TO ATL, ZTL QUERIED US ABOUT OUR ALT. WE RPTED LEVEL AT FL190. I THEN SWITCHED TO XPONDER #2 AND ASKED CTR WHAT IT WAS RPTING. HE SAID FL190 AND TOLD US THAT #1 RPTED 300 FT HIGH. THERE WAS NO CONFLICT AND SAFETY OF FLT WAS NOT AN ISSUE. THE DISCREPANCY WAS RPTED TO MAINT.

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.