Air carrier medium large transport is told by controller that they lost their mode C readout. Aircra...

Attributes
ACN	309650
Time
Date	199507
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : bld airport : las
State Reference	NV
Altitude	msl bound lower : 17000 msl bound upper : 17100
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute airway : zla
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : commercial pilot : atp pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 8700 flight time type : 3000
ASRS Report	309650
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe other anomaly other
Independent Detector	other controllera
Resolutory Action	flight crew : overcame equipment problem other other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Departing out of las for a flight to dfw. After leveling at 17000 ft for a few mins the controller asked us for our altitude. I told him 17100 ft. I asked if there was a problem. He said he lost our mode C. I changed xponders. He reported mode C 'is ok.' I do not know if there was a problem, but any time you are asked to 'say altitude' it gives cause to be concerned.

Original NASA ASRS Text

Title: ACR MLG IS TOLD BY CTLR THAT THEY LOST THEIR MODE C READOUT. ACFT WAS 100 FT HIGH.

Narrative: DEPARTING OUT OF LAS FOR A FLT TO DFW. AFTER LEVELING AT 17000 FT FOR A FEW MINS THE CTLR ASKED US FOR OUR ALT. I TOLD HIM 17100 FT. I ASKED IF THERE WAS A PROB. HE SAID HE LOST OUR MODE C. I CHANGED XPONDERS. HE RPTED MODE C 'IS OK.' I DO NOT KNOW IF THERE WAS A PROB, BUT ANY TIME YOU ARE ASKED TO 'SAY ALT' IT GIVES CAUSE TO BE CONCERNED.

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.

Air carrier medium large transport is told by controller that they lost their mode C readout. Aircraft was 100 ft high.