DC9 crew had coordination problems when the controller asked the aircraft altitude.

Attributes
ACN	481890
Time
Date	200008
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : iad.airport
State Reference	VA
Altitude	msl bound lower : 10000 msl bound upper : 10600
Environment
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : iad.tracon
Operator	common carrier : air carrier
Make Model Name	DC-9 30
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : intermediate altitude
Route In Use	arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : cfi pilot : multi engine pilot : commercial pilot : atp
Experience	flight time last 90 days : 35 flight time total : 5100 flight time type : 400
ASRS Report	481890
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : crossing restriction not met non adherence : clearance other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Clearance to descend and maintain 10000 ft/250 KTS V143 at roberts. At 25 DME, I was at 250 KTS 10600 ft, ATC asked/inquired about altitude of aircraft. Given vector to dullas. Captain reported a higher altitude deviation. I think VOR's may have been on different frequencys causing different DME reports for roberts. Continued flight/landing uneventfully.

Original NASA ASRS Text

Title: DC9 CREW HAD COORD PROBS WHEN THE CTLR ASKED THE ACFT ALT.

Narrative: CLRNC TO DSND AND MAINTAIN 10000 FT/250 KTS V143 AT ROBERTS. AT 25 DME, I WAS AT 250 KTS 10600 FT, ATC ASKED/INQUIRED ABOUT ALT OF ACFT. GIVEN VECTOR TO DULLAS. CAPT RPTED A HIGHER ALTDEV. I THINK VOR'S MAY HAVE BEEN ON DIFFERENT FREQS CAUSING DIFFERENT DME RPTS FOR ROBERTS. CONTINUED FLT/LNDG UNEVENTFULLY.

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.