Confusion between air carrier medium large transport flight crew and ATC about clearance altitude.

Attributes
ACN	134792
Time
Date	199001
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : fwa
State Reference	IN
Altitude	msl bound lower : 25000 msl bound upper : 29000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Flight Phase	cruise other
Route In Use	enroute airway : zau
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 14000 flight time type : 150
ASRS Report	134792
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Deviation

Narrative:

En route from dca to ord at FL310, controller issued us instructions to maintain FL250. I acknowledged that we were leaving FL310 to maintain FL250. A short time later we were issued a clearance to maintain FL290. I said we were at FL270 with a clearance to maintain FL250. The controller stated 'you cleared yourself to FL250.' I asked what he wanted. He stated 'maintain 270.' later that evening I received a message from our dispatcher to call him. I returned the call and he stated that the controller had reviewed the tapes and had indeed cleared us to FL250 and he wished to apologize. I believe his 'maintain 250' call was meant to be a speed reduction and not an altitude assignment. Probably omission of of 'fl' and/or 'KTS' during instructions had a lot to do with this misunderstanding.

Original NASA ASRS Text

Title: CONFUSION BETWEEN ACR MLG FLT CREW AND ATC ABOUT CLRNC ALT.

Narrative: ENRTE FROM DCA TO ORD AT FL310, CTLR ISSUED US INSTRUCTIONS TO MAINTAIN FL250. I ACKNOWLEDGED THAT WE WERE LEAVING FL310 TO MAINTAIN FL250. A SHORT TIME LATER WE WERE ISSUED A CLRNC TO MAINTAIN FL290. I SAID WE WERE AT FL270 WITH A CLRNC TO MAINTAIN FL250. THE CTLR STATED 'YOU CLRED YOURSELF TO FL250.' I ASKED WHAT HE WANTED. HE STATED 'MAINTAIN 270.' LATER THAT EVENING I RECEIVED A MESSAGE FROM OUR DISPATCHER TO CALL HIM. I RETURNED THE CALL AND HE STATED THAT THE CTLR HAD REVIEWED THE TAPES AND HAD INDEED CLRED US TO FL250 AND HE WISHED TO APOLOGIZE. I BELIEVE HIS 'MAINTAIN 250' CALL WAS MEANT TO BE A SPD REDUCTION AND NOT AN ALT ASSIGNMENT. PROBABLY OMISSION OF OF 'FL' AND/OR 'KTS' DURING INSTRUCTIONS HAD A LOT TO DO WITH THIS MISUNDERSTANDING.

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.