A misunderstood clearance results in an altitude bust and track deviation.

Attributes
ACN	122721
Time
Date	198909
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : nrt
State Reference	FO
Altitude	msl bound lower : 9000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : nrt
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 4 Turbojet Eng
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude
Route In Use	departure sid : sid enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Route In Use	enroute : pacific
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 10000
ASRS Report	122721
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance non adherence : required legal separation other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance
Consequence	Other
Miss Distance	vertical : 500
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	other

Narrative:

Shortly after departure our flight was restr to 9000' by nrt departure. Leaving 8400' reported to departure control we were leaving 8400' for 9000'. All 3 crew understood departure to clear us to 10000' with traffic at 2 O'clock. I reported we had the traffic in sight and read back that we were leaving 9000' for 10000'. Traffic was not a factor, although minimum right/V sep may have been violated. Departure confirmed we had traffic in sight, but it appeared to us that he thought we were at 9000'. Upon my asking for confirmation for cleared altitude, we were cleared to 16000'. As a result of the foregoing we continued on radial of 140 degrees for about 4 mi beyond intercept of the cvc 179 degree right, and were then right/V on heading of 220 degrees for en route climb.

Original NASA ASRS Text

Title: A MISUNDERSTOOD CLRNC RESULTS IN AN ALT BUST AND TRACK DEVIATION.

Narrative: SHORTLY AFTER DEP OUR FLT WAS RESTR TO 9000' BY NRT DEP. LEAVING 8400' RPTED TO DEP CTL WE WERE LEAVING 8400' FOR 9000'. ALL 3 CREW UNDERSTOOD DEP TO CLR US TO 10000' WITH TFC AT 2 O'CLOCK. I RPTED WE HAD THE TFC IN SIGHT AND READ BACK THAT WE WERE LEAVING 9000' FOR 10000'. TFC WAS NOT A FACTOR, ALTHOUGH MINIMUM R/V SEP MAY HAVE BEEN VIOLATED. DEP CONFIRMED WE HAD TFC IN SIGHT, BUT IT APPEARED TO US THAT HE THOUGHT WE WERE AT 9000'. UPON MY ASKING FOR CONFIRMATION FOR CLRED ALT, WE WERE CLRED TO 16000'. AS A RESULT OF THE FOREGOING WE CONTINUED ON RADIAL OF 140 DEGS FOR ABOUT 4 MI BEYOND INTERCEPT OF THE CVC 179 DEG R, AND WERE THEN R/V ON HDG OF 220 DEGS FOR ENRTE CLB.

Data retrieved from NASA's ASRS site as of August 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.