B767 crew was issued a climb clearance based on a crossing latitude on an e-w flight.

Attributes
ACN	423799
Time
Date	199812
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : finn
State Reference	FO
Altitude	msl bound lower : 35000 msl bound upper : 38000
Environment
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B767 Undifferentiated or Other Model
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : atlantic enroute : other oceanic
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
ASRS Report	423799
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
ASRS Report	423800
Events
Anomaly	other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Air Traffic Incident	other
Situations
ATC Facility	procedure or policy : unspecified

Narrative:

Confusing ATC clearance. ATC facility: shanwick oca. Mia to mad via random routing. In cruise at FL350 we were encountering light chop with occasional moderate chop. I requested FL370 or FL380 at XA30Z. At XA35Z ATC issued the following clearance after 46N cleared to FL380 to be level prior to 45N. We previously passed 46N and were currently at 47n24w on an easterly course. We requested clarification and received the same clearance. We called leaving FL350 for FL380. ATC immediately replied maintain FL350, which we did. The clearance to climb was actually to take place over 1 hour away. Our route of flight took us from 44N, 46N, 47N, hidra 44N. We crossed 46N twice during our flight and interpreted the climb clearance to be immediate upon our initial 46N crossing. Contributing factors: not accustomed to fixes defined by lines of latitude when flying easterly or westerly courses. Had the clearance stated when south of 46N cleared to FL380, it would have been more evident.

Original NASA ASRS Text

Title: B767 CREW WAS ISSUED A CLB CLRNC BASED ON A XING LATITUDE ON AN E-W FLT.

Narrative: CONFUSING ATC CLRNC. ATC FACILITY: SHANWICK OCA. MIA TO MAD VIA RANDOM ROUTING. IN CRUISE AT FL350 WE WERE ENCOUNTERING LIGHT CHOP WITH OCCASIONAL MODERATE CHOP. I REQUESTED FL370 OR FL380 AT XA30Z. AT XA35Z ATC ISSUED THE FOLLOWING CLRNC AFTER 46N CLRED TO FL380 TO BE LEVEL PRIOR TO 45N. WE PREVIOUSLY PASSED 46N AND WERE CURRENTLY AT 47N24W ON AN EASTERLY COURSE. WE REQUESTED CLARIFICATION AND RECEIVED THE SAME CLRNC. WE CALLED LEAVING FL350 FOR FL380. ATC IMMEDIATELY REPLIED MAINTAIN FL350, WHICH WE DID. THE CLRNC TO CLB WAS ACTUALLY TO TAKE PLACE OVER 1 HR AWAY. OUR RTE OF FLT TOOK US FROM 44N, 46N, 47N, HIDRA 44N. WE CROSSED 46N TWICE DURING OUR FLT AND INTERPED THE CLB CLRNC TO BE IMMEDIATE UPON OUR INITIAL 46N XING. CONTRIBUTING FACTORS: NOT ACCUSTOMED TO FIXES DEFINED BY LINES OF LATITUDE WHEN FLYING EASTERLY OR WESTERLY COURSES. HAD THE CLRNC STATED WHEN S OF 46N CLRED TO FL380, IT WOULD HAVE BEEN MORE EVIDENT.

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.