Narrative:

Departing nagoya, japan, for agana, guam. Tokyo center issued clearance to 'climb and maintain FL330, at nogak climb to FL370.' clearance was read back to center and again during a subsequent position report (at adkak prior to nogak intersection) to tokyo radio. At nogak a climb was initiated from FL330 to FL370. Approximately 12 NM south of nogak at 35200 ft an onboard TCASII TA was received indicating traffic at 12 O'clock, 200 ft below, opposite direction. Climb continued to FL370. Passing FL360 subject aircraft passed approximately 1 NM west (off right wing), 1000 ft below. No evasive action was required, no TCASII RA was received. Commercial radio was advised and an ASR filed. 10 yrs of east asian flying has seen considerable improvement in the skills and abilities of japanese controllers. The conditional clearance issued by tokyo center to climb to FL370 at nogak appeared to be a nonstandard procedure, or at a minimum a type of clearance infrequently received. The clearance was verified twice, once with tokyo center and later with tokyo radio. In addition, all 3 flight deck crew members were in agreement as to the exact nature of the clearance (ie, the clearance was not 'expect FL370 at nogak'). The big sky theory in combination with onboard TCASII prevented a potential near midair event. Air crew actions could have included a third verification of the clearance prior to departing FL330. However, it is questionable if this step would have prevented this occurrence.

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Original NASA ASRS Text

Title: POTENTIAL CONFLICT DURING AN OVERWATER OP FOREIGN AIRSPACE. OPERROR.

Narrative: DEPARTING NAGOYA, JAPAN, FOR AGANA, GUAM. TOKYO CTR ISSUED CLRNC TO 'CLB AND MAINTAIN FL330, AT NOGAK CLB TO FL370.' CLRNC WAS READ BACK TO CTR AND AGAIN DURING A SUBSEQUENT POS RPT (AT ADKAK PRIOR TO NOGAK INTXN) TO TOKYO RADIO. AT NOGAK A CLB WAS INITIATED FROM FL330 TO FL370. APPROX 12 NM S OF NOGAK AT 35200 FT AN ONBOARD TCASII TA WAS RECEIVED INDICATING TFC AT 12 O'CLOCK, 200 FT BELOW, OPPOSITE DIRECTION. CLB CONTINUED TO FL370. PASSING FL360 SUBJECT ACFT PASSED APPROX 1 NM W (OFF R WING), 1000 FT BELOW. NO EVASIVE ACTION WAS REQUIRED, NO TCASII RA WAS RECEIVED. COMMERCIAL RADIO WAS ADVISED AND AN ASR FILED. 10 YRS OF E ASIAN FLYING HAS SEEN CONSIDERABLE IMPROVEMENT IN THE SKILLS AND ABILITIES OF JAPANESE CTLRS. THE CONDITIONAL CLRNC ISSUED BY TOKYO CTR TO CLB TO FL370 AT NOGAK APPEARED TO BE A NONSTANDARD PROC, OR AT A MINIMUM A TYPE OF CLRNC INFREQUENTLY RECEIVED. THE CLRNC WAS VERIFIED TWICE, ONCE WITH TOKYO CTR AND LATER WITH TOKYO RADIO. IN ADDITION, ALL 3 FLT DECK CREW MEMBERS WERE IN AGREEMENT AS TO THE EXACT NATURE OF THE CLRNC (IE, THE CLRNC WAS NOT 'EXPECT FL370 AT NOGAK'). THE BIG SKY THEORY IN COMBINATION WITH ONBOARD TCASII PREVENTED A POTENTIAL NEAR MIDAIR EVENT. AIR CREW ACTIONS COULD HAVE INCLUDED A THIRD VERIFICATION OF THE CLRNC PRIOR TO DEPARTING FL330. HOWEVER, IT IS QUESTIONABLE IF THIS STEP WOULD HAVE PREVENTED THIS OCCURRENCE.

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.