Potential conflict with less than standard separation.

Attributes
ACN	229584
Time
Date	199212
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : lppo
State Reference	FO
Altitude	msl bound lower : 37000 msl bound upper : 37000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : lppo
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute : atlantic enroute : other oceanic
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : other oceanic enroute : atlantic
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 120 flight time total : 4000 flight time type : 150
ASRS Report	229584
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation other anomaly other
Independent Detector	other flight crewa other other : unspecified
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment
Consequence	Other
Miss Distance	horizontal : 60000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error
Situations
ATC Facility	other physical facility

Narrative:

The aircraft I was flying had received numerous clrncs which were nearly non-understandable on HF. Each time, we questioned the clrncs and received the correct ones. While at FL350 we passed a company aircraft at FL370. We passed a reporting point and made a routine position report. Shortly thereafter we were SELCAL'ed and asked if we could climb to FL370. We could, and shortly thereafter, we were cleared to FL370. After climbing to FL370, it became obvious that the aircraft behind us was on our same routing. We had suspected that he was proceeding on a different routing because of the altitude clearance and also because he appeared on our TCASII to be angling off at a different direction when we made the turn at our reporting point. The aircraft behind us reported to the center that there was an aircraft very close in front of him at his same altitude, the center then cleared him to maintain FL390. The center then SELCAL'ed us once again and asked us what our next estimate was -- we responded 45 past the hour -- they had thought it was 52. The aircraft behind us was estimating that same point at 49 so no matter what time you go by, ATC did not have the 10 min separation required to issue us a clearance to FL370. While mins wise, we were close, our TCASII never showed closer than 10 mi.

Original NASA ASRS Text

Title: POTENTIAL CONFLICT WITH LTSS.

Narrative: THE ACFT I WAS FLYING HAD RECEIVED NUMEROUS CLRNCS WHICH WERE NEARLY NON-UNDERSTANDABLE ON HF. EACH TIME, WE QUESTIONED THE CLRNCS AND RECEIVED THE CORRECT ONES. WHILE AT FL350 WE PASSED A COMPANY ACFT AT FL370. WE PASSED A RPTING POINT AND MADE A ROUTINE POS RPT. SHORTLY THEREAFTER WE WERE SELCAL'ED AND ASKED IF WE COULD CLB TO FL370. WE COULD, AND SHORTLY THEREAFTER, WE WERE CLRED TO FL370. AFTER CLBING TO FL370, IT BECAME OBVIOUS THAT THE ACFT BEHIND US WAS ON OUR SAME ROUTING. WE HAD SUSPECTED THAT HE WAS PROCEEDING ON A DIFFERENT ROUTING BECAUSE OF THE ALT CLRNC AND ALSO BECAUSE HE APPEARED ON OUR TCASII TO BE ANGLING OFF AT A DIFFERENT DIRECTION WHEN WE MADE THE TURN AT OUR RPTING POINT. THE ACFT BEHIND US RPTED TO THE CTR THAT THERE WAS AN ACFT VERY CLOSE IN FRONT OF HIM AT HIS SAME ALT, THE CTR THEN CLRED HIM TO MAINTAIN FL390. THE CTR THEN SELCAL'ED US ONCE AGAIN AND ASKED US WHAT OUR NEXT ESTIMATE WAS -- WE RESPONDED 45 PAST THE HR -- THEY HAD THOUGHT IT WAS 52. THE ACFT BEHIND US WAS ESTIMATING THAT SAME POINT AT 49 SO NO MATTER WHAT TIME YOU GO BY, ATC DID NOT HAVE THE 10 MIN SEPARATION REQUIRED TO ISSUE US A CLRNC TO FL370. WHILE MINS WISE, WE WERE CLOSE, OUR TCASII NEVER SHOWED CLOSER THAN 10 MI.

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.