Narrative:

Problem arose due to loss of communication at FL370 near the lacki intersection on A300. We were in a non radar HF radio only environment. Clearance was given at the departure airport as 'as filed.' our filed route had a climb from FL370 to FL390 at the lacki intersection. Upon reaching lacki, contact was attempted on multiple frequencys along with guard with no success. Flight conditions affected the decision to climb (moderate turbulence and in and out of cloud tops) after continuous attempts, the decision to climb was made to the cleared altitude of FL390. Contact was finally made at huber intersection at XY23Z whereupon new york radio gave us an immediate descent to FL370 which was promptly complied with. While contact was lost, we maintained a constant visual search for other aircraft, which had not been possible at FL370 due to flight conditions. There are 3 items which could create a solution to the problem. First, a full route clearance should be given any time an aircraft will be operating outside of a radar environment where communications might be blocked, including all altitude changes. This would have clearance on tape along with altitudes. Second, more required reporting points with better long range communication over atlantic rtes. With more reporting points, errors on sides would be found earlier. Thirdly, if in the radio position report the next fix and the expected flight level at the next fix would catch any discrepancies before they occur.

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Original NASA ASRS Text

Title: FLC OF A BRITISH HAWKER HS125-700 (HS25) CLBED FROM ASSIGNED ALT DURING CRUISE ON AN OCEANIC AIRWAY AFTER REACHING THEIR FLT PLAN FIX FOR AN ALT CHANGE AND NOT BEEN ABLE TO CONTACT CTR AFTER SEVERAL ATTEMPTS. AFTER FINALLY CONTACTING THE CTR THEY WERE ASSIGNED BACK TO THEIR PREVIOUSLY ASSIGNED ALT.

Narrative: PROB AROSE DUE TO LOSS OF COM AT FL370 NEAR THE LACKI INTXN ON A300. WE WERE IN A NON RADAR HF RADIO ONLY ENVIRONMENT. CLRNC WAS GIVEN AT THE DEP ARPT AS 'AS FILED.' OUR FILED RTE HAD A CLB FROM FL370 TO FL390 AT THE LACKI INTXN. UPON REACHING LACKI, CONTACT WAS ATTEMPTED ON MULTIPLE FREQS ALONG WITH GUARD WITH NO SUCCESS. FLT CONDITIONS AFFECTED THE DECISION TO CLB (MODERATE TURB AND IN AND OUT OF CLOUD TOPS) AFTER CONTINUOUS ATTEMPTS, THE DECISION TO CLB WAS MADE TO THE CLRED ALT OF FL390. CONTACT WAS FINALLY MADE AT HUBER INTXN AT XY23Z WHEREUPON NEW YORK RADIO GAVE US AN IMMEDIATE DSCNT TO FL370 WHICH WAS PROMPTLY COMPLIED WITH. WHILE CONTACT WAS LOST, WE MAINTAINED A CONSTANT VISUAL SEARCH FOR OTHER ACFT, WHICH HAD NOT BEEN POSSIBLE AT FL370 DUE TO FLT CONDITIONS. THERE ARE 3 ITEMS WHICH COULD CREATE A SOLUTION TO THE PROB. FIRST, A FULL RTE CLRNC SHOULD BE GIVEN ANY TIME AN ACFT WILL BE OPERATING OUTSIDE OF A RADAR ENVIRONMENT WHERE COMS MIGHT BE BLOCKED, INCLUDING ALL ALT CHANGES. THIS WOULD HAVE CLRNC ON TAPE ALONG WITH ALTS. SECOND, MORE REQUIRED RPTING POINTS WITH BETTER LONG RANGE COM OVER ATLANTIC RTES. WITH MORE RPTING POINTS, ERRORS ON SIDES WOULD BE FOUND EARLIER. THIRDLY, IF IN THE RADIO POS RPT THE NEXT FIX AND THE EXPECTED FLT LEVEL AT THE NEXT FIX WOULD CATCH ANY DISCREPANCIES BEFORE THEY OCCUR.

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.