Narrative:

On jun/tue/89 I was PIC of an medium large transport, astronomy mission operating from the right seat of a modified medium large transport. At approximately XA55 local, after nearly 5 hours of an otherwise uneventful mission, a minor explosion occurred in the cockpit. A glass bottle of mineral water left in a recess above the copilot's forward windshield by a previous crew had frozen and burst, sending glass shards and ice onto me and the surrounding area. This explosive device had been placed behind panelling and was not visible prior to its failure. About 5 minutes later we made a 120 degree turn to begin a new series of observations on an easterly track toward the california coast. The astronomy mission requires a specific heading to be flown to keep the telescope pointed in the right direction. Ground track is not a factor in the scientific work, only in the coordination of ATC clrncs. If forecast winds are inaccurate, significant deviations from flight plan track can occur which are normally handled by obtaining a revised ATC clearance or by terminating data collection and correcting to the previously cleared track. On this occasion, however, due to the distraction of the exploding bottle, the effort to determine what in fact had exploded, and the subsequent cleanup of glass shards and slush, neither pilot checked the deviation from desired track after completing the turn. 20 minutes later, having returned within VHF range, we were astonished to note a 55 NM cross track error as the sic contacted ZOA. We advised oakland of our deviation from track. They established radar contact, confirmed our deviation, and cleared us to continue. Oakland later asked what equipment we were using and were advised that although INS was aboard, we had been essentially trying to anticipate where the telescope aiming requirements would put us at specific times for flight plan purposes. This incident was not intentional and should not have occurred. The largely unavoidable fatigue inherent in missions commencing shortly before midnight and continuing throughout the night, together with the distraction of the exploding bottle, undoubtedly contributed to the pilots' failure to notice the developing deviation. There was no accident nor any apparent traffic conflict as a result of this incident.

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Original NASA ASRS Text

Title: FLT CREW DEVIATES FROM TRACK.

Narrative: ON JUN/TUE/89 I WAS PIC OF AN MLG, ASTRONOMY MISSION OPERATING FROM THE RIGHT SEAT OF A MODIFIED MLG. AT APPROX XA55 LOCAL, AFTER NEARLY 5 HRS OF AN OTHERWISE UNEVENTFUL MISSION, A MINOR EXPLOSION OCCURRED IN THE COCKPIT. A GLASS BOTTLE OF MINERAL WATER LEFT IN A RECESS ABOVE THE COPLT'S FORWARD WINDSHIELD BY A PREVIOUS CREW HAD FROZEN AND BURST, SENDING GLASS SHARDS AND ICE ONTO ME AND THE SURROUNDING AREA. THIS EXPLOSIVE DEVICE HAD BEEN PLACED BEHIND PANELLING AND WAS NOT VISIBLE PRIOR TO ITS FAILURE. ABOUT 5 MINUTES LATER WE MADE A 120 DEG TURN TO BEGIN A NEW SERIES OF OBSERVATIONS ON AN EASTERLY TRACK TOWARD THE CALIFORNIA COAST. THE ASTRONOMY MISSION REQUIRES A SPECIFIC HDG TO BE FLOWN TO KEEP THE TELESCOPE POINTED IN THE RIGHT DIRECTION. GND TRACK IS NOT A FACTOR IN THE SCIENTIFIC WORK, ONLY IN THE COORD OF ATC CLRNCS. IF FORECAST WINDS ARE INACCURATE, SIGNIFICANT DEVIATIONS FROM FLT PLAN TRACK CAN OCCUR WHICH ARE NORMALLY HANDLED BY OBTAINING A REVISED ATC CLRNC OR BY TERMINATING DATA COLLECTION AND CORRECTING TO THE PREVIOUSLY CLRED TRACK. ON THIS OCCASION, HOWEVER, DUE TO THE DISTR OF THE EXPLODING BOTTLE, THE EFFORT TO DETERMINE WHAT IN FACT HAD EXPLODED, AND THE SUBSEQUENT CLEANUP OF GLASS SHARDS AND SLUSH, NEITHER PLT CHECKED THE DEVIATION FROM DESIRED TRACK AFTER COMPLETING THE TURN. 20 MINUTES LATER, HAVING RETURNED WITHIN VHF RANGE, WE WERE ASTONISHED TO NOTE A 55 NM CROSS TRACK ERROR AS THE SIC CONTACTED ZOA. WE ADVISED OAKLAND OF OUR DEVIATION FROM TRACK. THEY ESTABLISHED RADAR CONTACT, CONFIRMED OUR DEVIATION, AND CLRED US TO CONTINUE. OAKLAND LATER ASKED WHAT EQUIPMENT WE WERE USING AND WERE ADVISED THAT ALTHOUGH INS WAS ABOARD, WE HAD BEEN ESSENTIALLY TRYING TO ANTICIPATE WHERE THE TELESCOPE AIMING REQUIREMENTS WOULD PUT US AT SPECIFIC TIMES FOR FLT PLAN PURPOSES. THIS INCIDENT WAS NOT INTENTIONAL AND SHOULD NOT HAVE OCCURRED. THE LARGELY UNAVOIDABLE FATIGUE INHERENT IN MISSIONS COMMENCING SHORTLY BEFORE MIDNIGHT AND CONTINUING THROUGHOUT THE NIGHT, TOGETHER WITH THE DISTR OF THE EXPLODING BOTTLE, UNDOUBTEDLY CONTRIBUTED TO THE PLTS' FAILURE TO NOTICE THE DEVELOPING DEVIATION. THERE WAS NO ACCIDENT NOR ANY APPARENT TFC CONFLICT AS A RESULT OF THIS INCIDENT.

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.