Chronology of events
11:48:07 Cougar Flight CHI91 departs St. John's.
12:05:52 CHI91 advises Gander Area Control Centre (ACC) that they have levelled off at 9,000 feet and that their estimated time of arrival at the Hibernia platform is 13:10. Speed is 110 knots.
12:15:05 Rapid loss of main gearbox oil pressure occurs. No abnormal indications of any kind recorded on flight data recorder prior to this event.
12:15:19 CHI91 begins a right turn.
12:15:24 Main gearbox oil pressure decreases to approximately five psi.
12:15:27 CHI91 issues mayday call to Gander ACC and begins descent from 9,000 feet. They are 53 nautical miles from St. John's.
12:15:32 CHI91 advises Gander ACC that they have main gearbox oil pressure problems and requests immediate clearance to return to St. John's.
12:15:43 CHI91 heads back to the coast. Their heading is 290 degrees and their speed is 120 knots.
12:17:04 Main gearbox oil pressure reaches 0 psi.
12:17:25 CHI91 advises Gander ACC that they are heading for nearest land. Their heading is 292 degrees and their speed is 122 knots.
12:17:42 CHI advises Gander ACC that they have lost all main gearbox oil pressure. CHI91 is descending through an altitude of 5,740 feet.
12:18:25 Gander ACC advises CHI91 that they are 42 miles from Cape Spear.
12:19:10 Gander ACC advises CHI91 that search and rescue has been notified.
12:19:18 CHI91 advises Gander ACC that Cougar dispatch has been advised and that another helicopter is being readied.
12:22:20 CHI91 levels off at approximately 800 feet. Their heading is 292 degrees and their speed is 133 knots.
12:24:44 A power interruption to the Flight Data Recorder/Cockpit Voice Recorder occurs.
12:25:36 CHI91 advises Gander ACC that they are preparing to ditch.
12:25:52 St. John's radar records CHI91 at 800 feet. CHI91 subsequently descends to 300 feet in approximately 29 seconds which equates to an approximate rate of descent of 1,000 feet per minute.
12:26:26 St. John's radar records the last radar return of CHI91 at 300 feet.
12:26 Gander ACC advises search and rescue that CHI91 has ditched. Cougar dispatch confirms the ditching with search and rescue, and advises that they will launch Cougar 61 as a rescue helicopter.
12:42 A Provincial Airlines patrol aircraft arrives at crash site and observes two people in orange immersion suits in the water.
13:07 Cougar rescue helicopter departs St. John's.
13:25 Cougar rescue helicopter arrives at crash site and spots two people (one of whom is later confirmed dead), two rafts and helicopter debris.
13:33 Cougar rescue helicopter lowers a rescue person toward the people in the water.