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Ditching in Open Seas – Can it Happen to You? – November 24, 2014

Robert Novells’ Third Dimension Blog

November 24, 2014

Good Morning—I hope the weekend was good for one and all and hopefully we are all prepared for a new week. Today I want to talk about a safety issue – ditching. This is something we don’t think about very often but because I have done North Atlantic crossings in corporate jets, as well as large transport aircraft, it is something we need to think about.

If you are involved with flying the NAT tracks in to Europe, the NOPAC in to Asia, or just flying the Caribbean please consider doing the International Flight Procedures course at FSI as well as the water survival training. We are all familiar with the saying, “Plan for the worse and hope for the best,” so be prepared.

Between Rocks and a Wet Place

(An EMS crew chose to ditch, rather than risk flaming out during another approach to a remote island airport.)

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Incomplete preflight and en route planning by the flight crew of an emergency medical services (EMS) aircraft, and the crew’s late recognition of the slim chances for a safe landing on a small South Pacific island, forced a tough decision: to attempt another approach in darkness and deteriorating weather conditions — and risk a flameout over hostile terrain — or to ditch the aircraft with power before the fuel tanks ran dry, said the Australian Transport Safety Bureau (ATSB).

The crew of the Israel Aircraft Industries Westwind 1124A chose the latter. Unable to see the ocean surface, they used their radar altimeter to time the flare. All six occupants survived the hard impact with the sea and were able to escape from the partially submerged aircraft before it sank. Their survival of the Nov. 18, 2009, ditching was facilitated by the underwater-escape training that they had received, said the ATSB in a final report released in August.

The accident occurred at Norfolk Island, a planned refueling and rest stop for an EMS trip from Sydney, Australia, to Apia, Samoa, and back to Melbourne, Australia. The island, a self-governing territory of Australia, is about 1,420 km (767 nm) off the east coast of Australia and about 3,000 km (1,620 nm) southwest of Samoa.

The aircraft was ditched on the return flight to the island, after the pilots, a physician and a flight nurse had flown to Samoa, taken an eight-hour rest break and boarded a patient and a passenger.

Partial Fuel Load

Before the late-afternoon departure from Samoa, the pilot-in-command (PIC), who had 3,596 flight hours, including 923 hours in the Westwind, telephoned Airservices Australia to file a flight plan and to receive a weather briefing. The forecast for Norfolk Island called for visibilities greater than 10 km (16 mi), scattered clouds at 2,000 ft and light southwesterly winds. The briefing officer also told the PIC that the ceiling was expected to become 2,000 ft broken a few hours after the estimated time of arrival.

“The PIC did not obtain any other en route or terminal meteorological information, notices to airmen (NOTAMs) or additional briefing information from the briefing officer, such as the availability of facilities at any potential alternate aerodromes,” the report said.

The Westwind’s main tanks were topped, but no fuel was added to the tip tanks for the flight to Norfolk Island. Investigators estimated that the aircraft departed from Samoa with 7,330 lb (3,325 kg) of fuel; maximum fuel capacity is 8,870 lb (4,023 kg).

The copilot was the pilot flying; she had 1,954 flight hours, including 649 hours in type. As the aircraft neared the planned cruising altitude of Flight Level (FL) 350 (approximately 35,000 ft), air traffic control (ATC) told the crew that they would have to descend to FL 270 due to crossing traffic. Concerned with the increased fuel consumption at the lower cruise altitude, the PIC requested and received clearance to climb to FL 390 instead.

Higher Headwind

“The PIC reported that, once established at FL 390, he reviewed the fuel required for the remainder of the flight against the fuel remaining in the aircraft,” the report said. “He recalled that the 80-kt headwind experienced thus far was greater than expected” and extended the estimated time of arrival at Norfolk Island by 30 minutes.

“The flight crew reported calculating that, due to the increased headwind, the flight could not be completed with the required fuel reserves intact and that they adjusted the engine thrust setting to achieve a more efficient, but slower, cruise speed. The flight crew recalled satisfying themselves that the revised engine thrust setting would allow the aircraft to complete the flight with the required fuel reserves intact.”

About two-and-a-half hours into the flight, the PIC asked ATC for the current weather conditions at the destination. The controller said that a special report had just been issued, indicating that visibility was greater than 10 km and that the ceiling was overcast at 1,100 ft. “These conditions were less than the alternate minima for Norfolk Island Airport but above the landing minima,” the report said. “The PIC acknowledged receipt of that weather report but did not enquire as to the availability of an amended TAF [terminal area forecast] for the island.”

The pilots told investigators that initially they did not recognize the significance of the lower-than-forecast weather conditions on the island. “They advised that if either had realised that significance, they would have initiated planning in case of the need for an en route diversion,” the report said.

A special report issued about an hour later got the crew’s attention. The reported visibility was 7,000 m (4.4 mi), and the clouds were scattered at 500 ft, broken at 1,100 ft and overcast at 1,500 ft. Although the weather conditions had deteriorated, they were still above landing minimums. And, uncertain that the aircraft had enough fuel to divert to the nearest suitable alternate — Nouméa, New Caledonia — the crew decided to continue to Norfolk Island.

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Enjoy the week and thank  you for letting the 3DB be a part of your week.

Robert Novell

November 24, 2014