Promech de Havilland DHC-2 accident

Two airplanes operated by the same company, a float-equipped deHavilland DHC-2 Beaver, and a float-equipped deHavilland DHC-3 Turbine Otter, collided in midair as they were en route to the same remote destination. The Beaver sustained minor damage to the floats, and the Turbine Otter sustained substantial damage to the top portion of the wings, the fuselage, and vertical stabilizer. The collision occurred over an area of coastal channels and fjords. The pilot of the Beaver stated that his airplane was the first of three company airplanes to depart. Once airborne, and clear of the class E airspace, he changed radio frequencies to monitor a common traffic advisory frequency. He said that about 15 minutes after departure, while in level cruise flight, about 2,000 feet above the water, he felt a sudden thump, followed by a pronounced airframe shudder. He then observed the top of the left wing of the Turbine Otter to his left side, just under the floats of his airplane. He said that just after the two airplanes collided, the Turbine Otter made a left, descending turn, away from his airplane. He said that after determining that he still had full flight control, he elected to return to the operator's base of operation. The pilot of theTurbine Otter said that his airplane was the second of three airplanes. He said that he departed about 5 minutes after the Beaver, and proceeded on a northerly heading, while climbing the airplane to about 2,200 feet. He said that he changed radio frequencies to monitor a common traffic advisory frequency. He said that about 10 minutes after departure, he heard one of the passengers seated in the rear of the airplane yell "airplane." About two seconds later, the pilot heard a loud scrape on the top portion of the airplane. The pilot said that just after the impact, he experienced some difficulty in controlling the airplane, but was soon able to regain partial control, and subsequently made an emergency landing in the ocean waters in the channel. The pilot of theTurbine Otter reported that his airplane was about 10 knots faster than the Beaver.

Verbatim NTSB analysis and probable cause from the NTSB dataset