the US major and which had replaced the aircraft's usual, five-abreast, slimline charter seating configuration for this trip. Cdr F.G. Dustin, who had accompanied [then Cdr] Byrd on his second Antarctic expedition in 1934, was among the passengers. The flight routed over the North Pole via Greenland, Alaska, the Philippines, Japan, Australia and New Zealand to Antarctica, where it made the historic landing at McMurdo Sound. From there it routed over the South Pole, before crossing the International Date Line a second time and proceeding northwards to southern Argentina, Brazil, West Africa and Europe. Rome was the first European stop, from where the flight continued to Moscow via Copenhagen (where an Aeroflot navigator joined the flight deck), before night-stopping in London and returning to Boston the following day, 3 December 1968. The en route stop in Moscow also made Modern Air the first US commercial airline to operate a charter flight to the erstwhile Soviet Union. Modern Air's historic arrival in Moscow was memorable for a different reason as well. In common with other contemporary jet aircraft types, such as the Boeing 707/720, deHavilland Comet, Douglas DC-8, Sud Aviation Caravelle and Vickers VC-10, Convair's 880/990 lacked an auxiliary power unit (APU). This made the Convair jets dependent on an external ground power unit (GPU) to provide electrical power for the aircraft while stationary on the ground, including starting the engines. When Polar Byrd I needed power externally supplied by a GPU to start its engines at the end of the stopover in Moscow to resume its journey, it was found that the Soviet GPUs could not be connected to the CV-990s air intake valve due to an incompatibility between the ground equipment's fittings and the aircraft's valve. This necessitated flying in a Modern Air GPU from West Berlin and resulted in the delay of the onward flight. It also resulted in a subsequent collaboration between Modern Air's maintenance department and Garrett AiResearch to design and test a CV-990 APU, which was located in a hollow area behind the fuel tank inside the aircraft's inboard anti-shock body on the starboard wing. This however proved unsuccessful, resulting in the unit's removal after the first installation. The Byrd Center kept half of the $700,000 it had raised for its historic round-the-world transpolar trip, which cost $250,000 to organise. This left Modern Air with a profit of $100,000. Polar Bird II Modern Air's second