G-ALSD was a Boeing 337-10-28 Stratocruiser with an interesting history.

Originally it had been ordered by the Svensk Interkontinental Lufttrafik Aktiebolag (SILA), a Swedish airline aimed at international traffic. SILA was the second airline to order the 377, and signed for four aircraft in February of 1946. As such, 15946 would have been the fourth of SILA's four Stratocruisers, with the registration SE-BDR reserved for it.

Before the aircraft were delivered, though, a lot happened. In August of 1946, SILA went into a partnership with Denmark's Det Danske Luftfartselskab A/S (DLL) and Norways Det Norske Luftfartselskab AS (DNL), with the three companies making up the Scandinavian Airlines System. SILA ended up giving one Stratocruiser each to DDL and DNL. In 1948, the Swedish airline company AB Aerotransport ended up joining SAS, and integrated its fleet into the airline.

Meanwhile, a series of accidents over the South Atlantic would forever change the fate of these four Scandinavian Stratocruisers. In January of 1948, British South American Airways (BSAA) Avro Tudor 'Star Tiger' (G-AHNP) disappeared enroute between the Azores and Bermuda. One year later, in January of 1949, BSAA Avro Tudor 'Star Ariel' (G-AGRE) disappeared between Bermuda and Jamaica. Neither aircraft were ever found - and the type was grounded, leaving BSAA without long-range aircraft. The airline was forced into a merger with BOAC, who suddenly required additional long-range aircraft for their new South American lines. Meanwhile, SAS was standardising its fleets, and soon BOAC and SAS came to an agreement: SAS would allow BOAC to take over their four orders for Stratocruisers, while SAS in turn took the occasion to standardise its long-range fleet on Douglas DC-6s. As such, the four Scandinavian Stratocruisers changed hands before they were even completed, becoming G-ALSA to G-ALSD - SAS' SE-BDR became BOAC's G-ALSD while still on the production line.

G-ALSD made its first flight on November 9th 1949 and was delivered to BOAC on December 16th 1949, where it was baptised as RMA Cassiopeia. She would spend the next nine years flying mainly trans-Atlantic services for BOAC. With the jet-age dawning at the end of the 1950s, BOAC negociated a trade with Boeing: it would hand back its 14 surviving Stratocruisers (G-ALSA was written off in a fatal accident at Prestwick on Christmas Day 1954) as a downpayment on its Boeing 707s.

Via a New York aircraft broker, the Oakland-based airline Transocean Airlines (TALOA) managed to acquire the ex-BOAC fleet of Stratocruisers. They were planning to use them on non-scheduled services between Oakland and Tokyo, and from New York to Oakland. G-ALSD arrived in Oakland on September 7th 1958 when she became TALOA's N85Q; however when TALOA had the aircraft re-registered in 1959 so they were in one neat continuing series (N401Q to N414Q) she became N403Q.

The Stratocruisers arrived with TALOA at a moment the airline was going through some financial turmoil; they hoped to solve it by purchasing Cubana's order for Boeing 707s and leasing the aircraft to Japan Air Lines; however reportedly Pan Am blocked this deal because they didn't want the competition, and without the lease from JAL, TALOA went under. They called in the receivers in July of 1960, and by September 1960 their Stratocruisers were auctioned off to an aircraft broker. N403Q ended up in the Mojave desert, where she was slowly reduced to spares as the Super Guppy program started a new life for the Stratocruisers; she was scrapped sometime around 1980.