WHBM

Malaysia Singapore Airlines wasn't around for very long. Originally just Malayan Airlines, with Singapore as its base and hub, as part of a complex pollitical restructuring when the country was rearranged as Malaysia and Singapore (it wasn't a simple split) the airline was renamed, although it extensively branded itself as MSA, as each country didn't really care to be associated with the other. Batches of aircraft were very precisely registered with alternate aircraft in each country, though like SAS in Europe run as a common pool. The international jet services continued to focus almost wholly on Singapore, but the regional propeller flights were mainly across Malaysia. Quite soon they fell out, but MSA (inevitably with UK expat management and pilots) had developed a notable reputation for themselves as such, they were one of the first to ignore IATA and start offering free drinks and substantial catering in Y. Both carriers wanted to keep the initials, so when it split in two (most management stayed in Singapore) one wanted to be Malaysia State Airlines, or MSA, and the other to be Mercury Singapore Airlines, or MSA. In the end it was agreed on Malaysian Airline System, MAS, and Singapore International Airlines, SIA, and the use of these three-letter abbreviations was common for some years, although it then dropped away.