British United Island Airways (BUIA) was formed in November 1968 as part of a reorganisation of the BUA group of companies. It was a regional sister airline of British United Airways (BUA), Britain's largest wholly private, independent airline of the 1960s. It operated a network of regional, short-haul scheduled routes linking a variety of destinations within Europe, including year-round services from both Channel Islands to BUA's Gatwick base.

BUIA's origins could be traced to the BUA group's acquisition of Jersey Airlines and Silver City Airways in 1962. BUA's management amalgamated the Channel Islands scheduled passenger and freight services of these airlines (named the Duchess Services by Jersey Airlines) and Silver City's northern division to create a single airline, BUA (C.I.).

BUIA's creation followed the BUA group's 1968 reorganisation. It involved merging the operations of Channels Islands-based BUA (C.I.), Isle of Man based British United (Manx) Airways and Morton Air Services.

When British & Commonwealth (B&C), the BUA group's majority shareholder, decided to sell BUA to Caledonian Airways in November 1970, BUIA was not part of this deal. Prior to BUA's sale to Caledonian, BUIA changed its name to British Island Airways (BIA).

BUIA commenced operations on 1 November 1968 as a wholly owned subsidiary of BUA (Holdings) Ltd, taking over BUA's regional domestic and international routes, the majority of which served the Channel Islands and the Isle of Man on a seasonal basis.

BUIA's main operating bases were at Gatwick, Southampton, Blackpool (Squires Gate), Exeter, Jersey and the Isle of Man. Services from Gatwick and Southampton to the Channel islands and from Blackpool to the Isle of Man and Belfast operated year-round. All other services were seasonal summer only services. Dublin and Paris Orly were among the international destinations served.

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