Merchant aircraft carriers (MAC) were minimal aircraft carriers used during World War II by Britain and Holland as an emergency measure until the United States-built escort carriers became available. They were bulk grain carriers or tankers built with flight decks and small islands, but no catapult or other aircraft support facilities. They operated with civilian crews, under merchant colors, and carried their regular cargo while serving as aircraft carriers. Their fighter planes were primarily intended to attack long-range reconnaissance aircraft such as the Fw 200 Condor and the Junkers Ju 290 to prevent tracking of convoys.

The scale of the conversion was small, hence it could be completed in a short time, five months is quoted as being typical.

The tanker conversions had no hangar, the grain ships did but it was small (four Fairey Swordfish was the limit). Flight decks were around 460 feet long on the tankers and between 413 and 424 for the grain ships, width was 62 feet in all cases.

Work on the first two (Empire MacAlpine and Empire MacAndrew) was started in June 1942. By October of that year a decision had been made in favour of ten more (four tankers, six grainers) and a total of 32 was eventually planned although only the nineteen below actually were completed.

The 'Air Party' consisted of an Air Staff Officer (Lt-Commander), the aircrew, a doctor, a batsman (landing control officer), ten ship's gunners, four signalmen, and three or four AB seamen. The Merchant Navy part of the crew might have an extra mate and/or wireless operator but was otherwise unchanged.

The aircrew on each ship formed one flight of No. 836 Squadron FAA which was based at RNAS Maydown in Northern Ireland.

Ships

• MV Empire MacAlpine
• MV Empire MacAndrew
• MV Empire MacCabe
• MV Empire MacCallum
• MV Empire MacColl
• MV Empire MacDermott
• MV Empire MacKay
• MV Empire MacKendrick
• MV Empire MacMahon
• MV Empire MacRae
• MV Acavus
• MV Adula
• MV Alexia
• MV Amastra
• MV Ancylus
• MV Gadila
• MV Macoma
• MV Miralda
• MV Rapana