Alpha will fund the purchase through loans and a pounds 20.7m share placing and open offer. It will issue 16.7 million new shares on a one-for-nine basis at 126p a share. Its shares closed up 4p at 141p.
DynAir provides services including luggage handling, maintenance and fuelling. Rodney Galpin, Alpha's chairman, said DynAir was "a substantial and cash-generative business which has an established name".
The operation had a turnover to December 1994 of $130.8m, and operating profits of $10.6m. In the first half of this year sales were 9 per cent higher than in the same period in 1994.
Alpha, launched on the stock market by Forte in January 1994, has been pursuing acquisitions, joint ventures and other opportunities as the airline industry consolidates.
Alpha's catering operations have been under pressure as airlines have reduced spending. Margins in the US have also been held back by the refurbishment of its flight kitchen at JFK Airport in New York.
Alpha was expected to expand its other airport services, and this is the most significant move yet.