His first experience of climbing came after his parents moved to Letchmore Heath while Alex studied for his A-levels at Watford Grammar School.
Almost as soon as he entered the school, MacIntyre joined the London Mountaineering Club and frequently went on weekend climbing trips to north Wales.
During this period, MacIntyre and his climbing partners ascended the Grandes Jorasses giant ice sheet, The Shroud, in a single day,[4][5] and also accomplished the first non-sieged ascent of the Harlin Direct on the Eiger North Face.
He climbed with a number of international groups, whose ascents included attempts on major objectives such as Dhaulagiri, Changabang, Shishapangma[7] and Makalu.
In the autumn of 1982, at the age of 28, MacIntyre was killed by a single stone while setting up a new route on Annapurna's South Face with French alpinist René Ghilini.