James Cuthbert Mercer was born in Caversham, Dunedin, on 16 September 1886, the son of Robert Mercer, a gardener, and his wife, Sarah Jane Speed. Educated in Dunedin, Bert (as he was known) undertook an apprenticeship at Vickery's bicycle shop in Invercargill. Later, as cars became popular, he worked as a mechanic in Invercargill, Dunedin and Ashburton.
Mercer's business acumen showed early when he ran garages in Amberley and Waikari to service motor vehicles throughout North Canterbury. He was a regular and successful competitor in early reliability trials with his Hupmobile. Mercer was living in Waikari when he married Eleanor Jane Trethewey in Ashburton on 21 May 1913. They were to have two daughters.
Bert Mercer gained his first experience of aviation in 1908 when he had a ride in a gas balloon. After the Canterbury (NZ) Aviation Company was formed in 1916 to train pilots for the war in Europe, he moved his family to Sockburn, on the outskirts of Christchurch, and joined as a mechanic. He received flying training and, although he was too old to be sent overseas, was kept at Sockburn as an instructor.
Following the war the company was reduced to displays and joyriding to stay in business and Mercer joined Rodolph Wigley's Timaru-based New Zealand Aero Transport Company. Regular operations were planned and Mercer undertook a number of development flights. On 25 October 1921 he set a one-day distance record, from Invercargill to Auckland, in a de Havilland DH9. When the company joined the general collapse of New Zealand's fledgeling civil aviation industry in 1923–24, Mercer went back into the motor trade in Christchurch. He had his own garage in Hereford Street and was later head of engineering at another garage.
Mercer undertook regular flying refresher courses at Sockburn. When the Canterbury Aero Club started in 1928 he was its first pilot instructor, by now sporting his characteristic moustache. Introduced to the West Coast by two of his pupils, he recognised the region's potential for an airline. No road existed in south Westland to service the scattered homesteads, bush camps and prospectors' huts, and the pioneering settlers of the 1930s still depended on infrequent coastal shipping. Mercer encouraged the West Coasters to form airstrips beside their homesteads, and he made frequent trips across the Southern Alps in Gipsy Moths and, later, a Fox Moth. He saw the usefulness of this diminutive four-passenger single-engine biplane, and during 1934 organised local capital to set up his own airline.
In November 1934 Mercer resigned from the Canterbury Aero Club to concentrate on his airline, based in Hokitika. Air Travel New Zealand was one of the first two companies to be granted a licence under the Transport Licensing (Commercial Aircraft Services) Act 1934, and was the first in New Zealand to start scheduled services when Mercer flew its Fox Moth south from Hokitika on 18 December 1934.
At first Mercer, with his daughter Billee, boarded with another family beside the airfield. He was joined by his wife and other daughter in 1937 when a house was built for his family. The airline proved a success from the start, growing to include five aircraft by 1938. Mercer was a popular figure, tall and slim with his jacket pockets always bulging with handy items and sweets for the children of south Westland.
He expected hard work from his staff but was always willing to make emergency flights or drop newspapers to remote huts. Mercer also flew coastal patrols around Fiordland for the Royal New Zealand Air Force, a practice started in September 1939 after the German steamer Erlangen left Dunedin without bunkering and was thought to be trying to refuel with wood.
Air Travel took over the Cook Strait Airways route to Nelson during the war. Mercer was returning from there as a passenger in the company's Dragon aircraft on 30 June 1944 when the pilot was forced to fly low through the Hope River area. The aircraft was caught in turbulence and crashed on the side of Mt Hope near Kawatiri. The pilot and four passengers received serious injuries but were rescued after spending many hours in atrocious conditions. Another passenger was killed outright and Mercer died of his injuries and exposure during the night, not long before rescuers arrived. His funeral at Hokitika was attended by hundreds of West Coasters and high-ranking representatives from the army and air force. Mercer was survived by his wife and two daughters.
Bert Mercer is still remembered for his airline, which opened up a remote region. Its essential character was retained under two later ownerships from 1947, until the Haast Pass road was completed in 1965 and improved communications in south Westland made air travel no longer crucial.