Vladimir Martynenkov told Russian TV he was unaware he had entered the runway.
Mr Margerie, 63, chief executive of the French oil firm, was killed in the crash along with three crew members.
Russian investigators have alleged that the driver of the snowplough was drunk at the time, but his family has denied this.
The Russian authorities have launched a criminal investigation. Mr Martynenkov, 60, was detained after the crash, which took place in poor weather at Vnukovo airport, south-west of Moscow, at around midnight on Monday.
His family insisted he was not drunk. “My client has chronic heart disease, he doesn’t drink at all,” his lawyer Alexander Karabanov told Interfax news agency.
“When I lost my bearings I did not notice when I drove out on to the runway,” Mr Martynenkov told Russia’s Channel One TV.
“The plane was preparing to take off, and I practically didn’t see it or hear it because the machine was running. I didn’t even see the lights, I did not see a thing, and then the crash happened.”
Although there had been snow in Moscow, it was not thought to be lying thick on the ground when the Dassault Falcon plane clipped the snowplough and burst into flames.
Christophe de Margerie was one of France’s leading industrialists and was returning to Paris, reportedly after a meeting on foreign investment with Russian Prime Minister Dmitry Medvedev at his country residence outside Moscow.
Total announced on Wednesday that his job would be taken over by Philippe Pouyanne, the current head of the company’s refining and chemicals division.
Thierry Desmarest, who served as chairman and chief executive from 1995-2007, will become Total’s chairman until the end of 2015, when Mr Pouyanne will take on both posts.
Mr de Margerie’s trademark grey handlebar earned him the nickname “Big Moustache”, and his was one of the most recognisable faces of the global oil industry.
French Prime Minister Manuel Valls said he was an extraordinary business leader while President Francois Hollande praised his “independent character and original personality”.
More recently, he had become an outspoken critic of European sanctions against Russia, arguing that such actions would simply push Russia closer to China.
Total, France’s second-largest listed company, is one of the biggest foreign investors in Russia and is planning to double its output from the country by 2020.
Despite the sanctions, it has continued work on a liquefied natural gas project with Russian firm Novatek to tap vast natural gas reserves in north-western Siberia and it signed a deal in May with Lukoil to develop shale oil in western Siberia.
Investigators began looking at the plane’s flight voice and data recorders on Wednesday, Ria Novosti reports. French investigators arrived in Moscow late on Tuesday to take part in the inquiry.
The role of air traffic controllers is likely to be part of the investigation.
Pictures from the scene show the driver of the snowplough looking shocked but walking unaided and without any obvious serious injury. (BBC)
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