The Air Force Once expenses were listed under "DNC Travel Offset Account." All of Clinton's plane expenditures during the campaign, except the Air Force One flight, have been categorized as under "Travel."

A Clinton aide told CNBC that the costs associated with Clinton's July 5 Air Force One flight from Washington to Charlotte , North Carolina, with President Barack Obama was included in that total. That day was the first official joint campaign event for Obama and Clinton.

The Hillary Clinton campaign has disclosed in its August Federal Election Commission filings that it has paid $36,602.99 in the campaign's use of Air Force One.

No specific details were disclosed with the "DNC Travel Offset Account." When asked for a breakdown of the expenses to determine the exact cost for Clinton's travel on Air Force One on July 5, the campaign declined, referring back to the total of $36,602.99 paid. As with Clinton's other charter plane expenditures in FEC reports — no details on dates or destinations have been disclosed.



Asked if the costs associated with the use of Air Force One and Two by Obama or Vice President Joe Biden on behalf of Clinton were included in that total, campaign spokesman Josh Schwerin said: "As is the standard practice, the campaign is covering its portion of the costs."



For every hour Air Force One is in flight, it costs $206,337, according to a Freedom of Information Act letter obtained by the nonprofit Judicial Watch.



"According to FEC rules, the campaign has to pay airfare that would be comparable to a private charter," said Josh Stewart, deputy communications director for the Sunlight Foundation, a nonpartisan organization that advocates for disclosure and open government. "But unfortunately, Air Force One is one of a kind 747 so you can't get an apples-to-apples comparison. But the price looks comparable."

Chartering a Boeing 747 through PrivateFly costs $16,877 an hour.



"The president, vice president and first lady each may engage in official, political and campaign-related activities, either separately or in combination," FEC deputy press officer Christian J. Hilland said during a July interview. "Official expenses are paid by the U.S. government; the costs of political activities are paid for the national party committee and campaign expenses are paid by the candidate's campaign committee and must be disclosed."