http://www.vox.com/policy-and-politics/2016/11/16/13641538/trump-plane-secret-service
When he’s president, Donald Trump will fly on Air Force One. Which means the Boeing 757 that Trump owns through a holding company will be free for use by Ivanka, Melania, Eric, Donald Jr., or whomever else. And if Trump requests Secret Service protection for those people, he will probably get it. And when Secret Service agents fly alongside a protectee, they use their budget to pay airfare. Which in the case of a flight on the Trump jet would mean paying Trump for the seats on his plane.
In other words, by asking for Secret Service protection for family members who fly on his plane, Donald Trump can directly funnel taxpayer money into his own pocket
For any of the Trump or Pence clans assigned a protective detail due to safety risks— and the rancor of the 2016 vote could well produce many — Secret Service travel on a Trump-owned plane means the agency would need to reimburse the aircraft’s owner. In this case, the president.
“So then you have government money going into the pockets of the president and his children,” said Brett Kappel, a lawyer who specializes in political finance and ethics at Akerman LLP. The Trump transition team did not respond to email requests seeking comment. The Trump family has also hired private security guards, although it is unclear how Trump’s election will affect the extent of private security used. The Secret Service has assumed full authority for protecting the president-elect and vice-president elect, including a new no-fly zone the Federal Aviation Administration has established until Jan. 21 over Trump’s Manhattan residence.
But this is exactly what Trump did during the campaign, billing the federal government $1.6 million for granting Secret Service agents the right to fly on his plane.* The reason we know that is because it was a political campaign, so all the financial details were filed with the Federal Election Commission. With the campaign over, however, the plane just becomes part of Trump’s opaque web of privately held companies, so the amount of money he is funneling from the federal government into his pocket won’t be disclosed on that end.