Prince Harry and Meghan Markle are allowed to take commercial flights, but Prince Charles and Queen Elizabeth aren’t. And the reason for this has just been revealed.

In the book “The Firm,” royal author Penny Junor said that there is an outright ban for the monarch and the future king to take normal passenger flights. But Prince Harry and Markle are allowed to take commercial flights because they are not heirs to the throne.

“Since 9/11, the Queen and the Prince of Wales no longer travel on scheduled airlines because of the security risk. Nor do they ever fly together in the same aircraft – they never have – and the Prince of Wales does not as a rule fly with his sons… He needs the Queen’s permission to do so and there have been occasions in the past where she has refused it,” she said.

Junor also revealed that there were two exceptions from years ago wherein Prince Charles, Prince William, and Prince Harry were allowed to take the same flight. This happened following the death of the Queen Mother. At that time, the three royals flew back home together from Klosters.

The second exception took place following the death of Princess Diana. In 1997, Her Majesty gave Prince Charles and her two grandchildren to take the same flight from Balmoral to London.

According to Junor, the rule was put in place to ensure that in case of emergency, the members of the royal family won’t be harmed or killed at the same time.

Meanwhile, there has also been so much talk surrounding the recent flights that the members of the royal family took. Prince Harry and Markle were criticized for taking a private jet to and from their vacation destination.

The Duke and Duchess of Sussex have been preaching about the dangers of climate change. However, using a private jet for traveling is causing harm to the environment.

Prince William and Kate Middleton were also praised for taking a commercial flight with their children. But it was revealed that their trip wasn’t economical after all.

Prince Charles, Camilla Parker-Bowles, Queen Elizabeth, Meghan Markle and Prince Harry
Pictured: Prince Charles, Camilla Parker-Bowles, Queen Elizabeth, Markle and Prince Harry stand on the balcony of Buckingham Palace on July 10, 2018. Getty Images/Tolga Akmen