A peculiar yet logical Royal rule may lead to Prince George and his sister Princess Charlotte being separated once he reaches the age of 12.

This rule, which isn’t new, will prevent Prince George from traveling with his father or sister. It’s the same rule that Prince William had to follow when he turned 12. The rule exists to safeguard the monarchy in case of accidents, aiming to protect the line of succession. Prince William is the immediate heir to the throne if anything happens to King Charles, while George is third in line and Charlotte is fourth. In the event of an accident involving an aircraft or other means of transportation, the rule helps secure the line of succession by preventing them from all traveling together.

News of this unusual rule came to light just before Prince George’s 11th birthday on 22 July, as shared by King Charles’s former pilot, Graham Laurie. He told OK! magazine: “We flew all four: the Prince, the Princess, Prince William and Prince Harry, up until Prince William was 12 years old. After that, he had to have a separate aircraft and we could only fly all four together when they were young with the written permission of Her Majesty. When William became 12, he would fly normally in a 125 from Northolt and we would fly the 146 out with the other three on.”

It’s likely that if the family wishes to travel together now, they would need permission from King Charles as the current monarch. If this tradition continues, it means that once George turns 12, he will need to travel separately from his family for the remainder of his life.

While plane crashes are rare today, three members of the Royal family have tragically lost their lives in aviation accidents in the past. Princess Cecile, Prince Philip’s sister, died in a crash in 1937; the late Queen’s uncle, Prince George, Duke of Kent, passed away in 1942; and her cousin, Prince William of Gloucester, lost his life during an air show in 1972.

A few months ago, Prince William, Princess Charlotte, and Prince George were seen attending a Taylor Swift concert, causing much excitement and leading to a backstage selfie with the pop star. Prince William and his son have also been seen spending time together, including being spotted at the UEFA England match in Berlin this past July.