#According to J K Rowling, people could fly without a broom, just it is extremely difficult and risky. (more so than Wandless magic)

JK Rowling. Yes, nearly all wizards use wands, which makes magic easier to channel. Wandless magic is sophisticated and takes more talent.
Q. So would that work the same for brooms? Would more advanced wizards/witches not need a broom to fly?
JK Rowling. Exactly. Wands and brooms (and flying cars) are tools that channel magic. The most gifted can dispense with them.
Q. Are there many wizards/witches at Hogwarts who can do magic and fly without wands or brooms?
JK Rowling. No, there's a cultural tradition of using wands and broomless flight is (as you might imagine) very risky!
_(Source)

We could interpret Kennilworthy Whisp's "No spell yet devised enables wizards to fly unaided in human form" as referring exclusively to spells and not to wandless magic.

According to J K Rowling, people could fly without a broom, just it is extremely difficult and risky. (more so than Wandless magic)

JK Rowling. Yes, nearly all wizards use wands, which makes magic easier to channel. Wandless magic is sophisticated and takes more talent.
Q. So would that work the same for brooms? Would more advanced wizards/witches not need a broom to fly?
JK Rowling. Exactly. Wands and brooms (and flying cars) are tools that channel magic. The most gifted can dispense with them.
Q. Are there many wizards/witches at Hogwarts who can do magic and fly without wands or brooms?
JK Rowling. No, there's a cultural tradition of using wands and broomless flight is (as you might imagine) very risky!
_(Source)

We could interpret Kennilworthy Whisp's "No spell yet devised enables wizards to fly unaided in human form" as referring exclusively to spells and not to wandless magic.