Australian tennis legend and Christian pastor Margaret Court has publicly announced she will stop flying Qantas "where possible" in protest at the airline's promotion of gay marriage.

"I am disappointed that Qantas has become an active promoter for same-sex marriage," Perth resident Ms Court said in the letter published in The West Australian newspaper.

"I believe in marriage as a union between a man and a woman as stated in the Bible.

"Your statement leaves me no option but to use other airlines were possible for my extensive travelling."

The nation's other major domestic airline Virgin, and its founder Richard Branson, also support gay marriage.

Qantas chief executive Alan Joyce recently had a pie thrown in his face in front of hundreds of people at a business breakfast in Perth by Tony Overheu, 67.

Mr Overheu said it was in protest at what he was said was "corporate bullying" including Mr Joyce and 20 chief executives of major companies signing a joint letter in support of marriage equality.

He was charged by police with assault and banned by Qantas.

Ms Court, a 74-year-old senior pastor at Perth's Victory Life Church and critic of homosexuality and same sex marriage for decades, said in the letter she had proudly promoted Qantas during her days "of never losing a tennis match while playing for my country".

Ms Court amassed more major tennis titles than any other player in history. (AAP)

"I love all people and will be pleased to talk to your board at any time," she wrote.

"But it won't be in the Qantas lounge."