But this week, the carrier stands accused of having a racist policy that discriminates against some Black passengers. And despite that criticism, it isn’t backing down.

As reported Monday, Ryanair has started telling South Africans traveling to the U.K. that they must answer a questionnaire to prove they are indeed South African—name the highest mountain in South Africa, name the country’s capital, and so on. This is supposedly a measure to counteract the high number of fake South African passports that are out there, which is a genuine problem that the South African government has been flagging to other countries.

The contentious issue with Ryanair’s questionnaire is that it is in Afrikaans.

Afrikaans is a language that is largely based on the archaic Dutch that was spoken by 17th-century colonists from the Netherlands. It was the mother tongue of the racist apartheid regime that ruled South Africa from 1948 to the early 1990s, and as such it is widely seen as a “white” language, though that is not quite accurate—early Afrikaans was shaped by the slaves brought to the Cape Colony from what is now Indonesia, and it remains the primary language of their descendants. Either way, the apartheid government tried forcing students of all colors to learn Afrikaans, which sparked the lethal 1976 Soweto uprising among other pushbacks.

Today, Afrikaans is but one of South Africa’s 11 official languages, and very few of South Africa’s Black majority speak it. Hence the problem with Ryanair using it as a means to prove South African–ness—and hence the consternation that greeted Ryanair’s decision to double down, even though British authorities say the test is not required.

“Ryanair must ensure that all passengers (especially South African citizens) travel on a valid SA passport/visa as required by U.K. Immigration,” the airline told the BBC.

“This is breathtaking, Ryanair, and racist,” tweeted Phumzile Van Damme, a former South African lawmaker. “Do you know the history of South Africans being forced to learn Afrikaans during Apartheid? A language only spoken by 13% and mostly white people in South Africa. Just say you don’t trust black people and be done with it.”

Some called for the British government to step in, to secure passengers’ human rights. And Melanie Verwoerd, the former South African ambassador to Ireland, wrote in the Irish Times that the episode was damaging Ireland’s image in the eyes of South Africans.

“I’m not sure who advised Ryanair on this, but whoever it was gave them the worst possible advice,” Verwoerd wrote. “Black people from all countries are all too familiar with being treated with a much higher level of suspicion and questioning by immigration officials in Europe than their white counterparts…Whether intended or not, Ryanair’s ill-advised and frankly idiotic questionnaire would only add further insult to injury.”

Ryanair told Fortune it had nothing to add beyond the statement it had given to the BBC.