A storm of controversy has erupted on social media after a US airline barred two girls from boarding a flight because they were wearing leggings.
The girls were refused access on a United Airlines' Denver to Minneapolis route over the weekend because they were flying as guests of employees, and so were subject to the airline's dress code.
The unexpected rule was revealed by frequent traveller Shannon Watts, who witnessed the girls being stopped before boarding.
"A @united gate agent isn't letting girls in leggings get on flight from Denver to Minneapolis because spandex is not allowed?" she tweeted.
"She's forcing them to change or put dresses on over leggings or they can't board. Since when does @united police women's clothing?"
She said the girls' father had shorts on, but would have been allowed to board.
"The father had shorts on. Two young women in leggings booted from flight and a girl had to put a dress on over leggings in order to board."
A sexist rule?
United initially responded saying it had a right to bar passengers who are "barefoot or not properly clothed" under a "contract of carriage".
But as outcry over the incident gained momentum on social media, the airline clarified that everyday passengers would not be banned from their routes for wearing leggings.
"To our customers ... Your leggings are welcome!" it said in a statement, adding that the policy against leggings applied to United pass travellers; typically employees or their friends or family, who are also seen to represent the company.
"Our regular passengers are not going to be denied boarding because they are wearing leggings or yoga pants," a spokesman said. "But when flying as a pass traveler, we require this pass travelers to follow rules, and that is one of those rules."
This policy also bans midriff-baring tops, attire that reveals undergarments or is designated as sleepwear or swimwear, mini-skirts, shorts that fall less than 3 inches above the knee or dirty or torn clothing.
Fury on Twitter
Leggings: controversial clothing?
The incident hit a nerve with many people on Twitter, who were unconvinced by United's explanation and argued that girls and women are unfairly targeted by the policy.
Watts, who originally reported what happened, said: "This behavior is sexist and sexualizes young girls. Not to mention that the families were mortified and inconvenienced.
"As the mother of 4 daughters who live and travel in yoga pants, I'd like to know how many boys United has penalized for the same reason."
"Rules for dress that disproportionately affect girls and women are outdated and need to be changed immediately, @United," a Twitter account called Girls Really Rule said.
"I don't usually travel in leggings, but strongly considering them now," someone else added.
Model Chrissy Teigen even got involved, tweeting this:
A father chimed in saying he was about to board a flight with two daughters dressed in leggings:
Yet more people called on United to release full details of their pass traveller policy, to see whether it was disproportionately weighted against women.
In a world where companies are increasingly under scrutiny for their sexist dress codes, this debate couldn't be more relevant.
However United Airlines chooses to frame it, a policy that sees women of any age banned for wearing leggings cannot fail to send out a message of gender inequality and needs to be redressed immediately.