The women are often dres-sed in figure-hugging uniforms, totter around on high heels, and some carriers choose women crew members for their looks as much as their abilities, it is said.
When female employees "lose their glamour" they can also lose their jobs.
While the average tired businessman may feel it is all innocent titillation and part of the lure of one airline over another, unions argue that it is sexist, demeaning and can lead to sexual harassment.
"Passengers are expected to trust and obey cabin-crew instructions in an emergency. The Barbie [doll] image, which implies little intelligence but lots of sex appeal, endangers that relationship. It undermines wo- men's dignity and damages airline safety," according to the International Transport Workers' Federation (ITF).
In one case outlined by the federation, a passenger pinched an attendant's bottom on numerous occasions as she was passing his seat, touched her breasts while she was serving his meal and later stood up behind her, grasped her by the hips and simulated sexual intercourse. "His fellow passengers cheered him on his actions," according to federation officials.
The federation, which represents 480 transport unions with more than five million members, believes that all airlines at one time or another have sought to exploit the notion that air travel includes being served by a physically attractive "hostess".
It also points out that there are few women cabin crew members who haven't at some time suffered some form of touching, verbal insinuation, "sexual power play", or even assault from a passenger.
Singapore Airlines is one of many carriers whose promotional material is cited by the federation for allegedly demeaning female cabin crew. Stuart Howard, ITF aviation secretary, said: "Their promotional material is full of soft-focus, curvy, Singapore girls. It's all about the magic of the Oriental woman."
Some smaller companies are far worse, with one Brazilian airline carrying explicitly sexual cartoons in in-flight magazines .
The Swiss-based carrier Cross-air has come in for ITF criticism for campaigns such as the one above emphasising the attractiveness of its female staff. The airline employs only women and sets a retirement age of 35, according to Mr Howard.
Even British Airways, which is said to have a relatively good record, is accused of exploiting the femininity of staff. One advertisement shows a business passenger metamorphosing into a baby with a woman in twinset and pearls holding him. The federation says that emphasising the supposed maternal instincts of female cabin crew undermines their role in air safety.
The federation is to grade airlines around the world in terms of sexism - or a lack of it - and examples of good and bad employers are to be publicised by the end of the year.
The big airlines believe accusations of sexism are wide of the mark. Singapore Airlines says that the "Singapore girl" theme, "epitomises the airline's service on the ground and in the air and symbolises the standards all our employees aspire to". The carrier valued all its staff equally, both men and women.
A spokesman for British Airways said that employing staff because they were "pretty" was an archaic and sexist approach not adopted by BA. The "woman with the baby" advertisement was simply to convey "memories of motherhood".Reuse content