IN THE advertisements, the Cathay girls fix a sultry smile then avert their faces with Asian humility. But in the past three days this servile image has been smashed by the perfumed picket line, which has shown itself to be tough, resilient, and well-orchestrated. Hundreds of the glamorous women, more accustomed to serving champagne than shouting strike slogans, are braving the wintry conditions to brandish banners which scream their demands in bold coloured ink. As buses carrying the strike-breakers try to drive through the HAECO (Hongkong Aircraft Engineering Company) entrance, hands are slapping windows and doors in protest, while thumbs are turned down in disgust. ''Don't go in,'' they shout. ''We are protected by law. Come and join us, let us brave the cold together.'' Yesterday, the picket lines were swelling in size. The atmosphere was more like a carnival, with colleagues greeting each other like long-lost relatives as they arrived on the scene. Orchestrating the picket-line chorus line were 70 Flight Attendants' Union (FAU) ''communicators'', assigned to keep members informed and supervise the proceedings. The pickets have taken up residence on the second floor of the car park opposite, singing their slogans to arriving passengers. ''It's all right, it's OK, we are going to win this anyway,'' they sang. Some of the cabin crew turning up for work have ended up switching sides. ''Yes, we like our job, but they think just because we are young and we are girls we won't question them. They think they can carry on using us as dupes, they think we are dumb, we are bimbos, that we will accept anything they throw at us. Well, enough is enough,'' said Brooke (not her real name) who braved her union's directive to keep silent on the dispute. Brooke was down on the floor of Kai Tak, scribbling new banners as she spoke. She had brought a team of her friends into the airport lounge to solicit support from passengers. ''They keep on issuing us with directives, keep on telling us to improve our service more, they keep on asking so much from us, even our salaries are poor, they demand so much from us but they give us nothing in return. ''Even this strike is considered illegal by the company and they are threatening us with dismissal. Yes, we are worried for our jobs but we are going to fight for as long as it takes even if we don't go to bed at nights. ''I think the air hostesses that are working are pathetic, they don't know what is happening, they are just after more money. Management is picking them up from their homes in safe cars, taxis, they are even carrying their luggage for them. Suddenly theyhave become considerate. Then they are taken to restricted areas so none of us can get our hands on them.'' Another airline hostess said those working were even permitted to use the first class lounge as a sanctuary, then said: ''Yes, but just wait till after the strike, they will have to clean up that very same lounge.'' Another colleague said: ''It's getting cold but together we stand, divided we fall, we are united in this cause. We have supporters all around the world. ''No, we are not worried about losing our jobs, we are too strong and nothing we are doing is illegal. I don't believe that as a result of this strike they can make our life really miserable, there are too many of us.'' Another said: ''I'm getting married in two days' time in London but it looks as if I will have to delay it for a while. This strike is very important.''