NORTHWEST AIRLINES FLIGHT ATTENDANTS ARE KEEPING AN EYE OUT FOR PASSENGERS WHO MAY BE SHOWING SIGNS OF THE MYSTERIOUS, FAST MOVING DISEASE CALLED SARS.... ALSO KNOWN AS SEVERE ACUTE RESPIRATORY SYNDROME. NORTHWEST AND OTHER AIRLINES WITH EXTENSIVE ROUTES TO ASIA, ALSO FACE SOME POTENTIAL ECONOMIC PROBLEMS AS TRAVELERS GROW MORE CONCERNED ABOUT THE DISEASE. NORTHWEST'S ASIAN ROUTES MAKE UP ABOUT 25 PERCENT OF ITS REVENUE. JOEL DENNY IS AN AIRLINE INDUSTRY ANALYST WITH US BANKCORP PIPER JAFFREY. HE SAYS IT TOOK A WHILE FOR SARS TO AFFECT NORTHWEST'S BUSINESS.