Patrick Cau, a former United Airlines flight attendant, will plead guilty on Monday to making bomb threats against an airplane. Cau, a German citizen who sometimes uses the last name Kaiser, phoned in the threats on six United flights from pay phones across the country, according to court documents. He will be sentenced this fall and has agreed to pay restitution to United, which says it lost more than $267,000 because of the threats. Cau worked for United for 15 years and had filed a sexual harassment complaint against a male supervisor. United has declined to investigate the claim. In addition to facing jail time and stiff fines, Cau may also be deported.