Germanwings-owner Lufthansa has also changed its logo to grey. Carten Spohr Luftansa CEO, tweeted earlier: "We do not yet know what HAS happened to flight 4U 9525. My deepest sympathy goes to the families and friends of our passengers and crew. We 4U 9525. If our fears are confirmed, this is a dark day for Lufthansa. We hope to find survivors."