A Lisbon to London plane was forced to make an emergency landing in Porto because of “smoke on board.” The alert was sounded this afternoon around 4.45pm with emergency services rushing to the Tap Air plane after it landed. Authorities said that there were 194 passengers on the plane along with crew who were in need of help. Portuguese Civil Protection sources told respected Portuguese daily Correio da Manha: “There are 194 passengers on board and crew and passengers are in need of urgent