FLIGHT problems on Monday forced the ministers of defence and foreign affairs to cancel a trip to Uganda, where they were to stand in for President Nelson Mandela. “First they had flight clearance problems with some countries to the north and then there was a major technical problem with the aircraft they had chartered. It just became too late so they decided not to go,” foreign affairs spokesperson Marco Boni said of Foreign Minister Alfred Nzo and Defence Minister Joe Modise. The two ministers had intended to sign an investment promotion agreement between South Africa and Uganda. They were called on to represent Mandela, who cancelled his visit to Uganda on Sunday in the wake of the assassination of Sifiso Nkabinde.