M23 are Congo muitineers, but supposedly the UN forces still hold the airport. Like you said, best to call ahead - runway might be subjected to sporadic sprinklings of mortar shells.
M23 and the Congolese army were engaged in running battles in the centre of Goma from early on Tuesday morning. M23 made significant advances, particularly in the streets around the airport, which remained under the control of the UN peacekeeping mission, Monusco.
Goma falls to Congo rebels | World news | guardian.co.uk