The EM-120 uses 1 by 1 degree sonar-emissions at the sea surface. Each 1 degree beam width sonar ping expands to cover a circular area about 192 metres (630 ft) in diameter at 11,000 metres (36,089 ft) depth. Whilst mapping the Challenger Deep the sonar equipment indicated a maximum depth of 10,971 m (35,994 ft) at an undisclosed position.[29][30][31][32] Navigation equipment includes the Applanix POS MV320 V4, rated at accuracies of ½–to–2 meters.[33] RV Kilo Moana was also used as the support ship of the hybrid remotely operated underwater vehicle (HROV) Nereus that dove three times to the Challenger Deep bottom during the May/June 2009 cruise and did not confirm the sonar established maximum depth by its support ship.