Around 07:00 WIB, an aerial search revealed traces of an oil spill on the surface of the water near the location where the submarine was believed to have dived.[40][2] Achmad Riad later reported that an oil spill had been observed at multiple locations.[41] He added that Raden Eddy Martadinata had detected movement underwater at a speed of 2.5 knots (4.6 km/h), but was unable to obtain enough information to identify the contact before it disappeared.[41]