Mass Rescue Operation :
A mass rescue operation (MRO) is one that involves the need for immediate assistance to large numbers of persons in distress such that capabilities normally available to search and rescue (SAR) authorities are inadequate. (Source : COMSAR/Circ.31 : https://international-maritime-rescue.org/sar-operations/file/516-comsar-circ-31-guidance-for-mass-rescue-operations)
