1. The depth of sea can be found by echo depth sounding process and waves used are ULTRA SONIC and these can travel un deviated through a long distance, can be confiued to narrow beam and are not absorbed by medium.
2. Distance of aircraft = 30km = 30 x 1000m = 30,000m Total distance = 2 x 30,000 = 60,000m Time taken = 2 x 10-4 second
