Chapter 8: Sidescan Sonar

This chapter includes images of crews, equipment, and the environment within which they worked for many months. It also summarizes some of the accomplishments of the first year effort, including total area scanned, and equipment performance.

Together, between October 2014 and June 2015, the four vessels that conducted all of the sidescan sonar, sailed 248,000 kilometers (96,000 miles). That is the equivalent of 4.8 times around the world at an average speed of about 5 knots.

A lot of the sidescan was done by Fugro Discovery and her crew: 86,000 linear kilometers (33,000 linear miles), the equivalent of highway driving in slow motion.

In addition, Go Phoenix and her crew sidescanned 64,000 linear kilometers (25,000 linear miles).

Fugro Equator and her crew actually covered more ocean than any of the other vessels, but her time was split between bathymetric mapping early in the search, and sidescan sonar throughout 2015.

For all kinds of ocean floor scanning, Fugro Equator and her crew covered 114,000 linear kilometers (44,000 linear miles).

A fourth vessel, Fugro Supporter, had a somewhat different assignment. She and her crew used AUV technology to investigate features detected by sidescan and not fully resolved as to possible relevance to MH370. Supporter and her crew covered 44,000 linear kilometers of seafloor (17,000 linear miles).

It is not easy to convert all of that linear distance into actual square miles or square kilometers of scanned seafloor, largely because each vessel spends a slightly different amount of time getting to and from port, and because the speed at which vessels are able to scan depends on the equipment array they use. For example, Fugro Equator and Fugro Discovery used EdgeTech DT-1 sidescan sonar units. They were able to scan at about 2.3 knots, covering an area about 1.25 square miles in width for every mile moving forward.

In contrast, Go Phoenix deployed an SLH ProSAS-60. She was able to work at 1.9 knots, covering an area about 1.1 miles in width for every mile moving forward.

The following images are color-coded to identify each vessel, and give readers a sense of the seafloor covered and scanned as work progressed. Tracks shown in black are the areas Fugro Equator bathyscanned to prepare for subsequent sidescan sonar work. Yellow tracks are for Go Phoenix, orange for Fugro Discovery, turquoise for Fugro Equator.

gone-oct

gone-nov

gone-dec

gone-jan

gone-feb

gone-mar

gone-apr

gone-may

Group 1

For convenience, the following ~50 images have been organized in groups of 5 to 11 images. All of the crew and vessel images were taken by ABIS Chris Beerens of the Royal Australian Navy (RAN). All images used with permission.

This chapter ends with a bit of additional discussion.

Photo_27

Photo_37

Photo_42

Photo_50

Photo_94

Group 2
Photo_8

Photo_11

Photo_23

Photo_26

Photo_33

Photo_40

Group 3
Photo_43

Photo_45

Photo_46

Photo_67

Photo_96

Photo_97

Photo_103

Group 4
Photo_83

Photo_81

Photo_79

Group 5
Photo_10

Photo_12

Photo_13

Photo_16

Photo_24

Photo_25

Photo_29

Photo_30

Photo_31

Photo_32

Group 6
Photo_55

Photo_54

Photo_53

Photo_52

Photo_51

Photo_49

Photo_48

Photo_47

Group 7
Photo_100

Photo_92

Photo_91

Photo_90

Photo_89

Photo_88

Photo_85

Photo_77

Photo_69

Photo_61

Photo_58

Group 8
Photo_109

Photo_108

Photo_107

Photo_106

Photo_105

Photo_104

Photo_102

The central focus for each vessel and its crew revolved around covering seafloor areas to conclusively identify wreckage and debris associated with MH370, if encountered.

ATSB set its first-year goal at 60,000 square kilometers. That was the extent of the area they wanted to cover. They felt they had a reasonable chance of finding the aircraft if they met that goal, assuming the aircraft was actually resting in that part of the ocean. Weather and equipment issues slowed the effort, but they nevertheless completed about 54,000 square kilometers, or 90% of the stated goal. More importantly, they found objects that were sufficiently difficult to detect to convincingly demonstrate that the most important part of the effort was fulfilled with room to spare. They did something no one had ever done before, and they did it well.

As far as ATSB’s hope of completing even more seafloor, another impediment was logistical: about 30% of all crew and vessel time was spent in transit to port in Fremantle or sailing back to the search area. Each vessel had to refuel once every four weeks. Those treks consumed time and resources that could not be used in other ways.

Even in hindsight, there is no easy way to reduce downtime due to transit. Civilian vessels are generally not configured to refuel on the high seas, and it would be difficult to argue in favor of it. Survey vessels are relatively small, and refueling at sea would increase risks.

Alternatively, there are positive aspects to transiting back to Fremantle once a month. One is that it provides opportunities to rotate crews when needed, and rest others during transit.

As for forensic discoveries that might indicate MH370 is or was in the Southern Indian Ocean, none have emerged that have been published.

But there are positives in knowing nothing has been found. SIO is now a possibility we can cross off the list. It allows us to re-calibrate options and consider next steps. It matters that a number of unrelated objects have been located and identified: shipping containers, an old shipwreck, and deep underwater features that assure us the effort is doing what it needed to do. Our confidence in the crews and equipment can be high. If MH370 is anywhere to be found, there or elsewhere, those crews and that equipment will find it.