Charles Maclin, program manager for company searching for Flight 370, describes project
He says with no more black box pings, sonar now seeks a debris field at 14,800 feet
He says if found, then Remotely Operated Vehicles will be sent down for black box search
Maclin: Waves and winds can complicate recovery, but we'll succeed
Editor's note: Charles Maclin is a retired Navy captain and program manager for Phoenix International Holdings, a Maryland search-and-salvage company looking for Malaysian Airlines Flight 370 on contract to the U.S. Navy. He was the technical director for the search for the Korean Airlines jetliner that was shot down by the Soviets off Sakhalin Island in 1983. The opinions expressed in this commentary are solely those of the author
(CNN) -- The wreckage of Malaysia Flight 370 has yet to be found, and the world has been riveted as search operations attempt to pinpoint the aircraft wreckage on the seafloor and begin to raise it.
My company, Phoenix International Holdings, was tasked by the U.S. Navy through an established multiyear contract to join the search with the Navy's Towed Pinger Locator and Phoenix's Bluefin 21 Autonomous Underwater Vehicle, which is named Artemis.
Today, Phoenix and the U.S. Navy are working aboard the Australian Defense Vessel Ocean Shield.
But once the wreckage is found, what are the phases required to successfully recover the black boxes and plane wreckage that may have come to rest at a depth of close to 15,000 feet? Here is an explainer:
Phoenix looks for missing planes in the ocean, using ships, unmanned vehicles and other technology in complex operations ranging from the surface down to 20,000 feet. Phoenix has conducted 15 aircraft recovery operations in depths greater than 5,600 feet. In 2009, the company found and recovered the wreckage of Air France Flight 447 in the mid-Atlantic, at a depth of 12,800 feet.
How are we searching for Flight 370?
The reports coming from the search teams in the Indian Ocean are encouraging, but the batteries sending pings from the flight data and cockpit voice recorders are dead by now.
We have stopped using our Towed Pinger Locator, a device towed behind a ship that does just what its name says. Now we are using Artemis at 14,800 feet, the depth at which the possible pings from Flight 370 were heard. Artemis is programmed to conduct a side-scan sonar search, looking for a debris field. If it finds one, our search team will exchange Artemis's sonar module for a camera and have Artemis run a tight grid pattern over the area, taking photos. These photos will then be converted into a detailed mosaic.
What happens next?
Underwater MH370 moves at slow pace
The search vessel will then return to port to offload the search systems and load the Remotely Operated Vehicle for the recovery. Phoenix has two ROVs, Remora II and III, that can dive to 20,000 feet. They have been used dozens of times for deep ocean-recovery operations. They have precision navigation and tracking systems, high-resolution video cameras, high-intensity LED lights and claw-like "manipulators" that allow them to operate within the debris field with precision.
While the search vessel is being prepared for the recovery phase, the investigation team will analyze the photo mosaic to identify items to be recovered.
Of course, the flight data and cockpit voice recorders are at the top of the list. Phoenix then develops a comprehensive list of rigging equipment such as baskets, slings, ROV-friendly shackles and synthetic lift lines to conduct the recovery.
How do you find the "black box"?
Because is unlikely that the voice and data recorders will be identified in the photo mosaic, the ROV is deployed to conduct a methodical visual search for the recorders. This is a slow, deliberate process.
It can take more than two hours for the ROV just to reach the bottom, and four hours or more to bring debris to the surface. Recorders may be buried in the seabed or covered by debris. They are also hard to find because other items on an airplane can look a lot like them, especially when seen from a distance on a video screen.
In the Air France operation, which stretched for nearly two years, it took six days from the time of discovery of the wreckage field to recover the flight data and cockpit voice recorders.
Then what happens?
The next phase is the recovery of additional wreckage. During the Air France recovery, Phoenix recovered both engines, the forward landing gear, the electronics bay, cockpit fuselage section, seats, angle-of-attack sensors, numerous computers, the Jack screw and human remains. Phoenix search and recovery experts, using our Remora ROV, have developed many techniques for recovering critical items. Recovering human remains, of course, requires additional considerations and special treatment.
Of course, many other factors affect recovery. These include the depth of the wreckage, and the weight of the objects being retrieved, as these dictate the type and strength of the lift lines used; the capacity of the lifting equipment; and the kind of "motion compensation" equipment required to support items as they are lifted through the sea-air interface. Motion compensated gear offsets the forces generated by a rocking ship that may cause recovery lines to snap and drop the item being lifted.
Phoenix has been doing this sort of work for nearly two decades and has significant success in deep ocean recovery operations. But despite our well-rehearsed approach, every such operation has its own set of unique challenges, and Malaysia Airlines Flight 370 is no different.
Working at great depths, in an extremely remote part of the world, with the potential for heavy seas and high winds, will make this recovery operation as difficult as any we've faced.
Even with these challenges, we are confident that, once the wreckage is found, we will succeed in the task of recovering the black boxes from Flight 370.