July 21, 1999
Web posted at: 11:00 a.m. EDT

The following is an edited transcript of a chat with sonar expert John Perry Fish, who joined us from near the scene of the search for John F. Kennedy Jr.'s missing plane. CNN Interactive provided a typist for Fish, founder of American Underwater Search and Survey in North Falmouth, Massachusetts. The chat took place while the search was in progress on Monday, July 19, 1999.

Chat Moderator: Please tell us about the search operation at this time.

John Fish: The operation, the search operation, is currently deploying imaging sonar systems. These sonar systems provide a broad brush sweep of the sea floor and display an image of what's on the sea bed. The sonar is mounted in a torpedo-shaped tow body, which is towed by a surface vessel on a long wire. This puts the tow body near the sea floor and decouples it from ship motion. In order to accurately image the sea bed, the tow body must remain as stable as possible. It is towed at a height off the sea bed of about 5-10 meters, or 15-35 feet. The tow body has transducers which emit specially formed sonar beams.

Question from Nathan: Mr. Fish, what are the latest developments in the search for JFK Jr.'s plane?

John Fish: I don't have any information on the very latest developments. Currently, we are in a standby support role. We have worked in the past with the NTSB on a number of search operations, and if they require further assistance, then we are available.

Question from Nathan: Is this the same type of system used to find debris in the Flight 800 crash?

John Fish: The systems are similar with the exception that new sonar software has been developed in the time between the two accidents. This new sonar software can process data at a higher resolution and faster speeds than the previous systems. Otherwise, the equipment is essentially the same.

Question from Benjamin: How clear is this image? Can the searchers make out whether it is a plane or not using this technology?

John Fish: The image is quite clear, based on the technology used. But because the sweep covers a large area, small objects may not be as clear as larger structures. The system uses sound, rather than light, to create its images, and the physics of sound result in lower resolution imagery. If an aircraft is completely intact, such as [one] in Lake Washington in Seattle, the sonar image perfectly resembles an aircraft. That aircraft landed on the water and sank very slowly. If an aircraft has impacted the surface of the water, it is generally distorted, and no longer appears in the form of an aircraft in the sonar data. So sometimes, it is difficult to determine whether a target is part of the debris field or not.

Question from Rick: What survey swath width is being used? 100 meter? 50 meter?

John Fish: I believe they are using different swath widths and different frequencies, but 100-150 meters would make sense.

Question from What: What is the likelihood that the submerged plane is still intact?

John Fish: I really can't speculate on that at this time. I don't know.

Question from piscesgirl: Why does the search process seem like its taking forever to get anywhere?

John Fish: That's a good question. Mobilizing sub-sea search operations takes time because heavy equipment and vessels need to be moved into the search area. Also, the vessels must move at a slow, methodical pace through the search area in order to adequately cover it. This presents the appearance of taking excessive time, when in reality, it represents a methodical approach.

Question from Annie: Mr. Fish, do you believe that the bodies will be found?

John Fish: I really can't comment on that, because we don't know what the wreckage is like.

Question from GHS75: Is there generally a lot of debris in this area of the sound?

John Fish: There are approximately 18 shipwrecks, ranging from 40 feet to 300 feet in length, some as old as 1870s, some as recent as 1960s. There are also a number of boulder fields and areas of rugged bottom, but the majority of the search area is clean, flat sand.

Question from trish: Is this search taking longer because of the lack of the black box?

John Fish: Not necessarily. It is possible that the acoustic signal from data recorders could be detected more quickly than the wreckage itself. However, the acoustic signaling device on the black boxes [does] not always provide a strong enough signal to be detected.

Question from Erdem_B: What is the depth in the area you are searching?

John Fish: The depth ranges from 80 to 130 feet.

Question from any: How long will they continue the search in the event nothing is discovered?

John Fish: I think it is very unlikely that nothing will be discovered, but I can't answer the question on how long.

Question from Jessica: What are the next steps now that sonar scan is complete?

John Fish: I don't believe the sonar scan is complete. After the target is located with acoustics, sonar, it is then inspected optically, either by divers, or by remotely operated vehicles (ROVs). These will represent optical inspection of the targets. When the right debris field is located, then recovery efforts will commence.

Question from blah: Has the sonar found anything yet?

John Fish: I believe several targets have been located by sonar.

Question from Mimi: Have divers been sent in yet?

John Fish: And today, divers are inspecting the targets.

Question from canuck99: Is there more pressure among searchers to find the victims because of who they are?

John Fish: I can't comment on that. Most people who are involved in these kinds of search operations are very dedicated, regardless.

Question from lex: Is the plane most likely in many pieces?

John Fish: I really can't speculate on that until we see the debris field.

Chat Moderator: Have you taken part in the search efforts?

John Fish: No.

Chat Moderator: Will you join the search effort?

John Fish: We don't know, possibly.

Question from EFREN: Does the search continue 24 hours?

John Fish: I believe it does, yes.

Question from any: Mr. Fish, they said yesterday there were three or four targets they wanted to closer examine. ... Have these targets been successfully investigated?

John Fish: I think they were planning to do that today, and I am not sure of the status currently.

Question from tj_a^2: Has there ever been this amount of resources allocated for a search of a private plane before?

John Fish: I don't know the answer.

Chat Moderator: What is happening there now?

John Fish: The sonar search operations continue, and the U.S. naval vessel Grasp is headed to the search area today. The seas remain relatively calm. The winds are lighter than they have been for the past few days, making sonar imaging easier.

Question from What: Have you had any problems with boaters in your search area?

John Fish: I believe the Coast Guard is maintaining a radius around the search area, preventing problems with boaters.

Question from PBettio: How was the weather in the area at the time of the crash? Was weather a factor?

John Fish: As I understand it, it was hazy at dusk.

Question from Lisa: How strong are the ocean currents in the two search areas?

John Fish: The currents are tidal currents, and they run between 1 to 1.5 knots, and because they are tidal, every six hours there is a slack water period. These currents are considered to be light in sonar operations.

Question from Jeroen: In case the bodies are out of the plane, will the sonar react on them?

John Fish: Sonar typically will respond much better to metallic objects.

Question from Traci: Is there any chance they will find the bodies?

John Fish: I really can't speculate on that.

Question from Erdem: Do you use robots for deeper searches?

John Fish: Yes, we do. We use robotic technology. That was the ROV we spoke of earlier. Even for shallow searches, where a diver would have to spend excessive amounts of time underwater.

Chat Moderator: Will robots be used for this search?

John Fish: The vessels, search and recovery vessels, are equipped with robotics, and the operation will dictate what tools are used.

Question from KeithofWV: Is body recovery going to occur prior to debris recovery?

John Fish: I can't speculate on that, but that is a typical procedure, in my experience.

Question from Jerrod: Because of the debris that exists on the bottom of the ocean, is our technology good enough to make distinctions?

John Fish: The technology is good, but it is very important to have experienced operators to make that distinction.

Question from Rick: How much of the 24 square miles has been covered at least once?

John Fish: I don't know if it has all been covered at least once yet.

Question from skateon: Are the divers' lives endangered?

John Fish: No. No more than usual for this kind of diving depth.

Chat Moderator: What else can you tell us is happening in the search today?

John Fish: The weather seems as though it is going to contribute to successful search operations, and as far as I understand, they are proceeding around the clock.

Chat Moderator: Do they proceed after dark?

John Fish: That's pretty standard, diving, sonar operations will go around the clock, along with diving and ROV operations, as long as there are enough personnel for shift changes.

Question from Traci: Why did it take them almost four hours to start searching after they received the phone call?

John Fish: I'm not really in a position to answer that, except to say that I know that things have to be verified. When a call comes into the police or Coast Guard, the call has to be verified, and actually four hours is not bad. There are some missing aircraft that the search has not started for over a day.

Chat Moderator: Thank you John Perry Fish for joining us today to discuss the search for JFK Jr.'s plane.