Last February, Public Safety divers in New York evaluated the use of Harris Acoustic Products Hand Held Sonars, both the DLS-1 and the new DLS-3 Explorer, in under ice operations.
The DLS-3 Explorer is based upon the very successful Harris DLS-1 sonar with features and capabilities designed specifically for public safety divers.
Harris worked with State, County, and Municipal police organizations during diving exercises to get their inputs as to what will make an effective sonar that will meet the needs of Public Safety divers for both police work and Homeland Security tasks. The DLS-3 Explorer is the result of those cooperative efforts.
Since Public Safety divers never know when they will be called upon to search for evidence or to retrieve a drowning victim, they must train for deployment under all conditions. The New York State Police Scuba team conducts an annual winter under ice training exercise at Lake George, New York. The lake at that time of year is generally covered by at least 8 to 10 inches of solid ice.
The primary concern when diving under any conditions is personnel safety. This is particularly important when a diver is blocked from reaching breathable air by solid ice. One of the scenarios that the police divers train for is to find and lead to safety an under ice diver that has become separated from his tether. The standard response by a diver that loses his safety line is to ascend to the under ice surface and to stay put. He will wait for a rescue diver to find him.
A rescue diver is always standing by, ready to enter the water as soon as there is trouble. The line securing the rescue diver to his tender is longer than the line used by the lost diver. Theoretically, if the rescue diver swims out to the end of his line away from the last know position of the lost diver, and then swims in a circular path back toward the lost diver, the rescue diver’s line should come in contact with the stationary lost diver. All of this takes time. There is also a risk that the rescue line will miss and the procedure must be repeated, taking even more time.
Time is of the essence because this is one of the few instances of underwater recovery when a rescue is possible. To be able to rescue a lost diver rather than recover a drowning victim puts a lot of pressure on the scuba team to act quickly but safely. The State Police wanted to try a new technique using our hand held sonars to locate an under ice diver and then to swim directly to him.
To test this technique, they had a diver immersed in the water through a small ice hole about 80 feet away from the main access point.
Teams of two divers then took turns finding the “lost diver” using the traditional swim out and swing an arc technique.
Although the water was relatively clear, they had to be well within 10 feet of the diver before they were able to see him. Because of the low visibility, the rescue teams never saw the “lost diver” but had to depend upon their safety tether catching the diver.
After performing the standard method, the divers received a Harris DLS-1 Hand Held Sonar. The New York State Police have been using the DLS-1 sonars since they purchased four of them in March 1998.
They originally became exposed to our sonars when they were called in to help recover victims and debris from the crash of TWA 800 off Long Island, New York in July 1996. The US Navy divers that were supporting that effort brought AN/PQS-2A sonars with them that they shared with the police. The AN/PQS-2A sonar is the military standard for diver assisted mine hunting and is what our DLS-1 is based on. Harris helped develop the AN/PQS-2A with the Navy and built a large number of them on the first production contract. We also loaned the TWA 800 dive teams four of our DLS-1 sonars for the duration of the recovery.
At Lake George, the rescue diver with the DLS-1 submerged at the entry hole until he and the sonar were beneath the thick ice. He then slowly swung the sonar through an arc of about 120º. All of the other divers and myself were surrounding the access hole and were anxiously waiting to see if the sonar could detect the “lost diver”. The rescuer only had a rough idea of the direction to the “lost diver”. After making just one sweep with the sonar, he took off on a beeline toward him. The bright yellow safety line trailing behind the rescue diver pointed straight as an arrow, confirming a positive detection and successful “rescue”.
After a number of standard and sonar assisted “rescues” with different dive teams, it became exceptionally clear that using sonar was a much faster way to get right to a “lost diver”. On more than one occasion the rescuers swam right into the “victim” as they followed the clear sonar signals.
After confirming that the DLS-1 sonars created a significant time advantage over the old method, the teams tried the DLS-3 Explorer hand held sonar. This is the first time it was used under such rigorous conditions. It operated perfectly. Everyone using the DLS-3 found the “lost diver”, in some instances in less than a minute after submerging. The smaller size and reduced weight and buoyancy of the DLS-3 made it easier to use. Its simplified controls made it easier to operate in the dim, shadowy under ice environment.
The Harris Acoustic Products’ sonars worked very well under these adverse conditions and will be incorporated into the New York State Police under ice protocols. Hopefully some day they will be able to assist in the rescue of a diver that otherwise might be lost.