Libations Too
New member
Rob,
My suggestion is if you really want to run down the value of the PLB, have a conversation with the USCG SAR group and find out what their experience has been. That would be really helpful to the folks here on the board.
- rob
OK...this has taken longer than I thought but here is what I have found. It's a pretty long answer. Please do not shoot the messenger!
I spent a lot of time searching the internet and I spoke directly with:
• Lt JG Steven Barry who is a Watch Supervisor at USCG Sector San Francisco, California. Steve's personal recommendation for the singlehanded sailor was to carry both a handheld VHF and a PLB; the Command Level recommendation is for a Category 1 (self activating) EPIRB for the boat.
• Lt Tim Martin and Lt Kevin Sullivan at the USCG District 11 Rescue Coordination Center at Alameda, California. Kevin is a sailor and recommended both a PLB and a handheld VHF radio for "on-my-person" safety gear...and if he had to choose one over the other he recommended the PLB.
•Chief of Operations Sam Baker at US Mission Control Center for the COSPAS-SARSAT system in Suitland, Maryland. (Sam is a sailor and is owner of a C&C 37/40+ that he sails mostly on the Chesapeake Bay. His recommendations in order of preference were (1) a Category 1 (self activating) EPIRB for the boat stored outside the cabin, (2) a PLB "on-your person", or perhaps (3) a handheld VHF "on-your person" if the local Rescue 21 system was operational and sailing location/conditions supported line-of-sight communication).
My summary answsers to a few questions:
What time delay might be associated with the launch of a SAR effort if the sole source of distress information was obtained from a PLB or EPIRB? The answer appears to rest primarily with the quality of the initial beacon signal, the type of position data that is associated with the initial signal, and how long it takes to remove ambiguities associated with the position data or to evaluate those ambiguities at the RCC level. The elapsed time from beacon activation until the alert message is received by the local Rescue Coordination Center is no more than about 2 minutes for beacons activated between 70 S latitude and 70 N latitude...with essentially all of the steps automated.
Clearly the best scenario would be one where the PLB/EPIRB signal was received without error at the U.S. Mission Control Center for satellite-based search and rescue operations, where the signal included encoded location data (from an integral or companion GPS), and where the Rescue Coordination Center (local to the distress event) was able to make immediate contacts (based on the PLB/EPIRB registration form) to confirm that the situation was not an accidental activation of the EPIRB/PLB. In this best scenario a launch of SAR efforts might begin within as little as a few minutes from the time the PLB/EPIRB activation (assuming a location within the Gulf of Farallones). The goal for Sector San Francisco is to launch a SAR effort in no more than 30 minutes from receipt of an alert message from the RCC.
The worst scenario for a PLB/EPIRB rescue would be one where the digital signal was not clear, where location data was incomplete or ambiguous (less than 20% probability of accuracy), and where no EPIRB/PLB registration information was available. In cold northern California waters such a situation may delay a SAR launch until it is too late for the person in the water (MY OPINION ONLY). Where GPS data is not encoded in the beacon signal (no integral or companion GPS) determining beacon location is by Doppler techniques from low-altitude earth orbit satellites...and it could take up to an hour for the first satellite to pass over the beacon.
I'll admit that I was hoping for more precise information regarding the delay that can be associated with validation and evaluation of a PLB/EPIRB signal, but due to the number of variables it is just not possible. What was good to understand is that the first several steps (from beacon to satellite, from satellite to Local User Terminal, from Local User Terminal to Mission Control Center, and from Mission Control Center to local Rescue Coordination Center) are all automated and no human intervention is required. Evaluation at the local Rescue Coordination Center takes many issues into consideration and is where many of the variables come into play that can cause delay.
Are the expected delays different for a PLB than for an EPIRB? The direct answer is simply no. There is nothing about a good signal from a PLB when compared to that of an EPIRB, or the stated procedures within the COSPAS-SARSAT system or within the USCG that would cause a delayed response in launching a SAR effort simply due to signal originating from a PLB. However, where the signal does not contain location data, the alert will go to the Air Force Rescue Coordination Center in Florida that is responsible for handling all U.S. land-based rescue efforts. As soon as location data are available, and if those location data show a coastal or offshore location, the USCG will also receive an automated message from the Mission Control Center.
A more qualified answer would focus on things like antenna performance, antenna position, battery life, etc. But for a person in the water due to a MOB situation (where an EPIRB is simply not available) these distinctions make little difference. Where the situation is associated with a disabled (but floating) vessel or where people are in a life raft or other emergency vessel the advantages of antenna performance, antenna position, battery life, etc. are arguably more important and an EPIRB would be the clear better choice.
Can a response to a PLB/EPIRB be fast enough to effect rescue in cold northern California waters? This question is focused on a situation where the person is in the water...and the boat has sailed on. The answer to this too is subject to many variables, some of which were mentioned in my answers to questions above related to delays. Other variables relate to the person in the water, their degree of fitness, personal body characteristics, etc. The simple answer, somewhat confirmed by personal preferences expressed by the people with whom I spoke, suggest that the answer is definitely yes. This is where the initial signal contains good location information and where the PLB/EPIRB registration is clear about where and how the beacon might be used. For example, if using a PLB the registration form should definitely indicate that it is being used as an item of safety gear on a boat or on a PFD. This will alert the RCC that even though many PLBs are used on land that this one in particular is most often used at sea. Such clarity of information on the PLB registration form can be very important to minimizing the "evaluation" delay at the Rescue Coordination Center.
What about a handheld VHF radio? A handheld radio is subject to line-of-sight transmissions. If the radio can make a line-of-sight connection to a USCG receiving antenna then it can be effective in sending a MAYDAY distress call. According to USCG District 11 Rescue Coordination Center the Bay Area system can pick up a 1-watt transmission at a 1-foot elevation 20 miles offshore. I was impressed with this information. The positive aspect of the VHF radio is that as the person in the water, you can have direct communication with the USCG, which can also be important when rescue personnel arrive. And you may also be heard by a nearby vessel that can come to your immediate assistance.
The potential downside to the VHF radio is that while allowing direct communication it does not by itself (at the moment) help with providing the USCG with reliable position data. What this means is that the person in the water must have a very good situational awareness and be able to describe their position to the USCG radio station operator. This in turn must be translated into lat/lon coordinates or passed on as a narrative description of location. Obviously the effectiveness of this activity depends on the skill and situational awareness of the person in the water. Similarly, the sea state, the affect of wind in the microphone, and the ability of the person in the water to speak clearly and maintain communication may be a factor in establishing and maintaining contact with the USCG or another radio operator.
By about mid 2010 the Rescue 21 system should be operational here in the Bay Area. This system provides upgraded VHF receiving equipment that will improve the ability of the USCG to locate people based solely on the VHF radio distress transmission. Though not operational at this time in this area, the operational history in other locations suggests that if a signal is received by a single receiving tower that a Line-of-Position can be determined within +/- 2 degrees from the tower. If multiple towers receive the signal, then a near fix is possible. This will greatly enhance the ability of the USCG to evaluate and launch a SAR based solely on a VHF radio transmission.
Similar to the Rescue 21 system in its effectiveness is the DSC system that is currently operational with VHF radios. Currently I am aware of only one manufacturer of handheld DSC radios (Standard Horizon HX850S) but others may be available too. The DSC radio embeds a GPS fix with a VHF burst that is automatically recognized as a distress call. When speaking with the USCG District 11 staff, I was left with the impression that such equipment, if properly set up, could greatly facilitate the "evaluation" effort at the local Rescue Coordination Center.
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