Zion National Park Search & Rescue PLB Test Kevin Killian Park Ranger/SAR Coordinator Zion National Park Introduction In 2006, following the line of duty death of park ranger Jeff Christensen in Rocky Mountain National Park, the National Park Service directed all parks to supply all employees entering the backcountry proper safety equipment to provide for communication. One way that NPS units have met this mandate, especially in areas where radio communications are poor or non-existent, is through the use of Personal Locator Beacons (PLBs). Zion National Park requires that all employees working in the backcountry in areas with poor radio access carry a functioning PLB. Zion National Park contains some of the most spectacular and rugged terrain in North America, the majority of which is open to and regularly accessed by the visiting public. Of specific note are the world-renowned slot canyons which draw visitors of varying levels of fitness and skill from across the globe. Some of these canyons are easily reached by hikers without special gear or skills, but many are inaccessible except through the use of ropes and climbing techniques such as rappelling, scrambling and anchor building. In addition to visitors, park employees often enter these canyons as part of their regular duties, including patrols, wildlife monitoring, and vegetation surveys. The park s radio system, while functional and modern, does not provide full communication capability in the vast majority of these difficult to access areas. The most commonly available PLB units are manufactured by ACR Electronics; other units are available from McMurdo and NAT. Both use similar technology, including GPS capability. There have been doubts as to the efficacy of the PLB technology in the deep, narrow slot canyons of Zion National Park. An ACR PLB was tested in various commonly accessed backcountry areas throughout the park in an effort to determine if a PLB is the proper tool to use to carry out the NPS mandate for personnel safety in the backcountry of Zion National Park. SAR Satellite System Overview The SAR satellite system involves geosynchronous Earth orbit (same rotational speed as the planet, aka GEOs) and low Earth orbit (faster rotational speed, aka LEOs) satellites. When a PLB is activated, it sends out a 406 MHz signal which includes the identification number of the unit. The satellites pick up the 406 MHz signal of the activated PLB and send it to ground stations (5 in the United States). The ground stations notify the Mission Control Center (MCC), operated by NOAA, which filters the data and sends all new signals to the Air Force Rescue Command Center (AFRCC). The AFRCC in turn makes notifications to the state or agency having jurisdiction (AHJ) over the signal s actual or suspected location. The GEOs detect the signal (and attached registration data) but are unable to give positional data unless a GPS signal is attached to the burst. In most cases, if the beacon is GPS enabled, the second or third signal sent to the GEO will have GPS coordinates attached to it. In the absence of GPS data, the registration data is the only means the AFRCC has to determine who to notify due to a lack of position fixing ability of the GEO satellites. The delay in attaching GPS data to the signal is a factor of the ability of the onboard or externally attached GPS unit to fix its location. In many areas with limited or no sky view, the GPS may not function and GPS data will not be transmitted. The LEOs, passing overhead in the US an average of every 90 minutes at varying angles of approach, detect the 406 MHz signal as well. Due to the travelling nature of these satellites, they are able to transmit positional data through interpretation of Doppler shift (frequency changes based on the satellite s position relative to the source). Based on this information, in the absence of GPS burst data, AFRCC is able to identify a general location of the beacon and identify the AHJ responsible for responding to the beacon alert. 1
During this test period, the UIN (Hexadecimal Identifier) of the PLB that was used was identified by NOAA as being specifically for testing purposes. The satellites picked up this signal as if it were any other beacon, processed the signal as normal and reported the data to the NOAA MCC. The Test Procedures Starting on July 1, 2008 a PLB test was conducted using an ACR ResQfix 406 MHz personal locator beacon, UIN: 2DDC 54E558 FFBFF. This PLB was supplied by the manufacturer and specifically programmed for this test with the standard 406 MHz SARSAT/COSPAS frequency and a 121.775 MHz test homing frequency. The tests were conducted in the following areas of Zion National Park: Date Area Descriptor Lat/Lon 1. 7/1/08 Zion EOC Upper parking lot N 37 12.5 W 112 58.9 2. 7/2/08 West Rim Campsite #8 N 37 19.2 W 112 59.1 3. 7/3/08 Orderville Canyon 1 st obstacle N 37 18.5 W 112 56.6 4. 7/4/08 Zion Narrows, Deep Ck. Deep Creek confluence N 37 21.5 W 112 57.1 5. 7/7/08 Pine Creek Canyon The Cathedral N 37 12.8 W 112 56.6 6. 7/8/08 Hidden Canyon ¼ mile up canyon from the mouth N 37 15.9 W 112 56.3 7. 7/11/08 Keyhole Canyon Between rappels #1 and #2 N 37 13.6 W 112 54.2 8. 7/17/08 Zion Narrows, Wall St. Wall Street area N 37 18.6 W 112 57.0 9. 7/19/08 Subway Up canyon from the last rappel N 37 18.5 W 113 03.1 10. 7/20/08 Clear Creek South facing alcove, 22 hrs N 37 12.9 W 112 56.2 Using satellite predictions provided by NOAA, I chose the best time of day to run the test based on maximizing the number of SARSAT satellites that would be providing a footprint of coverage over the test area while considering the length of time it would take participants to reach the test location, conduct the test and return to Park Headquarters within daylight hours. When the tests were conducted, the unit was delivered to the test area, placed stationary on the ground with GPS antenna facing skyward and activated for a predetermined period of time, generally not exceeding 2 hours. Park employees participating in this test were generally out of radio contact during the beacon activation period. Prior to starting the day s test, all participants received the day s test plan and synchronized their watches with the dispatch radio console. Prior to starting each day s test, I advised NOAA of the test location and the planned test times. Blair Boyd in the NOAA MCC compiled the satellite hit data and faxed it to me at the conclusion of the day s test. He also served as an invaluable resource in deciphering the satellite predictions and explaining the science behind the process. At the conclusion of each day s test I sorted through the data received and compared it to the satellite predictions and the actual location of the beacon. When the beacon was able to transmit encoded GPS data, the location given on the NOAA report was indicated by an E solution meaning encoded data was present. When the beacon was not transmitting encoded GPS data, the location on the report was typically given as a pairing of A and B solutions with corresponding probabilities for each. This pairing resulted from the satellite s inability to fix the beacon s location with certainty based on the science of Doppler shift resolution. In the satellite hit reports, NOAA referred to a location as being ambiguous when low probabilities existed and resolved when the computers reached a relative certainty in the determination of the beacon s location. For reasons not clear to me, some resolved locations were quite far from the encoded GPS locations reported by the beacon in tests #1 and #2. For purposes of consistency, I mapped the resolved locations reported by NOAA regardless of the presence of encoded GPS data. Data points were mapped using TOPO! 4.0 software showing the actual beacon location and positions resolved through Doppler shift or encoded GPS data. Each hit was given a letter code corresponding to the order in which it was received. All tests were mapped individually; the maps are included at the end of this report. 2
The Tests Each test is summarized and followed by a data table. All times are reported in GMT. #1 Zion EOC This test was conducted as a control to determine whether or not the beacon actually worked, what our reported data would look like and how accurate the satellite predictions were. The beacon was placed on a rock in the parking lot of the Zion NP Emergency Operations Center and activated for just under 3 hours; this location had an unobstructed view of the sky. The beacon worked as expected, the satellite predictions were accurate, and the data delivered by NOAA was timely and, with some explanation, understandable. The results showed that a GEO satellite received the first alert at 1658 (simultaneous with PLB activation) and an encoded alert (with GPS data) at 1703. The GPS data transmitted was accurate. Additional alerts were received by LEO satellites at their time of closest approach (TCA). A finding of note in this test was the effect of various satellite angles on the ability of the satellite to detect the PLB signal. Angles of 55 and 44 allowed for reasonable Doppler shift resolution; an angle of 19 allowed for an encoded signal to be received but no Doppler shift resolution; an angle of 6 resulted in a non-detection pass. Resolved positions given in hit codes 1C and 1D plotted out.25 miles south of the true beacon location. Test Location: Zion EOC Location Code: 1 Test Date: July 1, 2008 Test on: 1658 Test off: 1952 PLB Coordinates: 37 12.5 N 112 58.9 W G12 1658 Beacon detected, no position data reported G12 1703 37 12.4 N 112 59.1 W 1A Position data from PLB GPS G12 1724 37 12.5 N 112 58.9 W 1B Position data from PLB GPS S11 1751 37 12.4 N 112 59.0 W 1C 55 Resolved by GPS, Doppler position 37 12.1 113 00.1 S9 1821 37 12.4 N 112 59.0 W 1D 44 Resolved by GPS, Doppler position 37 12.4 112 59.3 S10 1926 37 15.0 N 113 00.0 W 1E 19 Position data from PLB GPS, no doppler reported S11 1930 6 Beacon not detected #2 West Rim This test was conducted in a commonly used backcountry campsite with an unobstructed view of the sky. The beacon was activated for 1 hour and results were similar to test #1 in that an alert simultaneous with activation was received by a GEO with no position data, followed 5 minutes later by an encoded alert with accurate GPS position data. Subsequent LEO alerts from satellites were received with both encoded position data and Doppler shift data. Resolved positions given in hit codes 2B, 2C and 2D plotted out 1 to 1.5 miles west of the true beacon location. Test Location: West Rim Location Code: 2 Test Date: July 2, 2008 Test on: 1844 Test off: 1944 PLB Coordinates: 37 19.2 N 112 59.1 W G11 1845 Beacon detected, no position data reported G11 1850 37 19.2 N 112 59.2 W 2A Position data from PLB GPS S11 1910 37 19.1 N 113 00.1 W 2B 10 Resolved by GPS, Doppler position 37 18.3 113 05.6 S10 1914 37 19.5 N 113 00.0 W 2C 16 Resolved by GPS, Doppler position 37 22.2 112 59.3 S9 1937 37 18.6 N 113 00.6 W 2D 8 Resolved by GPS, Doppler position 37 11.2 113 05.8 3
#3 Orderville Canyon This test was conducted in a popular, easily accessed slot canyon which also happens to be the location of numerous injuries and rescues through the years. At the test location the E-W running canyon provided a partial sky view. The beacon was activated for 2 hours, no GEO alerts were received but 2 LEO alerts were. No GPS data was transmitted (GPS units generally do not work in the canyons) but one LEO was able to generate an ambiguous Doppler location (via a 68 pass) approximately 3 miles east of the true beacon location. Two LEO passes of 17 and 12 went undetected. Test Location: Orderville Canyon Location Code: 3 Test Date: July 3, 2008 Test on: 1709 Test off: 1909 PLB Coordinates: 37 18.5 N 112 56.6 W S11 1709 61 Beacon detected, no position data reported S9 1735 37 18.1 N 112 53.2 W 3A 68 Beacon detected, ambiguous position data (70%) S11 1849 17 Beacon not detected S10 1904 12 Beacon not detected #4 Zion Narrows, Deep Creek This test was conducted in the famous Zion Narrows, characterized by canyon walls which tower over 1,000 feet high. The canyon floor is in some places less than 50 feet wide. There is a partial sky view and the canyon runs generally N-S at this location. The test was conducted for 2 hours; no GEO or LEO hits were recorded. Missed LEO passes were at 14 and 11. Test Location: Zion Narrows, Deep Creek Location Code: 4 Test Date: July 4, 2008 Test on: 2358 Test off: 0159 PLB Coordinates: 37 21.5 N 112 57.1 W S7 0129 14 Beacon not detected S8 0133 11 Beacon not detected #5 Pine Creek Canyon This test was conducted in one of Zion s most heavily used slot canyons. The beacon was placed in the cathedral, a large room within this canyon that has been naturally carved out of the sandstone walls; there is no sky view and the canyon runs generally N-S at this location. The test was conducted for just over 2 hours; no GEO hits were recorded, one LEO hit was recorded (88 ) with no GPS or Doppler location data determined. Missed LEO passes occurred at 80, 3, 11 and 13. Test Location: Pine Creek Canyon Location Code: 5 Test Date: July 7, 2008 Test on: 1718 Test off: 1932 PLB Coordinates: 37 12.8 N 112 56.6 W S11 1728 88 Beacon detected, no position data reported S9 1742 80 Beacon not detected S10 1823 3 Beacon not detected S11 1906 11 Beacon not detected S9 1922 13 Beacon not detected 4
#6 Hidden Canyon Hidden Canyon is a popular non-technical canyon day hiking destination. This test was conducted where many rescues have occurred in the past, an area with a partial sky view in a N-S running canyon. 2 hours and 15 minutes of testing resulted in no GEO hits and one LEO hit at 56 with no GPS data. From this pass, an ambiguous Doppler position was determined which plotted out approximately 2 miles east of the true beacon location. Missed LEO passes occurred at 48, 1, 18 and 20. Test Location: Hidden Canyon Location Code: 6 Test Date: July 8, 2008 Test on: 1656 Test off: 1910 PLB Coordinates: 37 15.9 N 112 56.3 W S11 1707 37 15.9 N 112 54.4 W 6A 56 Beacon detected, ambiguous position data (77%) S9 1719 48 Beacon not detected S10 1813 1 Beacon not detected S11 1846 18 Beacon not detected S9 1859 20 Beacon not detected #7 Keyhole Canyon Keyhole Canyon is another of Zion s popular narrow and dark slot canyon destinations. This test was conducted for just over 2 hours in an area with no sky view in an E-W canyon. No GEO hits were recorded; one LEO detection (no GPS) with an ambiguous Doppler position approximately 3 miles east of the true beacon location was recorded on a pass of 64. Four other LEO passes were undetected with angles of 87, 18, 7 and 11. Test Location: Keyhole Canyon Location Code: 7 Test Date: July 11, 2008 Test on: 1730 Test off: 1939 PLB Coordinates: 37 13.6 N 112 54.2 W S11 1744 37 14.0 N 112 49.7 W 7A 64 Beacon detected, ambiguous position data (50%) S9 1750 87 Beacon not detected S10 1921 18 Beacon not detected S11 1923 7 Beacon not detected S9 1929 11 Beacon not detected #8 Zion Narrows, Wall Street This Narrows test was conducted in a similar location to #4 (high canyon walls with a partial sky view in a generally N-S canyon). Due to operator error, no accurate time frame can be determined for when the test was actually started and stopped. There were no GEO hits; one LEO hit was recorded at 77 with no GPS and an ambiguous Doppler position approximately 6 miles east of the true beacon location. Test Location: Zion Narrows, Wall Street Location Code: 8 Test Date: July 17, 2008 Test on:??? Test off:??? PLB Coordinates: 37 18.6 N 112 57.0 W S11 1720 37 16.8 N 112 52.9 W 8A 77 Beacon detected, ambiguous position data (50%) ***Note: Due to operator error, no accurate test time frame can be determined. All that is known about this test is that no other alerts were reported this day. 5
#9 Subway This test was run for around 35 minutes in a canyon with a partial sky view which runs NE-SW. No GEO hits were recorded, 2 LEO hits were recorded with no GPS data and Doppler positions ranging from 1-2 miles SW of the true beacon location. Test Location: Subway Location Code: 9 Test Date: July 19, 2008 Test on: 1754 Test off: 1829 PLB Coordinates: 37 18.5 N 113 03.1 W S9 1804 37 17.0 N 113 04.5 W 9A 31 Beacon detected, ambiguous position data (50%) S11 1819 37 18.0 N 113 04.6 W 9B 25 Beacon detected, ambiguity resolved #10 Clear Creek This test was conducted in a shallow slot canyon with the PLB located in an alcove with a partial sky view in a generally E-W running canyon. The test was run for 22 hours in a place where no GPS signal was received in an effort to determine the capabilities of the satellite Doppler locating system given multiple passes in which to resolve a beacon location. No GEO hits were recorded; out of 26 LEO passes, 10 hits were recorded. Initial Doppler positions were in excess of 10 miles W of the true beacon location. Over time, the system was able to resolve the position to less than 2 miles from the true beacon location. Successful hits occurred at angles greater than 25, missed passes occurred at lesser angles. Test Location: Clear Creek Location Code: 10 Test Date: July 20-21, 2008 Test on: 2245 Test off: 2052 PLB Coordinates: 37 12.9 N 112 56.2 W S10 2249 3 Beacon not detected S8 0004 37 11.4 N 113 03.5 W 10A 80 Beacon detected, ambiguous position data (77%) S7 0006 37 12.1 N 113 06.7 W 10B 87 Beacon detected, ambiguity resolved S8 0146 8 Beacon not detected S7 0147 8 Beacon not detected S9 0321 12 Beacon not detected S11 0338 37 13.3 N 113 02.5 W 10C 27 Beacon detected, ambiguity resolved S9 0500 37 12.8 N 113 03.2 W 10D 82 Beacon detected, ambiguity resolved S11 0518 37 13.2 N 113 01.2 W 10E 35 Beacon detected, ambiguity resolved S9 0640 7 Beacon not detected S10 0751 9 Beacon not detected S10 0932 37 13.0 N 112 59.9 W 10F 84 Beacon detected, ambiguity resolved S7 1043 1 Beacon not detected S8 1047 3 Beacon not detected S10 1112 13 Beacon not detected S7 1224 37 12.9 N 112 59.1 W 10G 44 Beacon detected, ambiguity resolved S8 1228 37 12.8 N 112 58.7 W 10H 52 Beacon detected, ambiguity resolved S7 1404 22 Beacon not detected S8 1409 20 Beacon not detected S9 1537 2 Beacon not detected S11 1557 12 Beacon not detected S9 1718 37 12.7 N 112 58.1 W 10I 47 Beacon detected, ambiguity resolved S11 1738 37 12.7 N 112 58.3 W 10J 74 Beacon detected, ambiguity resolved S9 1857 21 Beacon not detected S10 1917 16 Beacon not detected S11 1917 9 Beacon not detected 6
Summary of Results The results of these tests can be looked at in several ways. From the standpoint of the visitor to Zion NP, the results could appear to be discouraging in that the PLB failed to report precise position data to the satellites in many of the test locations. When individuals put their trust in a piece of equipment to notify rescue personnel of their predicament, they would naturally hope that the notification would be followed quickly by a rescue. In the case of Zion s slot canyons, however, this would not be the case. The initial notification to the AFRCC of the PLB s activation would seem to be likely within an hour or so of activation; the actual pinpointing of the victim s location is a bit more problematic. The park s recommendation to visitors with PLBs, based on the findings of this test, is that they should strictly adhere to the practice of letting others (preferably those who are listed as emergency contacts on the PLB registration) know their itinerary. Additionally, while compliance with the park s permit system is mandatory, visitors are encouraged to take full advantage of its usefulness as a secondary means of tracking in case of emergency. Having the PLB holder s name on the permit so a computerized search will produce helpful results, a complete and accurate accounting of vehicle descriptions, and a specific itinerary including trailheads and parking areas utilized are all ways to increase the probability of a timely rescue should the need arise. For the park employees utilizing this technology, however, the prospects are a bit brighter. Per park policy, all backcountry trips must be accompanied by a trip plan filed with the communication center. This trip plan must list all individuals on the trip and indicate the trip s start time, route and planned end time. Additionally, if a PLB is required, the identification number of that PLB is listed; the communication center is identified as the emergency contact for all units owned by the park. In case of an activation of a park PLB, the initial notification of PLB activation will come to the communication center. The trip plan associated with that PLB will be consulted and the planned route identified, resulting in a high probability victim location within minutes of notification which provides the opportunity for a SAR to be initiated immediately. The drawback to both scenarios, however, is that active participation in one s own rescue is required; a solo traveler who becomes incapacitated will not necessarily be able to activate their own PLB. A way to increase the probability that the notification chain will remain intact is to require minimum 2 person patrols and the presence of at least 2 PLBs per group when traveling in areas of high objective risk in case the person carrying the PLB gets physically separated from the rest of the party. Park management may dictate the minimum number of participants in work sponsored trips but cannot do the same for visitor groups. Park visitors who are venturing into similarly high risk areas should take this factor under advisement when planning their adventures in Zion NP. Acknowledgements This test would not have been possible without the assistance and support of the following individuals: Blair Boyd, NOAA MCC Ron Crowder, ACR Electronics The staff of Zion National Park My editor and wife, Jill 7
Test #1 Zion EOC
Test #2 West Rim
Test #3 Orderville Canyon
Test #4 Zion Narrows, Deep Creek
Test #5 Pine Creek Canyon
Test #6 Hidden Canyon
Test #7 Keyhole Canyon
Test #8 Zion Narrows, Wall Street
Test #9 Subway
Test #10 Clear Creek