1. When do I need to acquire an LGM MCC?
All MCC operators should plan to acquire a new MCC or to upgrade their current MCC to be commissioned as an operational LGM MCC by year-end 2018.
2. Does my LGM MCC require an associated MEOLUT?
No. The Council decided that an LGM MCC can be commissioned into the System without an associated MEOLUT. Such an LGM MCC will serve as a node for ground distribution of MEOSAR distress-alert data received from other MCCs, as well as data from an associated local LEOLUT or GEOLUT, if any. However, most MCC operators have elected to implement MEOLUTs associated with their LGM MCCs in order to distribute distress-alert data collected from the associated MEOLUT, as well as distributing data received from other MCCs.
3. What are the phases of MEOSAR system implementation?
The three phases of MEOSAR implementation are Early Operational Capability (EOC), Initial Operational Capability (IOC) and Full Operational Capability (FOC).
These three phases are described in Cospas-Sarsat document R.012, MEOSAR Implementation Plan (MIP), sections 10.4, 10.5 and 10.6, where the criteria for transition from one MEOSAR phase to the next are provided.
The COSPAS-SARSAT Council will decide and announce the start of each phase based on when the respective criteria have been met.
4. How will MEOSAR data be integrated into the existing LEOSAR/GEOSAR (LG) system during the EOC and IOC phases of MEOSAR?
During EOC and IOC, anticipated for the 2017-2018 time frame, LG MCCs and LGM MCCs will need to share data for processing in the operational system. This data sharing and processing will be accomplished automatically in some cases, but will require manual (human) intervention in other cases.
An LGM MCC will merge data from LEOSAR, GEOSAR and MEOSAR detections. It is expected that where there is nominal MEOSAR satellite and MEOLUT coverage available, most alerts will be detected first by the MEOSAR system with subsequent supporting data provided by the LEOSAR/GEOSAR system. LGM MCCs will send MEOSAR alerts to LG MCCs in a Cospas-Sarsat SIT 915 (text message) format. The body of the SIT 915 will contain the MEOSAR data in SIT 185 (plain text, RCC-style) format.
In the cases where LEOSAR provides the first independent-location calculation (e.g., when there are not sufficient MEOSAR facilities available in range of the beacon location for a MEOSAR location calculation) initial location with LEOSAR A and B Doppler positions could be confirmed by a later MEOSAR position received by an LGM MCC.
These SIT 915 messages, or their contents, will then be forwarded by LG MCCs to the RCC in the appropriate national formats. Note that this might require some manual intervention from the operators as some facilities may not yet be in place for SIT 915 messages to be automatically forwarded to RCCs. This process will cause some additional workload on MCC operators but is temporary until the time that all MCCs are commissioned as LGM MCCs.
5. When will the LEOSAR system be decommissioned? How much longer do I need to plan to support my LEOLUT?
At its 53rd Session, the Council noted (CSC-53/OPN/SR, section 4.2.6) the importance of sustainment of LEOSAR ground segment equipment and decided to encourage Participants, within available means, to ensure sustainment of their LEOSAR ground segment in accordance with the obligations described in their Letters of Notifications of Association with the Programme, pending future decisions of the Council related to the transition to MEOSAR FOC and the phase-out of the LEOSAR system.
Current information indicates that four of the five SARSAT satellites which currently comprise the LEOSAR space segment are currently operating beyond their expected design life: Sarsat-7 (expected end-of-life 2001), Sarsat-10 (2008), Sarsat-11 (2009) and Sarsat-12 (2012)).
However, five future LEOSAR payloads are planned for launch in the 2017 – 2021 time frame. If these plans come to fruition an operational LEOSAR space segment may be available well into the 2020s.
6. When will my LGM MCC be commissioned?
After the commissioning of the nodal USMCC and FMCC, priority will be given to the commissioning of other nodal MCCs (AUMCC, CMC, JAMCC and SPMCC), as they become ready. Nodal MCCs will commission other MCCs within their Data Distribution Region at the discretion of the Nodal MCC and, in part, will be based on the individual MCC’s readiness to be commissioned. In this context, other MCCs may be commissioned before all Nodal MCCs are commissioned.
7. Since Second Generation Beacons (SGBs) are also currently being developed, will the MEOSAR system be backward compatible with the current generation of 406-MHz distress beacons?
Yes, MEOSAR will detect and locate the current (C/S T.001-compatible) generation of 406-MHz distress beacons.
The MEOSAR system will attain FOC for the current generation of beacons no earlier than 2020. The availability of second-generation 406-MHz distress beacons (SGB), having enhanced features, is anticipated shortly after MEOSAR FOC. SGB design is optimized for the MEOSAR system and will provide improved detection and localization performance, a return link service, and enhanced data fields and functionalities (e.g., a distress-alert cancellation function).
8. Will MEOLUTs require changes to support second-generation beacons or ELTs for aircraft distress tracking (ELT-DTs) to meet new International Civil Aviation Organization requirements coming into effect in 2021?
The MEOSAR system will evolve rapidly in the next few years, with upgrades required to process the more advanced signal technology of SGBs, and the computation of an independent location for fast moving beacons (i.e., ELT-DTs activated in flight). Participants owning or preparing to procure MEOLUTs and LGM MCCs should consider including the necessary provisions for these predicted system upgrades, as well as other likely enhancements to MEOLUT and MCC specifications, as part of vendor maintenance contracts.
9. What is the expected coverage area of a MEOLUT?
A MEOLUT’s coverage area is the portion of the Earth where the MEOLUT meets its expected performance, i.e., timely beacon detection and independent location.
The Cospas-Sarsat MEOLUT Commissioning Standard (document C/S T.020) requires each Administration provide the Declared Coverage Area (DCA) in which its MEOLUT meets performance expectations that are defined in the MEOLUT Performance Specification and Design Guidelines (document C/S T.019). As defined in document C/S T.019, the DCA must be equal to or larger than the Minimum Performance Area (MPA), which is an area equivalent to a circle with a radius of at least 1,000 km from the MEOLUT. Working closely with your vendors, you should ensure that a rigorous engineering analysis is performed to verify that your MEOLUT(s) will meet the minimum performance standards for your Declared Coverage Area and that the DCA covers your area of interest.
MEOLUT performance is expected to extend beyond its Declared Coverage Area, even if not fully meeting the C/S T.019 specifications.
The size of the MEOLUT coverage area depends on many parameters, including the number and relative position of MEOSAR satellites that are both tracked by the MEOLUT and also in view of any given beacon within the coverage area. The coverage area of most MEOLUTs is anticipated to be a circle with a radius of at least 3,000 km from the MEOLUT, but this will depend on the configuration of the MEOLUT and a range of different declared coverage areas are expected.
Some assumptions to determine the MEOLUT coverage area are defined in document C/S T.019, section 5
10. How will “global coverage” for the MEOSAR system be defined?
Global coverage by MEOSAR is defined as meeting performance requirements for a beacon located anywhere on the Earth. MEOSAR relies on a methodology based on the satellites’ mutual visibility of the beacon and the MEOLUT in order to calculate a beacon’s location (i.e., there is no storage of alert signals at the satellite). Three large constellations of MEOSAR satellites will provide real-time, instantaneous relay of distress messages to MEOLUTs. However, MEOSAR also requires that there be enough MEOLUT ground stations to ensure that any point on the Earth can be seen by at least three satellites that at the same time are being tracked by a MEOLUT.
The geographic distribution of MEOLUTs necessary to achieve MEOSAR global coverage is being studied. The Council will decide on the configuration needed when the necessary studies on the subject are completed.
11. Can I plan to operate my MEOLUT in networked mode to increase its coverage area?
Yes, many administrations plan to network their respective MEOLUTs thereby significantly improving the coverage of every MEOLUT in that network. It should be noted that networking is optional and each MEOLUT first must be commissioned as a “stand alone” MEOLUT to ensure the adequacy of its capabilities to meet performance requirements if the network is unavailable.
MEOLUT networking is encouraged as it enhances system performance and supports redundancy of the Cospas-Sarsat Ground System.
12. What is the difference between a MEOSAR satellite footprint and the area in which I can expect my MEOLUT to detect and locate a beacon?
Due to their orbital altitude over the Earth (from 19,000 to 23,000 km), MEOSAR satellites have a very large footprint (i.e., the area on the Earth’s surface that can be “viewed” by a satellite). The MEOSAR satellite footprint is almost as large as the GEOSAR footprint (located at 36,000 km of altitude).
A MEOLUT will detect a beacon located within a given satellite footprint, but to calculate the beacon’s location (independent of any location information transmitted in the beacon distress message) the signal needs also to be detected by at least two other satellites, tracked by the same MEOLUT. As a first approximation, the MEOLUT coverage can be considered to be the geographical area where those visibility conditions are consistently met. However, the accuracy of the location generated will depend on many factors.
The following figure illustrates the area of mutual visibility at a given point in time between the MEOLUT, the beacon and three MEOSAR satellites:
It is important to understand that the illustration above represents MEOLUT visibility coverage at a moment in time, and that the required calculation for Declared Coverage Area (See FAQ 3.9) is more complicated, needing to account statistically for the changing geometry over time due to satellite movement over the entire DCA where beacons may be transmitting. Working closely with your vendors, you should ensure that a rigorous engineering analysis is performed to satisfy you that your MEOLUT(s) will meet the minimum performance standards for your Declared Coverage Area.
13. How many antennas (channels) does a MEOLUT need to operate properly?
In Cospas-Sarsat a “channel” is considered to be a signal path between a satellite and an Earth station that is tracking that satellite. Therefore, in conventional terms, a LUT has a number of “channels” equal to the number of antennas that it has. (“Active” or phased array antennas allow a single antenna module to track many satellites simultaneously). There is no required minimum number of MEOLUT antennas or channels stated in Cospas-Sarsat specifications. This is, in part, explained by the fact that Administrations may need coverage areas of different sizes and, therefore, placement of MEOLUTs and the number of antennas at a MEOLUT will vary according to those coverage-area needs. A general rule is the greater the number of channels, the larger the resulting coverage area. However, this is true only to a point past which each additional channel contributes an increasingly smaller addition to the coverage area. This is why it is very important to perform a careful engineering analysis not only of the number of channels, but also the placement of the MEOLUT and other considerations.
The minimum requirement that defines MEOLUT coverage is that you need to have beacon message detection from at least three satellites to calculate a 2-dimensional beacon location (latitude and longitude). Note that detection of the beacon message is needed before an independent position calculation can be performed (to locate a beacon that does not provide its position encoded in the message, or to verify an encoded location).
Even though a MEOLUT may be tracking a satellite that also has view of the beacon, it is possible that the satellite will be unable to relay the beacon message (signal obstruction by debris or other objects, inadequate radiation from the beacon antenna in the direction of that satellite, etc.). Hence, more than three satellites being tracked by the MEOLUT and having simultaneous view of the beacon may be needed to ensure that at least three satellites successfully detect the beacon message and relay the data to the MEOLUT for processing. The number of additional satellites that must be tracked (corresponding to the need for additional MEOLUT antennas to ensure relay of the beacon message from a minimum of three satellites is dependent on the statistical probability that any one satellite successfully relays the distress message.
The difference in MEOLUT coverage associated with different numbers of antennas was discussed in detail at Joint Committee 28, which concluded that:
- in general, a greater number of available antennas provides a larger coverage area,
- once a certain level is reached, increasing the number of antennas does not significantly increase the coverage area,
- for the same number of antennas, high latitude MEOLUTs provide a larger coverage area than lower latitude MEOLUTs (due to favourable satellite geometry in high latitude regions).
While this study is not the only method to define MEOLUT coverage, it can be used as an illustration of the variation in coverage as a function of the number of antennas.
14. What is my “Declared Coverage Area” and how does it affect commissioning of my MEOLUT?
Each Administration will declare the coverage area over which the performance of its MEOLUT will be tested and demonstrated during commissioning. Refer to question 9 for more details on the Declared Coverage Area (DCA).
In addition, the MEOLUT Commissioning Standard, C/S T.020, states that the MEOLUT shall be commissioned with all assets that comprise the MEOLUT. However, if the DCA assumes fewer assets, for example, fewer antenna beams, then commissioning results shall also be reported for a MEOLUT in that configuration. In this way, additional assets such as additional antennas can be considered as redundant in order to achieve the required MEOLUT availability.
Commissioning of both configurations can be done at the same time or successively, as might be required if additional assets are added later.
15. How can MCCs assist their supported SPOCs and RCCs to prepare for receipt of MEOSAR data?
It is important that MCCs liaise with their supported SPOCs and RCCs to inform them that MEOSAR data will soon be delivered operationally (see FAQ 3.2). The white paper at Attachment 1 and the Power Point presentation at Attachment 2 might be useful for this purpose.
Australia has submitted a new version of document C/S G.007, the RCC Handbook, to include the MEOSAR system. It is anticipated that the new Handbook will be issued in English shortly after anticipated Council approval at the CSC-57 Session in December 2016. ICAO will issue the Handbook in the six official languages of the United Nations (Arabic, Chinese, English, French, Russian and Spanish) to facilitate better use by RCCs and SPOCs globally.