Wings Magazine

The 406 saga round three

As the song goes – “Let’s start at the very beginning. A very good place to start.”

September 25, 2008  By Rob Seaman

As the song goes – “Let’s start at the very beginning. A very good place to start.”
So here goes…..

The monitoring system for ELTs air, marine, land is called COSPAS-SARSAT. This system dates back to the 1980s and was a partnership between Canada, France, USA, and the USSR. Back then, it served primarily analog radio beacons operating on 121.5 MHz and related frequencies (e.g. 243 MHz). The ELTs of that time pre-dated the satellite system and were originally designed in the 1950s for military aircraft. Since the commissioning of the COSPAS-SARSAT system, technological advancements have been continuously incorporated to improve its reliability and functionality. That said with time all things change. The digitally-encoded beacons operating on 406 MHz today are now the system standard. They offer rapid, reliable, and accurate position information coupled with the ability to identify the specific vessel, aircraft, or personal location beacon that it is registered to. According to Carole Smith of the National Search and Rescue Secretariat, “the basic tenet of the 406 MHz technology is to take the ‘search’ out of ‘search and rescue’.”

The International Civil Aviation Organization (ICAO) and the International Maritime Organization (IMO) mandate safety requirements for aircraft and maritime vessels, and work closely with the COSPAS-SARSAT program. According to the background provided by Smith, back in the late 1990s these organizations recognized the limitations of the 121.5 MHz beacons and the superior capabilities of the 406 MHz alerting system. Accordingly a recommendation was tabled to COSPAS-SARSAT that a system-wide transition be made.

Since space technology must be designed, tested, and scheduled for production years before its proposed launch, the COSPAS-SARAT Council recognized that a firm phase-out date for 121.5/243 MHz satellite processing had to be established.  This would enable countries to commit resources to the present and future health of the 406 MHz system, while ensuring adequate provisions were made for 121.5/243 MHz coverage up to the transition date.  The users of the system would also have an opportunity to re-equip themselves for the change.  In October 2000, following detailed deliberations, the COSPAS-SARSAT Council made the decision to cease satellite processing of 121.5/243 MHz signals by February 1, 2009.   This decision was reaffirmed by the Council in October 2006.


Smith says that as a result of this decision, a number of participating countries have enacted policy and legislation in support of the transition to 406 MHz, and have invested millions in redesigning COSPAS-SARSAT satellite payloads and ground station infrastructure. She notes that Canada has also made a commitment to participate in the next-generation 406 MHz satellite system – the Medium Earth Orbit or MEOSAR constellation — including a significant investment in space and ground segment technology. These satellites offer the best of both worlds – large footprints, global coverage, and position calculations that will not rely on Doppler processing

In Canada, marine emergency position-indicating radio beacons (EPIRBs) and personal locator beacons used on land (PLBs) have already switched to a primary frequency of 406 MHz. So the aviation community is the last hold-out to embrace the technology change.

So now we know why this change is necessary. The problem is that change never seems to come easily to some – especially when it’s mandated, and requires an outlay of money to make it happen. But then there are some things in life that you just cannot fight. The mandating of safety equipment in transportation systems is frankly one of them.

Opinions and passions aside, there are some simple facts that really should be considered here. First – as you can see – this is not a new or issue, nor one that is uniquely Canadian. It is in fact an international decision that dates back in the late 90s – so it is by no means new. No surprise here folks! We all knew it was coming.

Second – like it or not in – February of next year, the monitoring of the old analog 121.5/243 MHz ELTs by satellite will be going dead. So the only way your old analog ELT will be heard after that date is if a local aircraft or receiver unit that is looking for you just happens get close enough to your location to pick it up. The real-world level of safety provided by 121.5/243 MHz ELTs will be virtually zero after Feb 2009!

Those are the facts – plain and simple. Transport Canada really had no choice other than to act in the manner they did as the responsible regulatory authority.

A media release from Transport Canada, dated August 8, 2008, stated “The Government of Canada is proposing performance-based regulations that will require aircraft to be equipped with an emergency locator transmitter (ELT) operating at the 406 MHz frequency or any other alternative means of notification of emergency and location of aircraft, provided that the system meets an equivalent level of performance as a 406 MHz ELT. Current regulations require most aircraft to be equipped with a functioning ELT that can transmit on 121.5 MHz frequency.
"Our government is proposing emergency locator transmitter equipment because it is the aircraft's lifeline to search and rescue services, and helps save lives," said Minister Cannon in the release. "Our government remains dedicated to keeping Canada's transportation systems and Canadians safe and secure."
The release continues by saying, “these regulations will harmonize Canadian requirements with international standards. The International Civil Aviation Organization mandated the use of 406 MHz ELTs for all international commercial passenger-carrying operations and has recommended the use of such ELTs for all other aircraft by February 1, 2009.”
The proposed amendment was published in the Canada Gazette, Part I, on August 9, 2008. Canadians have 75 days in which to review the proposed amendment and respond to it. The Government of Canada would then review the comments in order to develop a final amendment for publication in the Canada Gazette, Part II.”

Without question, the role of the government must be to protect its citizens and as part of that, mandate safety equipment. Such is also the case with cars, boats and trains. Safety Technology changes is constantly evolving.  We as a society need such oversight and such governance. Without it – or worse yet under a static and never changing environment – accidents and deaths would be much more prevalent than is the case right now.
According to Kirsten Goodnough, a spokesperson for Transport Canada, the department is considering a two-year implementation period with specific conditions to provide flexibility for the modification of the Canadian fleet that will ensure proper provisions are in place to meet the demand. Goodnough says that Transport Canada has been consulting with stakeholders throughout the regulatory process to inform the aviation community of their roles and responsibilities under the proposed regulations and to seek input on various issues associated with the implementation.

The subject of reliability is an issue that has become the focus of some in this discussion. Carole Smith, as part of her role with the NSS has been responsible for assembling some facts and data on the entire 406 ELT subject – which she is quite happy to share. “I hear various reliability figures pertaining to ELTs being circulated around the aviation community – and all are negative. I haven’t seen any substantiation, however, of these numbers” she says. Smith continues with the observation that while the government would likely be the first to admit that extensive data on ELT survivability is not readily available (work is being done to remedy this), the fact is that ELTs do save lives. In support of this, Carole points out the recent example of an auto-activated ELT that saved the life of 3-year old Kate Williams when the C-172 in which she was a passenger crashed last October near Golden, BC. As Smith notes, “Sadly, the two adults up front – her grandfather and his business partner – were killed on impact. Without the ELT’s automatic activation, it is probable that Kate would have succumbed to exposure before the aircraft was found.”

In defense of the ELT, Carole observes that while it is a fact that ELTs do not operate 100 per cent of the time, neither do air bags or smoke detectors, for that matter. What she does add to the discussion is that many of the ELT “failure” statistics, involve first-generation ELTs (TSO-91), which were not as robust or built to as stringent a standard as the 2nd or 3rd generation ELTs now on the market. In addition, human factors such as poor maintenance or improper installation have also been found to be significant in crashes where ELTs have failed to operate. There are several reports published and readily available that give validity to these claims – so it is more fact than opinion. And while some argue that the US has not totally embraced the 406 ELT – so why should we? – in 2007 the NTSB sent a formal letter to the FAA recommending that it mandate the use of 406 MHz ELTs (the 3rd generation) in the United States. As for those US registered aircraft that operate in Canada (or most other nations) after February 2009 without the change to a 406 – they will not be under the first line of response capability in this country – or their own for that matter. The current “best opinion” is that if the CARS amendments are passed, and the exemption successfully applied (i.e., the 2-year transition period), American aircraft will be subject to the same terms and conditions as Canadian aircraft.  A US-registered aircraft may therefore be quite legal flying around Southern Ontario without a 406 MHz ELT during some or all of the two-year transition period, much like its Canadian counterparts. This still requires some clarification from Transport Canada.

As to the discussion of accuracy and initial detection, the bottom line is that 406 MHz ELTs offer dramatically improved alerting capability, and location accuracy, than the older 121.5 MHz analog units. For starters, the 121.5 MHz ELTs, are analog as noted earlier. That makes them incompatible with the geostationary search and rescue (GEOSAR) satellites now in use and coming on line. The 406 MHz digital ELTs are compatible in every way.

When a 406 MHz ELT is activated, it can be detected almost immediately by a GEOSAR satellite and the alert relayed to the appropriate Mission Control Centre within minutes. As the 406 ELTs are registered individually, Canadian rescue authorities will know what aircraft may be in distress and to whom it belongs, as well as the applicable emergency contacts. If the 406 MHz ELT is also equipped with a GPS navigation interface, its precise position will also be known. This is a quantum improvement over the 121.5 technology.

Continuing the comparison, in the polar areas not covered by the GEO satellites, or where terrain features may be a concern, the moving LEOSAR satellites can more readily detect 406 MHz beacons. Working in harmony with both types of SAR satellite systems, 406 MHz coverage is therefore global. There is an additional bonus for 406 MHz equipment. Because the 406 MHz ELT signals are digital, they can be stored on board most LEOSAR satellites until they come within view of a ground station where the signals are downloaded. This is referred to as “store and forward” capability.  Analog 121.5 MHz ELT signals cannot be stored on board any satellite, which may result in a few “missed” satellite passes until a LEOSAR satellite, a ground station, and a 121.5 MHz ELT are all within view of one another. Analog 121.5 MHz ELTs do not therefore have “store and forward” capability, which may extend the time required to detect and locate an ELT.

The final point of consideration and discussion is how the 406 ELTs stack up against some of the alternative products being toted by some as worth consideration such as PLBs and personal satellite devices. At the present time, only 406 MHz ELTs are designed specifically for aviation use. They are the only devices that are equipped with an automatic activation sensor and they produce a location accuracy of 5 km or less (without a GPS interface). As some avionics and safety expert have expressed, the “disqualifying factors” for SPOT not being accepted by Transport Canada as ELT substitutes are the lack of automated activation, and a location accuracy that is greater than the 5 km radius provided by a 406 MHz beacon. SPOT sends out an electronic breadcrumb once every 10 minutes, which at, as little a speed as say, 90 kts – translates to one position report every 27 km. That creates a pretty large search area.

Also noteworthy here is that SPOT devices involve a third party monitoring, and forwarding distress messages. In comparison, alerts from COSPAS-SARSAT beacons (ELTs, PLBs, and EPIRBs) are automatically distributed to the appropriate government rescue centre. The SPOT system works through a commercial call service, GEOS Alliance, based in Texas. While by definition this may not be detrimental, it does add at least one other step through which a very urgent message must pass. The GEOS monitors the SPOT system 24/7 for “911” alerts. The call centre staff however does not monitor continuously the status of the electronic breadcrumb trail generated by those who have subscribed to SPOT’s tracking service. So, if no one on board the aircraft can hit the “911” button, the monitoring group may not know that the aircraft is in distress or has crashed until it is reported overdue. Once that happens, the breadcrumb trail could then be useful in figuring out the aircraft’s last known position. The monitor center also may not know who to contact in an emergency. These factors are far from desirable, and SPOT does not have true integrity as an Emergency Locator System, not at this time anyway.

It does bear noting that Transport Canada has left the door open in it’s 406 MHz ELT rulemaking to other new technologies that may emerge and that would provide an equivalent level of safety to the 406 Mhz. ELT.  The fact is however that no other such new technologies were identified at the time of the 406 MHz ELT rulemaking.

The Bottom Line:  The simple fact is that ELT Technology is changing, not really a surprise in this technology-driven world, and considering that the existing analog ELT technology is over 30 years old!  The ideals of safety need to be embraced. The people making regulatory decisions have embraced them, and are obviously doing so with considerable thought and planning. And that is what we have them in place to do. Change is always a challenge, but it is inevitable. Otherwise we would still be flying a glorified Wright kit with a lawnmower engine and hand made prop off a soggy grass strip.


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