Eurocontrol postpones deadline for ELS mode-S implementation

 - February 1, 2007, 10:28 AM

Europe’s ambitious program to introduce mode-S surveillance datalink technology has once again been rescheduled to account for operational and technical difficulties. On January 13, Eurocontrol announced a “rationalization” of the implementation timetable for mode-S elementary (ELS, known in North America as “upgraded mode-S”) and enhanced (EHS) surveillance for IFR flights in general air traffic (IFR/GAT).

The provisional council of the European ATC agency said that it had become necessary to “align” the compliance deadlines for the initial ELS phase and the more advanced EHS due to “an increasing number of technical and operational difficulties.”
The main change is effectively to postpone the final ELS compliance deadline by 24 months from the March 31, 2005, date that has been looming large for the industry to the same March 31, 2007, deadline that applies for EHS. Eurocontrol has also introduced further latitude for EHS compliance in that operators that have achieved the standard for at least 90 percent of their fleets by March 30, 2007, can obtain a two-year extension, to March 31, 2009, to upgrade the remaining aircraft from ELS to EHS standards.

Finally, aircraft that are to be withdrawn from service by Dec. 31, 2007, will not be required to have a mode-S retrofit at all, a provision that will prompt some operators to calculate whether or not it is economically viable to upgrade older business aircraft and may trigger some fleet replacement purchases.

Most business aircraft manufacturers have plans in place to enable ELS compliance for just about all of their current-production and legacy models. In this respect, the main advantage of the revised Eurocontrol timetable is that it allows more time for operators and shops to complete the required Service Bulletin (SB) and supplementary type certificate (STC) modifications.

Anxious to avoid the impression that the “rationalization” constitutes a procrastinator’s charter, Eurocontrol has emphasized that the extension is not a “general alleviation to delay installation plans” and that it is intended to allow breathing space for those operators who have experienced “difficulties beyond their control.” The agency urged operators to complete transponder retrofits at the earliest opportunity, warning that, “No further exemptions will be possible, for whatever reason, beyond these final dates for aircraft compliance (i.e. March 30, 2007).”

The EHS mandate period still officially begins on March 31, and operators subject to it are still required either to establish with Eurocontrol that their aircraft already meet this standard or to apply formally for an exemption that runs through the 2007 deadline. In fact, the regulatory agency has granted operators three months of latitude, until June 30, for registering with Eurocontrol’s Exemption Coordination Cell (EEC).

The EHS mandate applies to any IFR/GAT operations by an aircraft with an mtow of more than 12,500 pounds (5,700 kilograms) or a maximum cruise speed greater than 250 ktas. Aircraft below these thresholds will be required to meet ELS requirements when flying in ELS or EHS airspace. Initially the EHS requirement covers German, British and French airspace, although officially the transition period for France does not begin until March 31 next year.

ELS will initially take effect in the airspace of Belgium, France, Germany, Luxembourg, the Netherlands and Switzerland. It will therefore affect not only the majority of aircraft flying between most points in western Europe, but also many aircraft flying across or over the continent. For IFR flights, all new production aircraft have been required to be ELS-compliant since March 31 last year.

For VFR operations, new production aircraft are still required to be ELS-equipped by the March 31, 2005, deadline. Transponder retrofits and upgrades on existing aircraft will need to be completed by March 31, 2008, subject to agreements with individual Eurocontrol member states.

Operators can obtain EHS exemptions to cover the following circumstances:
• Where an aircraft’s avionics do not permit the extraction and transmission of the full set of downlink airborne parameters (DAPs).
• For aircraft operators who show a clear intent to equip their aircraft as soon as practicable after March 31, 2005, but before March 30, 2007, and who experience genuine technical issues or supply problems, causing delays that are beyond their control. In these circumstances, operators can also apply for a partial alleviation from the mode-S elementary requirements to install the wiring for aircraft identification reporting at the same time as the wiring for the enhanced surveillance DAPs.
• For aircraft conducting flights, under existing rules, for the purpose of flight testing, delivery, or transit into and out of maintenance bases.
• For aircraft that intend to conduct only occasional IFR flights (less than 30 hours per aircraft each year).

Full details of the mode-S programs and of the EEC exemption process are available at the Eurocontrol Web site: Eurocontrol is issuing a revised aeronautical information circular to outline full details of the revised mode-S compliance arrangements.

Mode-S allows secondary surveillance radar (SSR) to more selectively interrogate aircraft within their range. Mode-S elementary surveillance automatically identifies each aircraft with its own flight code and gives its current position and altitude. By gathering and processing from so-called DAPs, enhanced surveillance will give air traffic controllers even more useful information, by also providing the heading, speed and selected flight level of each aircraft interrogated.

The DAPs will initially cover the following eight parameters: magnetic heading, airspeed, selected altitude, vertical rate, track angle rate (or true airspeed if this cannot be supplied by the aircraft’s avionics), roll angle, groundspeed and true track angle. As such, mode-S enhanced promises to be a significant tool for air traffic management safety and efficiency. It will greatly reduce the radio communications workload for both controllers and pilots, cutting the potential for miscommunications in the process. In addition, controllers should find it easier to separate aircraft safely while maximizing airspace utilization. The data gathered will be invaluable for safety functions such as short-term conflict alerts and minimum safe altitude warnings.

Eurocontrol has stated that any aircraft that fall below the parameters for EHS compliance will be able to operate under ELS standards indefinitely.

Mode-S should overcome radio frequency “pollution” in Europe, where ground stations repeatedly interrogate aircraft transponders. Eurocontrol is arranging for ground stations to be “clustered” so that each will be informed when a particular aircraft has already been interrogated for its flight data. The agency has acknowledged that some of the technical delays that have forced the revised mode-S compliance timetable have been with the ground stations, so the situation is not entirely the result of problems with airborne equipment.

Andrew Kennedy, an EEC official with Eurocontrol’s mode-S program unit, told AIN that the benefits of mode-S will be evident incrementally from the beginning of next month’s transition period because a significant number of aircraft will be compliant by this date. In this respect, mode-S differs from other airspace management reforms such as RVSM that are necessarily “all or nothing” in the way they are applied. This is an important point for those operators who have made the necessary investment of time and money to meet the original deadline who might feel that the promised benefits have been undermined by others who have stalled over compliance.

Bizplane Makers Get Set for Mode-S

Business aircraft manufacturers have been preparing mode-S compliance solutions for their fleets during the past couple of years. As of press time, most had firm plans in place at least to meet the ELS requirement for all current production models and all but the oldest of their legacy products.

Several airframer engineering managers told AIN that meeting the mode-S compliance deadline has proved challenging, following so closely the major RVSM upgrades in Europe just a couple of years ago. They added that the close implementation sequence between the ELS and EHS requirements has created serious technical headaches, and these appear to have influenced Eurocontrol managers to allow further latitude for compliance.

All new production examples of the Learjets 40, 40XR, 45, 45XR and 60 are now ELS-compliant on delivery. According to Learjet director of customer support engineering Steve Crawford, the company has also prepared STCs for the out-of-production Learjet 20, 30 and 50 series. Not all of these are fully approved because the manufacturer is waiting for customers to request the modification so that an aircraft is available to complete the necessary certification testing.

Bombardier has just issued SBs covering modifications for earlier Learjet 40s and 45s that were delivered before ELS compliance was achieved from the production line. It also has an STC covering work needed for earlier Learjet 60s.

The Canadian airframer has already achieved the more advanced EHS mode-S compliance for Learjet 60s numbers S/N 285 and later. Crawford said that the manufacturer cannot achieve the EHS requirement for the Learjet 40 series until transponder supplier Honeywell has a European TSO in place, which is not expected until April. Bombardier’s goal is to deliver Learjet 40s and 45s with EHS starting in July, with SBs for the existing fleet to follow soon after.

Among the larger Bombardier business aircraft, Challenger 300s, Challenger 604s and Global Expresses (including the latest Global XRS edition) that were delivered with certificates of airworthiness after March 31 last year were ELS-compliant. Service Bulletins for older 604s and Global Expresses have been available for almost a year and this month Bombardier will issue an SB for just six 300s that were not delivered with the ELS specification.

David Field, Bombardier’s director of customer support for the Challenger and Global Express series, said that ELS mode-S STCs will be offered for older Challenger 600s. However, as yet, the manufacturer has not received any requests for these upgrades and so it does not have the aircraft it needs to complete the approval process.

Field told AIN that EHS efforts are now focused on getting compliance for current production aircraft, adding that there is still significant work to be done. Service Bulletins covering the EHS upgrades for existing 300s, 604s and Global Expresses are expected to be in place by the end of the third quarter of this year, and operators have been advised to apply for the necessary exemptions while they wait for these SBs. The first Global 5000s, due to be delivered around April, will meet ELS standards but will likely require further upgrades for the EHS standards.

The Lufthansa Bombardier Aviation Services facility in Berlin has already installed about 20 SBs on a mix of Learjets, Challengers and Global Expresses. Managing director Andreas Kaden said that the turn times on these modifications are getting shorter as his staff gains experience. There are about 260 Bombardier aircraft registered in Europe and another 60 or so in regions such as the Middle East that are likely to want mode-S upgrades.

Between May and August last year, Cessna issued no fewer than 19 SBs covering transponder installations and upgrades to make the Citation family compliant with the ELS requirement. In fact, since around the spring of last year, Cessna has delivered most new production aircraft to this standard and the published SBs now cover all Citations produced since 1979.

As yet, there is no upgrade planned for the original Cessna 500 Citation I series, with its analog instruments, and Cessna intends to address this on a case-by-case basis with individual operators who may want to fly into mode-S airspace.

According to Cessna customer service supervisor Marcelo Casenove, the airframer will spend the first three-quarters of this year focusing on how to achieve enhanced mode-S compliance for the Citations. It already has an SB to upgrade the glass-cockpit-equipped Citation 560 Ultra/Encore and 560XL Excel.

Initially, the main emphasis will be on developing mode-S enhanced surveillance SBs for the current production Citations. Casenove told AIN that Cessna is still working with its avionics vendors on proposals for the analog legacy aircraft and as yet has no firm timeline for offering these upgrades.

There are now more than 500 Citations based in Europe, and the manufacturer’s service centers in France, the UK, Italy and Germany have all been busy installing the mode-S elementary SBs.

Dassault Falcon
Dassault has now issued mode-S ELS SBs covering the following Falcons: the 50EX, some 900Bs, the 900EX, the 900C with the Honeywell Primus 2000 flight deck, the 2000 and the 2000EX. Various STCs are also available for the Falcons 50, 10 and 20.

According to John Ferrara, an avionics specialist with Dassault Falcon Jet’s customer service department, the STCs can be installed through the French airframer’s own service centers in Paris; Wilmington, Del.; and Little Rock, Ark., as well as at the factory-authorized Jet Aviation facility in Basel, Switzerland. “Our vendors have been fantastic,” he commented. “At one stage the lead time was no more than four days to a week with (transponder supplier) Collins, but it is now a little longer as the deadline approaches.”

Dassault is now working on achieving compliance with the mode-S enhanced surveillance standard. It hopes to have most SBs published by the end of June this year, allowing plenty of time to meet the March 30, 2007, compliance date.

Gulfstream 500s and 550s meet mode-S elementary requirements on delivery, as do the G300 and G400 from S/N 1525 onwards. As of late December, Gulfstream was still working on upgrade plans for its other aircraft types and, at press time, no further details of these programs were available.

Hawker 400XPs and 800XPs are now being delivered with the ELS requirements. According to Dennis Hildreth, Raytheon Aircraft’s product manager for these jets, an SB for the ELS modification is already available for fielded 400XPs with Rockwell Collins ProLine IV avionics and AMS-5000 flight management systems (FMS), as well as for 800XPs with the Collins ProLine 21 suite. By the end of June this year, the manufacturer intends to offer an ELS SB to cover 400XPs and 800XPs that have Honeywell avionics installed. Raytheon is still evaluating whether to pursue ELS SBs for all older, out-of-production Hawker types (including those built by British Aerospace before Raytheon bought the program) and Beechjets that have different avionics suites.

By the middle of this year, Raytheon’s goal is for all current-production Hawkers to be delivered with EHS capability. EHS SBs are now being prepared for fielded Hawker 400XPs and 800XPs with the same avionics equipment as the current production models, and these should be available later this year.

Raytheon is still looking at plans to develop EHS SBs for the older Hawkers. It has yet to announce a firm timetable for this work but is committed to addressing the issue by 2007. As with other older business jets, some of the 1970s-vintage Hawkers might not have to meet the EHS requirement on the exemption grounds outlined above.

Of Raytheon’s Beechcraft product range, the Premier I jet, along with the King Air 350 and 200 twin turboprops, now meets the ELS standard. According to Beechcraft product manager Scott Tychsen, the manufacturer is now working with its Raytheon Aircraft Services engineering subsidiary to develop a solution for the King Air C90B.