When Ireland extended the control zone around its shores, it had to look at new maritime-patrol aircraft.


CHARLIE 253 IS HEADING home after an 8h patrol. According to Irish Air Corps Maritime Squadron commander Maj Michael McNulty, it has been a typical mission for the crew of the CASA CN-235 - depart from Casement Aerodrome on Ireland's east coast, travel to the assigned section of Ireland's maritime-control zone, and collect routing data on 120 or so vessels in the sector.

It sounds straightforward, but missions are often fraught with problems, not least from the weather. The maritime squadron's area of operations has a very difficult climate. A typical patrol will encounter one or more weather systems, with associated turbulence and icing. Sea states of force six, with surface winds of 30-40kt (55-75km/h) are more the rule than the exception. The CN-235s, however, are up to the job.

Ireland's reason for operating CN-235s can be traced back many years. When the country joined the European Union (EU) - then the European Economic Community (EEC) - in 1975, it had a small air force with an essentially military role. The air force consisted of a single squadron of fighters for an intended (but never fulfilled) strike role; a squadron of piston-engine trainers which could, if needed, provide light-strike cover; a squadron of Reims-Cessna F172s for army co-operation duties and border patrols; and four Aerospatiale Alouette III helicopters, which shared army co-operation and search-and-rescue (SAR) roles. There was also a pair of elderly de Havilland Doves used for liaison and mapping duties. These, plus the Alouettes, performed the only duties "in support of the civil power".

By 1977, this had begun to change. Ireland claimed control of a 320km (170nm) economic zone around its shores, and the EEC Commission suggested that Ireland should accept responsibility for policing the zone itself. Obviously, the two major areas of economic interest were mineral and fishing rights. The mineral rights would have required only minimal surveillance, but fishing rights were becoming increasingly contentious and would have required constant surface and air surveillance, not to mention upgraded SAR capability.


As an interim measure to establish fishery patrols, two Beechcraft King Air 200s were leased, then purchased, from Sweden's United Beechcraft, with the intention of giving the Air Corps an opportunity to study the market for more suitable aircraft. Although not strictly a military one, the task was assigned to the Air Corps - Ireland's only state-controlled air operator apart from the commercially operated airline, Aer Lingus.

It was 1988 before the Air Corps was given the go-ahead to issue a requirement for fixed-wing aircraft capable of patrolling the 342,000km2 (132,000 miles2) of Irish coastal waters - an area which forms about one-fifth of the EU's Atlantic coastal waters.

The Irish Department of Defence, in conjunction with the Department of the Marine, sought proposals from 42 potential suppliers for an "...off-the-shelf package to come complete from just one principal". It did not want an untried aircraft or system - the Air Corps, with its experience of being the first military operator of the Aerospatiale Dauphin helicopter in multiple roles, believed that it would stretch resources too far to add this role. Nor did it want an aircraft or radar system near the end of its service life - traditionally, Air Corps' aircraft have served for 20 years and more, with all Alouettes introduced into Air Corps' service since 1963 still operational.

The requirement was for an undefined number of aircraft (it was up to the tenderer to state how many would be the minimum needed), complete with radar and other equipment to patrol the 342,000km2 area, with minimum requirements to cover each sector.

Col Kevin Hogan, the Air Corps' group commander at Casement Aerodrome, at Baldonnel, says that CASA submitted two proposals - one for eight CASA C.212s, and the other for two CN-235s. Dornier submitted an offer for four or five 228s. "We eliminated Fokker because their proposal was for the then 33-year-old F27 Friendship - we might have been interested in a Fokker 50 proposal, but we had to remember that our aircraft might still be in service in 2020, when the Friendship would be a long-forgotten 63-year-old design. Another proposal which would have interested us came from de Havilland Canada, but their Dash 8 offer come with a recommendation that we go to another company to have the radar fitted. We wanted to reduce complications, and, if necessary, argue with just one supplier," Hogan says.

Hogan says, that CASA offered a nose radar, but the Irish wanted the 360¡ coverage which only a belly radar can provide. Provincial Airlines in Canada demonstrated a Litton radar with an Adams integration system linked to an on-board personal computer and, when CASA agreed to fit it to the CN-235, the deal was done.

"We ended up with a proven airframe and engines, plus a proven radar system and three navigation systems, forward-looking infra-red [FLIR], a reporting and data-link system recorded also on tape and a management system, all without taking on any new and untried technology. We also have date, time and location video and hard-copy evidence for courts when needed," says Hogan. "Plus, we have an aircraft which can airdrop dinghies for up to 50 survivors."


Two hours before a patrol's departure, says McNulty, "...the six main crew - pilot, co-pilot, search and airborne radar operator [SARO] and assistant SARO, photographer and launch specialist/technician begin their preparation and flight briefing". This includes gathering weather reports and forecasts, selecting possible diversion airfields and checking their current status, along with the status of all SAR units in the area to be covered. The expected seasonal deployment of fishing fleets, including updated reports and likely positions of recent offenders, is also checked, and contacts with Irish Naval Service vessels are discussed and determined. Normal patrol time would typically be 7-8h, says McNulty.

The patrol is generally flown at 1,000ft (300m) and 180kt, but the normal height for visual inspection of each surface target is 200ft, while speed ranges from 130-150kt, depending on aircraft weight and weather conditions.

A range of data is collected on each surface target - its position, class and type of vessel, its registration and radio call sign (which is sometimes displayed on the side of the wheelhouse), its activity (including deployment of nets and lines) and its track. A 70mm photograph is taken of each vessel, and the time and date of each sighting recorded.

All data are datalinked immediately through the military network to the naval authorities for any required action. The Air Corps works closely with the Naval Service, and most patrols are conducted in conjunction with naval vessels. Encrypted military communications are maintained throughout the patrol.

If the weather is poor, the SARO can provide a radar-controlled approach on to the target, using the FLIR to augment data, if necessary.

The two CN-235s were delivered to Baldonnel in December 1994. The delivery flight included a short patrol operation in the Irish economic zone, and the first full patrol took place on the following day. This was possible because of the squadron's experience gained over the previous 17 years, its operation of the prototype CN-235 (albeit without the equipment included in the purpose-built aircraft) and because of a successful in-house training programme. The Air Corps has sought training quotations from external sources for radar operations and tactical navigators. The quotations received were higher than the available budget would allow, however, so the decision was taken to complete as much as possible internally.

The two new CASA aircraft are used for the same workload as is the prototype, but they are equipped so that they can be used as competent detection tools. In the first ten months of operation, 237 patrols were flown for a total of 1,700 flight hours, and more than 6,000 sightings have been recorded - an average of over four per flight hour.

"Our major problem with the CASA CN-235MPA," says McNulty, "is that we did not have it ten years earlier."

Source: Flight International