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Rotorcraft and TPs combine capabilities to meet demands of special missions


Need for operational innovation demands collaboration and interoperability in mixed fleet ownership and operation.

By Don Van Dyke A
TP/Helo/CFII, F28, Bell 222
Pro Pilot Canadian Technical Editor

The multirole Textron King Air 350ER is a large-cabin, long-endurance option for light cargo delivery in remote areas. It also serves as a battlefield surveillance and attack platform. Although rugged and robust, it still requires at least a rough field from which to operate. This affords an opportunity to apply mixed-fleet teaming with an SMA helicopter to good effect.
Historically, special mission aircraft (SMA) were relatively large to house installed special electronics and accompanying power supplies.

Over time, advances in technology reduced the size, weight, and power (SWaP) requirements of mission avionics, as well as their required cooling systems.

Today’s SMA are often repurposed commercial-off-the-shelf (COTS) platforms which are configured to meet specific and often challenging mission requirements. Benefits are maintained in 3 ways. First, investment in aircraft design is borne by the original equipment manufacturer (OEM) in meeting commercial demand.

Second, selecting COTS aircraft allows military procurement to keep pace with commercial demand. Finally, procuring COTS aircraft avoids the financial and operational risks of standing as a sole client in a military market.

Custom SMA design, support, and planning were covered previously in Pro Pilot (Jun 2016), while procurement guidelines and certification standards were discussed in Apr 2018, and a compendium of selected platforms was presented in Apr 2019.

SMA market

The largest SMA market is North America, but the fastest-growing sector is Asia Pacific. The airborne early warning and control (AEW&C), and intelligence, surveillance, and reconnaissance (ISR) segments currently dominate global needs. The SMA market was valued at $12.7 billion in 2019, and is currently projected to reach $16.8 billion by 2027.

While the economic impact of the Covid-19 pandemic remains ill-defined, it is generally agreed that the SMA market will likely take 2 to 3 years to recover. Contractions planned by OEMs resulted in reduced SMA production and deliveries in 2020, although demand for medevac-configured SMA increased during the same period.

table 1An encouraging market prospect is the rapid growth in military spending by major and emerging economies. Table 1 identifies OEMs producing helicopter and turboprop (TP) SMA airframes, as well as a range of corresponding technology providers and integrators. Mixed fleet operations allow categories of aircraft to supplement or complement each other’s features and capabilities.

Given range, speed, endurance, and resilience – especially in the austere environments typical of many SMA operations – helicopters are more closely aligned with TPs than they are with turbojets. Thus, the reach and effectiveness of helicopter SMA operations are enhanced primarily by teaming with TPs.

Technology advances have stimulated conversion of several current SMA to unmanned aerial vehicle/remotely piloted aircraft system (UAS/RPAS) equivalents as substitutes, decoys, loyal wingmen, or force multipliers. As their use is increasingly pervasive, Table 1 includes OEMs of unmanned platforms suitable for operational pairing with manned SMA.

The need for actionable intelligence is ever more critical and increasingly available through improvements in sensor technology, high-resolution cameras, electro-optics, and infrared systems which enable the capture of clear images of areas of interest. Selected OEMs and integrators of technological payloads are also provided in Table 1.

table2All SMA airframes, components, and systems must meet ICAO and State of Manufacture regulatory requirements to ensure the safety of operations and to mitigate risks associated with defective components. The effects of external shape changes on SMA, such as flight control, stall prevention, and warning systems are evaluated, and configurations are updated accordingly.

Based on payload type, the sensor segment is projected to have the highest growth rate in the SMA market. Optical sensors used for military or law enforcement applications include both visible and infrared sensors. EO/IR systems provide total situational awareness, even in low light conditions.

Many types of radar and electronic intelligence (ELINT) sensor are used to establish situational awareness and provide early warning and in-depth analysis of intercepted signals to detect, confuse, or deceive all kinds of countermeasures and communications without entering the threat zone.

SMA applications and payloads

Table 2 presents a range of selected civil and military roles in which SMA are often employed. Environmental monitoring is especially important since climate change is acknowledged as having been a primary catalyst causing drought, intense heat waves, devastating fires, loss of sea ice, accelerated sea level rise, floods, avalanches, and other catastrophic events.

Aviation is challenged to foster environmental stewardship by meeting aspirational goals for reduction of CO2 emissions and carbon-neutral growth. To assess the effectiveness of these efforts in mitigating adverse consequences, SMA are used to monitor the environment and to provide humanitarian assistance insofar as possible.

Helicopter SMA are particularly well suited for rescue, inter-hospital transfers, and repatriation to mainland healthcare services. Escalating geopolitical tensions, rising territorial disputes, ongoing unrest in various regions, threats to marine borders, and spreading irregular warfare suggest increased need for high-seas antipiracy and maritime drug interdiction operations involving mixed SMA fleets. Teaming helicopter and TP SMA extends the reach and effectiveness of both platform types in these roles.

The Florida Keys Mosquito Control District operates 2 Airbus H125s in a mixed fleet of 6 helicopters and 2 Britten-Norman BN-2T Islanders to control disease-carrying larval and adult mosquitoes before they can mature. Timing is critical to the effectiveness of these activities.

Operational innovations

Some SMA platforms perform largely as business aircraft, although with reversibly customized interiors and external hardpoints for specialized equipment, while others are the most innovative and technologically advanced designs available.

Realizing optional piloting expands the concept of mixed-fleet teaming significantly.

In the case of helicopters, the prospect of remotely-controlled or autonomous aircraft had to await validation of VTOL controls and respective regulations. The Bell 525 Relentless is the first fly-by-wire (FBW) commercial helicopter.

The integrated triply-redundant flight control system design promises superior full-authority inflight handling, maneuverability, and stability.

The FBW system can determine an intelligent, controlled, informed, and predictable aircraft response in a number of situations (eg, engine failure, autorotation), automatically adjusting commands to achieve maximum flying precision and performance.

Furthermore, testing continues to refine technology for optionally-piloted flights in helicopters not originally intended to be unmanned. For instance, Sikorsky first demonstrated optionally-piloted flight using a UH-60 Black Hawk. Later, Transport Canada certified the Rig Approach providing a first-of-its-kind automated approach capability for the Sikorsky S-92.

In May 2016, Sikorsky successfully demonstrated autonomous S-76 helicopter flight over 30 miles, planned, monitored, and executed by an operator using only a tablet device.

Derived from the Pilatus PC-12, the USAF’s U-28A Draco provides on-call/surge capability for improved ISR in support of special operations forces. Most U-28As are fitted with EO/IR cameras and SIGINT systems to geolocate and monitor hostile communications.


SMA act as low-cost multirole platforms supporting wide-ranging (and often highly classified) missions. Interoperable mixed-type fleets involving piloted, remotely-controlled, or autonomous SMA can perform complex, life-saving missions, potentially with enhanced safety, reduced environmental footprint, lower cost of ownership, and superior functionality.

Mixed fleets of rotorcraft and TP SMA can team in complementary ways to discover, observe, and share information regarding tactical or natural disaster situations using sensor, mapping, and imaging applications.

Depending on circumstances, mixed-fleet SMA can be used to transfer critical and useful payloads such as food, first aid, or ammunition to isolated and often remote locations.

Other applications include target sharing support with artillery units in ground operations; intelligence and/or target detection, surveillance, and tracking support with high-resolution camera and gimbal systems at high altitude; agricultural missions; meteorology; and mobile base station.

Key SMA market drivers include identifiable needs and objectives, technical innovation, performance (aircraft endurance, payload, speed, range), short turnaround fielding, and costs (procurement, modification, and operating). Operational goals will seek to improve utility, redundancy, and reliability, creating greater value in the process while containing costs.

Upgraded avionics (digital technologies, sensors, communications, multiple integrated platforms) and shrinking form factors will encourage the use of ever smaller aircraft in special missions.

The prominent challenges facing the rapidly changing SMA market include the considered evolution of appropriate responses to increasing terrorism, insurgencies, and conflicts; electronic warfare and countermeasures; cybersecurity threats; market and budget constraints; lack of expertise and trained pilots and operators; and regulations and ethical considerations.

The same creativity and ingenuity which led to the first examples of special mission aircraft will undoubtedly yield currently unimaginable operational benefits.

DonDon Van Dyke is professor of advanced aerospace topics at Chicoutimi College of Aviation – CQFA Montréal. He is an 18,000-hour TT pilot and instructor with extensive airline, business and charter experience on both airplanes and helicopters. A former IATA ops director, he has served on several ICAO panels. He is a Fellow of the Royal Aeronautical Society and is a flight operations expert on technical projects under UN administration.