Communication, communication, communication – it’s a mantra that forms the foundation of a successful working environment where multiple team members each have a distinct role to play. The importance of synergy between the crew is never more vital than during special operations, especially when the life of the crew and the passengers/patients could be jeopardized by the slightest miscommunication. For instance, with police operations, communication between the pilot and the tactical flight officer is essential to be prepared for hazards as well as to be able to stay on target; for search and rescue (SAR), the pilot needs to speak to the technical crewmember to ensure that the hoist is directed accurately and is stable; while for helicopter emergency medical services, the pilot needs to be advised when the patient is packaged, stable and ready to be transported. And these special missions are often in heightened moments of stress, with inclement weather, or under particular time pressures, so that any hindering or obfuscation of the crew communications will be felt even more acutely than during ordinary flight. Not to mention the noise, vibration and cramped cabin spaces inherent in aviation making the working conditions more challenging than one could expect from an office job, for example.

John Peterson, Executive Director of Aviation at Iridium – a global satellite communications company providing access to voice and data services – agrees: “Medical missions are complex. They often occur in high-stress environments in less-than-ideal locations under time constraints, depending on the condition of the patient.”

Jarrett Lunn, Chief Pilot for Talon Helicopters – a Canadian SAR organization – also relies on clear crew communication to enable efficient and safe operations: “In our hoist rescue operations, clear communication is essential to a safe and efficient operation. We have hoist operators calling out precise aircraft movement commands to the pilot, and if there are any breaks in the communication line it will quickly affect the flow of our operation. From helmets to microphone covers to aircraft communications systems, all of this equipment needs to be considered and set up in the best possible way for the operation.”

As well as communication between crewmembers, coordination with the ground resources and one’s wider organization has come along remarkably in recent years, with integrated communication platforms providing push-to-talk from the crew to the ground over radio, satellite and even cellular networks. Technological advances also go some way toward improving the lot of the flight crew, with better noise reduction, increased mobility from being wireless, and more stable data transfer providing less static and higher-fidelity sound, making for more efficient and safer operations. Recognizing the utility of being in communication with operations under their oversight, Peterson added: “The coordination of weather, location, condition of the patient and other information is critical to successful safe missions. The ability to have an ‘angel on your shoulder’ in operations watching and monitoring while the crew is focused on the mission increases safety and mission effectiveness.”

The coordination of weather, location, condition of the patient and other information is critical to successful safe missions

Situational awareness

The avionics equipment that is standard in the cockpit of an aircraft ensures that, at the very least, the pilots and crew can talk to each other and there is a clear division of labor, so each individual knows who is in direct control of what and who is there for support or to coordinate at any one time. Regarding the importance of this ability to talk to one another, Héctor Estévez, CEO of CENTUM research & technology – a developer and manufacturer of aeronautical mission systems – said: “Effective crew and operational communication is vital for ensuring safety, efficiency, and overall mission success in emergency situations. It plays a crucial role in coordinating tasks, responding to emergencies, and maintaining situational awareness. Effective communication ensures the network’s uninterrupted availability in critical operations.”

Advances from the old analog systems to the more complex digital ones allow for more channels, more operators and more options for which frequency or network each operator is able to speak on. Furthermore, the size, weight and power (SWaP) of these intercom devices has come down, significantly allowing for greater versatility, especially when SWaP is at a premium due to the restrictive sizes of special missions craft. No longer are the crew in the rear necessarily tethered to the aircraft by long spiral cables, either. Bluetooth and other wireless methods of data transfer have been employed to allow medics, rescue swimmers and other first responders the ability to leave the aircraft while their communications remain connected with the rest of the flight crew. This is particularly important when the time taken to unplug and disconnect can hamper the performance of vital lifesaving procedures, and the break in connectivity can also mean a break in important communication.

Reuben Mann, Head of Marketing for SKYTRAC – a satellite communications and intelligent connectivity solutions provider – described the benefits of wireless technology in the cockpit and cabin: “Wireless crew communications offer operators the ability to simplify the equipment required, reduce clutter in the cockpit and cabin, and minimize onboard weight through elimination of cables. Further, wireless systems are often scalable, as it is relatively easy to add new crew members onto the system. Wireless systems are also highly integrable with other devices.” 

The improvements also now include true 3D audio, so that crew are more easily aware of who is speaking and when, reducing fatigue and confusion, and increasing situational awareness.

Push-to-talk or voice-operated switch

Push-to-talk (PTT) is a feature of communication that is common among pilots and special operations. When one wants to talk, they simply depress a switch and that initiates broadcast onto the frequency or channel that the communications device has been assigned to. For pilots, the button is often embedded in the control column, allowing them to speak without having to take their hands off the aircraft controls. For other crew and colleagues, the push-to-talk button may be attached to their helmet, the headset or handset, depending on their needs and equipment. Communications can either be closed, open within close proximity of the flight crew, or switched to broadcast for interaction with remote colleagues.

For mission-critical operations, truly global connectivity is an important capability that ensures effective communication, even in the face of natural disasters and severe weather events that can disrupt ground infrastructure

Peterson explained: “PTT is integrated into the avionics and works like the traditional aviation radios. It is not on an open frequency, which can introduce other users and hamper the mission. PTT is a service that works within the established talk group and only stakeholders are communicating in the language they understand focused on the mission in front of them at that moment.”

Mann added: “Iridium-based satellite PTT offers multiple features that improve operations. First and foremost, Iridium’s truly global connectivity ensures that the crew is always connected, no matter the location. For mission-critical operations, truly global connectivity is an important capability that ensures effective communication, even in the face of natural disasters and severe weather events that can disrupt ground infrastructure. The low-Earth orbit network also ensures low-latency, clear communications with military-grade encryption, offering speed and security for operators seeking the highest levels of protection.”

Alternatively, instead of a manual switch to engage transmission through the microphone, there are voice-operated switches (VOX) that turn on when someone speaks and off soon after they finish. This has the benefit of saving space and leaving the operator’s hands free, but runs the risk of a permanently open microphone if there is noise being captured. There are settings that can help to minimize this, as Lunn described: “We choose very specific microphones which work well in a noisy environment and also ensure our VOX settings are configured to knock out any unwanted noise, while still allowing the crew to talk without keying a PTT system.”

Background noise

When speaking on a mission, it is essential to be heard and understood. Verbal communication is a quick and efficient way for crew to confer, improving situational awareness, identifying and alerting each other about hazards and providing updates on the status of the operation, as well as issuing instructions and making decisions. Background noise, distortion and loss of clarity are the enemy of conveying information. Lunn explained how trying to work through noise can take its toll on an aircraft crew: “Background noise becomes fatiguing on crews and can lead to distractions in the aircraft.”

Background noise becomes fatiguing on crews and can lead to distractions in the aircraft

Special missions environments are full of noise, especially when associated with aircraft. The spill or bleed of sound can be a distraction and can drown out conversations that need to be heard. The engines, air over the wings and fuselage, wind, weather and vibration all contribute sounds that need to be filtered out or overcome, especially if you have to have the cabin doors open for access and egress. Also, aircraft, especially helicopters, are designed to be as light as possible to allow for more capacity to carry passengers and equipment for a higher useful maximum take-off weight. This has the consequence that the airframe is light and thin, which does little to dampen the penetration of unwanted noise. Trying to shout over a jet engine is a fool’s errand, so talking relatively normally into a microphone is the best way to be heard while not getting hoarse.

However, this too is fraught with problems, especially in relation to the sound that the microphone picks up. It is not much help if you are still in a loud environment and all that noise is also collected and transmitted over the channel that you are talking on. As well as the ambient sounds, the microphones themselves are subject to handling noise. In a recording studio, one has systems and equipment to help reduce this – such as thick, padded walls – but this clearly isn’t an option on aircraft. Digital systems have been introduced to filter out background noise, and these are getting more sophisticated so that, in unusually loud or disruptive situations, the press of a button can eliminate all non-vocal sounds. But the problem isn’t just on the pickup from microphones; there is also the unwanted sound that can penetrate the headset or helmet, especially if headgear is ill fitted and doesn’t form a tight seal around the ear.

Consequently, helmet and headset manufacturers spend an enormous amount of time ensuring that the design of the ear cups fit snugly, securely and comfortably for use in loud environments and for extended periods of time. Helmets and headsets use passive noise cancelling to keep sound away from the ear canal, using materials that absorb sounds as well as providing safety and ruggedness from impacts. Helmets especially are an investment in time and money as the user needs a unique fitting for their particular head shape, so they cannot be interchanged between users like headsets. Manufacturers are aware that the consequences of getting this wrong can lead to difficult working conditions, but also hearing loss in the long term. To mitigate the issues associated with the obstacle of extra and invasive noise, active noise reduction/cancellation (ANR/C) is now being added to headgear. ANR/C uses a processor and a built-in microphone to analyze the ambient sound and then overlays a reversed matching sound wave to the ears, so that phase inversion decreases the ambient sound that you are trying to avoid and you are left with only the sounds that you intend to hear. As well as adding weight to the headgear, they also require extra power, but, thankfully, this is only by a small amount.

Bands and frequencies

Crew communications can be made either seamless or intolerable by the electrical loom, or broadcast method. Interference, static or obstruction can all cause the transmissions to be rendered unusable or difficult to comprehend. Robust wiring and keeping the jacks and ports clean are often the easiest way to keep crew communicating clearly and freely among themselves. However, when the personnel on the aircraft need to report back to base or to another aircraft, special missions operators are often faced with a variety of situations that can hinder clear transmission of audio. Radio is the standard and it has a lot that makes it a superior mode of communication – the legacy method that is fully supported by the aviation infrastructure. General aviation tends to use the very high frequency (VHF) band – between 118MHz and 137MHz at intervals of 25kHz, giving 760 usable frequencies to talk on, with some slightly lower frequencies to be used by specialist organizations and categories, and some frequencies for navigation uses. The distance that these frequencies cover depends on a few factors, such as height and the power of the transmitter, but they are usually approximately between 100 and 200 miles, and require near line of sight. This is often fine for straightforward missions, but if you regularly operate in remote, mountainous or extreme environments, then you will either need to be able to be wholly independent or invest in another form of audio data transmission.

This is where satellite communication systems are an exceptional alternative. Acknowledging how satellites act to join parties together, Mann stated: “The main benefit to operators that satellite PTT provides is clear communications through the elimination of radio interference, the ability to group different aerial assets together for coordinated missions, and the reliability of always connected / truly global connectivity.”

Satellite technology has extended the capabilities of aircraft communications much farther than before

With a much larger range and not inhibited by geographical prominences, satellite technology has extended the capabilities of aircraft communications much farther than before. And the connectivity is not limited from radio to radio, but can connect the radio on the aircraft to conventional telephones on land by accessing the phone network. Seeing satellites as a supplement to standard communications, Peterson described how they are invaluable as an added resource: “Wireless communication is subject to the ability to see the antenna. With VHF and long-term evolution (LTE; 4G) you have to have a tower near your mission. With satellite you have to have line of sight to the satellite. This is why no single solution is perfect, and crews should take the primary, alternate, contingent, and emergency (PACE) [option]. The use of multiple available networks makes for the best solution and makes for successful seamless communications. Even today we are seeing our mobile phones include Wi-Fi/LTE/satellite. This provides the most reliable service possible, no matter where you are in the world.”

Several SAR agencies have the capability to patch phones through their routing centers, but onboard satellite communications systems are able to do this directly without a third party. Not limited to voice data, either, the data transmission rates are high enough to support a wealth of other features. Additionally, the growth of the 5G cellular network is providing another platform on which to talk, enabling greater data transmission for stable data and voice communications in busy urban environments. Useful for when the airwaves may be overloaded and the lines of communications need partitioning, such as during large sporting events or humanitarian crises, or simply for ground crew to coordinate with the flight crew by using an app on their smartphones.

The growth of the 5G cellular network is providing another platform on which to talk, enabling greater data transmission for stable data and voice communications in busy urban environments

Having the ability to have a stable connection, wherever you are, ensures that support, information and collaboration can always be relied upon. Satellites and satellite networks aid in this regard to bolster and enhance communications when radios or cellular networks are not able to provide the requisite performance in remote or rural locations. “Iridium is the only network that delivers and maintains connectivity anywhere in the world,” said Peterson. “Each satellite is connected to its neighboring satellites via crosslinks, creating a web of coverage around the entire planet. Additionally, its location in low-Earth orbit delivers a fast, low-latency connection, while its L-band frequency provides a reliable and weather-resilient signal, which are ideal network characteristics for providing continuous connectivity. Iridium also has high-quality voice channels that operate on the highest quality of voice codec and have the highest priority on our satellite network to ensure a voice channel is established and not interrupted. Iridium Connected aviation terminals provide options for least-cost routing and automatic switching between LTE and satellite,” he said.

As well as cell phones themselves, the development of technology that uses the cellular network is advancing. Describing the developments that his company are making in creating cellular networks in situations where the infrastructure is limited or damaged, Estévez said: “The goal of the Communication Cell of CENTUM research & technology is to restore communications in emergency situations caused by natural disasters, such as fires, earthquakes, or floods. One of its key features is its portability, which allows its integration into different platforms like vessels, helicopters, drones, or vehicles. It can be used in different scenarios in air, ground, and sea operations.”

The growth of cellular coverage means that more people are better connected for longer periods of time, improving the foreknowledge of the operators moving into a rescue scenario, making it easier both to narrow down a more precise position of the person requiring help and to get updates on their health and safety status. “Radios and satellite phones are great and are used frequently in our operations,” said Lunn. “Recently, the benefit of more cell phone coverage in our SAR area has simplified a lot of our missions. We are able to retrieve locations off of a cell phone and we can communicate to our subject through simple text messages.”

The importance of having a backup in case one form of communication is lost is emphasized by Estévez: “Having the capability to communicate over a cell phone network enhances operational resilience. Not only because it ensures communication redundancy, enabling crewmembers to stay connected even in remote areas or when one network is unavailable, but also to guarantee external communication with other emergency teams or organizations that are required for a specific mission during an emergency.”

This growth in coverage also has wider benefits for communicating with people needing to be rescued. Lunn experienced this recently: “Just two nights ago, we were called in for a night hoist rescue of a climber who was stuck clinging to a cliff, unable to go up or down. They were able to use one hand to use their cell phone and call 911 for help and our SAR managers were able to send a text when we were en route; it simply said, ‘Turn on your phone flashlight once you hear the helicopter inbound.’ A simple text like that allows us to find the subject very quickly while flying in on night vision goggles.”

They were able to use one hand to use their cell phone and call 911 for help and our SAR managers were able to send a text when we were en route

Conclusion

As special operations require a whole range of interdisciplinary crews, and interdepartmental and inter-organizational cooperation and coordination, being able to speak clearly and hear perfectly what is being said is the very least that needs to be asked of the communications devices and headgear. Challenging situations as well as inherent environmental obstacles make this aspect of special operations particularly difficult to overcome. But it is an essential safety consideration, so avionics and equipment manufacturers are constantly adjusting, improving and innovating their solutions to provide better and more options to deliver clear and stable communications with more coverage in any environment. Helmets and headsets have ANR to protect hearing and enable clearer understanding, and have more platforms for talking within the aircraft and to other operators and command centers than ever before.