Degraded visual environment (DVE)-induced spatial disorientation (SD) is the leading cause of fatal helicopter accidents. The European Union Aviation Safety Agency’s (EASA) Annual Safety Review for 2023 noted that degraded visibility conditions continue to feature as an subject in the factors behind helicopter accidents.

As the saying goes, ‘an ounce of prevention is worth a pound of cure’ – meaning that it is easier to stop something from happening in the first place than it is to repair the damage afterwards. It’s an aphorism that holds good when it comes to regulating helicopter operations and helping pilots assess and manage the risk of IIMC.

The EASA has regulatory frameworks in place that require all pilots flying helicopter emergency medical services (HEMS) operations, for example, to have completed a minimum of 30 minutes of flight by sole reference to instruments in a helicopter or in a flight simulation training device (FTSD) within the previous six months. From 24 May 2024, EASA will be strengthening this requirement by referring directly to IIMC, and for HEMS pilots to have completed flight training that equips them with the skills to escape IIMC.

So, what are the technologies available to train pilots to deal with DVEs during normal training flights, as well as for real-life IIMC scenarios?

In-aircraft training systems

Oklahoma-based AT Systems has patented an in-aircraft training device that trains pilots for DVE – such as IIMC and brown-out/white-out – during normal training flights. The device was originally designed for military training and attaches to a helmet without the need for modification, producing a DVE controlled by an instructor-operated iPad.

“Our system puts a pilot into the aircraft and by varying the visibility of our system we expose the pilot to conditions conducive to visual illusions. Where we excel is the aircraft provides the vestibular inputs to create vestibular illusions as well,” said AT Systems’ Tyson Phillips, co-inventor of the patented ATS Device for in-aircraft IIMC and DVE training.

Phillips asserted that missing vestibular illusions are the critical key to DVE-induced SD training: “Simulators don’t have the range for the 20 seconds of sustained motion required to create vestibular illusions. We are capable of training day, night and night vision goggles (NVG) – we also are compatible with head-mounted systems like heads-up display (HUD). Our NVG system does not touch the goggles, which can cause damage to the tubes, violate the warranty or potentially violate regulations.”

Simulators don’t have the range for the 20 seconds of sustained motion required to create vestibular illusions

He continued: “Without automation in the cockpit, the safety pilot is being distracted by being a system operator. AT’s system prevents such an occurrence by automating all training, which provides a more standard training plan to the organisation. We also have built-in safeties that, if they sense exceedance of user-defined limits of pitch, roll and vertical speed, the system will go clear bringing the training pilot back into visual meteorological conditions.” The system is standalone and does not connect to anything on the aircraft because all the sensors are onboard.

Working with operators to improve flight safety

SKYTRAC approaches the problem from another angle. Its SATCOM systems are installed on over 2,500 aircraft around the world, while its SkyWeb platform boasts more than 7,500 users spanning all seven continents.

David Balcaen, Technical Program Manager at SKYTRAC, explained: “With SKYTRAC’s satellite and cellular airtime, operators from nearly every segment of aviation can benefit from intelligent connectivity that empowers pilots and operational control centers (OCCs) to avoid IIMC and other dangerous scenarios.”

Although SKYTRAC does not actively train pilots, it does work with operators to enhance flight safety through advanced situational awareness and capabilities, such as flight data monitoring and real-time exceedance alerting. With its TrooTrax Mission platform, operators can be informed before launching into risky situations.

“TrooTrax Mission performs hundreds of weather checks along a typical visual flight rules (VFR) flight route,” explained Balcaen. “Radars, storm vectors, Airmets, METARs, TAFs, and advanced forecast layers are all actively analysed over the time of the flight along the intended route using criteria set by the operator.”

All legs of a flight route are then rated as ‘Clear’, ‘Close to Minimums’, and ‘Below Minimums’ to quickly indicate the likelihood of an IIMC scenario, as Balcaen revealed: “Comprehensive settings can be established for the whole fleet or per aircraft type, and provide operators with the ability to rapidly change flight plans when faced with inclement weather.”

During flight, SKYTRAC’s global satellite connectivity solutions is able to provide pilots with real-time weather updates through the use of connected electronic flight bag (EFB) applications like ForeFlight and RocketRoute. “This essential connectivity ensures that pilots are aware of upcoming weather, lightning, and other storm data for increased situational awareness,” assured Balcaen.

SAR, HEMS, and police are all specialist areas of aviation that are well regulated within the UK

Can more regulation help?

Regulation and simulation training can only do so much. The UK Civil Aviation Authority (CAA) had this to say when asked to comment: “Search and rescue (SAR), HEMS, and police are all specialist areas of aviation that are well regulated within the UK. Technology has allowed for greater situational awareness within most modern SAR, HEMS, and police aircraft,” said a CAA spokesperson. “Use of EFBs with moving map displays or a Helicopter Terrain Awareness and Warning System (HTAWS) are examples of how pilots can avoid IIMC by having greater situational awareness.”

In the USA, the addition of operation control specialists (OCS) into HEMS dispatch and flight monitoring has contributed to the reduction of accidents over the past 12 years. “More knowledge does lead to safer flying,” said Balcaen. “Leading operators use TrooTrax Mission to ensure all OCS have timely and comprehensive weather and hazard information on hand.”

He continued: “Being better prepared and knowing where you can go, and recognising that when flying in minimum ceiling and visibility that an off-field landing is more likely, pilots and operators should have potential landing spots ahead of time.”

Increasing minimums

Phillips believes that increasing minimums could be a start. “One challenge I see with the younger pilots that I work with is we tell them not to fly if visibility is bad, but they don’t know what that means. A lot of pilots have never seen lower visibility, and we often operate in areas with less than ideal weather reporting stations. So, even with increased regulation, more effective training is critical,” he said.

“Our first phase of training is to demonstrate each visibility below three miles, show the pilot what it looks like, to give them the information they need to identify unsafe conditions sooner. Unfortunately, I don’t believe we can regulate ourselves out of this problem. Pilots will make mistakes or flat-out bad choices. We owe all pilots effective training with a focus on avoidance, but we must also touch on recovery,” he added.

We owe all pilots effective training with a focus on avoidance, but we must also touch on recovery,

More effective training

Phillips believes that a noticeable gap in training has been the absence of visual and vestibular illusions combined: “The industry has never trained the combined visual and vestibular illusions experienced during actual IIMC encounters. By exposing the pilot to these encounters, we are ‘training the brain’ to handle the conflicting sensory data. During high stress events, the brain responds intuitively based on previous training,” he explained. “The problem has been that pilots have not been exposed to the combined illusions and the brain does not have a basis of knowledge to react from, leading to delayed or incorrect input. With effective training, we believe if the pilot is exposed to full blown SD, it will make a significant impact, equipping the pilot to make better decisions sooner.”

He continued: “By training in-aircraft with a controllable visibility limiting system, like the ATS Device, which includes the required automation and safeties to conduct training safely, we will better prepare the pilot to make better decisions, leading to a reduction in accident rates.”

Regulatory and training initiatives

A spokesperson for EASA commented: “Other relatively recent rulemaking initiatives taken to incentivize instrument flight rules (IFR) flying with helicopters include the regulation from December 2021 on point-in-space (PinS) departures and approaches. The largest benefit will be for commercial air transport operations and more specifically for HEMS. This also creates low-level IFR routes for rotorcraft.”

The increased accessibility to virtual reality simulation devices will help train pilots in effective recovery techniques that were not previously so easy

The spokesperson continued: “In terms of training, the increased accessibility to virtual reality simulation devices will help train pilots in effective recovery techniques that were not previously so easy when only real helicopters were available. The EASA Rotorcraft Roadmap has specifically focused on supporting the implementation of a broader range of simulation devices for rotorcraft.”

Prevention is better than cure

By far, the biggest focus with regard to VFR into IIMC is around pilot decision making, with the aim being to prevent pilots encountering such situations in the first place. In September 2023, EASA launched a safety promotion campaign specifically around this topic that was developed with pilot and instructor Mona Seeberger. “The campaign includes articles on EASA’s rotorcraft community and for those of other organizations as well as a series of videos with Mona covering ‘Avoidance Before Take-off’, ‘Avoidance after Take-Off/ In the Air’, ‘Recovery in the Air’ and ‘Night VFR’,” said the EASA spokesperson. “The campaign has been collaborated at a global level through the Vertical Aviation Safety Team (VAST) and is based on material already developed by Helicopter Association International (HAI).”

Non-rulemaking initiatives

In the ongoing fight against IIMC and its consequences, new initiatives may offer some improvements.

The availability and access to accurate real-time onboard weather information on ‘easy-to-use, or commonly available hardware’ is also developing in Europe

“Technological developments – like the ‘panic-button’ autoland technology – may become available for rotorcraft, although at a cost due to the need for technology such as four-axis autopilot systems among others,” said the EASA spokesperson. “The availability and access to accurate real-time onboard weather information on ‘easy-to-use, or commonly available hardware’ is also developing in Europe and would help to provide more relevant and timely information to pilots in the cockpit to aid real-time decision making,” they declared.

A last word

Legislation cannot always be expected to provide the answer for improving flight safety. The importance of regular and effective training with a focus on IIMC avoidance, and increased access to VR simulation and training devices to help train pilots in effective recovery techniques as well as real-time live reporting data, will hopefully go some way towards reducing the occasions on which DVEs are recorded as a causal factor in the narrative reports on helicopter accidents.