Brownout, Whiteout, and Landing in the Degraded Visual Environment: Practical Lessons for Helicopter Crews

In 2012, a NATO task group produced a report titled Rotary-Wing Brownout Mitigation: Technologies and Training. The study emerged from the intense operational tempo of helicopter operations in Afghanistan and Iraq, where brownout-related mishaps persisted despite advances in training and technology. At the time, I was well into my second Coast Guard tour and had accumulated experience conducting rescue and security operations in environments ranging from New England snow to the sand and dust of the U.S. Southwest. Although the NATO report was written for military operations overseas, its lessons resonated immediately—and they remain highly relevant today for search and rescue (SAR), air ambulance, and other civil helicopter operations that may land in degraded visual environments (DVE). 

Recently, Alex Pollitt provided an excellent synopsis of this report in his blog “Competent Aviator.” What follows is a distilled, operationally focused interpretation of those lessons for helicopter crews today. 

Anticipating Brownout and Whiteout Hazards 

There is a large body of research—and an unfortunate number of mishaps—demonstrating that pilots are highly vulnerable to illusions in degraded visual environments. Brownouts and whiteouts do not simply obscure vision; they actively deceive the brain. Two hazards dominate most DVE accidents: 

1. Undetected drift – Unsensed and undetected lateral movement until ground contact or obstacle strike occurs. 

2. Vection (illusory motion) – The sensation that the helicopter is drifting or accelerating in one direction when it may actually be stationary or moving in another direction due to circulating dust or snow. 

Knowing these illusions exist will not prevent them, but what does help is sensitivity to the threat combined with disciplined, pre-planned responses: 

• Increased reliance on instruments and symbology as visual cues degrade. 
• Standard (accurate, bold, and concise) crew callouts to actively monitor drift, height, power, and trend. 
• A shared mental model of how the dust or snow cloud will develop and where visual references are expected to disappear (e.g., a crew member in the door calling the approach of the cloud). 
• Mental rehearsal of transitions so that when references are lost, the crew already knows how they will respond—together. 

Pre-Flight Planning and On-Scene Assessment 

Brownout and whiteout risk management begins well before the aircraft is enveloped in a cloud. Operators outside of hostile environments often have advantages that combat crews do not: additional time for planning or on-scene assessment, greater flexibility, and often the ability to choose an alternate landing zone with less potential for DVE. These advantages should be deliberately exploited. 

Landing Zone Assessment 

Fine sand, dust, or powdery snow will result in recirculation. If there is an opportunity to select a surface that is more tightly compacted—gravel, grass, packed snow, or hardened ground—it can significantly decrease and delay obscuration. 

Wind Considerations 

Plan to approach into the wind or with a crosswind that blows the obscurant to the opposite side of the helicopter from the flying pilot’s field of view whenever possible. Even light winds help carry dust or snow away from the cockpit and preserve visual references. Any downwind component will do the opposite and should immediately elevate concern. 

Go-Around Planning 

For every approach with brownout or whiteout potential, the crew should be spring-loaded to wave off or go around. Before descent: 

• Pre-brief the escape path. 
• Consider terrain, obstacles, and power margins. 
• Be mentally and procedurally prepared to execute a go-around without hesitation. 

A delayed go-around is often more dangerous than an early one. 

Crew Briefing 

Hard-earned lessons learned emphasize the importance of clearly establishing: 

• Pilot flying duties and actions and pilot monitoring duties and actions. 
• How drift, height, power, and trend will be monitored and articulated. 
• What standard callouts are expected from non-flying crew members. 
• Most importantly: empowering all crew members to call for a go-around. 

Choosing the Right Approach 

Selecting the right technique for the conditions and executing it with discipline and a shared mental model is critical to a safe and efficient landing in a potential degraded visual environment. Regardless of technique, two principles are universal: 

1. Stabilize early – Approach the landing on a consistent profile with minimal drift. 

2. Go around immediately if unstable – Hesitation after references degrade and stability is lost is a recurring factor in accidents. 

Commonly Used Techniques: 

1. No-Hover Landing – This technique minimizes time in the dust by keeping the cloud behind the aircraft until touchdown. Ideally, the cloud reaches the pilot’s field of view as the helicopter is settling onto the ground. Pilots with combat experience have trained me in this technique. The timing and profile necessary to avoid an early brownout requires training, precision, and carries increased tail-strike risk in some aircraft types. While effective in hostile environments landing on consistent surfaces (a reasonable slope without without uneven terrain that will damage the undercarriage of the aircraft), I generally do not recommend this technique for most civil SAR operations, as it requires extensive practice and high levels of whole-crew coordination. 

2. Slow Run-On Landing – This approach keeps the dust or snow cloud aft through touchdown, simplifies a go around, and allows a more stable profile to touchdown, but it relies heavily on the appropriate surface and adequate landing distance. I have used this technique at remote, unplowed airfields—flying down the runway at a speed that keeps the snow cloud behind the pilots’ field of vision and slowly rolling onto snow-covered pavement. 

3. High Hover with Vertical Descent – A highly controlled option that demands HOGE power. Rotor wash initially generates significant dust or snow, but if there is hard-packed ground or a crust layer beneath, the cloud may dissipate with patience. Because civil SAR does not include adversary threats, this is often my preferred technique for off-airport DVE landings when HOGE power is available. Starting high and descending slowly can eliminate the need to fly in a DVE altogether. Descend too quickly, and total obscuration may occur—requiring an instrument takeoff (ITO). 

4. Low Hover and Land – This technique is used when landing off-airport in an unprepared LZ with uncertain surface quality and insufficient HOGE power to hover down patiently. It requires one or more fixed, reliable references near the intended touchdown point—such as a sturdy low pine (below rotor height) or a distinct, immovable rock with sufficient contrast. The approach is flown so the reference is placed just outside the pilot’s window, allowing stabilization in a low DVE hover before a slow, deliberate landing necessary for the unprepared surface. The major threat is losing this reference low to the ground, requiring an instrument takeoff near terrain and obstacles. It can be optimal to combine techniques by harnessing close in references for a low hover at the bottom of the high hover with a vertical descent approach.

Final Thought 

Brownout and whiteout accidents rarely result from a single error. They are most often the outcome of an unanticipated degraded visual environment, insufficient DVE evaluation, delayed go-around decisions, undetected drift, and breakdowns in crew coordination. 

Through anticipation, planning and briefing, disciplined execution of the appropriate technique, effective crew communication, and a shared commitment to early go-arounds, helicopter crews can operate safely—even when visual cues disappear.