The dangers of poor weather conditions for helicopters

By Ing. Benjamin OWUSU

Rotary-Wing Aircraft or Helicopters play a vital role in a wide range of aviation industries, some of the helicopter services are:

(1) Emergency Medical Services (both Civilian and Military Operations)

(2) Commercial Transport (for Charter Services)

(3) Law Enforcement (for Police, Military, Customs & Excise, Immigration, and Fire Service duties)

However, unlike Fixed-Wing Aircraft or Aeroplanes, helicopters are particularly vulnerable to unfavourable weather conditions.

Flight Crew and Passengers on board a helicopter are likely to face significant risks when flying in such unfavourable weather conditions.

Why Poor weather increases the risk of helicopter accidents  

Flight Crew or Pilots are highly trained to handle various weather-related issues or challenges, but poor weather conditions significantly increase the risk of pilot disorientation, mechanical strain, and decision-making errors.

When visibility is low, pilots must rely more heavily on instruments, which requires specialised training and quick reaction times.

Adverse weather also places additional stress on helicopter components, potentially leading to malfunctions or failures in mid-flight.

The pressure to complete missions under high-risk circumstances (Poor Weather Conditions) can lead to poor judgement calls, increasing the risk of weather -related serious incidents or accidents.

Weather Hazards That Pose a High Risk to Rotary Wing or Helicopters

In Ghana, the following are identified as weather hazards that present a risk to Rotary-Wing Aircraft or Helicopters:

• Low Visibility and Fog
• High Winds and Turbulence
• Thunderstorms and Lightning
• Heavy Rain and Flooding

It is therefore prudent to understand these hazards and take appropriate precautions.

(Low Visibility and Fog: Rotary-Wing or helicopters normally rely on Visual Flight Rules (VFR) under clear weather conditions for visual navigation. This means that, the pilots navigate using outside visual references rather than relying solely on instruments for safe operations.

However, thick fog or heavy rain can reduce visibility drastically to dangerous levels, increasing the risk of Controlled Flight into Terrain (CFIT) accidents. This means that pilots may struggle to navigate obstacles, other aircraft or terrain if sightlines are not clear. So, Instrument Flight Rules (IFR) training and equipment are essential in such conditions.

High Winds and Turbulence: Generally, helicopters operate at lower altitudes and are more vulnerable to sudden wind shifts. Furthermore, high winds, turbulence, and downdrafts can make it difficult for pilots to maintain control, especially when hovering or landing.

 Thunderstorms and Lightning: Thunderstorms present multiple hazards to rotary-wing aircraft or helicopters, including the following; severe turbulence, wind shear, hail and lightning strikes.

Even though rotary-wing aircraft or helicopters are designed to withstand lightning, a direct strike can cause significant electrical system failures, damage avionics, and compromise flight control systems. Pilots must avoid flying in or near thunderstorms whenever possible due to unpredictable nature of storm cells which are individual thunderstorm units that can develop into larger storm systems.

Heavy Rain and Flooding: Excessive rain impacts visibility and also affects engine performance. This is because, water ingestion into engine intakes may lead to power loss, reducing a rotary-wing aircraft or helicopter’s ability to sustain flight.

Safety Measures for Helicopter Operations

The following are factors to be considered for safe operations of helicopters in Ghana:

• Pre-Flight Weather Assessment
• Instrument Flight Training
• Avoidance of High-Risk Weather
• Advanced Avionics and Safety Equipment
• Proper Maintenance Procedures

(i) Pre-Flight Weather Assessment: Flight Crew must thoroughly evaluate weather conditions before departure by using up-to-date meteorological reports and forecasts.

(ii) Instrument Flight Training: Pilots must be adequately trained in IFR to help them to safely navigate poor visibility conditions.

(iii) Avoidance of High-Risk Weather: If weather conditions deteriorate beyond safe operational limits, pilots should delay take-off or seek an alternative route or cancel the scheduled flight.

(iv) Proper Maintenance: Regular inspections and compliance to Approved Maintenance Programme (in the case of civil aircraft) or Maintenance Planning Document (in the case of military aircraft) can mitigate the possibility of a helicopter experiencing mechanical failure due to bad weather exposure.

The writer heads Crawley Aviation Consult