How bad weather affects aviation and investigations into aircraft disasters

Weather conditions around Mount Kenya and Aberdare forest are perhaps the harshest when it comes to flying a light aircraft in Kenya.

As such, it has witnessed more plane mishaps compared to other regions.

Towards the end of 2007, Major (Rtd) Solomon Nyanjui, then the head of Kenya Wildlife Service airwing, survived an eight-day ordeal when the helicopter he was flying developed mechanical problems and crashed in Mount Kenya Forest.

Two years earlier, he had crash-landed not far from the Aberdare in another case of mechanical failure.

While the two incidents were directly linked to bad weather conditions, the Meteorological department often warns pilots of small planes against getting too close to the landmasses, especially in times of adverse weather.

Mount Kenya is Africa’s second highest peak and is usually misty most of the year. The weather around the Aberdare Ranges is no different.

Big role

According to an aviation expert, while the weather could have played a big role in the crash of the small, propeller-powered Cessna C208 in the Aberdare, the final approach route to Jomo Kenyatta might also have been a factor.

Investigators need to also establish the kind of on-board weather detecting equipment the plane had.

A pilot, who has flown around such terrain for years states, that under normal circumstances, an air traffic controller will not lead a pilot into an area with the kind of terrain such as that around Mount Kenya and the Aberdare.

“The two regions are risky. It requires a pilot who knows the area very well to overfly this section. Even the big jets from Jomo Kenyatta International Airport are usually given enough clearance to avoid the two mountains,” says Captain Antony Kiroken who has flown both fixed wing planes and helicopters for 19 years.

In aviation, the entire world is divided into different sectors with a particular segment requiring a certain flying altitude.

Kiroken says usually, a pilot will request for a particular route upon takeoff depending on his final destination. The normal route to approach the country’s main airport as well as Wilson Airport is through the Ngong Hills.

“At this point we should assume that she knew the terrain well,” he says.

Modern planes too are equipped with weather-detecting equipment that should clearly “see” further through the haze and cloudy conditions. Planes that are more specialized can detect such adverse weather and related turbulence.

“With a good on-board computerized system coupled with a pilot’s knowledge of local weather patterns, it is possible to detect some adverse climate. Modern planes are also equipped with advanced tracking devices that should make search and rescue activities much easier,” says Kiroken.

While the best course of action is to avoid adverse weather altogether, experts say not all thunderstorms can be detected by the onboard equipment.

“Despite their often dramatic visual characteristics, thunderstorms can be difficult to see from the cockpit. Thick haze can make them hard to spot, and powerful convective activity can hide inside banks of normal, innocent-looking clouds,” states Safety Advisor, a rough guide to common aviation risks published in the US.

Radar (acronym for radio detection and ranging is the most common method for detecting adverse weather. It works when a weather station sends out a signal of microwave energy in all directions.

When the signal hits a solid object such as raindrops, it is reflected back and by measuring the elapsed time, it can determine the distance of the object.

But this system has limitations too.

For example, the signal may not detect clouds that have no precipitation. In addition, it may not work well in lower altitudes or mountainous regions that can block the signal.

The effects of adverse weather on a plane are numerous.

“In some parts of the world, pilots have been slammed violently against seatbelts, airplanes have emerged from thunderstorms with doors blown off, leading edges smashed in, windshields broken out,” says the aviation safety guide.