DALLAS – Turbulence in flight is the phenomenon involving the airplane’s irregular, annoying and unpredictable motion causing it to fly in an undesired attitude, altitude, and direction.
If this situation is severe and uncontrolled, it can cause injuries to passengers and crew and damage the airframe.
Various factors cause turbulence, including:
Thermal heating on the earth’s surface by solar radiation on a hot sunny day warms the air, making it less dense and rising vertically into the atmosphere. The rising air mixes up with the air above, leading to a turbulent airflow/wind, which can alter an aircraft’s flight path in severe cases.
Wake Vortex that trails from the wing tips of larger, heavier, and low-speed aeroplanes causes turbulent air, which poses a danger to any lighter aircraft following. To minimize the effect of wake turbulence, air traffic controllers (ATC) allow enough time for the vortex to dissipate by the appropriate separation between those departing. In the case of landing aircraft, controllers apply a safe distance between aircraft on approach.
Solid terrain, such as tall buildings and trees near the approach and takeoff, causes the wind to change direction and speed, creating vortices near the ground. These vortex systems impact turbulence on airplanes during takeoff and approach. This is called mechanical turbulence.
Mountain ranges cause the wind to flow perpendicular to it as it oscillates like a wave and can result in turbulence up to the lower stratosphere (the second layer of the atmosphere). Such waves pose a great turbulence danger to an airplane approaching the mountain from the leeward side.
Thunderstorms are associated with up-and-down movements of air currents, which cause turbulence when the aircraft enters them. The turbulence associated with thunderstorms exists even outside the storm, up to 50 miles in its vicinity. Pilots frequently alter headings to avoid areas of bad weather.
How Pilots Deal With Turbulence
Turbulence can be unnerving to passengers. But it’s not dangerous and is often more of an inconvenience than a safety issue.
If turbulence happens or is expected in any phase of flight, pilots are trained to deal with it in the following ways:
Use of seat belts
To avoid passengers being shaken back and forth or hitting their heads, seat belts should be left loosely fastened at all times. It’s very important to keep your seat belt on even when the seat belt sign is off. However, pilots will always turn on the seat belt sign when turbulence is expected.
If turbulence worsens, the captain will inform the cabin crew through the public address system (PA) to take their seats and put on seat belts.
Analyzing SIGMET chart
Pilots analyze SIGMET (Significant Meteorological Information) reports to plan and prepare for necessary actions if they encounter hazards like turbulence. SIGMET features Jet streams, thunderstorms, heavy clouds, turbulence reports and Icing
Use of Weather Radar
Weather Radar can detect precipitation and thunderstorm clouds, as they are associated with turbulence. Pilots use weather radar and coordinate with ATC to avert away from thunderstorms and heavy clouds.
PIREP is a pilot’s report of the preceding aircraft to the following pilots flying in a particular airspace. When pilots encounter turbulence, they report its intensity, location, time, altitude, and aircraft type so that the following pilots can adjust their height or track to avoid it. A pilot may ask clearance from the ATC to climb or descend to avoid reported or experienced turbulence.
Radio Transmission Frequency (RTF) and TCAS Display Monitoring
Traffic Alert and Collision Avoidance System (TCAS) display and designated RTF monitoring help awareness and enable pilots to be more proactive in asking ATC for assistance in avoiding wake vortex turbulence from other aircraft.’
“Liftoff before and land beyond” technique
When an ATC gives a wake turbulence caution to a pilot taking off or landing behind a larger aircraft, a pilot will be alert and avoid wake turbulence.
On the final approach and behind larger aircraft, the pilot of a smaller general aviation aircraft stays at or above the larger aircraft’s final approach path and aims to land beyond its touch-down point, provided the remaining landing distance is adequate to bring it to a stop.
Airliners must plan their landing within the touch-down zone markings at the beginning of the runway. Controllers will vary the distance between landing aircraft based on the preceding and the following aircraft size.
Mountain Wave Avoidance
When pilots expect to encounter turbulence when flying in mountainous areas, they usually plan to fly at least 50% higher than the height of the mountain peak above the surrounding base of terrain to provide an adequate margin of safety and recovery if strong turbulence is encountered.
Also, pilots approach mountain ranges at a 45-degree angle to make an immediate escape turn if severe turbulence is encountered and avoid the leeward side of the mountain ranges where strong downdraft may prevail.
Penetrating the turbulence
It is not possible for pilots to avoid flying in turbulence, such as in areas around the equator, areas with tall buildings that disturb the wind, or on a hot afternoon with a marked inversion.
Do not worry! Pilots are professionally trained to bring you safe and comfortable flights. In such instances, pilots establish and maintain engine power settings to obtain and fly turbulence penetration speed and maintain level flight until the airplane gets out of turbulence.
Averting Passenger Fears
In the event of turbulence, I advise passengers to remain calm and fasten their seat belts any moment the seat belt sign is on or they are instructed to do so by the cabin crew. Fastening seat belts minimizes the chances of injury during severe turbulence.
Also, have faith in your pilots because they are highly skilled, expertly trained and equipped with modern technology to fly through or avoid turbulence.
I wish you safe and enjoyable flights.
Featured Image: Turbulence can be an unnerving experience for airline passengers but pilots and cabin crew are trained to deal with whatever the weather throws at them. Photo: Fabrizio Spicuglia/Airways.