Aircraft Operators and Occupants Can Predict and Prepare for Turbulence Encounters despite Increasing Prevalence of Extreme Weather Phenomena

The Safety In­ves­ti­ga­tion Au­thor­ity of Fin­land (SIAF) has com­pleted an in­ves­ti­ga­tion into a se­ri­ous in­ci­dent on a flight op­er­ated by Nor­we­gian on Au­gust 11, 2024. The air­plane en­coun­tered tur­bu­lence dur­ing land­ing prepa­ra­tions on a night ser­vice from Rhodes, Greece, to Helsinki, Fin­land, re­sult­ing in in­juries to two cabin crew mem­bers. It landed at Helsinki air­port with­out fur­ther in­ci­dent.

The cabin crew was unaware of a thunderstorm or possible turbulence along the airplane’s route. The flight crew requested a change of route, initially to catch up with the schedule, and subsequently for thunderstorm avoidance. Despite the captain’s intention to avoid the cloud by deviating to the east, the aircraft penetrated the top of the developing cloud in an area where it was subjected to violent vertical currents. Cabin members in the aft section of the airplane became repeatedly weightless and hit aircraft structures.

“The pilots’ situational awareness was based on meteorological information received several hours earlier at the airport of departure, i.e. Rhodes. This data showed only isolated rain showers and thunderstorms moving to the east over Estonia. Therefore, their awareness regarding thunderstorms and the weather front was deficient. Because Norwegian’s Boeing 737-MAX 8 airplanes do not have provisions for updating an en-route weather forecast received at the departure aerodrome, only on-board weather radar picture and meteorological information from the aircraft’s communication addressing and reporting system, or ACARS, are available to the pilots,” explains the investigator-in-charge Janne Kotiranta.

“In a way, there was a silver lining in the investigated incident because most passengers were already seated and strapped-in when the disturbance occurred. They had previously been instructed to fasten the seat belts for landing,” Kotiranta adds.

Turbulence can be avoided by keeping an adequate distance from a thunderstorm during deviation. However, company procedures do not prescribe a clearance to the clouds during thunderstorm avoidance. The SIAF recommends that the airplane operator defines minimum clearances and procedures for thunderstorm avoidance.

The report also found that company training syllabi do not give insufficient attention to communications between pilots and cabin crew during turbulence-related events. The company had previously experienced similar turbulence-related occurrences that had taken the cabin crew by surprise. The SIAF therefore recommends that the company improves crew training on communication between pilots and cabin crew.

“Even though research indicates that climate change is increasing the prevalence of turbulence and other extreme weather conditions, people should not avoid boarding an airplane; however, once seated, keep yourself buckled-up, and you’ll be safe,” Kotiranta stresses.