Loss of control in flight (LOC-I)

N.B: For up-to-date information on LOC-I events, change language selection to Finnish. 

Loss of Control in Flight 2023

In 2023, 15 cases of loss of control in flight were reported. The number was below the average of 2013-2022 (18.3) and roughly one half of the number of the previous year. Most of the cases occurred in drone operations, as in the previous years. 

In manned aviation, there were six losses of control reported, which was slightly below the average for 2013-2022 (7.6). The situations occurred in recreational aviation, commercial air transport and general aviation. One of the cases was classified as an accident and one as a serious incident. As for the accidents, their number was clearly below the average of the previous years (approx. 5), and more or less at the average concerning serious incidents. 

In commercial air transport, LOC-I cases are rare. Two situations of this kind occurred during the year. They involved a very brief loss of control due to a sudden downdraft in or close to a thundercloud. 

In general and recreational aviation, there were four LOC-I cases, which is below the average for the years 2013-2022 (6). 
One of the cases led to an accident, when the control of an ultralight was lost due to the motor shutting down and the pilot had to carry out an emergency landing in a stand of pine. Another was classified as a serious incident, in which the wing of a general aviation aircraft on a test flight struck the runway after a sudden gust of wind tilted the aircraft.

In general and recreational aviation, the number of LOC-I cases has been decreasing for a long time. This is a good trend for overall safety, because LOC-I situations often lead to accidents. The collision energy in these type of accidents is high, which means that they often lead to loss of human life.

The investigation  (External link)by SIA into the fatal accident during an aerobatic show in Selänpää last year is still ongoing. So far the case in question has been classified as CFIT, but if the investigation finds that it was a LOC-I situation, the event type will be specified. 

Drone operations involved the largest share of LOC-I cases reported last year, nine cases. However, this number was clearly below the average and amounted to approximately one third of the figures for the previous year. A large number of cases involved losing control of a DJI Matrice 300 RTK device for a variety of reasons. There is a degree of uncertainty in statistics on drone operations, because the number of operators is large and it is likely that the level of awareness of the reporting criteria varies. Specifications to the reporting criteria are also expected from the European Union Aviation Safety Agency EASA during 2024. 

Types of incidents that contribute to LOC-I events

In addition to the cases described below involving laser interference, bird strikes or fire and smoke, other types of situations to be monitored that may contribute to the loss of control in flight include being under or over the aircraft’s speed limit, incidents due to a wake vortex, deficiencies in deicing and anti-icing, faults in the flight control systems and different kinds of loading errors, such as the placement of the load contrary to the loading instructions or errors in the attachment of the load or weight calculations.

Of the types of cases mentioned above, ones reported numbering above the average in 2023 included low speed and high speed cases. In many cases an aircraft carrying out commercial air transport was involved, but the events did not have any serious consequences. A very typical case involved speed momentarily exceeding the limit values specified due to weather conditions such as turbulence or a gust of wind. A large share of the cases occurred during the approach, when the speed of the aircraft, for example, momentarily exceeded the speed limits for the use of flaps. Several situations in which the limits were exceeded momentarily in a strong tailwind were also reported during the cruise phase of the flight. 

A slightly above-average number of cases related to loading the aircraft were also reported. In such situations, for example, the actual loading of the aircraft was carried out in a way different from what was required in the loading instructions, the load was tied incorrectly or insufficiently, or the actual weight of the load and the weight recorded in the weight calculations differed from each other. However, the cases did not have any serious consequences. Deficiencies such as poorly secured load are often observed only at the destination (typically at Helsinki Airport) when the aircraft is being unloaded. In other words, the actual mistake may have been made at the departure airport, usually abroad.

As a positive observation in 2023 it can be noted that the number of deficiencies in deicing and anti-icing reported was clearly lower than in the previous year, and the figure was now at the same level as the average. Ice accumulating on the surfaces of the aircraft may have a significant impact on its flying characteristics, and in the worst case, it may lead to loss of control of the aircraft.
In the autumn of 2023, Traficom published updates to the winter operations bulletins, in which icing and its prevention have also been described very comprehensively. Bulletin (PDF)  (External link)targeted at airlines and bulletin  (External link)for general and recreational aviators.

Laser interference

A detailed review of laser interfence situation is available here (External link). 

Bird strikes

A detailed review of bird strikes and an interactive report of them is available here (External link). 

Fires and smoke detection on aircraft

One of the indicators pertaining to aircraft loss of control that is monitored by Traficom is fires or smoke detection on aircraft. A fire on an aircraft is a situation which may quickly lead to the loss of control and destruction of the aircraft.

There were 10 smoke detections reported in 2023, which is exactly the average for 2013-2022. In most cases, there was merely smoke detection in the cockpit or cabin, but no actual fire. To ensure safety, many such cases led to the flight diverting to the closest suitable aerodrome. In one of the cases during the second quarter, the smoke formation was so strong that the passengers were evacuated from the aircraft.

Several cases in which a passenger smoked in the toilet of the aircraft were reported last year. These cases also include the use of electronic cigarettes. There were no serious consequences from the cases, but due to the risk of fire, both regular smoking and the use of electronic cigarettes are prohibited. Last year, one case of smoking led to a fire in the toilet of the aircraft. Fortunately, the fire could be extinguished quickly.

In October, Traficom published a bulletin  (External link)concerning unruly passengers. Smoking on the aircraft is also one of the types of such behaviour. 

Tieto.traficom also has an overview of cases related to disruptive passengers (External link).