That does not mean the heat caused this crash. The BEA report does not establish such a conclusion. It simply provides the environmental measurements that investigators must consider when reconstructing the aircraft's performance.
The aircraft's calculated take-off distances were also compared with the actual flight data. The report found that the theoretical distances were consistent with the distances recorded during the accident flight.
At first glance, the available information suggested that the aircraft had begun the take-off within normal operating conditions.
Then came the first warning from inside the cabin.
Chapter 2: βThere's Smoke!β β The First Warning Before the Crash
The most striking detail in the preliminary report is the moment when an instructor noticed something unusual inside the aircraft.
During the take-off rotation, as the aircraft was accelerating and preparing to leave the runway, an instructor seated toward the rear shouted that there was smoke.
He pointed toward the front-right area of the cabin.
The pilot did not appear to hear the warning and continued the take-off.
A second instructor, seated in the middle of the aircraft, then also shouted that there was smoke. He pointed toward the same general area, near the floor.
The two instructors agreed to partially open the side door to ventilate the cabin.
This sequence is central to the investigation because it establishes that more than one person reported a possible smoke problem before the aircraft lost control.
It also creates a difficult question: if smoke was present, why could investigators not see it in the available recordings?
Two separate warnings
The fact that two instructors independently reported smoke is important.
A single observation can sometimes be mistaken. Light reflecting from a surface, dust, vapor, or an unusual smell may be interpreted incorrectly in a stressful environment.
But when two people point toward the same general area and report the same problem, investigators must take the reports seriously.
The instructors were familiar with parachuting operations and the aircraft environment. Their warning was not a casual comment. It was an observation made during a critical stage of flight.
The BEA report records their words and actions but does not determine what substance or condition they were seeing.
The distinction is crucial. The preliminary report establishes that smoke was reported. It does not establish that investigators found visible smoke in the cabin or identified its source.
Why the side door was partially opened
The instructors agreed to open the side door slightly to ventilate the cabin.
From their perspective, the action was an attempt to improve the conditions inside the aircraft. If smoke was present, opening the door could help remove it or reduce its concentration.
However, opening an aircraft door during take-off or flight is not an ordinary action. The effect depends on the aircraft's design, the door configuration, airflow, and the phase of flight.
The BEA report describes the decision but does not state that opening the door caused the accident.
It would therefore be inaccurate to claim that the instructors' action was responsible for the crash. The investigators must establish the sequence of events and assess whether the door's position had any measurable effect on the aircraft's behavior.
This is one of the details that makes the preliminary findings so important: they reveal what happened, but they do not yet provide a complete explanation of why it happened.
The pilot may not have heard the first warning
According to the BEA, the pilot did not appear to hear the first instructor's shout.
That wording should be treated carefully. It does not necessarily mean the pilot ignored the warning. The report describes what investigators could infer from the available evidence.
During take-off, pilots are dealing with engine power, aircraft speed, runway alignment, control inputs, and the transition from ground movement to flight. The cockpit environment can also be noisy.
A warning from the rear of a cabin may be difficult to hear, particularly if the aircraft is accelerating and the engine is operating at high power.
The second warning came from another part of the cabin, but the report does not provide evidence that the pilot had enough time to understand the situation and respond before the aircraft's performance began to change.
The available sequence indicates that the aircraft continued its take-off and then experienced a significant reduction in engine gas-generator speed.
The engine parameters suddenly changed
Shortly after the smoke warnings, the gas-generator speed, identified in the report as Ng, decreased by approximately 10 percent.
At around the same time, the propeller speed, identified as Np, briefly fluctuated before returning to its nominal value of 2,000 revolutions per minute.
The change in Ng was particularly significant because the report states that the reduction had not occurred during the five preceding take-offs that investigators compared with the accident flight.
The BEA also states that the Ng value remained stable after the reduction until the end of the available recording.
At the time of the preliminary report, investigators had not determined whether the decrease was commanded or occurred because of a malfunction.
That distinction is important.
A commanded reduction would mean that the engine setting changed as a result of an input or control action. A reduction that was not commanded could indicate a mechanical, fuel-related, or other technical problem.
The preliminary report does not establish which explanation applies.
Understanding Ng and Np
The two engine parameters may sound highly technical, but they help explain why investigators are examining the aircraft's engine so closely.
Ng refers to the speed of the gas generator within the turboprop engine. The gas generator is a central part of the engine's operation, producing the hot gas flow that drives the turbine.
Np refers to the rotational speed of the propeller.
In a turboprop aircraft, the engine and propeller work together to produce thrust. A change in gas-generator speed may affect the engine's ability to deliver power, while propeller speed provides another important indication of how the propulsion system is operating.
A brief fluctuation in propeller speed does not automatically identify the cause of a malfunction. It must be considered alongside other recorded parameters, physical examinations, and the engine's condition.
The BEA's preliminary findings show that the propulsion system experienced an unusual change during the take-off sequence. They do not yet identify the exact failure mechanism.
Why the smoke and engine changes matter together
The timing of the smoke warnings and the engine parameter changes is one of the most important aspects of the case.
The instructors reported smoke in the front-right area of the cabin. Soon afterward, the engine's gas-generator speed fell by approximately 10 percent.
That sequence raises the possibility that the two events were connected.
For example, an issue in the engine compartment or a system near the forward cabin could potentially produce both a visible or perceived smoke condition and a change in engine performance.
But this remains a line of investigation, not a confirmed explanation.
The investigators need to determine where the reported smoke originated, whether it was actually smoke, and whether the engine's performance change was caused by the same underlying problem.
The preliminary report specifically says that the origin of the reported smoke had not been established.
The mystery of the missing smoke in the recordings
One of the most puzzling findings is that none of the examined videos showed visible smoke escaping from the aircraft.
The BEA examined five GoPro cameras carried by the instructors. The recordings began during taxiing and continued through the take-off sequence until the loss of control. Some footage showed the cabin interior, while other sections showed the outside of the aircraft.
No visible smoke was identified in the recordings.
Investigators also obtained video from a witness on the ground, a surveillance camera, and a moving vehicle. Those recordings likewise did not show smoke coming from the aircraft.
This does not automatically prove that the instructors were mistaken.
Smoke may be difficult to see depending on its density, color, lighting, location, and the camera angle. A small amount of smoke near the floor may not be clearly visible in a recording, particularly if the camera is facing another direction.
The cameras may also have been unable to capture the precise area where the instructors pointed.
There is another possibility: the instructors may have observed something that looked like smoke but was not smoke from a fire.
The investigation must consider all of these possibilities.
The fact that no visible smoke appears in the footage is a significant finding, but it is not enough by itself to dismiss the eyewitness reports.
The last recorded moments
The aircraft's recorded flight parameters provide another important piece of the story.
The BEA used data from a Garmin GI-275 electronic flight instrument, as well as information extracted from the GoPro recordings.
The aircraft initially accelerated and rotated in a way that was similar to the two preceding flights. The rotation occurred at approximately 60 knots.