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INVESTIGATION REPORT

The BEA investigations are conducted with the sole objective of improving aviation safety and are not intended to apportion blame or liabilities.

BEA2018-0571.en/February 2021

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Accident to the AYRES - S2R - T34 Turbo Thrushregistered F-GOKZon 08 August 2018at Diatar (Mauritania)

Time Around 05:50(1)

Operator MIDAIRType of flight Aerial workPersons on board PilotConsequences and damage Pilot fatally injured, aeroplane destroyedThis is a courtesy translation by the BEA of the Final Report on the Safety Investigation published in November 2020. As accurate as the translation may be, the original text in French is the work of reference.

(1)Except where otherwise indicated,

times in this report are local.

ORGANIZATION OF THE INVESTIGATION

In accordance with Annex 13 to the Convention on International Civil Aviation, Mauritania, as state of occurrence, opened a safety investigation and set up an investigation committee.

The president of the investigation committee delegated the safety investigation, by letter dated 15 August 2018, to the French civil aviation safety investigation authority, the BEA. The investigation was carried out with the participation of the Mauritanian and Senegalese safety investigation authorities, each authority having appointed an accredited representative. Although the accident occurred in Mauritania, the flight was to have been exclusively carried out in Senegal and concerned French and Senegalese organizations.

The report was the subject of an official consultation with the Senegalese and Mauritanian accredited representatives.

Collision with ground during a night flight for an aerial spraying mission

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1 - HISTORY OF THE FLIGHT

Note: the following information is principally based on data from the onboard GNSS receiver and statements.

The pilot took off at 05:40 at night(2) from dirt runway 33 at Podor aerodrome (Senegal) for a crop spraying mission in a region of Senegal situated at around 80 km east of the aerodrome.

Around 05:50(3), the aeroplane collided with the ground in a field situated on the right bank of the Senegal River, in Mauritania, close to the district of Diatar.

Figure 1: Accident flight path

2 - ADDITIONAL INFORMATION

2.1 Site and wreckage information

Note: the site examinations were limited to observations and the taking of a few samples due to the dangerous nature of the spray product spread over the accident site and the wreckage.

The site of the wreckage was located in a field at around eight kilometres south-east of Podor aerodrome.

(2)The aeronautical night comes to an end

15 minutes before sunrise between the

latitudes 0° et 30°. At Podor, the day of

the accident, sunrise was at around 06:40.

(3)According to aural witnesses in

a village close to the accident site.

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The debris was dispersed over a distance of around 125 m and a surface area of 1,700 m². The point of impact and the debris were oriented on a 330° heading. The path of the plane before the impact was thus in the opposite direction to the planned route to get to the spraying zone, and was in the direction of the threshold of runway 33 of Podor aerodrome.

Source: BEAFigure 2: Distribution of debris from F-GOKZ

Debris was located close to a tree before the point of impact. It was probably the result of the left wing of the aeroplane colliding with the tree.

The wings and the rear part of the airframe were located around 80 m after the point of impact.

A detailed examination of the wreckage could not be carried out on site. Nevertheless, the following observations were made:

� the aeroplane was complete on impact with the ground; � the rudder and elevator controls were continuous; it was not possible to check the

continuity of the roll controls; � the damage observed on the propeller seemed to indicate that the engine was

operating at the time of impact.

The photos taken on site were sent to Pratt and Whitney Canada, the engine manufacturer, who confirmed that the engine was operating at the time of impact with the ground.

The fuel flow control lever was found in the “shut-off” position. The aircraft manufacturer indicated that the lever could only be put in this position by manually unlocking a safety device. The investigation was not able to determine whether this action had been carried out by the pilot before the accident or by an outside person after the accident.

Due to the access difficulties to the accident site, it was not possible to recover and move the engine. No other engine examination was carried out and it was not possible to evaluate the power output from the engine at the time of impact.

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Blades missing from the turbine were not found on the site. The cause of this damage was not determined.

The aeroplane tank contained 129 l of spray product which corresponded to approximately 82 kg of pure Fenthion (see §2.5 and §2.9). This quantity of spray product could treat approximately 25 ha of farmland. All of the spray product was dispersed when the aeroplane collided with the ground. It was not possible to determine the surface area of the contaminated ground.

2.2 Aerodrome information

Podor aerodrome is situated in the Saint-Louis region, in the north of Senegal, at around 1 km from the Senegal River which constitutes the border with Mauritania. It has a dirt runway oriented 15/33 measuring 1,560 m in length. The aerodrome’s altitude is 20 ft (6 m).

The aerodrome does not have an aerodrome control service or a weather station. It does not have night lighting.

2.3 Pilot information

The 66-year-old French pilot held an aeroplane commercial pilot licence issued by the French civil aviation authority in 1978 along with single-engine piston (land) and Snow/Ayres single-engine turbine class ratings. He held a night flight rating.

He also held a helicopter commercial pilot licence issued in 1981.

He had logged more than 6,000 flight hours as pilot-in-command on aeroplanes and close to 5,000 hours as pilot-in-command on helicopters.

The pilot was the manager of the French aerial work company, MIDAIR. The latter owned F-GOKZ.

2.4 Meteorological information

A witness situated in the village close to the accident site indicated that it was pitch-dark at the time of the accident, the wind was calm and there was no precipitation.

On the day of the accident, sunrise at Podor was at around 06:40(4).

2.5 Aircraft information

The aeroplane registered F-GOKZ was an S2R T34 built by the American manufacturer, Ayres Corporation (Thrush Aircraft today), and specially designed for agricultural work. It was equipped with a PT6A-34AG turboprop designed by Pratt and Whitney Canada.

The day of the accident, the aircraft was carrying 129 l of avicide. The estimation of the weight and balance made during the investigation found that they were within the manufacturer’s recommended envelope.

(4)Official sunrise time according to the

2018 astronomical calendar.

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The aeroplane held an airworthiness review certificate renewed on 5 June 2018. The continuing airworthiness and maintenance of the aircraft were ensured by an approved maintenance organization. The pilot was the manager of this organization. The aeroplane’s maintenance documents showed that the pilot had carried out the 100-hour maintenance inspection of the airframe and engine on 22 June 2018 at Saint-Louis, Senegal. At the date of this inspection, the aeroplane had logged an operating time of 6,223 hours. The work performed had not found any anomaly and the aircraft was considered ready to be returned to flight without carrying out a checkout flight on the completion of the work.

2.6 Examination of GNSS receiver

The aeroplane was equipped with an AG-NAV GNSS receiver. It is regularly used in the scope of spraying missions as it allows the pilot to programme the different positions of the target fields.

This receiver was recovered from the accident site by the investigation team and examined by the BEA. The data read out made it possible to reconstruct part of the accident flight path. The path stops after a flight time of eight minutes, at around nine kilometres from the accident site. It was not possible to determine why the last minutes of data were not recorded. Neither was it possible to determine if, despite this absence of recorded data, the GNSS receiver was still operating on the aircraft.

The analysis of the path of the occurrence flight found that F-GOKZ took off at 05:40 from runway 33 of Podor aerodrome. The aircraft then made a left-hand U-turn and established a cruising altitude of 380 m (refer to Figure 1). The last recorded positions indicate that the aircraft was en route and its speed was stabilized at around 200 km/h.

2.7 Medical and pathological information

An autopsy was carried out on the pilot’s body at Nouakchott (Mauritania). The examination report indicated that the pilot died as a result of the aeroplane’s collision with the ground.

Additional toxicological examinations were carried out and found a very low concentration of Fenthion in the pilot’s urine and blood showing that the latter had not suffered an intoxication likely to cause an incapacitation while flying.

2.8 Spraying mission information

A service provision contract had been signed between the French company, MIDAIR, owner of the aeroplane, and the Senegalese company, Air Technical Services (ATS), to treat and spray crops. This mission was carried out for the Directorate for Plant Protection of the Senegalese Ministry of Agriculture.

In the scope of this contract, MIDAIR was solely responsible for providing the aeroplane and the pilot. ATS, the mission operator, was responsible for defining the zones to be treated and organizing the associated flights. ATS agents were present at the aeroplane’s take-off site in order to, in particular, load the spray product on the aeroplane.

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The spraying mission was planned for a maximum period of two months or 50 flight hours. Its purpose was to treat rice crop zones, situated along the Senegal River between Saint-Louis and Matam, with an avicide product. The treatment had to be carried out while the birds were asleep, i.e. either at the beginning of the night or before sunrise. The pilot had chosen to take off early morning, while it was still dark, in order to arrive in the zone before sunrise. This meant that he could carry out the return flight and land in daylight.

A document, supplied by ATS, listing the flights carried out indicated that the pilot had started the spraying flights on 3 August and had carried out at least six flights each lasting for around one hour.

ATS was also responsible for providing MIDAIR with all the authorizations required by the Senegalese civil aviation authorities to operate the aeroplane in Senegal.

On 20 July 2018, ATS asked the Senegalese National Agency of Civil Aviation and Meteorology (ANACIM) for an aerial work permit in accordance with the requirements of Annex 4 of Senegalese Aviation Regulation No 6 regarding aerial work. The ANACIM issued by letter of 20 July 2018 an exceptional operation authorization to ATS to carry out the crop spraying missions requested. In this letter, the ANACIM indicates that it had carried out an inspection of the aeroplane on 18 July 2018, which was considered satisfactory, at Saint Louis airport.

2.9 Spray product information

The avicide used was Fenthion 640 ULV(5), an organophosphorus compound which is toxic for humans in the event of skin contact, ingestion or inhalation. When used as an avicide, it is recommended to use around 5 l per hectare.

Fenthion belongs to the category of toxic, liquid organophosphorus pesticides and in this respect is considered a dangerous product according to the definition in ICAO document 9284, “Technical Instructions For The Safe Transport of Dangerous Goods by Air” (see paragraph 2.10). As indicated in Senegalese Aviation Regulation No 18, Senegal classes articles and substances in accordance with the provisions of the ICAO.

2.10 Regulatory provisions concerning the transport of dangerous goods during crop spraying operations

2.10.1 ICAO provisions

Annex 18 to the Convention on International Civil Aviation, “The Safe Transport of Dangerous Goods by Air” and Doc 9284 set out the fundamental principles for the safe transport of dangerous goods by air.

Chapter 1.1.5 of Doc 9284 identifies general exceptions and states, in particular, that “Except for 7;4.2, these Instructions do not apply to dangerous goods carried by an aircraft where the dangerous goods are […] for dropping in connection with agricultural […] activities.”

(5) Ultra Low Volume. The concentration of Fenthion in the avicide was 640 g

per litre of solution.

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Section 4.2 of part 7 concerns the information to be provided to employees.

“An operator must provide such information in the operations manual and/or other appropriate manuals as will enable flight crews and other employees to carry out their responsibilities with regard to the transport of dangerous goods. This information must include instructions as to the action to be taken in the event of emergencies involving dangerous goods, and details of the location and numbering system of cargo compartments […].”

The other ICAO provisions are not, therefore, applicable to the transport of dangerous goods in the scope of crop spraying missions, in particular those relating to the information to be provided in case of an aircraft accident or incident (section 4.7 of part 7):

“4.7.1 In the event of:a) an aircraft accident; orb) a serious incident where dangerous goods carried as cargo may be involved,

the operator of the aircraft carrying dangerous goods as cargo must, without delay, provide to emergency services responding to the accident or serious incident, information about the dangerous goods on board, as shown on the copy of the information provided to the pilot-in-command. As soon as possible, the operator must also provide this information to the appropriate authorities of the State of the Operator and the State in which the accident or serious incident occurred.”

2.10.2 Senegalese regulatory provisions

The transport of dangerous goods by air in Senegal is subject to the provisions of Senegalese Aviation Regulation No 18 relating to the safe transport of dangerous goods by air.

This regulation directly refers to the ICAO instructions. It states, in particular, in chapter 4 relating to Exemptions that the articles and substances normally classed in the dangerous goods category, which are intended for the specific purposes specified in the Technical Instructions, shall be excluded from the provisions of this regulation.

The transport of dangerous goods in the scope of crop spraying missions in Senegal is therefore excluded from the regulatory provisions of Senegalese Aviation Regulation No 18 and in particular, the provisions of chapter 9.6 regarding the information to be provided in the case of an accident or incident concerning an aircraft.

2.11 Sanitary aspects

ATS indicated that the different authorities and populations had been informed of the dangerous nature of the product before the bird control campaign started.

The DPV specified that its operations are always accompanied by an information/raising awareness campaign beforehand, targeting the local authorities (traditional, administrative and religious) and local populations (in particular farmers and breeders) on the sites to be sprayed. They are informed, in particular, of the date, time and duration of the spraying operations as well as of the dangerous nature of the product used. They are alerted about the importance of avoiding going to the sites treated for at least two weeks, of taking their livestock there or even of eating weak or dead birds.

However, several villagers, the Mauritanian emergency services and representatives from the Mauritanian and Senegalese authorities travelled to the site shortly after the accident and without specific protection, thus exposing themselves to health risks.

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3 - CONCLUSIONS

The conclusions are solely based on the information which came to the knowledge of the BEA during the investigation. They are not intended to apportion blame or liability.

Scenario

During a flight carried out as part of a crop spraying mission, the aeroplane collided with the ground around ten minutes after take-off. The pilot had taken off at night for the needs of the mission as the avicide treatment used had to be sprayed at night. He planned to carry out the return flight by day.

The examination of the accident site, and in particular the scars on the ground and the orientation of the wreckage, suggest that the pilot had aborted his mission and was on a reverse course towards the aerodrome. It is possible that this manoeuvre was due to a technical failure. It is probable that the aeroplane then collided with the ground owing to the small number of visual references available at night, overhead an uninhabited agricultural area.

In the absence of path data for the end of the flight, it cannot be excluded that the pilot experienced spatial disorientation and unintentionally carried out a reverse course and lost altitude up to the impact with the ground.

Safety lessons

The Senegalese company, ATS, the aeroplane operator in the scope of the spraying mission, and the Directorate for Plant Protection, the service customer, indicated that they had warned the various authorities and local populations of the dangerous nature of the product used, before carrying out the spraying operations. Despite this, villagers, personnel from the Mauritanian and Senegalese authorities and emergency service officers travelled to the accident site, contaminated by the product, without personal protective equipment.

The investigation was unable to assess the effectiveness of the communication channel set up, in providing information to the local authorities.

This occurrence serves as a reminder of the importance of providing information in an effective and precise manner to the local authorities and civil aviation authorities in countries and regions which may be crossed by a flight transporting dangerous goods. In the event of an accident, this information must permit individuals who have to proceed to the accident site, to make use of suitable personal protective equipment.

The monitoring of flights by the operator could permit information about any accident and the protective measures to be taken, being quickly provided to the local authorities and emergency services, before they intervene.