On 17th of January 2016, an important mining company, requested the support from AVSAN to monitor a risk situation that occurred in one of its mining operations in central Chile.
During the phase of cabling the detonators for a mesh blast, personnel responsible for handling the explosives found a flaw in a well packed already with explosives, under such conditions it was required to evacuate the area and activate an security protocol.
According to the explosives protocol it is required to watch over the area and monitor the temperature of the zone with installed explosives; the only way to allow safety access to the zone affected was by ensuring that no "hot spots" above +40°C could be found in the zone monitored.The different constrains for this mission of monitoring the temperatures were: a remote zone with restricted access, with an allowed proximity of not less than 500m, at 3800m ASL and with an environmental temperature that changes quickly between +5°C to +22°C.
The challenging mission was tough to be performed, because it was required to fly over the zone of interest located 500m away from the take off point, capture thermographic pictures (searching for values above 40°C) and return safely with the equipment.
There were no previous antecedent for operation of multi-propeller in area, only in previous occasions in 2015 (January and April) the company AVSAN was surveying the area using fixed wing UAVs for topography and digital cartography. This mission was a new milestone in our service experience, because we are the first ones using an unmanned multirotor platform (md4-1000) in the problem area.
Our first flight was performed on 17th of January at 10:00 with an environmental temperature of +16°C, the take off point was located at 580m from the area of interest and the measured height for the mission was 3860m ASL. The flight mode was completely under DPH simultaneously broadcasting the thermal image to the base station (FPV).
The flight duration was approximately 7 minutes, during which it captured thermographic information from the zone of interest. After analysing the datasets from the multiple pictures by the company ENAEX (responsible for the installation of explosives in the chore), they determined that the conditions were not suitable for safe access in the zone for their specialist to schedule the mesh detonation.
With the collected data it was possible to determine that it was required to keep monitoring the zone during the following days with the purpose of finding a time window in which the environmental conditions could allow safe access for their specialists (no measurable surface points with temperature above +40°C contained in the zone of risk).
During this flight the system experienced a loss of stability, that according to our experience is caused by the effect of height/air density in the environment and the faster consumption of energy from the battery, which made the Pilot perform the manoeuvres required to land abruptly over an inclined area, which caused the propellers to hit some stones and were damaged permanently. In general the equipment only had some scratches and a light dent on the body structure; after replacing the damaged propellers with new ones, we were ready to fly again.
On Monday, 18th of January at 08:51, the mission was the same as the previous day, which was to capture pictures from the zone of interest identifying the "hot spots". On this flight attempt with the md4-1000, the take-off point was shifted towards to the zone of interest (ZONE 1 - point of observation),in order to reduce the trajectory.
In summary the flight was performed successfully without inconvenience, having a duration of 8 min, the information was collected as planned. From the analysis of the data by ENAEX it was determined that the area was still not safe for entry of the explosive specialists.
Thanks to the information obtained it was possible to determine that it was required to keep monitoring the zone during the following days, looking for a possible time window that could allow safe entry with no "hot spots" or temperatures above +40°C.
On Tuesday 19th of January, it was agreed to perform the thermographic sampling at 06:00 when no sun light was present, considering that it could facilitate more accurate thermographic samples and discard any interference that could be produced by the sun on the zone of interest.
Another important consideration to perform the task at this time was the low environmental temperature, which is an advantage for the performance of the md4-1000 under the effect of height/air density. Considering the fact that denser air increases the efficiency of the propellers, the equipment experiences higher propulsion with less load to the battery. Therefore the efficiency of the system improves.
The flight had duration of 9 min with successful data collection for the security analysts.
In this case the collected thermographic data analysed by the safety specialist confirms (gave the green light) that the explosives team could enter the zone containing the mesh blast. It was possible to determine that there were no "hot spots" with temperatures above +40°C.
The explosives and detonator specialists entered carefully and quickly into the zone of interest to perform their task of repairing the problems of cabling in the well; thanks to the team work by the personnel on the field and the safety specialist it was possible to execute the blast of the zone successfully.
In summary, it was possible to demonstrate the successful execution of missions with diverse environmental constrains are possible to be performed using the md4-1000, which allows execution of tasks with high level of complexity and eliminating the risk to the personnel on field. Thanks to the use of this UAV it was possible to maintain the operations from a safe distance from the zone that was marked dangerous.
It is important to remark that under the extremely hostile environmental conditions during which the mission took place, we are very pleased with our md4-1000 capabilities to satisfy the challenges of the different tasks on the field.