The NTSB has been quick to embrace drone technology. Bill English, Investigator in Charge of the Atlas crash, developed the NTSB’s Unmanned Aerial Systems (UAS) program several years ago when he realized the benefits drones could bring to accident site documentation. “We have a very good solid bedrock foundation for how to conduct robust investigations,” English says, “That foundation lets us use cutting edge technologies like this to improve the quality and efficiency of safety work.”
Drones are able to gather high resolution images, preserving perishable evidence like ground scars, presence of hazardous materials, and the position of control surfaces, which can get moved as wreckage is collected. Aerial photographs have always been an important feature of major mishap investigations, but drones make those photographs faster, easier, and safer to collect. In situations like the Atlas Air crash and the dozens of other accidents the NTSB drone team has supported, photographing the accident site captures valuable evidence before the wind, weather, and waves disturb the scene. Drones can also capture perspectives that might not otherwise be possible – for instance the way the terrain looked to a pilot on approach, or the position of wreckage that is unstable and hazardous for an investigator to approach.
The images taken by drones can also be used to create accurate maps of the accident scene. Before the advent of digital cameras with the ability to embed GPS coordinates in images, investigators used graph paper, pencils, and hand held GPS units to record the location of major pieces of wreckage. Investigators had to anticipate what measurements might be important before the basics of the accident were even known. Now, drones take overhead and oblique images that are combined into a three-dimensional map of the terrain and wreckage. This 3D model, known as an orthomosaic, can be accurate down to the centimeter both for relative position of the pieces of wreckage, and also for the absolute position of the wreckage on the planet. Investigators can return to the maps over and over, even years later, to take measurements that they didn’t know were important at the time. 3D models can be used in unexpected ways too. English recalls the crash of an MD-83 in 2017, in which the orthomosaic his team produced was used to model local winds around a hangar, helping investigators understand how wind contributed to the accident.
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