Locating Missing Persons with Rotorcraft

The activity of locating missing persons using the latest technologies of rotorcraft and remote sensing includes such features as new applications and state-of-the-art algorithms for imagery interpretation. However, patience remains the most important attribute for this activity


Illustration: Bigstock

Any incident involving a missing person is a traumatic event for the family, the organization and in some cases – for a whole country. The Israel Police receives about 5,000 missing person reports each year – of which hundreds evolve into actual searches (most missing persons return home safely), and a few dozen cases reach the stage of significant search and rescue operations.

The main reasons for people reported missing in Israel are field trips that went wrong, mental illness and old-age conditions, children who became lost, floods and in some cases – voluntary absenteeism (people escaping or committing suicide). Countless natural disasters occur around the world every year – avalanches and mudslides, earthquakes, massive floods and so forth – and similar disasters might take place in Israel as well.

Missing-in-Action situations in the military context are normally (but not exclusively) caused by operational reasons or pursuant to abduction by hostile elements. In IDF, servicemen are declared missing in the context of air, sea and land operations, during training and operational activities. Pilots might go missing owing to aircraft crashing in the Mediterranean Sea or in the Sea of Galilee, IDF Navy people might go missing pursuant to the loss of a surface vessel or a submarine, and ground forces personnel might go missing in unsuccessful combat operations from which some soldiers never returned. In some rare cases, soldiers are declared missing for no known reason.

The process of searching for missing persons involves several dimensions. The time dimension: between close to real time and several hours; a short while after the person's absence – days to weeks; a long while after the person's absence – years. The information collecting dimension: questioning of involved parties, intelligence investigation and analysis of photographic materials. The personal dimension: a background check regarding the missing person – an attempt to understand and analyze possible behavior patterns.

The Eitan (Hebrew acronym for 'Locating of Missing Persons') Unit of the IDF Personnel Directorate includes a missing person search team that employs airborne sensing resources. The team has been operational since 2004 and complements the other investigative dimensions that are carried out in parallel.

The method of searching for missing persons from the air involves several advantages and disadvantages. The advantages are high accessibility to the scene with regard to space and time, the ability to scan relatively large areas, a good viewing angle and few obstructions. In most cases, photographic source material may be obtained for scene comparison purposes, and if video footage is available, observers will be able to spot movement. The disadvantages are less-than-optimal resolution, the need for aircraft (resource availability) and the need for specialized skills in order to interpret the imagery from the scene.

The activity known as remote sensing from the air includes an advanced technology that is already in use by military organizations, mainly in the form of thermal imaging. A thermal sensor is, in fact, a video or still camera that photographs the target area using a wavelength that is not visible to the human eye and detects the heat emitted by every object or body. Thermal sensing is based on the fact that different materials possess different heating and cooling characteristics, and the differences are discernible. A photograph of this type may be taken at any time of the day, but will appear different when taken at different hours, owing to the heating and cooling of the surrounding environment over the course of the day.

Every incident involving missing persons may consist of any one of several scenarios: a voluntary absentee who went into hiding, a visible living absentee or an absentee who's no longer alive. In the latter case, the time of death and the surroundings where the body is found are of the utmost importance.

During the final days of the Second Lebanon War, searches were conducted on August 12, 2006 for Sergeant-Major Keren Tandler, a female airborne mechanic who had been killed in the crash of an IAF CH-53 helicopter that had been shot down by a Hezbollah missile. The missing person search team was alerted during the night to search for Keren, whose body had not been found in the ground search and she was declared missing in action. For many hours, the team scanned the area very thoroughly using a remotely-piloted aircraft, analyzed data such as the point from which the helicopter had taken off, the route along which it flew and complex physical calculations, in order to focus on a specific search area.

The team scanned the area carefully. The scans yielded six suspicious points, namely – points where the presence of a body could not be ruled out. For the rest of the area, the team was reasonably certain that the body was not there. A special operations force on the ground checked all six points thoroughly, but they found nothing.

At the end of that long night, the Eitan team reported that in all likelihood, Keren was not located in the specified area and recommended that the search focus on the wreckage of the helicopter. At around 12 noon on the following day, Keren's body was found under one of the larger parts of the wreckage which had not been scanned previously.

The description of this incident illustrates a typical situation of searching for missing persons using remote sensing. The Eitan team acquired the know-how through numerous studies and trials in which the participants were Yoav Stoller from the missing person unit, Superintendent Hagai Wax from the Israel Police Forensics Department and the author of this article.

Today, a new technology for carrying airborne sensors is being introduced into service: rotorcraft. Rotorcraft offer several advantages over the classic UAVs: they can hover, go down to very low levels, provide high-resolution imagery and scan areas automatically; they offer a high degree of availability and are not dependent on external operators. On the other hand, this technology is restricted by several disadvantages: insufficient technical reliability, a limited operating range, a limited endurance and a limited carrying capacity.

Rotorcraft are fairly common worldwide and police forces, fire departments, ski resort rescue teams and other elements have been using them regularly to locate missing persons.

One should bear in mind the fact that the rotorcraft technology is still fairly new on the scene, and it will be interesting to observe the directions in which it would develop in the coming years. New applications are introduced regularly and state-of-the-art algorithms offer amazing imagery interpretation capabilities.

Civilian rotorcraft are employed subject to the strict regulation of the aviation authorities: the operator and the rotorcraft must be licensed, the rotorcraft must be maintained professionally and the operator must train professionally in rotorcraft operation and in imagery interpretation. The day is not far when rotorcraft will be employed in combination with UAVs or independently, and missing person incidents, like other emergencies, will be managed based on the quality, reliable information provided by these systems. Until that day, we are required to improve the reliability of rotorcraft platforms and endeavor to develop and incorporate algorithms that would help us interpret and understand the imagery information professionally and in real time.

In conclusion, several important rules apply to the specialized skill of interpreting missing person search imagery: study all of the information available regarding the case and the personal details of the persons involved. Suspect any bit of information other than a verifiable fact, including timetables and locations. Review the scene and define what is being sought and how the object of the search should look at this time. Reduce the search area to an absolute minimum according to the data available to you. Try to find a reference from a time prior to the missing person incident. Scan every inch carefully and mark every suspicious point according to the previous definitions. Try to verify every bit of suspicious information. Finally – have patience, patience and more patience. 


Chen Granas is a member of the missing person investigation team of the Eitan Unit and a thermal imagery interpretation expert