Tactical Advantage - Part I
Thermal Imaging Tactics
By Kevin P. Means
San Diego Police Department
This article originally appeared in Vertical 911 Magazine.
Tactics: a mode of procedure for gaining advantage or success.
The use of tactics applies to any scenario in which one entity is opposed to another and is trying to gain the upper hand on an opponent. And, while no single tactic applies to all scenarios, there are some very effective ones that, if mastered, can significantly enhance the safety and effectiveness of air and ground units in most situations.
In all situations, maintaining tactical flexibility allows officers to shift gears quickly and effectively when something unexpected happens.
After aviation safety, officer safety is an aircrew’s first priority. As an aircrew, our tactics should reflect that. And, both air and ground units should have a clear understanding of how they're going to work together.
The best way to accomplish this understanding is for ground units to ride with the aircrews, and for us to attend their pre-shift lineups and discuss issues associated with our common missions. This lets ground units put a face to the voice they hear on the radio, and helps build relationships.
Our tactical opponent, meanwhile, is anyone who commits or attempts to commit a crime and then tries to escape. There are three law enforcement responses to this opponent and their actions: prevention, detection and apprehension.
Prevention is difficult to measure in terms of success. But, we do know that the high-profile presence of a law enforcement helicopter can help prevent criminal activity — even if only on a short-term basis.
Detection and apprehension is where aircrews can excel. Our effectiveness here depends on factors we can control, including: tactics, technical proficiency, crew co-ordination, air/ground unit co-ordination, and law enforcement skills and judgment. Any shortfalls in these areas can negatively impact safety and effectiveness.
Most law enforcement helicopters are similarly equipped with thermal imagers (forward-looking infrared [FLIR]), searchlights, GPS mapping systems, stabilized binoculars and a variety of radios. Night vision goggles (NVGs) are also being used by an increasing number of agencies, but, while they have some tactical uses, they primarily increase situational awareness (aviation safety).
Having technology available is only one part of the equation; its effective use is the other. This begins long before we arrive at a call, with Preparation H (Preparation Helicopter), which ensures our equipment is ready to use and that we're proficient in its use. It means we turn the FLIR on well before it is needed, or practice with it before we get into a real-world scenario. That preparation can make the difference between a suspect escaping and getting caught.
On a Call
Let's examine a typical law enforcement call in a large city. It’s 1 a.m. and one or more suspects are breaking into a parked car. Ground units are about five to 10 minutes out and we have a three-minute estimated time of arrival. How do we work that call from an aircrew perspective? The first priority is to get there safely and quickly, or at least get close enough to see the suspects without alerting them. This is easier to do if we know the layout of the streets, if we're flying high enough and if we use our technology effectively.
If time permits, tactical flight officers (TFOs) should always enter the location of a call into the helicopter’s mapping system, even when the crew is familiar with the area. Why? It’s surprisingly easy for pilots to be off course by 10 or 15 degrees while en route to a call — even with familiar locations. It's also not unheard of for a crew to mistake one street for another and fly in the wrong direction. The mapping system’s information also provides several benefits: it confirms the location of the call; helps the pilot fly a direct course; and allows TFOs to familiarize themselves with the names, shapes, sizes and locations of streets near the call. This helps TFOs locate the call on the FLIR display from a distance, and helps them establish a perimeter if a suspect runs.
Part of using technology effectively requires flying the helicopter appropriately: higher altitudes mean fewer obstructions between the suspects and us. We can fly higher because modern thermal imagers have the ability to zoom in well enough for us to see people at significant distances — distances at which suspects don't usually think we can see them.
TFOs should be looking for suspects long before the aircraft arrives at the call. Waiting until we’re overhead to begin a FLIR search wastes valuable time and surrenders a huge tactical advantage: surprise.
The suspects near the school in Figure 1 (below) are very difficult to see, because the aircraft is more than a mile away and the FLIR is zoomed out. They can probably see our helicopter, but if it’s a significant distance away, and not flying toward them, they may not think we’re looking for them.
As soon as they know we're coming for them, they’re probably going to run, hide, jump in a getaway vehicle or a combination of these things. One of our goals is to minimize their ability to do this, undetected.
In Figure 2 (below), we see the FLIR is zoomed in: the suspects are clearly visible, even though the helicopter is still more than a mile away. As long as we can see the suspects, we should continue to watch them from a distance until ground units are nearby. Then, we can move in on them in a coordinated manner. In the meantime, the TFO can familiarize himself or herself with the names of nearby streets, thereby providing ground units with potential approach routes that keep them out of the suspects’ sights.
These procedures enable the aircrew to watch and record the suspects’ actions without alerting them until everyone is ready to move in. Some exceptions to this would be if the crime involved violence, or if no ground units were available.
If we don’t see anything while en route, the pilot should fly to the scene while the TFO continues to search as they approach, as he or she may see someone run who wasn’t visible from a distance. When suspects run, they often stop and hide somewhere away from the crime scene if they think they haven't been spotted. When we’re watching them with the FLIR, stopping and hiding is exactly what we want them to do.
When trying to locate suspects, there's a strong temptation to illuminate them with our searchlight, but, in this situation, that would tell them we've found them, and we're not ready to do that. The light would also illuminate the suspect’s path, and help him or her make such tactical decisions as: where to run; where to hide; when to move; and where and when to discard evidence. This increases our workload, as it's more difficult to keep a suspect in sight when he or she is running. It's also more difficult to establish a perimeter and direct ground units to a suspect who's running. Remember: the suspect knows we're there, knows who we are, knows we're looking for him, but doesn't know that we've found him, and, for the moment, we don't want to tell him.
One common misconception about FLIR work is that the tactics only apply to the TFO — nothing could be further from the truth. It’s very difficult for a TFO to keep a suspect in sight, for example, when half the pilot’s orbit is in the next county. Pilots play a crucial role in the safe and effectiveoperation of the aircraft. Aircraft positioning during FLIR missions is a dynamic and deliberate form of flying.
When a suspect hides behind or underneath something, TFOs should immediately switch the FLIR to a field of view that allows them to watch the perimeter of the obstruction. This applies to any scenario, whether the suspect knows he or she has been spotted or not. For example, when a suspect runs around the corner of a building, a common mistake is to leave the FLIR zoomed in on him, essentially chasing him with the FLIR. As it can take a few moments for the aircraft to round the same corner, the suspect could escape from an area of the perimeter that’s not visible to us due to the FLIR's narrow field of view.
TFOs must develop the ability to recognize when this is about to occur, and zoom out at a rate that exceeds the suspect's ability to escape from the perimeter of the obstruction. The obstruction may be something as small as a car or as large as a building, but the tactic is the same — keep the perimeter in sight whenever the suspect isn’t visible. This is easy to conceptualize, but often gets overlooked during the stress of a pursuit.
In pursuit situations involving potential obstructions, the pilot should position the aircraft to give the TFO more of an overhead view of the obstruction than a side view. Side views, which have shallower search angles, often enable suspects to move from one structure to another without being seen — especially when buildings overlap in the FLIR's field of view. This essentially makes the perimeter much larger, and proportionately more difficult to contain. Higher altitudes help create steeper search angles, which reduce or completely eliminate the suspect's ability to move from one building to another without being seen.
In Figure 3 (below), the helicopter is in a left-hand orbit at 600 feet above ground level (AGL), about two blocks from Building B. A suspect is hiding between buildings A and B. In this orbit profile, a blind spot exists on the right side of Building B, where it overlaps with Building C. A quick suspect could duck down and move from Building B to C without being detected.
As the aircraft continues to orbit, another blind spot is created on the left side of Building A, where it overlaps with Building B (see Figure 4 below). The suspect now has the ability to duck down and move around the left side of Building A, undetected.
A suspect trying to escape in this manner is moving on the backside of our orbit. When pilots fly less-effective orbits, it’s easier for suspects to do this, because they know if they can’t see the helicopter, we can’t see them. If the pilot continues to orbit in this manner, the suspect will be able to move from structure to structure without being seen.
The orbit profile in Figure 5 (below) is steeper and gives us a much better view of the perimeter of Building B. The aircraft is now flying at 1,100 feet AGL, about one-and-a-half blocks from Building B. The suspect may still be able to hide from us by hugging the wall of Building B, but as long as we can keep the perimeter of that building in sight, he or she won’t be able to move from building to building without being seen.
Do our tactics have an effect on aviation safety? Absolutely! The simple act of flying higher not only provides more effective search angles; it minimizes exposure to such risks as terrain, wires, towers and gunfire. We also have more time to react to an engine failure or other aviation emergencies, and our flyover noise is reduced, which enables ground units to hear their radios better, and keeps the neighbors happy… well, happier.
Higher orbits also enable pilots to fly faster during FLIR searches, and faster orbits enhance flight safety.
For example, if a FLIR search is being conducted at 500 feet AGL, the pilot will not be able to fly much faster than 40 knots. Any faster and the image will be moving too fast across the display for the TFO to conduct an effective search. Even the best TFOs need time to find and evaluate heat sources.
If the pilot maintains the same search angle, however, but orbits at 1,000 feet AGL and 60 knots, the FLIR image will look the same as it would at 500 feet AGL and 30 knots (see Figure 6 below).
The FLIR has the ability to zoom in more than enough to compensate for the increase in altitude, but now we’re moving at twice the speed and altitude, so safety and effectiveness are enhanced.
Remember, good tactics and good tactical flexibility promote increased suspect apprehension and improves safety for all concerned.