A former ‘Night Stalker’ explains how US military pilots plucked Americans from hostile territory in Kabul

• As the US raced to get people out of Kabul before the August 31 withdrawal deadline, many were unable to make it to the airport.
• Amid the scramble, US troops conducted missions to extract people from around Kabul using ground vehicles and aircraft.
• Air operations in an urban area are inherently dangerous, but the US has a unit that specializes in such missions.
• See more stories on Insider's business page.

As the August 31 deadline to evacuate all US troops and citizens, their Afghan partners, and other foreigners in Afghanistan approaches, US and coalition forces are racing to get as many people as possible out of the country.

But reaching the airport in Kabul is far from easy, as shown by the suicide attack there on Thursday killed 13 US troops and scores of Afghans.

For the past week, the CIA and US troops, as well as other coalition special-operations units, have been conducting sorties within Kabul to extract US citizens and others unable to make it through the city.

In addition to ground convoys, the US military conducted several helicopter extractions from sites around Kabul, according to the Pentagon. In one such operation, US forces moved some 350 US citizens to the airport.

The US Army's 160th Special Operations Aviation Regiment is the unit the military often turns to for such evacuations, especially from hostile territory. The "Night Stalkers," as they're known, were deployed in Kabul.

The most dangerous terrain

Night Stalker pilots pride themselves on being able to be anywhere at any time, plus or minus 30 seconds, but flying over an urban environment is particularly dangerous for helicopters because of the myriad places from which they could be targeted.

To be effective in an environment like Kabul, they would have to make several considerations when designing their missions. To begin with, route planning would be key.

"Flying in the urban terrain is the toughest of all environments. Planning is critical for rotary-wing operations, and navigation is very difficult in urban terrain. The enemy will create a nonlinear operational environment using urban terrain for cover and concealment," retired Chief Warrant Officer 4 Greg Coker told Insider, referring to an environment where threats of different kinds come from different sources.

Coker, a Night Stalker pilot and author of "Death Waits in the Dark," served for 30 years and completed 11 combat deployments.

Operations in an urban environment are also inherently dangerous because they significantly increase the risk of friendly fire incidents. The challenge is considerably greater during night operations, which special-operations units frequently conduct to leverage the advantage they have with night-vision and thermal devices.

There are ways to mitigate the risk.

The Night Stalkers would seek to know beforehand where the evacuees will be in order to account for things such as power lines or other overhead wires and structures like cell towers.

Planning also allows for de-confliction with other aircraft in the area and to assess the potential for collateral damage if they encounter resistance and have to open fire.

In addition, they would have to know of any key terrain nearby, such as hills, that could be an emergency rendezvous point for medical support or for rearming and refueling.

"Detailed planning is key. Aviators must know and understand the scheme of maneuver for the ground force," Coker told Insider.

US forces also provide air assets with items like colored cloth or infrared strobes so aircraft can "positively identify their location for day and night operations. If they do not look like the good guys, they are the bad guys," Coker said.

The worst-case scenario

There are ongoing threats to the airport in Kabul. On Monday morning, the US military shot down a number of rockets targeting the airfield.

Another consideration for any evacuation by helicopter - whether it's with the more cumbersome MH-47 Chinook or the more agile MH-60 Black Hawk - is the presence of man-portable air-defense systems, known as manpads.

These shoulder-fired missiles can easily bring down a plane or helicopter. A covert CIA effort to provide such missiles to the Afghan Mujahideen in the 1980s was devastatingly effective against Soviet aircraft, helping force the Soviets to withdrawal from Afghanistan altogether.

The Night Stalkers know this danger very well. In 1993, during a daytime operation by Delta Force and Rangers in Mogadishu, two MH-60 Black Hawks were shot down by rocket-propelled grenades, igniting a deadly, hours-long battle known as the "Black Hawk Down" incident.

Coker himself has faced the danger of manpads. During a daytime combat mission in Iraq in 2004, his AH-6 Little Bird was shot down by insurgents. Miraculously, he and his co-pilot survived and escaped the wreckage to be picked up by a Delta Force element.

Aircraft being shot down is perhaps the worst-case scenario for any helicopter evacuation. The US doesn't believe ISIS-K, the terrorist group behind the suicide bombing at the airport, has manpads capable of downing US military aircraft, according to Gen. Frank McKenzie, head of US Central Command.

"We know that ISIS would like to get after those aircraft if they can," McKenzie told reporters on Thursday. "They have taken shots at our aircraft on occasion without effect. We think that's going to continue."

The risk of a lucky hit, which could take down an aircraft carrying hundreds of people or troops, is always a consideration. "Military aircraft have a variety of self-defense systems," but charter planes and other aircraft without such systems are "more vulnerable," McKenzie said.

McKenzie said US troops monitor the Kabul airport's approach and departure patterns "religiously" at day and night to spot any threats. US and coalition aircraft already deploy countermeasures, such as flares, during landing and takeoff there.

"US military helicopters have Aircraft Survivability Equipment to defeat" infrared missile systems, such as the SA-7 and SA-14, Coker said. "The helicopter countermeasures use both passive and active ASE to protect against these weapons systems. Using terrain, speed, and low flight altitudes are key to urban operations."

US forces and their partners on the ground in Kabul remain on high alert for more attacks as the withdrawal wraps up.

The Night Stalkers' mission won't end once all evacuees are at the airport, however. As the US and coalition troops depart, the special-operations elements there are likely to be the last out, covering their conventional brethren before finally withdrawing.