WASHINGTON — The Air Force has cleared the crew of an American military C-17 cargo plane that took off from Hamid Karzai International Airport in Kabul last August with people hanging onto the wings, during the frenzied days of the Afghanistan evacuation.Twin reviews of the harrowing incident, in which human body parts were later discovered in the wheel well of the plane, concluded that the aircrew was “in compliance with applicable rules of engagement,” Ann Stefanek, an Air Force spokeswoman, said in a statement on Monday. The reviews were conducted by the Air Force’s Air Mobility Command and United States Central Command.It remains unclear exactly how many people died in the episode on Aug. 16, 2021, as a crowd of Afghans, desperate to escape the country after their government collapsed under the Taliban, climbed onto the outside of the plane and fell from it after the flight took off.Video of the horrific scene, recorded by the Afghan news media, circulated around the world.“This was a tragic event and our hearts go out to the families of the deceased,” Ms. Stefanek said in the statement. Pentagon officials said traumatized members of the aircrew were later sent for consultations with mental health professionals and chaplains.Ms. Stefanek said that the crew “acted appropriately and exercised sound judgment in their decision to get airborne as quickly as possible when faced with an unprecedented and rapidly deteriorating security situation.”Reporting From AfghanistanDuring the panic at the airport in the days after the fall of the Afghan government, American pilots and troops were forced to make difficult, on-the-spot decisions. Hours before the transport plane left Kabul, another C-17 had taken off with 640 people crowded on board — more than double the number planned for — after hundreds of Afghans who had been cleared by the State Department for evacuation surged onto the loading ramps, military officials said. The pilots decided that the immense aircraft could handle the load and took off, officials said. That plane landed at its destination safely.Early the next morning, a gray Air Force plane — call sign REACH885 — descended onto the runway. The lumbering jet was carrying equipment and supplies for the U.S. Marines and soldiers who were securing the airport in Kabul and helping with the evacuation of thousands of Americans and Afghans.Minutes after the plane had touched down, rolled to a stop and lowered its rear ramp, hundreds, perhaps thousands, of Afghans rushed forward.The crew members jumped back up into the plane and pulled up the loading ramp before they had finished unloading, officials said.By then, throngs of Afghans had climbed aboard the wings and, unbeknown to the crew, into the wheel well the landing gear would fold into after takeoff, officials said.The crew contacted air traffic control, which was operated by U.S. military personnel, and the plane was cleared for takeoff.The pilots taxied slowly at first. Military Humvees rushed alongside, trying to chase people away from and off the plane. Two Apache helicopter gunships flew low, seeking to scare some people away from the plane or push them off with their powerful rotor wash.REACH885 accelerated and was airborne.Minutes later, however, the pilot and co-pilot found that the landing gear would not fully retract. They sent a crew member down to peer through a porthole.It was then that the crew saw the remains of a still undetermined number of Afghans who had stowed away in the wheel well, apparently crushed by the landing gear. Scenes captured in videos of the flight showed other people plunging to their death.