Let's face it, we aviators are can-do people. When confronted with adversity, we find a way to accomplish our mission. However, even with the best of intentions, we occasionally do things we later wish we had done differently.At about 2 p.m. on Nov. 2, 2006, I gathered the Kiowa Warrior pilots of 6th Squadron, 17th Cavalry Regiment, Fort Wainwright, Alaska, for a pre-mission briefing. I was an OH-58D(R) standardization pilot/instrument examiner and we planned to conduct winter environmental training in day, night and night-vision goggle modes. Having previously completed the necessary academics, we updated the risk assessment and mission briefing forms to reflect crew changes. We also conducted a collective preflight of the aircraft, highlighting cold weather considerations. I departed for the day portion of the qualifications shortly afterward and returned about 4 p.m. as planned. I saw there wasn't going to be enough snow on the ground for everyone to get quality training.I began the night and NVG portion of the training at 5:30 p.m., and an hour later, the second pilot entered the cockpit so we could began his training. We conducted several required maneuvers at the airfield before departing the traffic pattern at 7 p.m. We then flew to a training area north of Ladd Army Airfield to conduct terrain flight and confined area operations. While hunting for snow to land in, the pilot identified an SUV that appeared to be stuck on its side. I assumed the controls and maneuvered the aircraft to get a better look. We saw a light and observed people inside the SUV. Knowing that sub-zero temperatures posed an immediate danger and seeing the condition of the SUV, I decided to land and assess the situation and render appropriate assistance as needed.I chose a flat open area along a trail 50 meters behind the SUV, which had broken through the ice, and executed an approach and landing. I aligned the aircraft with vehicle tracks on a trail in the landing zone and placed the skids parallel with the ruts, facing the vehicle. Two occupants got out of the SUV. I told the pilot to exit the aircraft and determine if they needed assistance. He opened the right cockpit door and was swinging his leg out when the aircraft settled to its left-rear side. I felt feedback in the pedals and believed the tail rotor contacted something. I'd barely announced that I was shutting down the engine when the aircraft began rapidly settling and listing to the left. The ice below began breaking under the skids and the aircraft sank into a muskeg water hole. Despite my best efforts to prevent it, the rotor blades struck the ground and severed the drive train. After the blades stopped, the pilot jettisoned the right door and exited, turning to assist me as I was now submerged in water up to my left armpit. The left chin bubble had broken while settling through the ice, causing water to fill the cockpit.I completed the emergency shutdown and, as I climbed across the cockpit and out of the aircraft, the pilot immediately pulled out his survival radio and emergency strobe. Using the "Guard" frequency, he contacted a Chinook flying in the airfield traffic pattern. The Chinook immediately responded and began orbiting over the accident scene. As they did, they relayed the situation and location to air traffic control, which sent crash rescue to the scene. I used my cellphone to call our squadron staff duty officer to initiate the pre-accident plan.Due to being wet and extremely cold, my cellphone stopped working and I could no longer assist in the recovery efforts. At minus18 F, I quickly began to suffer the onset of hypothermia. My required additional cold weather survival equipment was on board the aircraft, trapped beneath the ice. Emergency services arrived on scene within 20 minutes and immediately treated us for hypothermia. We were transported to the hospital for evaluation after the accident scene was secured.While at the hospital, I reflected on my actions. Could I have helped the individuals stranded in the SUV without having to land like the CH-47 that rendered aid to us? Would I have still landed?My answer is yes to both. But with regards to landing, I would've approached in more patient and deliberate manner, aware that not all hazards are obvious. A pilot's desire to help in an emergency must be tempered by understanding the risks involved and applying the necessary mitigation. Even good deeds need to be checked with careful counsel. If we ride to the rescue without mitigating the risks, the next rescue mission may be to save us.