Back in 1985 an Eastern Airlines 727 hit a mountain in Bolivia at about 19,500 feet, and Sikorsky dispatched a Black Hawk from the factory to attempt to look for survivors. Test Pilots Rus Stiles and Phil Pacini flew the mission (both former USAF mountain rescue and Special Operations pilots). They flew up to the crash site, and were prepared to land. After several very low, very slow passes, they determined that there were no survivors at the site, and decided not to land - soft snow, swirling clouds and threatening weather helped make the decision for them. This was the highest IGE operation I have ever heard of.