U.S. Airship Macon Moffett Field click to enlarge
The Blimp hangar is now being used by NASA click to enlarge
The purpose of these experimental flights was to evaluate a new technique for making instrument approaches in helicopters. Just a short history lesson regarding instrument flight in helicopters.
Years ago, when instrument flight was first developed. The rules and procedures pretty much pertained to airplanes only. This was mainly because most helicopters then and still today, are not equipped for instrument flight. Also when these conditions (IMC) instrument meteorological conditions, existed, helicopters could usually operate in special (VFR) visual flight rules and operated in non controlled airspace and also with permission from the controlling agencies, they could enter controlled airspace, again this would be with special flight conditions. As time went on, more and more helicopters are now able to operate in these weather conditions and also make instrument approaches for landing at airports around the country.
That's me on the far right along with two other NASA pilots click to enlarge
Typically, when an aircraft gets into the airport environment and is going to make an instrument approach for landing, The approach begins at a designated point and descends along a very shallow flight path to the airport. Usually at an approach angle of about 4 to 5 degrees. This enables the aircraft to descend at a very low rate. At the point where the approach ends, the pilots should be able to see the runway landing system and make his landing visually. This would be called the decision height. Usually around 200 feet above the ground, lower in some cases. If the pilot does not see the runway or approach lights, he aborts the landing and goes around for another attempt.