1.3 Blog Discussion: The US Aviation Industry

The Shift From Land Based Navigation to Space Based Navigation

In the early years, aviation was limited to flying below or between the clouds, limited by the pilot’s ability to navigate using ground references.

Gyan (n.d.). Pinturas Aviacion Primera Guerra Mundial [Painting]. Page 35.

As radio technology and aircraft instrumentation improved, the concept of radio navigation provided a literal path through the clouds- pilots could tune a non-directional beacon (NDB) or a Very High Frequency (VHF) Omnidirectional Range (VOR) beacon to determine their location over the ground and use the VOR to fly a path in the air.

A Lonely NDB

Soon to be decommissioned.

The downside to NDB and VOR navigation is that aircrews were limited to predetermined airways, created by the spacing and power output of the transmitters. Aircrews could not fly direct to a destination if there were not enough radio beacons along the path to navigate by.

This cost lots of money to commercial aviation in wasted flight time, and so the search was on for a better method. In 1974 the United States Air Force started a joint program named NAVSTAR-Global Positioning System based on calculating ephemerides (calculated locations of space objects) and using those tables to calculate locations on earth via the time difference of arrival of radio signals. (AIAA, n.d.)

Lockheed Martin GPS-2RM Navstar Satellite (Gunter, n.d.)

“On February 16, 1994, a significant milestone in American aviation occurred when the Federal Aviation Administration certified the first GPS unit for use in IFR operations” (Connor, 2014.) This milestone would start the move from ground based aviation to satellite based aviation, and subsequently a combination of both in the form of precision GPS improvement systems such as WAAS and LAAS or GBAS systems.

The venerable Garmin 155- the first TSO’d GPS for IFR operations.

The subsequent (and ongoing) shift from ground based to satellite based navigation has vastly improved efficiency within the National Airspace, and continues to improve as satellite guided autopilots allow closer separation of aircraft enroute and in the terminal area, making flights more efficient, saving time and fuel, and ultimately reducing costs to both operators and passengers.

References:

AIAA (n.d.). History of GPS Program. American Institute of Aeronautics and Astronautics. https://www.aiaa.org/docs/default-source/uploadedfiles/about-aiaa/press-room/videos/iaf-60th-anniv-gps-nomination.pdf?sfvrsn=9bc64bfa_0

Connor R. (2014, February 24). Twenty Years of GPS and Instrument Flight. Smithsonian National Air and Space Museum. https://airandspace.si.edu/stories/editorial/twenty-years-gps-and-instrument-flight

Gunter (n.d.) GPS-2RM (Navstar-2RM). Gunter’s Space Page. https://space.skyrocket.de/doc_sdat/navstar-2rm.htm