Thursday, June 19, 2008

Modern Navigation Management

NASA has just issued a report, Human Factors Considerations for Performance-Based Navigation. As the title implies, the advent of performance-based navigation is bound to change the kinds of mistakes that pilots make, and means that pilots need to learn new things.

First, what is performance-based navigation? I like to think of performance-based navigation as database navigation. Basically, it means a more complex flight path that is found in a database and must be followed within certain performance parameters. Many navigation systems can meet the performance requirement, so no specific system like "VOR" is specified. The performance requirement takes the rough form "within xNM of the centerline 95% of the time."

See, for example, the following approach chart into Palm Springs, California. Note the complexity of the path, including a circle, and the notation Special Aircraft and Aircrew Authorization Required; not just anyone can fly this. The procedure title includes the notation (RNP), for Required Navigation Performance; in this case, the RNP value is 0.3NM, which you can find in the minimums section. Converting, 0.3NM is about 1800 feet! The reward for this level of precision is a descent to 300 feet above the ground in a deep valley.



I have not had a chance to read the whole NASA report yet, but I was disappointed to read "Pilots must allow adequate time to properly load and brief their SID, STAR [sic], and approach charts." This is making me suspicious. Pilots don't decide how much time they have for this, management decides. In the charter world, there is a tremendous amount of pressure to get going now, especially when there is a "popup."

NASA has seen errors based on management pressure, the Challenger being the most prominent and heart-wrenching such failure. Did the researchers fail to understand these problems, or was it another case of management presssure?

Finally, the need to learn new things doesn't always mean that there is less need to learn old things. Consider NDB approaches, which I wrote about in Transitional Times last month; even if we don't use them much, they add a lot to our understanding of the whole navigation picture. Or, to consider an example outside of aviation, the availability of graphing calculators did not remove a single topic from the Calculus syllabus; students have to learn all of the old stuff and the new calculator techniques.

You use an amazing machine called a Flight Management System (FMS) to fly these approaches. We still need to perfect the MMS, or Management Management System.

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