Wednesday, August 17, 2005

Continuous Descent Approaches: Come on down!

I recently read how UPS is intending to incorporate Continuous Descent Approaches (CDAs) at their hub at Standiford Field in Louisville, KY. The CDA is characterized by an idle descent from cruise altitude, to approach configuration, and then to touchdown. Needless to say, the energy demands and time/distance calculations have to be right on the money -- out of energy, out of altitude, and crossing the threshold. Expectations are that a CDA profile would not only reduce fuel consumption, but also lower noise. The latter is especially important for carriers such as UPS and FEDEX, as the majority of their flights are at night -- working while the rest of us sleep.

I had the opportunity to briefly experiment with CDAs during my military career, and the results were positive even with the crude inertial nav and HUD systems we had back in the day. It is something to behold however, pulling the power to idle at 30,000+ feet and flying a profile all the way to slow-up, dirty-up, approach, and runway acquisition without ever touching the throttle. Takes some serious planning, at least in those days. Especially challenging at night and IFR. One area of concern, is the increased spool-up time of the engines in the event of a wave-off, given that the engines are very firmly settled at full idle RPM and quite cooled down.

I have no doubt that with today's advanced flight systems, software, and displays, a CDA can be reliably performed with limited flight separation...perhaps as close as 2-3 miles. Air Traffic Control will of course have to play a huge role in sequencing, separation, and merging...but that time has arrived, aided by new systems. It can be done, and it should be done. I wish UPS all the best.

1 comment:

Mohawk Man said...

mmmm not sure about all that.


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