Monday, February 19, 2007

Pitch or Power?

Not flying anymore, so no new GPS tracks or flight statistics. I'm back to just reading about other people flying (sigh).

I came across a piece in the February issue of Aviation Safety. "Author Ray Leis' advice that glidepath corrections should be made as follows: "Pitch controls altitude and power is used to control airspeed."" Ray responds: "Why not fly the ILS in the same way the best designed autopilots do?"

I humbly disagree. I have found that for me, it is best to eliminate as many variables as possible. If I can make airspeed a constant (say trimmed at 90 kts), then if course is steady (sometimes a big if) then the only correction I need make is for rate of descent. I do this by adjusting power. Nose attitude holds the airspeed and subtle changes to the power setting can be used to get that 500 (or so) ft/min rate of descent.

If I'm low and fast (or high and slow), adjusting speed first with nose attitude is usually enough to stabilize the descent. Regardless, I always adjust for constant speed first. I first learned to fly precision approaches when all we had was a DG and a voice on the radio on a dark cloudy night, no needles. I was taught to get on speed, and wait until the controller said "Going slightly above glide slope". At that point I would reduce power to begin my descent. That's what works best for me.

Now, as to why not fly like an autopilot? Probably because I do better with one variable at a time, whereas the autopilot can handle many.