Smoothing out pitch control

   The other day, I was flying with an instrument student who is progressing fairly normally toward his rating.  At a nearby airport he executed an ILS approach under the hood.  The approach went well until the airplane was within 300 feet of the DH for the approach, and then the glideslope needle seemed to go crazy for him.  There were slope excursions both high and low, ending with a full-deflection needle (the airplane too high).  The student said, “I just can’t seem to get that last part to stay stable.”  

    When we returned to our “home drome” (a VFR-only airport), I watched the student execute a VFR approach and landing from the traffic pattern.  On final, the airplane pitched up and down, causing the airspeed to vary by 10 knots during the final approach.  This was a strong clue.  The next day, I tried turning off the autopilot in a G1000 aircraft during an ILS, and used the pitch and bank directions from the flight director very carefully, ignoring everything else (this was in VFR conditions).  The slope stayed perfectly still on the approach. 

    What’s the clue?  The recent spate of articles about alpha, the angle of attack, are helpful.  When we fly an airplane at a constant power setting with a steady pitch angle, the airspeed (and angle of attack) will be constant.  For teaching or learning this skill, try these exercises: 

    Cover up all the flight instruments except the airspeed indicator. 

    Have the student (or yourself) fly looking at the outside picture, keeping the attitude rock-steady.  Wings level, no movement of the nose of the airplane relative to the ground picture outside.  This is flying straight, for sure.  Now find out if it’s level.

    Uncover the VVI, and observe either zero or a constant rate of climb/descent.  Adjust the pitch attitude to zero the VVI.  Hold the pitch steady.  Uncover the altimeter, read it, and cover it again for 30 seconds or a minute, uncover and (hopefully) read the same altitude. 

    A little back-and-forthing with the cover-ups should reinforce the idea that pitch control is visual, and not related to the feedback or feel of the control wheel in the hands of the pilot.  For new pilot students, establishing the visual pitch attitude while (relatively) ignoring the feedback from the controls is a bit of a challenge. 

    Then we apply this visual pitch control to flying the airplane down a glideslope or glidepath, and find that things are much smoother and more stable.