Energy management based solely on visual cues can result in aircraft performance hunting. Before finding a way to record and correct each approach, you must first have the basic parameters required to achieve specific aircraft performance for a stabilized approach. In order to establish some sort of measurable performance numbers first, I would personally try the following with your CFI:
- At taxi pattern altitude, establish a pre-determined airspeed, flaps + whatever power setting is needed to maintain that airspeed and altitude downwind— no change of flaps during the initial downwind descent; if you change the flap configuration during the initial descent, you risk losing sight of the aircraft‘s performance because 3 things change simultaneously, aerodynamics, pitch and power.
- Abeam the predetermined fixed reference point (ie runway threshold); try 60% power — ie) if 2300 rpm is the maximum rpm, 1400 rpm; start your initial descent at 500 fpm, trim and note speed.
- If it is a fixed-pitch propeller aircraft, adjust the throttle to maintain this predetermined RPM. If it is a constant speed propeller plane, adjust the manifold pressure, because it will change without your intervention throughout the descent.
- Rotate to your base leg at the standard 45 degree point while maintaining the power setting. Use 500 fpm as a guideline, but never at the expense of slow speed. Some airports with rising terrain around the runway will likely need a separate point at which you turn to base leg (i.e. altitude). It is at this stage that you will have a good initial perception of the performance of your aircraft. With constant power and descent in fpm, what does your speed and altitude look like relative to the track (not the terrain around the track)?
- During a stabilized approach, minor corrections are possible when you are able to make 2 “trade-offs” in your aircraft’s existing energy (speed and altitude). If you need to change 3 (speed, altitude and power), this is a big fix and your initial “glide” setup should be reconsidered:
- if it’s too fast and too high, your initial RPM setting should be reduced next time; try 100 rpm less, maintain that rpm and always start with 500 fpm.
- if it’s too slow and low, your initial RPM setting should be increased next time; try 100 RPM higher, maintain that RPM and always start with 500 fpm.
The key is to bring your approach profile to the point where you only have to make a pitch change at an established stable power setting until just before the flare. During the final approach phase, you should be able to to add frequent vertical sweep of the obstacle (if any), aiming point, and runway end, in addition to an already established sweep during downwind and base leg.