Originally Posted by
shumway76
An ex-airforce instructor tought this method of level off from glide descent - it seems this is the technique used in airforce PC7.
Assume glide descent speed is 70kts, cruise is 100kts.
- Initiate level off when 10% ROD of desired altitude.
- Simultaneously select full power and slightly higher than straight & level attitude.
- As airspeed increases, progressively lower the nose to straight & level attitude.
- 5kts before reaching cruise speed of 100kts, select cruise power.
- Hold straight & level attitude
- Trim
The main difference in this technique is that you select slightly higher than s&l attitude initially, then progressively lower to s&l attitude as airspeed reaches 100kts.
His reasoning is, as you are in a glide descent at 70kts, when leveling off if you select s&l (instead of slightly higher), you will still be descending due to the lower airspeed initially.
Any thoughts on this technique?
I think care needs to be taken when adopting SOP's from very different types. Idle power descents in turbine aircraft are quite common, especially when in a "slow down and go down" situation. However, other than the final approach there are very few instances that a gliding descent would be the optimal technique in a piston powered aircraft. I agree with the numerous other posters who questioned why you were in a glide descent to begin with.
If the object is to descend from one altitude to another (particularly in the context of cross country flight) than the most efficient way is to simply leave cruise power on and set a nose down attitude that will give you a 500 foot per min decent rate.
I also agree with PILOT DAR's point about "feeling" the aircraft. How ever what a 6000 hr test pilot can do with unconscious competence is a little harder for a 60 hour brand new PPL
. But his point is still valid and this is what every low hour pilot should strive for.
Straight and level, climbing, descending and, turning are the foundation exercises of flight training. Key to success in each, is attitude control. So in the context of descending, to fly accurately and smoothly the pilot must know what attitude to go to and then the amount of power set will give him the right performance. Sounds easy but in practice is IMO an often imperfectly learned skill. Too often climbing or descending involves pitching the nose up or down to a random attitude and accepting what ever results.
This is where covering the ASI in flight is a great exercise. Start with the simplest manoever, full power Vy climb. After covering the ASI pitch up to what you think is the right attitude to result in the Vy airspeed, let the aircraft stabilize and trim. Then uncover the ASI, adjust the attitude as necessary and repeat. It is amazing how quickly you will find you can nail the attitude which will result in exactly the Vy airspeed without ever looking at the ASI. Now do the same for the power off glide. Knowing this one is really important in the event of an engine failure, and then start picking random combinations of airspeed and power. Some dedicated practice will produce a situation where flying goes from random control inputs to the "feel" of a truly proficient pilot.