BPPP: By the Numbers

This article was published in the February 2017 issue of the American Bonanza Society magazine - www.bonanza.org

A large part of what I do as a flight instructor is providing flight reviews.  This gives me an opportunity to fly in many types of aircraft and observe different styles of flying.  A couple of weeks ago I was doing a flight review with a pilot and while performing maneuvers I noticed that he did not use consistent power settings for specific configurations of flight. I asked him if he would slow the airplane down to 120 knots in level flight, which he did, but it took a couple of adjustments of the throttle and trim.  I asked if he knew what power setting would give him 120 knots.  It took a moment, but he eventually gave me the right answer. It was clear that he did not routinely use pitch and power settings to achieve predictable performance of the aircraft. This is not uncommon, but it surprises me that some pilots I fly with haven’t heard of flying their aircraft by the numbers.

The By the Numbers (BTN) strategy is quite simple and has been an effective and safe way to fly aircraft since World War II. Author John Eckalbar did much to popularize this technique among Beech pilots in his book Flying the Beech Bonanza.  The technique is endorsed by the American Bonanza Society and taught in ABS’s BPPP as the preferred way of flying Beechcraft aircraft, making the aircraft much easier to fly and thereby increasing the level of safety. This methodology is particularly beneficial for pilots who exercise their instrument privileges, but also applies to pilots who are using their aircraft for VFR flight.

Instrument flying entails exact and precise control of your aircraft that requires changing of power settings promptly and accurately. There is very little time to try a throttle setting, wait to see how that affects the aircraft, and then readjust the throttle if needed at the same time you are looking through an approach chart and setting up your radios and GPS.  The BTN principle is rooted in the classic formula:  pitch + power = performance. It is nothing more than understanding that there is a power setting and attitude associated with airspeed and vertical speed.

There are nine phases of flight that require a change in aircraft configuration, and six settings a pilot can influence in order to affect indicated airspeed and vertical speed in a predictable way:

These phases along with their aircraft settings will give predictable performance as indicated in the sample PAC (Power, Attitude, Configuration) Chart for an O-470/ IO-470 powered Bonanza (see Figure 1 above). 

Initial Climb 

The goal is to gain as much altitude as possible in the shortest time.  This is done with full throttle (or red line), and maximum RPM.  In most Beechcraft aircraft, you will see about a 10 degree climb pitch with an associated airspeed close to what is noted in the takeoff checklist.  Flaps are normally up, and the gear is raised once a positive rate of climb is established. 

Cruise Climb 

Transition from Initial Climb to Cruise Climb is initiated by simply lowering the nose a few degrees and changing the propeller RPM.  This is done to provide for better cooling of the engine, better forward visibility, and a higher forward speed.  

Cruise 

Cruise configuration is something that should be very familiar to pilots, consisting of power settings derived from preflight motions intended to maximize range and speed.  Based on the numbers calculated for the conditions of the day, the pilot can expect to obtain predicted aircraft performance.  Small adjustments could be made to the cruise configuration to maximize fuel economy, speed or for comfort.  For example, I often fly a G36 Bonanza that doesn’t run as smoothly at 2300RPM as it does at 2350RPM. 

En Route Descent 

As the destination draws closer, you will be required to descend to an altitude for the approach segment of the flight or to pattern altitude.  En route descent numbers will give you good forward speed, a comfortable descent rate, and keep the engine warm.  Throttle control is important as the airspeed in the descent can easily creep into the yellow arc – a hazard if you encounter turbulence. 

Approach Level 

Approach configuration is a level flight attitude that will allow for enough forward speed, but be slow enough to convert to a landing.  This configuration is used when flying the approach and is slow enough to be able to drop the gear at the final approach fix, or to deploy flaps if needed at a phase in the approach.  The Approach Level configuration can also be used in the pattern for VFR pilots. 

Precision Descent 

The only change needed to transition from the approach level configuration is to extend the landing gear.  This will give between 500 and 600 feet per minute descent.  A slight power setting change may be needed to maintain the glide-path, but no trim changes should be necessary. 

Non-Precision Descent 

As with the Precision Descent configuration, the only configuration change required is extending the gear.  This will produce a stabilized descent of between 800 and 1000 feet per minute and should allow for a smooth descent to MDA.  On approaches that require an aggressive descent rate to meet MDA before the missed approach point, a reduction in power of a couple of inches will provide for an accelerated descent rate.

MDA Level 

Upon reaching MDA, a level off will be required to fly to the missed approach point.  This should be done with minimal aircraft re-configuration – by simply adding between six and seven inches of manifold pressure to maintain level flight.  The gear should be left in the down position. 

Missed Approach 

If a missed approach is required, the procedure will be very similar to the cruise climb procedure.  As depicted in the PAC chart, the procedure for a Bonanza with an IO-470 engine would be Full throttle, RPM at 2500, and 5 degrees up pitch.  After seeing a positive rate of climb, retract the flaps and gear. 

Knowing the numbers for your aircraft can you give you predictable performance for various phases of flight that are essential in the instrument environment, but also apply for every day flying such as initial descent, pattern entry, and landing. Besides the Precision and Non-Precision Descent configurations, all the other categories apply to VFR flight.  The Approach Level configuration would be used when flying the traffic pattern and while MDA Level may not be used, a pilot may find this configuration helpful if they find themselves in the pattern with the gear down for some reason.   

The By the Numbers technique reduces the workload for IFR flying and creates a safe and predictable flight environment for VFR flying as well. You can learn more about the technique in the BPPP Systems, Procedures and Techniques Course (BPPP Initial), available free to ABS members under TRAINING at www.bonanza.org.  Schedule some time with a BPPP instructor to review the numbers for your aircraft, and to fly a couple of scenarios to understand how this will help you fly your aircraft more precisely and effectively