The Importance of Performance Planning

I regularly grade tests completed by pilots enrolled in an annual recurrent training course offered at the school in which I am the Assistant Chief Instructor.  The test is open-book and many of the questions are reviewed in class.  Of the 50 questions, roughly five are related to some sort of performance planning or weight and balance.  It may come as no surprise but these questions are the ones that are often missed or skipped when it comes time to grade. 

Many pilots skip the performance-related test questions entirely because they have a “digital” version at their home base or they use a “worst-case” scenario when performance planning.  What is so concerning is that many pilots cannot even find the correct or appropriate performance chart when asked to work the performance question from the test.  Let’s take, for example, the Airbus H125.  Depending on the aircraft, the H125 can have a maximum gross weight of 4,961 pounds or 5,225 pounds.  The basic flight manual provides performance charts for the 4,961-pound MGW and Supplement 28 provides performance charts for the increase in MGW to 5,22- pounds.  While the most common H125 in the United States includes the MGW increase, pilots fail to recognize which charts to use.  This is common with the MD500D/E/F, BH205/212 and other aircraft we operate. 

This got me thinking about why pilots often struggle with doing accurate performance planning.  Like flight proficiency, ground proficiency dwindles over time.  If a pilot fails to practice checking his or her performance on a regular basis, the ability to rapidly “hand jam” a Hover Out-of-Ground-Effect chart or Weight and Balance dramatically decreases.  For many pilots, the condition of flight may change throughout the course of a shift, but a spreadsheet or tablet application is used to quickly ascertain if they can accept or complete a flight.  Getting this information quickly can be essential.  However, when there is ample time, how many pilots pull out the flight manual charts and check?

Just the other day, the weight and balance spreadsheet I use would not accurately reflect if I had certain accessories and/equipment installed (i.e. basket, mirror, cargo swing, removal litter kit, etc.).  Turns out, the formula had been corrupted during a download and I had to recreate the formula on Microsoft Excel.  We could debate the importance of being to use Excel on a different day, but I needed to confirm that my formula was correct before I published the final Weight and Balance calculation.  Knowing this, I pulled out the appropriate flight manual and flight manual supplements.  Armed with my No.2 pencil, a scratch pad and a calculator, I checked each accessory to confirm accuracy.  Thankfully, my Excel skills rose to the occasion.  However, I could not have known that without having confidence in my manual calculations.  Equally important, I knew where to find the information to check my work.

I decided I should check the HOGE performance (because I rarely rely on HIGE performance) at various weights, temperatures and pressure altitudes.  Interestingly enough, I realized that our Excel sheet did not include the most current Power Upgrade to the H125.  As a result, the HOGE reflected in the spreadsheet wasn’t as good as the performance calculated from the flight manual supplement.  While the spreadsheet was more conservative, I could handle significantly more on a long-line using the appropriate supplement.

On September 29^th, 2018, an AS350B2 experienced a hard landing in Ruidoso, New Mexico during an off-airport landing.  The landing zone was over 9,700’ MSL while the density altitude was over 12,000’.  Although the NTSB report acknowledged the pilot failed to perform preflight performance planning, there was next to no further discussion on the performance charts themselves.  Specifically, the conditions detailed on the performance chart. 

Depending on the make/model of aircraft you are flying, the performance chart will give you the conditions under which the performance can be expected.  For example, the chart may indicate a “No Wind” condition or less than a particular number of amps used.  The chart may also stipulate that various systems are off.  Usually, the notes section of these charts will tell you the amount of weight (or altitude) penalty that must be applied if you have wind or have a high amp demand.  For example, the MD500 states that you must reduce weight if using the cabin heater, engine anti-ice, or both.  These notes are critically important when operating at the upper end of the limits.  A weight reduction of 75 pounds might be the difference between arresting a rate of descent or drooping the rotor speed.

The other assumption most performance charts make is that the aircraft is passing a power assurance check.  In fact, most performance charts indicate that the chart is applicable when operating at maximum takeoff power.  Conducting an accurate power assurance check is critical to ensuring the performance charts are applicable.  Failed power checks mean the performance charts are no longer applicable because there is no penalty that can be applied for an engine that is under performing.  In many new aircraft, a power assurance check can be completed by a selection on the onboard engine health monitory program.  Like performance charts, these power checks need to be reviewed for accuracy and correctness.  For example, some power checks must include a correction for inlet barrier filters, particle separators, or sand filters.  If the onboard system does not account for that equipment (or was not programmed to), then the power may be falling below specified limits.  It is incumbent on the pilot to understand the conditions in which a power assurance check is considered satisfactory or unsatisfactory.  The best way to do this is to understand the chart that was used to develop the power check.

While digital performance charts are getting better at including these conditions, they must be reviewed and reviewed with an eagle’s eye.  The pilot must be familiar to recognize when s/he did not reflect these conditions in his or her planning.  The problem is, you must know where to find and how to read these charts.

I have found that the best way to combat inaccurate power assurance checks, performance planning and weight and balance is to practice doing them from time to time.  Perhaps a check can be done after a major maintenance event or repair.  A pilot can take the time to gather and review the charts that are appropriate to the aircraft configuration, study the notes and conditions and manually check.  Occasionally, I will make a clear photocopy of the charts so that I can write and draw on them without leaving marks in the actual rotorcraft flight manual.  I make the copy of the chart my scratch pad and run through various conditions. 

Not only does this give me practice but it confirms (or dispels) my knowledge of the limitations of the aircraft.  This knowledge helps me be informed in an ever-changing flight environment.  While I may not be able to tell you the exact weight limit to hover out-of-ground-effect at a given pressure altitude and temperature, I know that I can find it quickly or, at least, have to awareness to say “Stop!  This is too close and I need to check.”