National Academies Press: OpenBook

Development of a Small Aircraft Runway Length Analysis Tool (2022)

Chapter: 3 Aircraft Performance Data Collection and Analysis

« Previous: 2 Review of Small Aircraft Performance Literature
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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Suggested Citation:"3 Aircraft Performance Data Collection and Analysis." National Academies of Sciences, Engineering, and Medicine. 2022. Development of a Small Aircraft Runway Length Analysis Tool. Washington, DC: The National Academies Press. doi: 10.17226/26730.
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16 3 AIRCRAFT PERFORMANCE DATA COLLECTION AND ANALYSIS Review of various aircraft runway length performance documents (40-147) identified four types of aircraft performance data presented in runway performance documents for aircraft weighing up to 20,200 lb. (9,163 kg.). 1) Tabular aircraft performance data with pressure altitude, aircraft weight, airport temperature, and climb- weight temperature limits as independent variables, 2) Tabular aircraft performance data with pressure altitude, aircraft weight, and airport temperature as independent variables, 3) Nomograph runway performance data with density altitude, and aircraft weight, as independent variables, and 4) Nomograph runway performance data with pressure altitude, aircraft weight, and airport temperature are independent variables with integrated correction factors for the wind and runway gradient. 3.1 DATA WORKFLOW ANALYSIS The workflow to process, store, and validate the aircraft performance data follows three steps: 1. Data conversion and consolidation of data from the original format to a common spreadsheet table format. 2. Analysis of the spreadsheet data to estimate relevant correction factors and aircraft operational limits. 3. Data validation using trend and graphical data analysis. The first step to analyze aircraft runway performance data requires conversion of table data supplied in electronic or printed form (i.e., Adobe PDF format) to spreadsheet format. We use spreadsheets to consolidate multiple tables of the POH, AFM, and FPG documents into larger integrated data tables. Figure 9 illustrates the workflow process to convert aircraft performance tabular data into useful spreadsheet data tables employed by SARLAT. The top panel in Figure 9 shows the original takeoff field length performance data for the Cessna Citation Jet CJ3 for two airport elevation conditions (sea level and 3,000 feet) provided in Portable Document Format (PDF). The aircraft manufacturer data is converted to spreadsheet table format (i.e., Microsoft Excel) using the built-in conversion capabilities in Adobe Acrobat Pro software (see the middle panel in Figure 9). The conversion from PDF to spreadsheet format is far from perfect and the conversion of PDF tables into other formats may produce inaccurate numbers while exporting the data to spreadsheet form. To validate the accuracy of the converted spreadsheet data, we created a MATLAB2 computer program to make graphical validation plots like the lower panels presented in Figure 9. The process helps identify data conversion errors if the runway length trends produce crossings between performance curves for adjacent airport elevations. Figure 9 shows smooth and monotonically increasing takeoff field length performance curves for the Cessna Citation Jet CJ3 verifying expected runway length trends. 2 MATLAB is a trademark of the MathWorks. MATLAB is a programming and numeric computing software used in engineering analysis.

17 Figure 9: Aircraft Flight Planning Guide Data (top panels), Spreadsheet Data Consolidation (Middle Panel), and Validation Analysis of Takeoff Field Length to Clear 50-Foot Obstacle Data (Lower Panels) for the Cessna Citation CJ3 (C525B) with 60% and 90% Useful Loads. 3.2 TABULAR AIRCRAFT PERFORMANCE DATA WITH CLIMB WEIGHT TEMPERATURE LIMITS Runway length performance for many high-performance aircraft presents takeoff and landing field lengths for different takeoff weights, temperatures, and pressure altitude levels. The data includes climb weight temperature limits for every airport elevation-weight combination. Climb weight temperature limitations are important in airport design and are included in the SARLAT. Climb weight temperature limitations represent aerodynamic performance limitations for each aircraft. Figure 9 shows an example of tabular takeoff field length data for the Cessna Citation Jet CJ3 at two airfield elevations (see the top panel in Figure 9). The aircraft climb weight temperature limits are presented in the last two rows of the original aircraft manufacturer data (see the upper panels in Figure 9). We include the aircraft climb weight limitations and their corresponding takeoff field length requirements in the spreadsheet to form a complete data set. For example, according to the original performance data a Cessna CJ3 is limited to 44 degrees Celsius while operating from 3,000 feet airport elevation at 13,870 lb. The corresponding takeoff field length is 6,080 feet. The

18 climb weight temperature limit conditions are inserted into the spreadsheet as a new set of columns which represent new temperature operating conditions. To estimate the runway length for the new temperature conditions at lower airport elevations we use a Piecewise Cubic Hermite Interpolating Polynomial (PCHIP) (see the yellow cells in Figure 9).The red cells in the spreadsheet example show airport operating conditions unavailable in the aircraft performance manual. The SARLAT design philosophy is to present airport designers with information produced by the aircraft manufacturer (i.e., no extrapolation). From a practical viewpoint, the red cells in Figure 9 do not represent practical airport design conditions. Most airport design conditions in the United States involve mean daily maximum temperatures of the hottest month of the year ranging from 50-104 degrees Fahrenheit (10-40 degrees Celsius). The SARLAT has temperature limits between 5-40 degrees Celsius. The middle panel in Figure 9 presents a consolidated spreadsheet with takeoff field length for the Cessna Citation CJ3. The lower section of Figure 9 shows takeoff field length validation plots for the Cessna Citation CJ3 including climb weight temperature limitations. During the process of validation aircraft runway performance data, we found two anomaly data points in the Textron Aviation King Air 350ER POH data. In such case, we corrected the data using the Piecewise Cubic Hermite Interpolation available in MATLAB. 3.3 TABULAR AIRCRAFT PERFORMANCE DATA Some high-performance aircraft performance data includes takeoff and landing distance (or field length) data for different takeoff weights, temperature, and pressure altitude conditions without climb weight limitations. Figure 10 shows takeoff length data for the Daher/Socata TBM 850 - a high-performance, single-engine turboprop aircraft. The information provided by the aircraft manufacturer includes multiple aircraft weights, eight temperature conditions, and various pressure altitudes. The manufacturer includes correction factors for wind and a variety of runway surfaces. The right-hand side panel in Figure 10 shows sample validation plots for the TBM 850 takeoff distance to clear a 50-foot obstacle with a 60% useful load under dry and wet runway conditions.

19 Figure 10: Tabular Aircraft Performance Data (Left) and Validation Analysis (Right) for the Daher-Socata TBM 850 Turboprop Aircraft. 3.4 NOMOGRAPH RUNWAY PERFORMANCE DATA Most single-engine, piston-powered aircraft runway length data is presented in nomograph format. Aircraft runway performance nomographs contain three parts 1) airport conditions, 2) takeoff weight corrections, and 3) wind and runway grade corrections. Figure 11 shows a nomograph with a takeoff distance over a 50-foot obstacle for the Mooney M20V Acclaim – a piston-powered, single-engine aircraft. We employ scanning software (ScanIt 3 ) to convert the nomograph information into discrete performance points and then consolidate the data into a consolidated spreadsheet format. During the conversion of nomographs to spreadsheet format, we found that 10-11 data points for every airport pressure altitude condition produces an accurate representation of the nomograph data. Some aircraft manufacturers include simple correction factors for wind and runway grade independent of the takeoff distance nomographs. Others have wind and runway grade corrections as part of more complex nomographs with integrated runway grade information (see Figure 11). Figure 12 shows ground-roll distance validation plots for the Mooney M20V Acclaim for various wind conditions. 3 ScanIt is a trademark of AmsterChem, a software program to extract data from scientific plots.

20 Figure 11: Data Collection Points for Takeoff Distance Over 50-foot Obstacle for the Mooney M20V Acclaim. (Screenshot from ScanIt Software). Figure 12: Takeoff Distance Over 50-foot Obstacle Validation Plots for the Mooney M20V Acclaim (at 100% Useful Load). Some aircraft manufacturers present simpler runway length performance nomographs with density altitude and aircraft weight as independent variables. Figure 13 shows an example of such a nomograph for the Flight Design CTLS Light Sport Aircraft (LSA). Density Altitude (DA) and pressure altitude conversions are estimated using standard formulas (34, 35).

21 Figure 13: Landing Performance Chart for the Flight Design CTLS Light Sport Aircraft. (Source of Data: Flight Design, Screenshot from ScanIt). 3.5 SARLAT RUNWAY LENGTH OUTPUTS SARLAT reports multiple runway length metrics for every aircraft and airport design scenario. Depending upon the aircraft selected for analysis, up to six runway distance metrics are reported by SARLAT. Table 2 shows the runway distance outputs produced by SARLAT. The design philosophy in SARLAT is to report aircraft manufacturer data when available. For aircraft that do not include wet pavement correction factors, we employ a 15% correction factor to convert dry to wet pavement runway length distances. Analysis of aircraft performance data reported by several aircraft manufacturers leads us to conclude that a 15% correction factor is a conservative number for most airport design conditions (see Section 3.5.2). For single-engine, piston aircraft, SARLAT reports dry and wet pavement takeoff distances to clear a 50-foot obstacle. Landing distances reported are full stopping distance crossing the screen height (50 feet) for dry and wet pavement conditions. For twin-engine aircraft SARLAT reports accelerate-stop distance as an option to be evaluated by airport operators for consideration of local funding for a desired runway length. However, accelerate-stop-distance for a twin-engine piston aircraft is not eligible for Airport Improvement Program (AIP) funds under current policy. SARLAT users who may apply for AIP funds, should consult Appendix D of the report to estimate takeoff distance calculations for twin-engine piston aircraft that meet AIP program guidelines. Appendix D contains information about the difference between accelerate-stop distance and takeoff distance for six twin-engine, piston-powered aircraft included in SARLAT. For example,

22 Figure 51 shows the difference between takeoff and accelerate-stop distance for the Beechcraft Baron 58 vary from 450 to 1100 feet depending upon the airport elevation and temperature conditions. SARLAT reports up to six runway length distances for turboprop and turbofan-powered aircraft. Dry and wet takeoff field length, dry and wet landing distances, and two additional landing distances used in 14 CFR Part 135 on-demand operations. For 14 CFR Part 23 Commuter Category aircraft and for 14 CFR Part 25 aircraft, the takeoff field length reported in SARLAT is the largest of accelerate-stop, accelerate-go with one engine inoperative, or 115% of the all-engine takeoff distance to clear a 35 feet object above the runway. All three factors are reflected in the takeoff field lengths reported in SARLAT for turbofan engine aircraft. SARLAT considers second segment climb limitations in the takeoff field length data for turbofan aircraft. Second segment climb limitations consider airport temperature, airport elevation and aircraft weight (23). The additional landing distances are important to airport operators because many charter and fractional ownership services at small airports are flown under 14 CFR Part 135 rules. The provision of Part 135 landing distances allows airport designers to better communicate the operational needs of charter services to their airport clients. Business operations at small airports fall into three operational categories: Part 91K (fractional operations), Part 135 (charter operations) and standard Part 91 (private operations). The rule is that private operations by an owner of the aircraft are normally conducted under Part 91. The exception is when the same private operator allows the aircraft to be used in charter operations – a common practice today to offset the cost of operating corporate jets. In that case, Part 135 apply. Air taxi charter operations are normally carried out under Part 135 rules. Fractional ownership rules fall either under Part 91K or Part 135. Large charter and fractional companies enhance the safety of their operations by abiding to Part 135 rules (stricter landing margins, pilot crew rest periods, etc.) According to recent ARGUS/TRAQpak4 data the percent of hours flown by fractional and charter operations combined accounts for 52.5% of all Part 91/91K/135 operation hours in the United States. The same percentage was 43.7% in 2012. Moreover, the ten largest US fractional and charter operators accounted for 44.5% of the Part 91K/135 operations or 22.3% of all business aviation flight hours. Using such statistics, we conclude that six of every ten business jet and turboprop operations in the US maybe operated under Part 91K or Part 135. Table 3 shows the effective landing distance correction factors used to adjust landing distances according to rules in 14 CFR Part 135. For aircraft having a seating configuration of 10 passenger seats or more, SARLAT includes the accelerate-stop distance in computing the required takeoff runway length, in accordance with 14 Code of Federal Regulations Part 135. For turboprop aircraft with less than 10 seats, SARLAT reports takeoff distances because higher engine reliability of turboprop aircraft seldom results in aborted takeoffs. The current Part 23 certification criteria for small aircraft with fewer than 10 seats mandates takeoff distance instead of accelerate-stop distance. For turbofan (i.e., turbofan-powered) aircraft, SARLAT reports takeoff field length as the takeoff metric. Note that for turbofan-powered aircraft, the adjustments factors for Part 135 operations are slightly higher than for turboprop aircraft (see Table 3). 4 ARGUS TRAQPak data is a flight tracking service. https://www.argus.aero/flight-tracking- software/

23 Some aircraft manufactures provide two flap settings for turboprop and turbofan-powered aircraft. For example, aircraft takeoff performance data for the Textron Aviation King Air 350 contains flaps up and flaps approach settings. Since the objective of this tool is to provide the minimum runway length for airport design, we only consider the data with the flap setting that minimizes runway length requirements. Table 2: SARLAT Runway Length Outputs. Aircraft Class Reported Runway Distances Remarks Piston Single Engine Dry takeoff Takeoff distance to clear 50-foot obstacle Dry landing Landing distance crossing the runway threshold at screen height (50 feet) Wet takeoff Takeoff distance to clear 50-foot obstacle corrected for wet pavement conditions Wet landing Landing distance crossing the runway threshold at screen height (50 feet)– corrected for wet pavement conditions Piston Twin-Engine Dry takeoff Accelerate-stop distance Dry landing Landing distance crossing the runway threshold at screen height (50 feet) Wet takeoff Accelerate-stop distance corrected for wet pavement conditions Wet landing Landing distance crossing the runway threshold at screen height (50 feet)– corrected for wet pavement conditions Turboprop with less than 10 seats Dry takeoff Takeoff distance to clear 50-foot obstacle Dry landing Landing distance crossing the runway threshold at screen height (50 feet) Wet takeoff Takeoff distance to clear 50-foot obstacle corrected for wet pavement conditions Wet landing Landing distance crossing the runway threshold at screen height (50 feet)– corrected for wet pavement conditions 14 CFR Part 135 on- demand operation – dry pavement Landing distance at the intended destination airport within 70 percent of the effective length 14 CFR Part 135 on- demand operation – wet pavement Landing distance at the intended destination airport within 70 percent of the effective length and an additional 15% correction for wet pavement

24 Turboprop with 10 or more seats Dry takeoff Accelerate-stop distance in dry pavement conditions Dry landing Landing distance crossing the runway threshold at screen height (50 feet) Wet takeoff Accelerate-stop distance in wet pavement conditions Wet landing Landing distance crossing the runway threshold at screen height (50 feet)– corrected for wet pavement conditions 14 CFR Part 135 on- demand operation – dry pavement Landing distance at the intended destination airport within 70 percent of the effective length 14 CFR Part 135 on- demand operation – wet pavement Landing distance at the intended destination airport within 70 percent of the effective length and an additional 15% correction for wet pavement Turbofan engine Dry takeoff Takeoff field length in dry pavement conditions1 2 Dry landing Landing distance crossing the runway threshold at screen height (50 feet) Wet takeoff Takeoff field length in wet pavement conditions Wet landing Landing distance crossing the runway threshold at screen height (50 feet)– corrected for wet pavement conditions 14 CFR Part 135 on- demand operation – dry pavement Landing distance at the intended destination airport within 60 percent of the effective length 14 CFR Part 135 on- demand operation – wet pavement Landing distance at the intended destination airport within 60 percent of the effective length and an additional 15% correction for wet pavement 1 For 14 CFR Part 23 Commuter Category aircraft and for 14 CFR Part 25 aircraft, the takeoff field length is the largest of accelerate-stop, accelerate-go with one engine inoperative, or 115% of the all-engine takeoff distance to clear a 35 feet object above the runway. All three factors are reflected in the takeoff field lengths reported in SARLAT for turbofan engine aircraft. 2 SARLAT considers second segment climb limitations in the takeoff field length data for turbofan aircraft. Second segment climb limitations consider airport temperature, airport elevation and aircraft weight (23).

25 Table 3: Correction Factors Applied to 14 CFR Part 135.385 Landing Operations. Applicability Remarks Landing Correction Factor Large transport category airplanes Turbofan engine powered Dry runway Full stop landing at the intended destination airport within 60 percent of the effective length 1.67 Large transport category airplanes Turbo-propeller powered Dry runway Full stop landing within 70 percent of the effective length 1.43 Large transport category airplanes Turbofan engine powered Wet runway An additional 15% correction factor beyond Rule 1 1.92 Eligible On-demand operation Large transport category airplanes Turbofan engine powered Dry runway Full stop landing at the intended destination airport within 80 percent of the effective length 1.25 3.6 RUNWAY LENGTH CORRECTION FACTORS Runway length performance correction factors include runway grade, wind conditions, and runway surface. In most aircraft performance documents, the corrections are assumed to be independent of each other. After reviewing more than 90 aircraft documents, we found that wind correction factors for takeoff and landing distances are provided in most pilot operating handbooks. The review of the same 90 documents uncovered that many aircraft manufacturers do not provide information on runway grade and runway surface correction factors. The objective of this section is to estimate and justify correction factors for aircraft with missing runway grade and surface data. 3.6.1 Runway Grade Correction Examination of the takeoff performance of piston-powered aircraft shows large differences compared to the takeoff performance of turboprop and turbofan-powered aircraft. Specifically, power loading (the ratio of aircraft weight and engine horsepower) plays a role in the immediate climb performance of piston-powered aircraft compared to their turboprop and turbofan-powered counterparts. Therefore, we developed general runway grade correction model for piston-powered aircraft, turboprop-powered aircraft, and turbofan-powered aircraft to address gaps in the aircraft runway performance data. The SARLAT design philosophy is to use runway length correction factors directly from an aircraft manufacturer when available. The generic correction factors presented in this section are used when there is not aircraft manufacturer data available. Table 4 shows all runway grade corrections provided in runway performance documents for piston-powered aircraft. Most aircraft manufacturers suggest a simple correction (a non- dimensional multiplicative factor to correct runway length requirements) for every 1% uphill runway grade. Other manufacturers, provide runway grade correction factors that vary with pressure altitude (e.g., Cirrus SR20 and SR22 aircraft). Few aircraft manufacturers provide detailed correction factors integrated into the takeoff and landing performance nomographs (e.g., Mooney M20V Acclaim) as shown in Figure 11.

26 Table 4: Aircraft Manufacturer Runway Grade Takeoff Distance Correction Factors for Piston-Powered Aircraft. Aircraft Name Correction Format Correction for Every 1% Uphill Increase in ground roll Increase in takeoff distance Cessna Columbia 400 Single factor 6% Apply the generic correction Diamond 40 Single factor Not available 5% Mooney M20V Acclaim Nomograph Depends on pressure altitude Depends on pressure altitude Piper 24 Comanche Single factor 3% 3% Tecnam P2006T Single factor 5% 4% Cirrus SR 22 Single factor Sea level: 22% 5,000 feet: 30% 10,000 feet: 43% Apply the same correction to ground roll Using the Mooney M20V aircraft as representative piston-engine aircraft, we examined the takeoff runway grade correction factors for different pressure altitudes (see the blue lines in Figure 14). Figure 14 and the data provided by Cirrus SR20 and SR22 aircraft (see Figure 14 shows the effect of pressure altitude on runway grade correction factors. Using the Mooney M20V data, we developed a generic runway grade correction factor that increases the takeoff runway length required by 16% for each 1% grade (uphill) at sea level conditions. The takeoff runway length increases to 21% for each 1% grade (uphill) for pressure altitudes of 5,000 feet or above. Linear interpolation (see the red lines in Figure 14) is applied to intermediate pressure altitudes. Figure 14: SARLAT General Runway Grade Correction Model for Piston-Powered Aircraft.

27 We studied takeoff runway grade corrections for turboprop-powered aircraft. Figure 15 shows published aircraft manufacturer runway grade correction factors for three turboprop aircraft: the Beechcraft King Air C90, the Pilatus PC-12NG, and the Piper 46 Malibu Meridian at a typical airport design temperature 30 degrees Fahrenheit above International Standard Atmospheric (ISA) conditions (e.g., 89 deg. Fahrenheit at sea level). Figure 15 shows high variability in the runway grade correction factor across three aircraft. The Beechcraft King Air C90 has the largest correction factors in the group and is used as representative aircraft to develop a generic runway grade correction factor model for turboprop aircraft. Following a similar analysis process described above, other turboprop-powered aircraft in SARLAT (the Daher-Socata TBM 700, the Daher-Socata TBM 850, the Cessna 208 Caravan, and the Rockwell Commander 690B) use the generic model with a runway grade correction of 8% for takeoff distance for each 1 percent (uphill) grade at sea level. Similarly, a correction factor of 14% increase in takeoff distance for every 1 percent (uphill) grade for pressure altitudes of 5,000 feet or more (see the red lines in Figure 16). To be conservative in the analysis and consistent with other turboprop-powered aircraft, the same rules apply for correcting the accelerate-stop distance of the Rockwell Commander 690B. Larger turboprop aircraft such as the Textron Aviation King Air B350ER have detailed runway grade correction factors via a nomograph, and those values are used directly in the runway length calculations. Figure 15: Aircraft Manufacturer Runway Grade Correction Factors for Three Popular Turboprop-powered Aircraft.

28 Figure 16: SARLAT General Runway Correction Model for Turboprop-Powered Aircraft. The takeoff field length performance of turbofan-powered aircraft is also affected by runway grade. Table 5 shows the recommended runway grade takeoff field length correction factors for popular turbofan-powered aircraft. For some aircraft, the aircraft manufacturer recommends simple grade correction factors with two discrete numerical values (e.g., Cessna Citation Bravo and Citation V in Table 5). Other aircraft, like the Cessna Citation 560XL have more comprehensive grade correction factors tabulated as a function of zero grade takeoff field length. Examination of takeoff field length correction factors suggest that turbofan-powered aircraft have similar more pronounced non-linear effects compared to the turboprop and piston-powered aircraft data presented. This can be attributed to the faster takeoff speeds of turbofan aircraft and the greater effect of grade over longer takeoff distances compared to turboprop and piston aircraft. Figure 17 shows the takeoff field length correction grade correction factor for the Cessna Citation 560XL. The data is presented with pressure altitude in the x-axis to be consistent with other general grade correction factors models discussed for piston and turboprop-powered aircraft. The values presented suggests a takeoff field length grade correction factor at sea level is 13.2% for a 1% uphill runway grade. At 5,000 feet pressure altitude the takeoff field length grade correction is 17.2% for a 1% uphill runway grade. Takeoff field length grade correction factors can be as high as 65% for 2% uphill grade at 9,000 feet. Note that such values are consistent with the single number correction factors provided by Cessna for the Cessna Citation V and slightly higher than those quoted for the Cessna Citation Bravo. Because we do not have correction factors for all five turbofan-powered aircraft in SARLAT, we use the Cessna Citation 560 XL as representative values for runway grade correction of takeoff field length.

29 Table 5: Aircraft Manufacturer Runway Grade Takeoff Field Length Correction Factors for Turbofan-Powered Aircraft. Aircraft Name Correction Format Correction for Takeoff Field Length for 1% Uphill Grade Correction for Takeoff Field Length for 2% Uphill Grade Cessna Citation Bravo (Model 550) Single value for an individual grades 25% 55% Cessna Citation V (Model 560) Single value for an individual grade 20% 70% Cessna 560 XL Multi-dimensional table format See Figure 17 See Figure 17 Figure 17: Cessna 560 XL Aircraft Runway Grade Correction Factors. Temperature Conditions ISA + 30 Deg. Fahrenheit. Source of Data: Cessna Aircraft Company. Data Points Shown are the SARLAT General Grade Correction Factors Used. 3.6.2 Runway Surface Corrections The SARLAT is designed to provide runway length requirements for a variety of surfaces. That may include wet pavement, grass and gravel. Historically, wet pavement runway length can be estimated by adding 15% of runway length to the dry pavement runway values suggested by some aircraft manufacturer. For example, the Daher-Socata TBM 700 and the Daher-Socata 850 POH data suggests adding 15% to takeoff distance to account for wet paved runway operations. To verify such general correction factor, we analyze POH data for the Textron Aviation King Air 350ER for dry and wet conditions, respectively. Figure 18 plots the correction factor for four

30 temperature conditions operating at 90% of the maximum takeoff gross weight. The figure shows that a 15% correction factor to convert dry to wet pavement conditions is adequate for this class of aircraft. Figure 18 shows operational restrictions to less than 2,000 feet pressure altitude when operating at ISA+45 deg. Fahrenheit. SARLAT uses the wet pavement performance charts specified by the manufacturer if available. Otherwise, SARLAT uses a general 15% correction factor to convert dry to wet pavement conditions. Some aircraft performance documents include detailed grass runway performance (e.g., Mooney M20J and Textron Aviation King Air B350ER). Others, offer simple scalar values as correction factors to account for additional runway length required in grass operations (see Table 6). SARLAT contains detailed correction factors for aircraft with detailed grass correction data. Otherwise, we simply use the single values provided in Table 6 according to the aircraft manufacturer. SARLAT provides grass operation runway lengths for aircraft listed in Table 6. Some aircraft manufacturers do not provide correction in takeoff distance. I such case, we use 25% as the general correction factor for takeoff distance in grass operations. Figure 18: Actual Wet Runway Correction Factor for King Air 350ER at 90% Useful Load. The Horizontal Red Line is the 15% Correction Factor Assumed by Many Aircraft Manufacturers.

31 Table 6: Grass Runway Correction Information for Aircraft in SARLAT. Aircraft Name Height of Dry Grass Correction Factor in POH Increase in Ground Roll Increase in Takeoff Distance Cessna 150 Not available 15% Not available Cessna 152 Not available 15% Not available Cessna 172 Skyhawk Not available 15% Not available Cessna 177 Cardinal Not available 15% Not available Cessna 180 Skywagon Not available 15% Not available Cessna 182 Skylane Not available 15% Not available Cessna T206 Stationair Not available 15% Not available Cessna 208 Caravan Not available 15% Not available Cessna T210 Centurion Not available 15% Not available Cessna 310 Not available Not available 7.9% Cessna Columbia 400 Not available 30% Not available Cirrus SR-20 Not available Not available 20% Cirrus SR-22 Not available Not available 20% Cirrus SR-22 Turbo Not available Not available 15% Diamond 40 Star Longer than 4 inches 20% Not available Diamond 42 Twin Star Longer than 4 inches 20% Not available Piper 24 Comanche Greater than 5 inches Not available 25% Socata TBM 700 High grass Not available 25% Socata TBM 850 High grass Not available 25%

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Development of a Small Aircraft Runway Length Analysis Tool Get This Book
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 Development of a Small Aircraft Runway Length Analysis Tool
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An important operational characteristic of an airport is the length of its longest runway. The longest runway determines the types of aircraft that can use the airport and dictates the operational limitations at the airport.

The TRB Airport Cooperative Research Program's ACRP Web-Only Document 54: Development of a Small Aircraft Runway Length Analysis Tool provides a user-friendly computer tool to help airport planners and designers estimate runway length requirements for a variety of aircraft and design conditions.

Supplemental to the report are the SARLAT (for Windows and Mac) and the SARLAT Users Guide.

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