Evaluating Airfield Capacity (2012)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

A-1 A-1 Appendix A Prototype Airfield Capacity Spreadsheet Model User’s Guide

A-2 Evaluating Airfield Capacity A-2 INTRODUCTION The Prototype Airfield Capacity Spreadsheet Model (Airfield Capacity Spreadsheet Model) was developed for ACRP Project 03-17, “Evaluating Airfield Capacity,” and is intended to serve as a prototype modeling tool to help airport planners understand and determine airfield capacity. Airfield capacity is the estimated number of total operations that a given airfield configuration can facilitate in a given period of time and under a given set of assumptions regarding fleet mix, separation minima rules, weather conditions and technological aides. For many years the ability to quickly estimate an airfield’s potential operational capacity has been limited to rules of thumb for simple configurations and a lookup table provided in the 1983 FAA Advisory Circular 150/5060-5, Airport Capacity and Delay (the AC). Varying levels of sophistication from spreadsheet models to full simulation modeling continue to advance and provide additional tools for planners to assess the existing and future airfield capacity under varying scenarios. The Airfield Capacity Spreadsheet Model can serve as an intermediary between the existing lookup tables available in the current AC (some of which are replicated utilizing new calculations on this spreadsheet model) and full simulation modeling. The Airfield Capacity Spreadsheet Model is built on base calculations following the theory in the FAA Airfield Capacity Model (ACM) and applies variable separation, spacing and clearance standards following the guidelines included in FAA JO 7110.65, Air Traffic Control, and FAA EM-78-8A, Parameters of Future ATC Systems Relating to Airport Capacity/Delay. The FAA ACM referenced is discussed in detail in FAA RD-76- 128, Reference 1. The new spreadsheet model is designed to function as a working planning tool and is sensitive to most input changes that will dynamically represent real conditional changes on most simple to moderately complex airfield configurations. This spreadsheet modeling tool is intended to serve as a beginning-level capacity calculation option. The model is not intended for complex airfield calculations or for use when a higher degree of specificity is required when supporting large-scale airfield redevelopment projects or highly controversial capacity projects. As outlined in the model selection criteria in Chapter 5 of the guidebook, large-scale and expensive capacity-related projects can support and should require the use of more detailed simulation efforts. The checklists provided in Chapter 5 will help to determine if sufficient data is available or can be assumed to provide enough of the necessary inputs to run the various models. In the absence of specific input parameters, the model can, in many cases, still be used, as many of the base default parameters can be used for simple single or dual runway airfields without significant unique restrictions. The Airfield Capacity Spreadsheet Model can be used to generate average or high level hourly capacity metrics depending on the data available and depth of knowledge. Model worksheet areas have been formatted to print out on two sheets of legal paper for each of the three working models.

Appendix A A-3 A-3 The Airfield Capacity Spreadsheet Model calculates average hourly capacity levels for the following general airfield configurations: Single runway Dual parallel runways Dual intersecting runways Each general configuration can be uniquely adjusted to closely fit the conditions of the user’s specific airfield through selected input parameters. The flowchart in Exhibit 1 provides a process overview of the steps involved in using the spreadsheet model with the necessary inputs to estimate airfield capacity. Source: Landrum & Brown. Exhibit 1. Prototype Airfield Capacity Spreadsheet Model flowchart. •Single Runway •Dual Parallel Runways •Dual Intersecting or Converging Runways •Combine Scenarios •Meteorological Conditions (Visual and Instrument) •Runway Exits and Parallel Taxiway Availability •Control Tower Availability •Runway Crossing Demand and Touch-and-Go Operations •Distribution of Operating Aircraft Fleet (Small-Single Engine up to Heavy) •Average Arrival Runway Occupancy Times (AROTs) of Aircraft Classes •Average Approach Speeds of Aircraft Classes •Arrival to Arrival Separation Minima •Departure to Arrival Separation Minima •Standard Deviations in Actual Arrival and Departure Spacing •ATC Safety Buffers for Arrival and Departure Spacing Choose Base Model Input Airfield Conditions Input Fleet Mix Characteristics Adjust Separation Rules and Operational Buffers

A-4 Evaluating Airfield Capacity A-4 Determination of airfield capacity is essentially based on the average time of separation between arriving aircraft and/or departing aircraft, which allows for a certain number of arrivals or departures to occur in an hour. The Airfield Capacity Spreadsheet Model attempts to model the interactions of different aircraft classes in a given fleet mix that follow all of the inputs regarding minimum spacing and air traffic rules. When sufficient spacing occurs between successive arrivals or departures, often one or more departures or arrivals can be released between the pairs, allowing for true mixed operations on the airfield. The optimal capacity is typically a balanced mix of arrivals and departures or a 50:50 mix. DISCLAIMER Significant research has been undertaken to prepare these analysis models for ACRP and much precaution has been taken to ensure that the models provide useful and applicable results to the area of airfield capacity planning. Neither ACRP, LeighFisher, nor Landrum and Brown Inc. assume any responsibility for errors or omissions of components in the development of this model, or for any damages resulting in the use of results from the spreadsheet model analysis. The developing group shall in no event be liable for any financial implications or loss of opportunity alleged to the use of resulting information assumed from use of this model. SYSTEM REQUIREMENTS The Airfield Capacity Spreadsheet Model runs in Excel and suitable for all versions of Microsoft Office Excel 2003 or newer. If the user’s computer is currently successfully running Excel 2003 or newer, the spreadsheet model file should operate without any additional complication or issue. The Airfield Capacity Spreadsheet Model does contain some simple macros for resetting many standard inputs and therefore require the macro function to be enabled. In Excel 2007 or Excel 2010, the “Enable Macros” button should appear in the ribbon at the top of the spreadsheet when the file is opened. Excel versions typically suggest not allowing all macros to run without authorization; therefore, most configurations are set to ask before running a macro or to disable any macros upon opening the file and prompt the user to change the security settings if necessary. To access the security settings in Excel 2007 and 2010, select the “File” tab or the “Windows Office” icon and navigate to “Options\Trust Center\Trust Center Settings” to change the security settings to enable the use of macros. In Excel 2003, navigate to the security settings by selecting the “Tools” menu and choosing “Macro\Security” to change the settings to “Medium.” With the macros enabled, the functions in the Airfield Capacity Spreadsheet Model can perform as intended. If you encounter difficulty getting the “RESET INPUTS” button to work, more information is available on the “INTRO” tab on the spreadsheet. The model’s viewing area fits better on a wide screen monitor with a resolution of at least 1680 x 1050, but any monitor will suffice. Lower resolution monitors may not fully display the output section to the right without shifting the screen view more to the right.

Appendix A A-5 A-5 OVERVIEW The Airfield Capacity Spreadsheet Model consists of a macro-enabled Excel file (workbook) with several user tabs (spreadsheet tabs) that contain the operating configuration models, calculation worksheets, and supporting information on using the models and understanding the inputs and their individual effects on the output. The calculated output is the hourly airfield capacity determined by the combinations of the input data entered and model selections chosen as specific parameters for the airfield under consideration. The workbook contains an introduction tab, labeled “INTRO,” which contains some helpful definitions useful in navigating the model (see Exhibit 2). Note: A supplemental tab, labeled “Separation Layout” (not visible in the exhibit), provides a visual reference for understanding the determination of the arrival to arrival separation and interleaved departure time requirements described in the INTRO tab. Exhibit 2. INTRO tab. The INTRO tab also contains a legend, or “key” to the cell contents to help users identify the data associated with the fill and text colors used throughout the model (see Exhibit 3). Exhibit 3. Cell contents key. Next to the INTRO tab, a “Runway Layouts” tab has been included to graphically depict some of the terms and configurations illustrated within the models to help the user get a better understanding of the interaction involved in the models and the overall process involved in the calculations of the separation between aircraft (Exhibit 4). Exhibit 4. Runway Layouts tab.

A-6 Evaluating Airfield Capacity A-6 To protect the integrity o f the Airfield Capacity Spreadsheet Model’s information and formulas, all of the worksheets have been protected ; however, the user can unprotect them as needed. There is no set password for the ancillary tabs, and for the model tabs the password is set as “ pass ”. Caution: Do NOT change the password if you choose to unlock the models as the password is embedded in the macro codes. The next tab in the workbook is labeled “Lookup Table” (Exhibit 5). This tab opens a sheet containing a lookup table in the format of the AC’s Figure 2-1. This lookup table is just a sample of new lookup table results ba sed on iterations performed using the default settings and assumptions that are in line with those expressed in the AC. Exhibit 5. Lookup Table tab. Of the original 19 configurations presented in the AC, five have been populated which best represent the usable outputs from the three configuration models included in the Airfield Capacity Spreadsheet Model tool. Exhibit 6 shows the results of the Single Runway Model. Three runway configuration tabs can be employed by the user to estimate hourly airfield capacity—“Single Model,” “Dual Model,” and “Intersecting Model” (Exhibit 7). Each tab opens a separate, but comparable, spreadsheet model as designed for a single runway, dual parallel runway, or intersecting runway configuration. Exhibit 7. Single Model, Dual Model, and Intersecting Model tabs. Selection of a model that reflects the user’s airfield operating conditions is the first choice that must be made by the user. Default values are supplied in other sections of the model, but selection of the runway configuration is the f irst requirement in utilizing the Airfield Capacity Spreadsheet Model. The next sections of the User’s Guide provide explanations for use of the models reflecting the three airfield operating conditions provided in the Airfield Capacity Exhibit 6. Portion of Lookup Table showing single runway configurations. New Aircraft Group Mix Percentages Hourly Capacity Annual General Runway-Use Configurations A B C C C C D Operations/Hour Service Volume S-S S-T S+ L-TP L-J L-757 H VFR IFR Operations/Year 1.) 100% 0% 0% 0% 0% 0% 0% 90 66 223,000 25% 50% 25% 0% 0% 0% 0% 74 62 213,000 5% 20% 20% 25% 25% 5% 0% 63 56 206,000 0% 5% 10% 10% 65% 5% 5% 62 50 209,000 0% 0% 5% 5% 55% 5% 30% 60 48 225,000 Single Runway

Appendix A A-7 A-7 Spreadsheet Model, including details of the inputs that the user may enter or adjust to arrive at the hourly capacity output. It is assumed that the user will have limited knowledge of air traffic control rationale or FAA rules and guidelines on air traffic and pilot procedures regarding approach and departure routines. The explanations are intended to provide sufficient understanding to successfully use the capacity model, but not in such detail as to act as a tutorial on airfield capacity planning. The user is advised to become familiar with the spreadsheet tool as presented for the Single Runway Model (Single Model) before moving on to the Dual Parallel Runways Model (Dual Model) or the Dual Intersecting Runways Model (Intersecting Model), as the inputs and instructions for the latter two models build on information presented in the explanation of the Single Model.

A-8 Evaluating Airfield Capacity A-8 SINGLE RUNWAY MODEL The Single Runway Model (Single Model) is the simplest base configuration and will have the smallest number of variables, conditions and potential airfield conflicts. Having selected the Single Model, the user must then consider other inputs or choice selections. Defaults (a standard set of inputs) are provided as a starting point for using each m odel. The Dual Model and Intersecting Model have additional c onfiguration possibilities and will therefore have s ome additional input parameters to select or enter. There are basically two main areas for making inputs or choosing selections; General Inputs and Advanced Inputs. The general inputs allow the user to set up the conditions of the airfield and the fleet mix. These general inputs should be modified by the user, since the defaults that exist in the base model are unlikely to reflect the specific airfield and fleet mix conditions of the user’s airport. While these general inputs are not requirements, they are essential to the production of a reasonable and relevant hourly airfield capacity. Beyond the general inputs are the advanced inputs, w hich allow for further refinement of data such as separation mini ma requirements that can also be modified. The advanced inputs, or advanced features, can be either shown in the spreadsheet m odel or left hidden by the user with the use of Excel radio buttons. The advanced features incorporate standardized separation mini ma requirements between pairs of arrivals and pairs of departures for both VMC and IMC weather conditions. It should be noted that if a user does not provide inputs in the advanced features section, the defaults reflect those included in FAA’s EM- 78-8A report on airport capacity and delay. Cells within the runway configuration tabs are identified in a consistent manner to help the user quickly follow the flow of inputs, intermediate calculated values and outputs. A “RESET INPUTS” button is available in each runway configuration model near the top of the INPUTS section (Exhibit 8). Exhibit 8. RESET INPUTS button. The user can change all of the input settings while customizing the conditions of a given airfield, and then return all of the standard (d efault) settings back to the original values by clicking the RESET INPUTS button. The only settings that do not change back to default values when the RESET INPUTS button is clicked are the fleet mix share allocations, the VMC % occurrence under meteorological conditions, the operations assumption on touch-and-goes and the Runway Exit Availability and Full Parallel Taxiway selections.

Appendix A A-9 A-9 G eneral Inputs , Section 1 In the first section of general inputs the user makes selections regarding the specific operating conditions and air traffic control ( ATC ) practices for the airfield under consideration (Exhibit 9) . At a minimum in Section 1, the user must make an assumption regarding the percentage of total operations that consist of touch - and - go operations (see Operations Assumption on Touch - N - Go’s, in Exhibit 9). This percentage is likely to be 0 if there isn’t a flight training school or military airbase onsite. If the user has specific information on departure - arrival separation or the length of the common approach, the user can modify thi s information or rely on the defaults that are provided based on standard operating conditions as identified by FAA in ATC procedures. Exhibit 9. Single Model General Inputs Section 1. Another key adjustment within Section 1 is the percentage of time the airfield operates under v isual meteorological conditions ( VMC , % Occurrence ) and instrument meteorological conditions ( IMC , % Occurrence ) . The basic criteria for determining VMC or IMC is a cloud ceiling of at least 1 , 000 feet above the ground and visibility of at least 3 statute miles . VMC is assumed when exceeding the minimum requirement , and IMC is therefore assumed when below the minimum FAA guidelines. VMC and IMC can be determined from ASPM data sets available from FAA or deter mined from local weather history for the airport vicinity while following some general FAA guidelines . There are more conditional types , such as Marginal (MMC) and Poor Visual (PVC), but VMC and IMC are the two major conditions commonly used in determining an airfield ’ s capacity . Other inputs in Section 1 include the following: - D eparture - arrival separations (for both VMC and IMC conditions) - T he length of common approach - A rrival - arrival standard deviation - D eparture runway occupancy time (DROT, abbreviated as Departure ROT in the spreadsheet) standard deviation Departure - Arrival Separations are defined as the minimum spacing between an arriving aircraft and the runway threshold for a departure to receive clearance to occupy the runway and take off . This va lue can range from as little as 1 to 5 n autical miles ( nm, also noted as “ nmiles ” on some spreadsheet pages ) or more , depending on the

A-10 Evaluating Airfield Capacity A-10 surrounding conditions . Even though the default values have both been set at 2.0 nm in this model, the values for VMC and IMC are not always the same. The Length of Common Approach is the distance from the outer marker ( the point at which the aircraft is on final approach ) to the runway threshold . During this phase of flight , aircraft traveling at different speeds can possibly get closer or further apart as they descend on final approach to the runway . This value is typically between 5 and 10 n autical m iles . Arrival - Arrival S tandard D eviation and Departure ROT S tandard D eviation inputs are determined from actual ATC tower datasets or field observations at specific airfields . The input reflects the variance in consistency of pairs of arriv ing and departing aircraft in terms of seconds (sec.) . This variance helps to suffici ently buffer the necessary separation spacing desired . These are default values that reset when the RESET INPUTS button is clicked, and can be used as a common starting point if data are not available for more detailed analysis . The Z - value input is not co lored in green like the other inputs as it is a standard statistical value used to achieve a 95 percent confidence level . By using this set value, it is assumed that no more than 5 percent of operations will fail to remain within the assigned separations. G eneral Inputs , Section 2 The second section of general inputs is focused on the aircraft fleet mix and associated operating specifications, as well as selections regarding the availability and use of runway and taxiways . The Airfield Capacity Spreadshee t M odel has expanded the traditional four - category aircraft classification into a seven - category classification system to allow for more specificity of aircraft types and possible interactions with a more diverse fleet mix . The new categories have been dis cussed for some time, but are not formally agreed upon or used by FAA or the aviation consulting industry . The expanded classification system is used in the model to give the user more variability in identifying the specific fleet mix at the airfield under consideration. A summary of selected aircraft types and the ir corresponding fleet mix categories which are used in the A irfield Capacity Spreadsheet Model appear s separately on the worksheet’s “Fleet Mix” tab (Exhibit 10 ). Exhibit 10. Fleet Mix tab.

Appendix A A-11 A-11 Exhibit 11 illustrates the second section of general inputs as organized for the Single Runway Model. At a minimum in Section 2, the user must enter share allocations for the O perating Fleet Mix and make selections pertaining to the Runway, Taxiway and A irport Traffic Control Tower availability. The other inputs can be left as common defaults for a baseline determination of the hourly airfield capacity. E xhibit 11. Single Model General Inputs, Section 2. Explanations of the other inputs in Secti on 2 are provided below . The Operating F leet M ix inputs are set up with conditional formats to shade out the aircraft class options that are not selected and to highlight the aircraft classes that are included . The cell values are conditionally formatted to alert the user if the sum does not equal to 100 percent . This alert shows up as a message stating ( ADJUST VALUES ) , and a red summary total percentage appears to the right of the last column , as seen in Exhibit 12 . Exhibit 12. ADJUST VALUES alert me ssage. Fleet mix determinations can be made with FAA ASPM data, a irport traffic control tower (ATCT) counts, radar data , or some other available flight - log type data . For those airports without ATCTs , an operational fleet mix should be estimated that cons iders the airport’s based aircraft as well as the itinerant aircraft that operate at the airport. The goal is to best represent the operation al proportions of each aircraft class for use in a probability matrix that determines the likely pairing matches between each possible pair of aircraft classes. The average operational fleet mix probabilities, by aircraft class , are used by the Airfield Capacity S preadsheet M odel for calculations.

A-12 Evaluating Airfield Capacity A-12 For example: if a fleet mix has 50% Small-S aircraft operations and 50% Large-Jet aircraft operations, the probabilities for aircraft pairing would be as follows: • 25% S mall-S leading a Small-S • 25% S mall-S leading a Large-Jet • 25% Large-Jet leading a Small-S • 25% Large-Jet leading a Large-Jet A sample set of aircraft for each aircraft class is provided in Exhibit 13. Aircraft weights are based on manufacturers’ suggested Maximum Take Off Weight (MTOW), which can be determined from the manufacturers’ specification sheets, www.airliners.net/aircraft- data website, or other sources. The Arrival Runway Occupancy Time (AROT) is specific to each individual aircraft, as is the Approach Speed . For purposes of the Capacity Spreadsheet Model, averages of these inputs have been selected as defaults, but the data can be modified if the user has specific information on either of these two inputs. Default settings have been determined through evaluation of common aircraft specifications in each class. They are included in the default values that are linked to the RESET INPUTS button and can be adjusted as needed by the user. Varying airfields will have unique geographic or environmental conditions and/or requirements that will give higher or lower values than the defaults. The user can adjust the values up or down and perform a s ensitivity analysis to see the effects of varying the range of inputs for these two factors. After maki ng the fleet mix selections, the user should examine the Runway Exit Availability OR Full Parallel Taxiway, and Runway Crossing Delay input fields. The defaults for the Runway Exit Availability and Full Parallel Taxiway selections assume that the airfield will have adequate exit availability and a full parallel taxiway to avoid delays on the runway. Runway crossings are also assumed t o be negligible or minimal, and therefore not causing any noticeable delays under the default conditions. Choosing alternative conditions, s uch as fewer exits or a partial parallel taxiway, will decrease the calculated a irfield capacity by applying a proportionate factor to the o riginal capacity. The applied factors range from 0.75 to 1.0. IF the user inputs actual or real AROTs into the model, the Runway Exit Availability and selection should remain at the default setting and therefore no reduction in capacity would be included in the calculations. The exit reduction is intended for use with the other default inputs. Wh en a true AROT is determined, exit availability has already been factored into the AROT as the actual time until the runway has been cleared. Additionally, a full parallel taxiway is presumed to be the default case, and if a p artial taxiway or no taxiway is selected, the runway o ccupancy times will therefore be greater and capacity will be diminished. A proportionate factor is applied to the original capacity in conjunction with other limiting factors. The factors range from 0.5 to 1.0.

Appendix A A-13 A-13 Source: Landrum & Brown . Exhibit 13. Aircraft classifications. Aircraft Class Designations Sample Aircraft Category Small-S BE36 - Beech Bonanza 36 Description Small - Single Engine C172 - Cessna Skyhawk 172/Cutlass Weight < 12,500 lbs C210 - Cessna 210 Centurion PA28 - Piper Cherokee PA38 - Piper Tomahawk PA38 PA46 - Piper Malibu PC12 - Pilatus PC-12 TBM7 - Socata TBM-7 SR20 - Cirrus SR-20 Category Small-T BE19 - Beech 19 Sport Description Small - Twin Engine BE20 - Beech 200 Super King Weight < 12,500 lbs BE30 - Raytheon 300 Super King Air BE55 - Beech Baron 55 BE58 - Beech 58 BE9L - Beech King Air 90 C425 - Cessna 425 Corsair C441 - Cessna Conquest C500 - Cessna 500/Citation I DHC6 - DeHavilland Twin Otter PA44 - Piper Seminole Category Small-+ BE40 - Raytheon/Beech Beechjet 400/T-1 Description Small - Twin Engine C25A - Cessna Citation CJ2 Weight 12,500 - 41,000 lbs C560 - Cessna Citation V/Ultra/Encore C750 - Cessna Citation X CL30 - Bombardier (Canadair) Challenger 300 EMB120-Brasilia FA50 - Dassault Falcon/Mystère 50 GALX - IAI 1126 Galaxy/Gulfstream G200 LJ35 - Bombardier Learjet 35 LJ55 - Bombardier Learjet 55 SBR1 - North American Rockwell Sabre 40/60 Category Large - TP ATR 42 Description Large - Turbo Prop ATR 72 Weight 41,000 - 255,000 lbs Dash 8 Q100/200 Dash 8 Q300/400 Saab 340 RED denotes weight exception Category Large - Jet Airbus 318/319/320/321 Description Large - Jet Boeing 737 Series Weight 41,000 - 255,000 lbs DC-9 Series MD 80/82/83/88/89 Gulfstream III/IV/V CRJ100/200 CRJ700/900 ERJ135/140/145 EMB170/175/190/195 CL60 - Bombardier Challenger 600/601/604 Category Large - 757 Boeing 757-200 Description Boeing 757 Series Boeing 757-300 Weight 255,000 - 300,000 lbs Category Heavy Airbus 300/310 Description Heavy - Multi Engine Airbus 330/340/350 Weight > 300,000 lbs Airbus 380 Boeing 747 Series Boeing 767/777 Boeing 787 DC-10/MD-11

A-14 Evaluating Airfield Capacity A-14 The model makes some generalized assumptions as to the impact of not having enough properly spaced exits or not having a full parallel taxiway . The user is asked to make selections in only one of the two input cells for Runway Exit Availability OR Full Parallel Taxiway . The ma in assumption as stated previously is that the airfield will have a full parallel taxiway; IF NOT , the user should make a selection in that cell, OR the user can choose to select a runway exit scenario instead. DO NOT use both selections or the capacity value will be discounted twice by the applied factors . The final selection in this inputs section is to indicate “Yes” or “No” regarding the availability of an Airport Traffic Control Tower (ATCT) . It is assumed in the default case that the airport has a n ATCT . In the event that the user selects the “ No ” option, a 10% reduction to the existing calculated capacity is applied, and separation requirements are adjusted as needed in the case of IMC and dual parallel runways. Depending on the fleet mix and input conditions, the hourly capacity output will show an operations mix that may already be somewhat balanced or nearly 50 percent arrivals and 50 percent departures . This is not always the case . If the user does not want t o use any further advanced inputs, an assumption can be made t hat the average hourly capacity would be some proportional combination of the arrival s only capacity and the departure s only capacity . For example: Assume the arrivals only capacity is 40 op erations per hour and the departures only capacity is 60 operations per hour • 36 minutes in arrivals only mode = 24 arrivals • 24 minutes in departures only mode = 24 departures => 50% mix If the user wants to make adjustments to the default buffers and provide more gap spacing between arrivals and permit more departures in mixed operations, the user can click on the “S HOW Advanced Features” radio button (Exhibit 14) . Exhibit 14. SHOW Advanced Features button. The A dvanced I nputs S ection is displayed on clicking the SHOW Advanced Features button and is hidden again if the HIDE Advanced Features button is subsequently selected . The advanced input features are described and explained in the next section .

Appendix A A-15 A-15 Advanced Inputs, Section 1 The first section of Advanced Inputs allows the user to introduce a buffer to the average arrival to arrival separation and the average departure to departure separation (Exhibit 15). These buffers create more gap spacing, which in turn typically allows for more departures between arrival pairs in mixed operations. The buffer for arrivals can be applied in seconds or miles, depending on which approach is more common to local ATC or which data are available. Exhibit 15. Buffers. Method #1, as indicated in the model, is known as “gap spacing” and allows manual average increases to the minimum separation between arriving aircraft pairs to permit one or more departures to take off between the pair of arrivals. The Arrival Gap Spacing Buffer should be increased incrementally and the output observed after each change. The user can increase the buffer until the desired level o f additional departures is achieved or until the mix between arrivals and departures reaches a certain ratio. During the gap spacing adjustment process, the number of arrivals will decrease as more departures are added. The user should only increase the buffer if the change adds sufficient departures to compensate for fewer arrivals. The Departure Hold Buffer is not meant to be used to try and increase overall capacity; rather it will actually decrease airfield capacity a s a certain safety level may require more spacing before departure release based on specific operating conditions. Advanced Inputs, Section 2 The second section of Advanced Inputs deals with the arrival to arrival separation min im a referenced previously and is based on default levels as outlined in FAA EM-78- 8A, Airport Capacity and Delay. For the common user, the separation minima default values can be used in most cases and no adjustments a re necessary unless specific requirements exist. The Arrival-Arrival Separation Requirements are input in nautical miles and represent the min im um safe distance between the unique aircraft pairs listed in Exhibit 16. FAA report EM-78-8A, Airport Capacity and Delay, provides a set of guidelines for minimum separation distances. Each pair consists of a trailing and leading aircraft. Smaller aircraft are spaced farther behind larger aircraft due to the increased wake vortex from larger aircraft. Separation minim a are higher during IMC weather conditions than during VMC weather conditions. Overall minim um spacing defaults are set to 1.9 nautical miles in VMC and 3.0 nautical miles in IMC.

A-16 Evaluating Airfield Capacity A-16 Note: These are minimum separation distances and the resulting capacity outputs represent an optimistic outcome. If observed average arrival runway occupancy times are less than 50 seconds, 2.5 nautical miles can be used as the alternate mi nimum separation gap. To use the Alternative IMC Minimum v alue, the user needs to select the “Yes” option to the right of the separation inputs. W hen the RESET INPUTS button is clicked, the separation defaults will reset to whichever minimum value has been selected. Exhibit 16. Single Model Advanced Inputs Section 2, showing Arrival-Arrival Separation Requirements and Alternate IMC Minimum. The user can make suitable adjustments as necessary to increase the arrival-arrival separation requirements to better represent conditional requirements at the airfield under consideration. Advanced Inputs Section 3 The final Advanced Inputs section is focused on the separation requirements for spacing between departures. T he m inimum levels used as defaults are also outlined in FAA’s EM-78-8A, Airport Capacity and Delay . For the common user the separation minima default values can be used in most cases and no adjustments are necessary unless specific requirements exist. The Departure-Departure Separation Requirements are input in seconds (as opposed to nautical miles for arrival-arrival separation) and range from 35 seconds in VMC for successive small aircraft to 120 seconds when a small aircraft follows a 757 jet or Heavy jet (see Exhibit 17). A gain, this spacing is necessary to protect against the effects of the leading aircraft’s wake vortex. Typically, 60 seconds is used as the minimum separation between departures allowing the leading aircraft sufficient time to take off and clear the end of runway while not allowing the following aircraft to enter the leading aircraft’s wake vortex. These values are also mini mu m levels and can be increased if desired or required by local ATC.

Appendix A A-17 A-17 Exhibit 17. Single Model Advanced Inputs S ection 3, showing Departure-Departure Separation Requirements. All of the Advanced Inputs can be reset to the determined default values by clicking the RESET INPUTS button. Model Outputs The model output results are the VMC and IM C hourly operations capacity levels that can be used as individual components or a total hourly mix in evaluating the airfield capacity of an airport. The outputs section as outlined in Exhibit 18 estimates the Arrivals Only Capacity with or without touch-and-go operations (labeled Touch-N-Go or TNG ), the Departures Only Capacity , the Mixed Ops-Departure Capacity , and the Total Mixed Operations Capacity . As the user changes the inputs, these outputs change in value accordingly. Exhibit 18. Single Model Outputs. The inclusion of TNG operations occurs when the user inputs a percentage up to 50% in cell D11. A T-Factor (touch-and-go factor) is estimated in the General Inputs, Section 1 to allow a maxim um value of 1.4 when the maximum 50% input is used. The T-Factor is applied to the calculated arrivals to estimate a new total arrivals capacity. It is assumed that the majority of TNG operations involve flight training and are normally associated with small aircraft. Military aircraft may also perform significant flight training operations and would need to be uniquely accounted for in the fleet mix and airfield operating conditions. Specific f ocus on military aircraft is not discussed related to using this spreadsheet model.

A-18 Evaluating Airfield Capacity A-18 TNG operations are calculated by the spreadsheet and added equally to both the Arrivals Capacity (including TNGs) output and the Mixed Ops-Departure Capacity (including TNGs) output, as included in the input by the user. The Total Mixed Operations Capacity output assumes arrival priority and includes all achievable departures between arrivals. Departures Only Capacity only changes when adjustments to the departure-related inputs are increased or decreased. The Arrivals Percentage is arrivals hourly capacity divided by the total mixed hourly capacity and includes the TNG operations if they occur.

Appendix A A-19 A-19 Single Runway Model: Quick Reference Guide Step 1 : Cl ick the RESET INPUTS button to restore all default inputs to base conditions. Step 2 : Determine and Input the %VMC if available. Otherwise, use the default. (Note: Exhibit 19 shows input locations for steps 1 through 7). VMC and IMC capacities are typically cited separately and the overall average may not be necessary, but for determination of the annual capacity or annual service volume (ASV) the split between VMC and IMC will be necessary . Step 3 : Input the assumed percent of operations that occur as t ouch - and - g o es . No a djustments need to be made to the departure - arrival separations, common approach, or standard deviations for a base capacity determination. Step 4: Determine or estimate, then Input the share allocations of the airfield’s operational fleet mix. Remember, the total must add up to 100%, and only the selected aircraft classes will remain fully visible, as those inactive input cells will be shaded. Step 5 : Adjust A ROTs and Average Approach Speeds if supporting data or operational knowledge is available. Otherwise, use the default values which provide a usable base set of estimates. Step 6: Make selections with dropdown boxes as to the availability of runway exits, taxi ways, and an Airport Traffic Control Tower . Exhibit 19. Inputs, Single Runway M odel. 1 3 2 4 5 6 7

A-20 Evaluating Airfield Capacity A-20 Step 7: Make a selection as to the existence of runway crossing requirements. Input assumptions as to the number of crossings that oc cur in an hour and how long the average delay is in seconds. No adjustments need to be made to the runway crossing delay if data is unavailable (i.e., keep the input set to “NO” and 0) Step 8: Clic k the SHOW Advanced Features button to unhide the remaining input cells for further adjustment of the average arrival to arrival separation times and average departure to departure separation times that determine the hourly capacity outputs, as needed (Exhibit 20). Exhibit 20. SHOW Advanced Features and HIDE Advanced Features buttons. Step 9: Adjust m inimum a rrival pair s eparation distances (nautical miles, abbreviated nm or nmiles in the spreadsheets) and minim um departure to departure times (seconds, abbreviated sec) if knowledge of air traffic control guidelines, local requirements and methodology is available and understood (Exhibit 21). Otherwise, use the default values which provide a usable base set of estimates. Exhibit 21. Inputting separation distances and minimum departure to departure times. At this point all of the major inputs have been made and the results in the outputs section should represent the baseline arrival priority mode capacity and the departure priority mode capacity. Depending on the set of inputs and selections that were used, the operations mix may or may not be balanced. The model suggests two methods for arriving at a specific operations mix ratio or an optimum capacity level. 8 9 9

Appendix A A-21 A-21 The first method is identified as the Gap Spacing or gap stretching method, and it increases the average separation gap between each arrival pair to allow for more departures between arrivals. Gap spacing allows the user to achieve a more balanced operational mix, essentially creating a “one in, one out” condition for 50% arrivals and 50% departures (Exhibit 22). Exhibit 22. Method 1 (gap spacing). Step 10 (Method #1, Gap Spacing): Adjust the Arrival Gap Spacing Buffer by increasing either the time buffe r (seconds) or the distance buffer (nautical miles) until the desired output is achieved (Exhibit 23). Use only one option. The Departure Hold Buffer provides safety a ssurance before a departure is cleared for take off, but is not used as a part of the arrival gap spacing method. Exhibit 23. Using Method #1 (Gap Spacing) to adjust the arrival gap spacing buffer. Step 11 (Method #2): If a specific arrival percentage is desired, the user can take an algebraic approach and proportionally assign time segments where different operating modes would be conducted. Adjust the share allocations for Mixed Operations, Arrivals Only, o r Departures Only capacities to achieve the desired operations mix (Exhibit 24). Make sure the total sum of the inputs equals 100%. I f the total does not add up to 100%, a sum warning ( ADJUS T ALLOCATIONS ) will appear in red lettering underneath the heading VMC Allocations to alert the user. Exhibit 24. Using Method #2 to adjust the arrival gap spacing buffer. 10 11

A-22 Evaluating Airfield Capacity A-22 DUAL PARALLEL RUNWAYS MODEL The dual parallel runways model (Dual Model) i s developed in the s ame manner as the Single Model and therefore estimates hourly capacity using the same assumptions and methodology. All of the formatting and interpretations are the same and the models flow similarly. A few differences in the models are necessary to accommodate the additional interactions and air traffic rules surrounding two runways operating next to each other in parallel. The Dual Model also introduces a runway configuration caption at the top left of the worksheet (Exhibit 25).The caption includes a box at the far left that indicates the operational scenario selected by the user and four boxes that describe the dependency states of operations in VMC and IMC in the scenario. These t wo visual sections will help the user determine how to use and interpret the output results. Exhibit 25. Runway configuration caption in Dual Model with Scenario 1 selected. The Dual Model allows the user to select from eight different operations scenarios (four dependent and four independent). The configuration caption includes scenario number and illustrates arrivals in RED and departures in GREEN . The boxes on the right indicate whether dual simultaneous arrivals or dual simultaneous departures would be permitted based on the weather conditions and runway separation distance (a new input for the Dual Model). A dependent runway pair is not eligible for dual simultaneous operations. In Exhibit 25, Scenario 1 assumes arrivals only on Runway 1 and departures only on Runway 2. The dual parallel runw ay configuration is assumed to be dependent in all cases listed, and the example outputs are suggesting 28 arrivals and 42 departures under the given inputs. In each scenario, the presumption is that the runways are either dependent or independent in relation to each other; however, that is not consistently the case, as simultaneous arrival pairs and simultaneous departure pairs are considered independent at different runway separation distances. The table in Exhibit 26 provides a list of runway spacing ranges that determine dependency between the two runways for dual simultaneous arrivals or departures. From the table, it is evident that under VMC, a pair of runways can be considered independent for departures yet be dependent in regard to arrivals when the distance is between 700 feet and 2,499 feet.

Appendix A A-23 A-23 Under IMC, the same situation results when the distance is between 2 , 500 and 3,399 feet . The determinations for dependency in the model follow the criteria in this table. Source: FAA JO 7110.65 Air Traffic Control Exhibit 26. Parallel runway spacing — ranges under VMC and IMC. E xhibit 27 portrays the eight scenarios i ncluded as options in the spreadsheet model . The dotted line in the even - numbered scenarios suggests an assumption of runway independence and thus independent runway operations can be performed . Source: Landrum & Brown Exhibit 27. Dual parallel runways scenarios. Parallel Runway Spacing Arrivals Departures (distance between centerlines) Arrivals Departures DEP DEP less than 700 feet DEP DEP DEP IND 700 - 2499 feet DEP DEP IND IND 2500 - 3399 feet DEP IND IND IND 3400 - 4299 feet IND* IND IND IND 4300 feet or more IND IND *w/radar, DEP w/o radar IMC VMC

A-24 Evaluating Airfield Capacity A-24 The spreadsheet model for dual parallel runways requires additional inputs (beyond those in the Single Model) to account for the spacing requirements between aircraft as n ew conditions exist due to the potential simultaneous operations of two runways. Three new inputs make up a new General Inputs, Section 1 in the Dual Model. One new input is included in the Advanced Inputs, Section 1. The inputs that appeared in General Inputs Sections 1 and 2 in the Single Model remain the same, but in the Dual Model they are located below the new General Inputs, Section 1 (see Exhibit 28). Ne w General Inputs, Section 1 (for Dual Model) As was suggested in the detailed overview of the Single Model, the user can reset all the default inputs initially by clicking the RESET INPUTS button. After selecting the VMC and IMC occurrence percentages, the user chooses a Runway Scenario Selection (one of the eight scenario configurations for evaluation or comparison). The user must then select whether or not Divergent Departure Routes are in place to provide an opening situation for potential simultaneous departures (a Yes/No selection). Next, the user inputs the Runway Separation Distance i n feet between the centerlines of the two runways to determine, in VMC and in IMC, if operations between them are dependent or independent. Exhibit 28. New General Inputs, Section 1 (for Dual Model). Completing the new inputs section establishes the choice of an evaluation configuration, and conditions are illustrated for visual reference. Following the new General Inputs, Section 1, the remaining General Inputs sections contain the same inputs and selections as in the Single Model and should be utilized in the same manner. Ne w Advanced Inputs Items (for Dual Model), Section 2 In the Dual Model the user can choose to adjust the inputs in the Advanced Inputs sections. All but one of the inputs in this section of the model are the same as those for the Single Model. The new input for the Dual Model is a selection as to the Diagonal Separation Allowed (Exhibit 29). This is the diagonal distance between a pair of arrivals measured in nautical miles following the axis of the two parallel runways. Important: This input is only used if the user has selected either Scenario 3 or Scenario 5 as the Runway Scenario Selection in General Inputs, Section 1. Exhibit 29. Selection of diagonal separation allowed (in Dual Model Scenario 3 or Scenario 5).

Appendix A A-25 A-25 Depending on the distance between the runways, the guidelines on the diagonal distance suggest increasing diagonal separation as centerline distance increases . The diagonal distances associated with the model options range from 1.5 n m to 3.0 n m . The diagonal spacing reduces the longitudinal spacing required between a pair of arrivals, but the following pair must still maintain the minimum spacing between the leading pair, just as on a single runway the following aircraft must maintain the separation minimum distance with the leading aircraft. As was explained in the Single Model, Method # 1 or Method #2 can be used to adjust or optimize the operations mix . Method # 2 is mos t appropriate if the user wishes to determine a specific arrivals percentage . The outputs in the D ual M odel are set up in a similar fashion to the outputs in the S ingle M odel , but additional rows have been provided within the table to display capacity es timates for both Runway 1 and Runway 2 . Interpretation and sensitivity analysis using either adjustment method should be conducted in the same manner as in the S ingle M odel . Additionally, the D ual M odel provides some basic operation al scenarios for comparison , and the user can either use the model to estimate an optimal output ( such as two independent runways operating in a balanced mixed flow , Scenario 8) or some other partial operating flow ( such as Scenarios 1 through 7) . Outputs from the D ual M odel should be comparable to outputs from the S ingle M odel. For Example : If the user inputs the same data and makes the same specific selections in the D ual M odel and in the S ingle M odel, the results (outputs) should be equivalent . Assum e a single runway with optimal mixed operations and Scenario 8 , which assumes an independent dual parallel runway configuration with mixed operations on both runways . The D ual M odel result should be equal to twice (2x) the S ingle M odel result under the same conditions.

A-26 Evaluating Airfield Capacity A-26 DUAL INTERSECTING OR CONVERGING RUNWAYS M ODEL The Dual Intersecting Runway s M odel (Intersecting Model) is developed in the same manner as the Single Model and the Dual Model and will therefore estimate hourly capacity using the same assumptions and methodology . All of the formatting and interpretations are the same and the models flow similarly. A few differences in the Intersecting M odel are necessary to accommodate the add itional interactions and air traffic rules surrounding two runways operating with an intersection or a closing/opening configuration . Like the Dual Model, t he I ntersecting M odel includes a runway configuration caption at the top left of the worksheet to pr ovide example operating configurations for comparison (Exhibit 30) . The visual will help the user determine how to use and interpret the output results. Exhibit 30. Runway configuration caption in Intersecting Model. The I ntersecting M odel is set up t o allow the user to initially choose from eight different operations scenarios . The chart indicates the scenario number and illustrates arrivals in RED and departures in GREEN . In Exhibit 30 , Scenario 1 assumes arrivals only on Runway 1 and departures only on Runway 2 . Th is dual intersecting runway s configuration estimates outputs to be 36 arrivals and 36 departures under the given inputs. The presumption in the case of intersecting runways is that the runways are dependent in relation to each other, a nd therefore non - simultaneous runway occupancy guidelines are adhered to in the model assumptions . E xhibit 31 portrays the eight scenarios included as options in the Intersecting M odel.

Appendix A A-27 A-27 Source: Landrum & Brown . Exhibit 31. Intersecting runway scenario s. S ome additional inputs are included in the I ntersecting M odel to account for the spacing requirements between aircraft , thresholds , and intersections , as new conditions exist due to the potential simultaneous operations of two intersecting runways . S even new inputs are included as part of this model’s G eneral Inputs , Section 1 . The inputs that were included in the Single Model as General Inputs , Section 1 and General Inputs, Section 2 are consistent and remain the same , but in the Intersecting Model t hey are located below the new inputs. The new inputs appear first, at the top of the inputs section. New General Inputs , Section 1 (for I ntersecting M odel) As is true throughout the Airfield Capacity Spreadsheet Model, the user can reset all the default inputs initially by clicking the RESET INPUTS button. The first selection to be made in this section is to choose one of the eight scenario configurations for evaluation or comparison (see Exhibit 32) . This new section asks the user to then input the distance from threshold to intersection on each runway. Exhibit 32. New General Inputs, Section 1, for Intersecting Model.

A-28 Evaluating Airfield Capacity A-28 Next the user select s whether or not departure runway thresholds infringe on the Runway Safety Area (RSA) or Runway Protection Zone (RPZ) of the other runway, and if Divergent Departure Routes are in place to provide an opening situation for potential simultaneous departures . A description of the RSA or RPZ infringements is portrayed in Exhibit 33. Source: Landrum & Brown . Exhibit 33. Description of the RSA or RPZ infringements. The final new inputs are the average estimated deceleration and acceleration rates of arriving and departing aircraft, respectively . These values can be left at the default values of 5.3 feet/sec/sec and 8.0 feet/sec/sec for a diverse fleet mix, or they can be adjusted to a known estimate for a fleet which is predominantly one aircraft type. After updating the inputs in the new G eneral I nputs S ection, t he remaining G eneral I nputs sections contain the same material and inputs or selections as in the S ingle M odel and should be utilized in the same manner . The user can also choose to adjust the inputs in the A dvanced I nputs sections , which will appear the same as in the S ingle M odel . Method # 1 can be used to adjust or optimize the operations mix in the same way as explained in the Single Model overview . Method # 2 can be used as well to determine a specific arrivals percentage .

Appendix A A-29 A-29 The Outputs Section in the Intersecting Model is set up similarly to the Outputs Section in the Single Model, but has additional rows within the table to provide capacity estimates for both Runway 1 and Runway 2. Interpretation and sensitivity analysis using either adjustment method should be conducted in the same manner as in the Single Model. Additionally, the Intersecting Model provides some basic operation scenarios for comparison, and the user can either use the model to estimate an optimal output, such as two intersecting runways operating in a balanced flow with 50 percent arrivals on one runway and the remaining departures on the other runway (Scenario 1).

A-30 Evaluating Airfield Capacity A-30 ANNUAL SERVICE VOLUM E (ASV) DETERMINATIO N DATA NEEDED : - Hourly c apacity levels ( from spreadsheet model ) - % occurrence of meteorological conditions (% VMC, % IMC, etc . ) - Annual and daily traffic volumes - Peak h our traffic volume IF actual data are not available, use a best guess or estimate . Model results provide estimates of hourly capaciti es, and those values can be used to further estimate the number of aircraft operations that can likely be achieved on an annual basis for planning purposes . The annual capacity or annual service volume (ASV) is a planning metric that is used by airports an d airport authorities to plan airside and landside development and financial budgets for master planning and general operations requirements . In t he A irfield Capacity S preadsheet M odel , the tab labeled “ASV Estimate” opens a sheet that incorporates the A SV determination method as shown in the AC (Exhibit 34 ) . Exhibit 34. ASV Estimate tab. This method scales up the determined hourly capacities with hourly and daily demand ratios based on relationships between peak demand and annual activity . The following calculation is used to estimate ASV: ASV = C w * D * H Where C w is the weighted average of hourly capacities at their respective percent occurrence over a period of time . The model capacity outputs can be calculated for VMC and IMC, and for other marginal conditionals if the user has a more in - depth knowledge of the air traffic control environment and operating requirements . The ASV model asks the user to input the hourly capacity values determined from the single, dual or inters ecting models and also the percent occurrence of those meteorological conditions to arrive at C w . D and H are the demand ratios which represent the Annual Demand/Avg. Peak Month Daily Demand (D), and the Avg. Peak Month Daily Demand/Avg. Peak Hour Demand (H) . Daily traffic activity data for at least the peak month and the annual traffic volume is required to best determine these demand ratios .

Appendix A A-31 A-31 Annual data are readily available through the FAA Terminal Area Forecast database online ( http://aspm.faa.gov/main/taf.asp ); and daily traffic data are also available online in the form of operational counts from the FAA ASPM database ( http://aspm.faa.gov/ ) . Demand ratios should fall within the range of typical results shown in Exhibit 35 . Source: FAA AC 150/5060 - 5 , Airport Capacity and Delay , Table 3 - 2 . Exhibit 35. T able of typical results (demand ratios) . The user will need to determine or make an assumption as to the operating fleet mix at the airport under consideration . The mix index is selected from a dropdown box with three choices, 0 – 20, 21 – 50 and 51 – 180 . These values are determined from the following equation: Fleet Mix Index = %C aircraft + 3(% D aircraft) . C aircraft are designated as Large Aircraft (i.e. Large - TP (Q400) + Large - Jet (B737) + Large - 757), and D aircraft are designated as Heavy Aircraft such as a B767 or B747 . If the user does not wish to calculate the D and H demand ratio values , a midpoint assumption can be used from the table of typical results (Exhibit 35) after determining a fleet mix index to use. The model asks the user to make one final selection, which is to select whether or not to use weighting factors . These weighting f actors found in the model allow for additional lower capacity conditions to have a greater impact on the overall average . The use of weighting factors estimates a more conservative final ASV . The weighting factors shown on the “ASV Estimate” tab are source d from Table 3 - 1 in the AC . Determining ASV values using this method is a very common approach for estimating annual airfield capacity at small airports. Mix Index Daily (D) Hourly (H) 0 - 20 280 - 310 7 - 11 21 - 50 300 - 320 10 - 13 51 - 180 310 - 350 11 - 15

A-32 Evaluating Airfield Capacity A-32 GLOSSARY Airfield Capacity Terms Used in the Prototype Airfield Capacity Spreadsheet Model Aircraft Class—A category assignment to all aircraft models that places aircraft in a group with other aircraft of the same weight class. The aircraft classifications used in this capacity model are based on MTOW. Approach Speed—The recommended speed contained in aircraft manuals used by pilots when making an approach to landing. This speed will vary from different segments of an approach as well as for aircraft weight and configuration. (FAA JO 7110.65) Arrival to Arrival Separation—Either the longitudinal spacing provided for by Air Traffic Control and the aircraft pilots between two aircraft on final approach, or the time between sequential arrivals at touchdown. Arrival to Arrival Separation Standard Deviation (Delivery Error)—The average variance of a given set of data/observations for actual separation spacing in comparison to what was intended by Air Traffic Control guidelines and separation minima. Arrival Priority—A mode of airfield operations where departures may occur in a mixed operating mode but priority is always given to the sequenced arrivals and permits the maximum number of arrivals per hour. In a pure arrival priority mode, no departures occur. Arrival Runway Occupancy Time (AROT)—The average time an aircraft or aircraft group occupies the runway during landing, from the time the threshold is crossed until the arrival fully exits the runway. Centerline Distance—The tangential distance between the centerlines of two parallel runways. Common Approach Length—The distance between the arrival runway threshold and the outer marker or the point at which an arrival is considered to be on final approach. Converging Runways—Two runways that do not physically cross or meet, yet approach each other at some point and have interacting approach or departure paths. Depending on traffic flow, the runways may also be considered ‘Diverging’. Departure to Arrival Separation—The minimum required separation from threshold to an arrival on approach for a departure to receive clearance for take off.

Appendix A A-33 A-33 Departure Priority—A mode of airfield operations where departures are given priority and allows for arrivals to occur, but priority is given to departing aircraft unless a safety situation requires an arrival be permitted to land. Departure Runway Occupancy Time (DROT)—The average time a departing aircraft occupies the runway during take off until a clear lift off is reached. Dependent Runways—A pair runways that are configured as either parallel or intersecting and, due to proximity or infringement of protected safety areas, are considered as one runway and do not operate simultaneous departures or arrivals. A dependent runway pair may be dependent for arrivals yet independent for departures. Diagonal Separation—The separation between two aircraft approaching two parallel runways measured from the leading aircraft on route to the first runway, to the trailing aircraft in an arrival pair on route to the second runway. Fleet Mix—A descriptive representation of the types and shares of aircraft performing operations at a given airfield. (e.g., 40% Small-Single Engine, 50% Small-Twin Engine) Gap Spacing—A method of logically adding additional time between arriving aircraft or buffering the intended separation spacing to allow for at least one or more departures to occur. This process helps to achieve a more balanced flow while still maintaining arrival priority. IMC—Instrument Meteorological Conditions (when visibility is less than 3 statute miles and/or the cloud ceiling is less than 1000 feet above ground). Independent Runway—A single runway that is sufficiently distant from any other runway to operate dual simultaneous arrivals or departures and not have any operational conflicts. Intersecting Runways—Two or more runways that cross or meet at some point within their lengths. (FAA JO 7110.65) Maximum Gross Take Off Weight (MTOW)—The maximum gross weight that an aircraft should not exceed to take off safely. Includes fuel, passengers, and cargo. Non-Simultaneous Runway Occupancy (NSRO)—FAA rule that requires that no more than one aircraft occupy a runway at the same time. An arriving aircraft occupies the runway as soon as the threshold is crossed, while a departure may be considered to be occupying the runway from the time it enters the runway until either a certain altitude above the runway is reached during take off or when the departure crosses the end threshold.

A-34 Evaluating Airfield Capacity A-34 Runway Crossing Demand—A measurable requirement for crossing the runway to other runways, taxiways, or terminals. Assumes that no other route avoiding runway occupancy is available. Runway Protection Zone (RPZ)—According to AC 150/5300-13 the RPZ is trapezoidal in shape and centered about the extended runway centerline. The central portion and controlled activity area the two components of the RPZ. The RPZ dimension for a particular runway end is a function of the type of aircraft and approach visibility minimum associated with that runway end. Table 2-4 in AC 150/5300-13 provides standard dimensions for RPZs. Other than with a special application of declared distances, the RPZ begins 200 feet (60 m) beyond the end of the area usable for take off or landing. With a special application of declared distances (see Appendix 14 of AC 150/5300-13), separate approach and departure RPZs are required for each runway end. Runway Safety Area (RSA)—A defined surface surrounding the runway prepared, or suitable, for reducing the risk of damage to airplanes in the event of an undershoot, overshoot, or excursion from the runway. The dimensions of the RSA vary and can be determined by using the criteria contained in AC 150/5300-13, Airport Design, Chapter 3. Figure 3−1 in AC 150/5300-13 depicts the RSA. (FAA JO 7110.65) Runway Threshold—The official beginning or end of a runway marked by a series of 6 to 16 parallel white rectangular markings running in the direction of the runway. The runway threshold also starts the beginning of the Runway Protection Zone. Standard Deviation—A measure of how much variance occurs within a dataset or how much spread exists around a mean or average (or the average distance from the center point for all points around that point). Touch-and-Go—A pair of operations when an arrival makes a touchdown onto the runway and then immediately takes off again without stopping. The operational pair is counted as one arrival and one departure for a total of two (2) operations. VMC—Visual Meteorological Conditions (when visibility is at least 3 statute miles and the cloud ceiling is at least 1000 feet above ground).

Appendix A A-35 A-35 CONCLUSION Model Limitations While the model provides for significant input capabilities for a variety of items noted previously, if the airfield configuration is not in the model and/or the airfield is operated in many different configurations, the Airfield Capacity Spreadsheet Model would not reflect a total combined hourly capacity. The model’s results present the following information for visual meteorological conditions, instrument meteorological conditions, and an average condition: • Arrivals only capacity (with and without touch-and-go activity) • Departures only capacity (with and without touch-and-go activity) • Total mixed operations The model does not allow for the results to be combined in any way for when an airfield is operated in these capacities over the course of an hour, day, or year. The Airfield Capacity Spreadsheet Model also does not allow some of the features of detailed simulation modeling in terms of importing schedule or ASPM data. Recommendations for Further Work The Prototype Airfield Capacity Spreadsheet Model presents a first step toward a simplified version of the ACM and more fidelity than the current AC methodologies provide. With additional resources, the models could be expanded to allow for additional user inputs to depict more airfield operational conditions. It should be noted that a more detailed version of the models would also require the user to have significantly more data and knowledge of the airfield’s operating conditions.