Constraints for STOL Operations in South Florida Conurbation Cedric Y. Justin June 2021

Based on research previously published: Development of a Methodology for Parametric Analysis of STOL Airpark Geo-Density, Robinson et al. AIAA AVIATION 2018 Door-to-Door Travel Time Comparative Assessment for Conventional Transportation Methods and Short Takeoff and Landing On Demand Mobility Concepts, Wei et al. AIAA AVIATION 2018 Wind and Obstacles Impact on Airpark Placement for STOL-based Sub-Urban Air Mobility, Somers et al., AIAA AVIATION 2019 Optimal Siting of Sub-Urban Air Mobility (sUAM) Ground Architectures using Network Flow Formulation, Venkatesh et al, AIAA AVIATION 2020 Comparative Assessment of STOL-based Sub-Urban Air Mobility Operations in Massachusetts and South Florida, Justin et al. AIAA AVIATION 2020 Current Market Segmentation

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VTOL CTOL CTOL CTOL CTOL

Capacity ? 200-400+ pax Twin Aisle Are there 120-210 pax scenarios where Single Aisle an intermediate solution using 50-90 pax STOL vehicles and Regional Aircraft sitting in-  Design range below 300 nm Commuters between UAM 9-50 pax  Flight time below 1.5 hours Thin-Haul and thin-haul  9 to 50 seat capacity operations exists? 4-9 pax Sub-Urban  Missions 50-150 nm Air Mobility  4 to 9 revenue-seats

 Missions below 50 nm Urban Air Mobility 1-4 pax  1 to 4 revenue-seats

50 nm 300 nm 500 nm 3000 nm 6000+ nm Artwork Credit Uber Design Range 2 Introduction • Population, urbanization, and congestion Atlanta, GA Miami, FL Dallas, TX Los Angeles, CA have increased steadily over the past several decades • Increasing delays damage the environment and substantially impact the economy Driving time: 8 min. 16 min. 24 min. 30 min. Generated using OpenRouteService

VTOL STOL CTOL

Bell Textron XV-15 Pilatus PC-6 Cessna 208B + Minimal urban + Higher cruise + More efficient cruise footprint efficiency and speed + Higher cruise speed − Tradeoff between than VTOL + Well understood hover and forward + Shorter takeoff certification process flight efficiency distance than CTOL − Decreased flexibility − Noise during takeoff + Possibly feasible − Long takeoff distance and landing operations within − Limited applicability in − Mechanically complex urban environment urban environment Use Case

• South Florida Conurbation

– Wide sprawl yet ‘appropriate development density’ to enable placement and development of airparks

– Mostly flat terrain

– 6 counties stretching over 14,000 mi2 – 7.4 million inhabitants

– Seven commercial airports and several large cities including Miami, Ft Lauderdale, West Palm Beach, Ft Myers, Naples

– Some lengthy travels: MIA-PBI ~1hr30 PBI-RSW ~ 2h30 RSW-EYW ~5hr Technical Approach

Step 1: Step 2: Step 3: Step 4: Step 5: Step 6: Regulations & Suitable Parcel Weather Obstacle Ground Roll & Climb STOLport STOLport Design Identification Analysis Analysis Gradient Constraints Throughput

STOLport network geodensity

STOLport Design Land cadaster data Best practices for Obstacle Vehicle TO / LDG STOLport design Taxiway Land use / zoning runway orientation clearance performance Parking Stand Department of Weather observations requirements Revenue data Obstacle data Step 1: Regulation Review FAR Title 14, Section 91.119 – Minimum Safe Altitudes 1946: United States vs. Causby Case (Except Takeoff & Landing) Causby’s farm (Greensboro, N.C.) suffered as his chickens got anxious and died from US Supreme Court decided that property owners don’t own all airspace above An altitude allowing an emergency landing without undue hazard to persons or low-flying military aircraft taking off and landing at an airbase nearby (67ft above the their land as stated under common law (Justice Douglas noted that “Every property house, 63ft above the barn, 18ft above tallest tree) transcontinental flight would [otherwise] subject the operator to countless Over congested areas at 1,000ft above highest obstacle within 2,000 ft of aircraft The US government claimed all airspace above ground is public trespass suits. Common sense revolts at the idea.") Over non-congested areas, at 500ft above the surface except over water or sparsely Causby argued that low altitude flight entitles the land owner for compensation under Supreme Court also nullified the 1926 Air Commerce Act which states that the populated areas (for which 500ft from any person, vessel, vehicle or structure is an ancient doctrine of the common law (i.e. land ownership extended to the airspace US government owns all airspace ("if the landowner is to have full enjoyment of sufficient) above) the land, he must have exclusive control of the immediate reaches of the Helicopter can have waiver for specific routes and altitudes if this is in the public enveloping atmosphere“). The US committed a taking of the property air interest (i.e. saving a life) easement and compensation must be made Boundaries between private and public airspace undecided

1962: Griggs vs. Allegheny County 1973: City of Burbank vs. Lockheed Air Terminal Court ruled that, due to the Supremacy Clause, federal law/acts/constitution has CountyCourt owns decided and maintains that county the Greater had Pittsburghindeed taken Airport an with air oneeasement runway 3,250ftover City of Burbank passed an ordinance to prohibit jet aircraft takeoffs between 11pm from Grigg’s house andprecedent 7am to protect over local/state residents regulations from unwanted noise AirplaneGriggs’ regularly property flew and over house, as low as 11ft above Griggs chimney and LockheedCongress responded had essentially that curfew preempted was unconstitutional state and local as controla Noise overControl aircraft Act of noise 1972 regularlyGrigg’s between was entitled 30ft and to compensation300ft above Griggs’ house (federalwith the act) 1958 has supremacyFederal Aviation over local Act (nationalgovernment government laws has sovereignty over GriggsWhen argued designing the noise anfrom airport, regular the flights county prevented should ’enjoyment’ not have of purchased their house airspace) and the Noise Control Act of 1972 (which specifies emissions standards andonly that the the land county for had the taken airstrip an air but easement should overalso his have property purchased that constituted adjacent a for a variety of products and specifically targets aircraft noise and sonic booms) “taking”private requiring properties compensation for which a ‘taking’ of the air easement would take Justice Douglas “because there is need for efficient control of air traffic, only the Federal Aviation Administration, in conjunction with the Environmental Protection place (under Fourteenth Amendment) Agency, may regulate the subject of aircraft noise.” 1985: John Wayne Airport 1990: Airport Noise and Capacity Act (ANCA) John Wayne Airport takeoff and landing operations led to noise complaints from Congress feared more litigations such as at the John Wayne airport one would occur John Wayne Airport imposed new airport capacity plans The act regulated the ability to fly aircraft within the US as a function of noise nearby residents from Newport Beach nationwide Stage II aircraft could not be added to the fleet after November 1990 Residents Airport sued has the departure airport for thecurfews noise, resulting in regulations to flight operations Congress realized that a comprehensive and nationwide framework to regulate Unmodified Stage II aircraft over 75,000lb would be removed from fleet by 1999 Special takeoff and landing operations for noise abatement aviation noise was vital to the fitness of the country’s air transportation system Stage III aircraft can’t face unilateral restrictions from airport operators (curfew,  Airport maintains 10 permanent noise monitoring stations with flight/takeoff/landing operations) simply due to their noise unless airports and noise limits for daytime and nighttime hours. Three violations within aircraft operators reach a consensual agreement three-year period result in denial of use for three years A new category, Stage 4 is implemented starting in 2006 for new aircraft designs Step 1: STOLport Design

Runway Safety Area Taxiway Object Free Area (RSA)  Defined surface surrounding the runway prepared or (TOFA) • No vehicle roads or parked aircraft or other object not suitable for reducing the risk of damage to airplanes in the necessary for air navigation or ground maneuvering within event of an undershoot, overshoot, or runway excursion. OFA  Surface must be capable under normal dry conditions of • Vehicle may operate within OFA but must give right of way supporting aircraft without causing structural damage to to aircraft aircraft or injury to occupants  RSA must be cleared, graded, drained, with no hazardous surface variation Taxilane Object Free Area • No vehicle roads or parked aircraft or other object not  Surface must be free of objects except for objects that need necessary for air navigation or ground maneuvering within to be within the RSA because of their function. Objects OFA higher than 3 in must be on frangibly mounted structure • Vehicle may operate within OFA but must give right of way to aircraft Obstacle Free Zone (OFZ)  Defined volume below 150ft that precludes aircraft and other object penetrations except frangible NAVAIDS Runway to Parallel Taxiway  Sometimes combined with inner-approach OFZ (when • Minimum distance of 150ft between runway and parallel approach lighting system is present) taxiway or taxilane centerline for visual A-I runways used by  Sometimes combined with inner-transitional OFZ (runway small aircraft with sub 1.4sm approach visibility minimums)  Sometimes combined with precision OFZ (runway with Runway to Holdline Position precision approach, visibility less than ¾ miles and cloud • Minimum distance of 125ft between runway and holdline ceiling lower than 250ft) position for visual A-I runways used by small aircraft Runway Object Free Area (ROFA)

 Defined surface requiring clearing of above-ground objects General Aviation Parking Stands • Layout should maximize amount of stands while providing protruding above the nearest point of the RSA required taxilane Object Free Area and wingtip clearance  Object non-essential for air navigation or aircraft • Separation between stand is wingspan of design aircraft + maneuvering purposes should not be in ROFA 10ft  Object in ROFA should meet same frangibility requirements • Length of stand is length of aircraft + 3ft as for objects within the RSA • Apron locations that allow direct access onto a runway are  Acceptable for aircraft to both taxi and hold within the ROFA not recommended • Taxiways originating from aprons and forming a straight line across runways are not recommended Step 1: STOLport Design

• Short Runway Concept – Ideal scenario with minimum ground footprint – No supporting infrastructure

• Short Runway + Apron Concept – Addition of aprons for a more realistic scenario – Not ideal design since taxilanes are going straight to the runway

• Short Runway + Taxiway + Apron Concept – Most realistic scenario but largest ground footprint – Taxiway for increased throughput – Taxiway can be used to hold aircraft Step 2: Suitable Parcel Identification • Location and geometry of vacant land parcels to build STOLports need to be identified • Department of Revenue of Florida releases this information for tax purposes • GIS software is used to remove unsuitable parcels of land – Less than 2,500m2 (27,000ft2)

– Parcels not classified as either industrial or Mapwise: Online GIS application residential – Parcel in protected areas (National Parks, National Preserves…)

• About 30,000 vacant land parcels selected in South Florida • To improve likelihood of fitting long runway(s), small adjacent parcels are combined to form larger parcels

Before merging the parcels After merging the parcels Step 3: Prevailing Weather • Reviewed the literature to identify best practices to account for the impact of wind on runway orientation – FAA Advisory Circular 150/5300 provides standards and recommendations for airport design – Includes runway design, wind analysis, taxiway separation and apron / parking spot size • Runway design and orientation guidelines depend on: – Runway Design Code (RDC) – Aircraft Approach Category (AAC) – Airplane Design Group (ADG) FAA AC 150/5300-13 • Airplane Design Group (ADG) depends on aircraft size (tail height and wingspan) – Likely ADG Group I for STOL-based UAM and SUAM operations • Aircraft Approach Category (AAC) depends on approach speed – Likely AAC A for STOL-based UAM and SUAM operations

• Runway Design Code (RDC) depends on ADG and AAC – Likely RDC A-I for STOL-based UAM and SUAM operations – Possibly RDC A-II with increased automation to help with landings?

Step 3: Prevailing Weather • Appendix I of the FAA Advisory Circular recommends aiming for a wind coverage of 95% 18 • For a given runway heading, wind coverage is defined as the probability that the crosswind

component of the wind will not exceed the Allowable Crosswind Component Crosswind Component – RDC A-I runways, the crosswind component of the wind should be less or equal to 10.5kts at least 95% of the time • If the 95% wind coverage cannot be achieved with a single runway, additional (non-parallel) 36 runway(s) should be considered so that the combined wind coverage attains 95%

National Center for Environmental Information

 Need historical weather • Weather observations are retrieved observations to statistically from NOAA NCEI to extract wind determine the wind coverage information for the area surrounding the proposed airpark locations Step 3: Prevailing Weather

Runway headings meeting the 95% wind coverage objective South South Florida Step 4: Surrounding Obstacles • STOL SUAM would be operating most likely under 14 CFR 135 operational limits • AC 120-91A provides two methods for obstacle analysis – Area Analysis Method – Flight Track Analysis Method

FAA AC 120-91A • Area Analysis Method defines an Obstacle Accountability Area (OAA) where aircraft must be able to clear all obstacles during departure – Minimum vertical separation throughout OAA between flightpath and obstacle of 35 feet (can be increased if needed/desired) – if vertical separation requirement not possible, must be separated by at least 300 feet laterally when outside airpark boundaries – Deviation from runway centerline of up to 15 deg allowable Assumptions: Only straight-in approaches are considered in this analysis OAA is extended to the first 4,000ft Step 4: Surrounding Obstacles

 Need information about surrounding obstacles

• Use of LIDAR (Light Detection And Ranging) aerial survey available for free • Surveying method that measures distance to a target with a laser pulse

• Detailed mapping of the elevation ( 30cm x 30cm mapping)

• Good accuracy (9cm vertical accuracy and 115 cm horizontal accuracy)

• Ability to detect minute obstacles relevant for air navigation Step 4: Surrounding Obstacles

Unfeasible heading due to transmission tower Unfeasible heading at low climb gradient due to surrounding terrain Step 5: Ground Roll & Climb and Descent Gradient

• When obstacles interfere with the OAA, there are two options:

– Increase descent and climb  Tradeoff between ground roll and climb and gradients to increase altitude descent gradients quicker

– Reduce the ground roll so the aircraft lands further down Runway Runway + Apron Runway + Taxiway + Apron the runway and/or take-off sooner. This is similar to displaced thresholds South FloridaSouth Step 5: Ground Roll & Climb and Descent Gradient Runway Runway + Apron Runway + Taxiway + Apron Runway Runway + Apron Runway + Taxiway + Apron

17 Step 5: Ground Roll & Climb and Descent Gradient Runway Runway + Apron Runway + Taxiway + Apron Runway Runway + Apron Runway + Taxiway + Apron Step 6: STOLport Throughput • A Discrete Event Simulation is developed which simulates the operations in the vicinity of the STOLport • Several assumptions are summarized as follows: – The spacing between landings and between takeoffs is assumed to be 60s for wake turbulence separation purposes – Landing event based on an approach speed of 40kt, a mean deceleration on the runway of 9ft.s-2, and a taxi speed of 10kt – Ground operations such as passenger unload and load as well as aircraft servicing are assumed to be randomly distributed and following a symmetric triangular distribution between 5min and 10min – Takeoff event based on a taxi speed of 10kt, an average acceleration on the runway of 16ft.s-2, and a stall speed of 40kt Conclusion Runway Runway + Apron Runway + Taxiway + Apron • STOL-based operations are investigated in the South Florida conurbation – Promising geodensity achieved in higher-density environment where STOLport placement is desirable

• Results obtained in Florida were a bit harder to reproduce in Massachusetts – Smaller parcels makes it harder • Additional STOLport to fit long runways (i.e. >300ft) constructions need to be – Uneven terrain and obstacles accounted for in future studies to impact climb and approach increase the geodensity gradients – Parking lots (big box stores, – Need for crosswind runways at malls, hotels…) most locations in – Areas adjacent to interstates Massachusetts – Barges Thanks for Listening!