April 2014 

NASA/CR–2014-218247

Autonomous Flight Rules Concept:

User Implementation Costs and Strategies 

William B. Cotton 

Cotton Aviation Enterprises, Inc., Lakeway, Texas 

Robert Hilb 

Bob Hilb LLC, Prescott, Arizona 
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April 2014 

NASA/CR–2014-218247

Autonomous Flight Rules Concept:

User Implementation Costs and Strategies 

William B. Cotton 

Cotton Aviation Enterprises, Inc., Lakeway, Texas 

Robert Hilb 

Bob Hilb LLC, Prescott, Arizona 
Available from: 

NASA Center for AeroSpace Information 

7115 Standard Drive 

Hanover, MD 21076-1320 

443-757-5802 

The use of trademarks or names of manufacturers in this report is for accurate reporting and does not 

constitute an official endorsement, either expressed or implied, of such products or manufacturers by the 

National Aeronautics and Space Administration. 
i

Preface

This report was submitted in partial fulfillment of NIA Task Order Prime Contract NNL13AA00B, 

Subcontract T13-6500-CAE, with NASA Langley Research Center, Hampton, VA. The NASA Point of 

Contact for the task for which this report was generated is David J. Wing, Crew Systems and Aviation 

Operations Branch. 
ii 

Executive Summary 

This study was undertaken to discover and document the costs that would likely be borne by several 

classes of airspace users to equip their aircraft, train their personnel and conduct flight operations using 

Autonomous Flight Rules (AFR).1 AFR is a proposed advanced operating concept enabled primarily by 

airborne surveillance and an onboard automation system for traffic separation and conflict-free trajectory 

planning . AFR flights would be responsible for their own separation from all other aircraft and other 

hazards in the airspace but be free of most constraints imposed in the traditional Instrument Flight Rules 

(IFR) system, thus achieving unprecedented levels of flight efficiency and flexibility in their operations. 

In addition to estimating user costs for AFR, the study also examined the factors influencing transition 

strategies likely to be used, especially by those operators with large fleets of aircraft. The study assumed 

that AFR rules and procedures have already been established by the FAA and that means for certifying 

the required avionics and approving the operational procedures are in place. The Air Navigation Service 

Provider (ANSP) costs of implementing AFR are not part of this study. AFR was designed to minimize 

the impact on the ANSP in accommodating AFR aircraft, and so the primary expense is expected to be 

borne by the operators. 

To collect the necessary information to conduct this analysis, the investigators supplemented their 

own extensive aviation backgrounds with information gathering meetings held with avionics 

manufacturers, airline representatives, fractional ownership companies, representatives of the General 

Aviation (GA) and Business Flying community and Unmanned Aircraft Systems (UAS) manufacturers. 

Many of these meetings were held in person, and the rest were conducted via conference call using 

WebEx briefing presentations. Using the information obtained from these meetings, two representative 

avionics architectures were constructed for each class of airspace user, based upon different safety case 

outcomes that would dictate the certification difficulty and cockpit integration complexity. Analysis of 

these architectures enabled estimates of avionics acquisition costs to be made. The meetings also provided 

insight into the installation issues which enabled the estimation of those costs, in addition to the 

equipment acquisition costs. Training, maintenance, and other operations costs were also examined 

during these meetings. 

The four classes of airspace users considered in this study were airlines, fractional ownership 

operators, GA users, and UAS operators. Military operations other than UAS were not considered in this 

study but it is likely that those operations would benefit as much from AFR as the other user classes. 

Avionics systems incorporating airborne surveillance have been evolving in recent years from separate 

systems like the Traffic Alert and Collision Avoidance System (TCAS) to integrated surveillance 

platforms incorporating both active detection and Automatic Dependent Surveillance - Broadcast (ADSB) IN technology. The term "hybrid surveillance" is used to describe the integrated surveillance function 

and it is usually physically contained in a TCAS/Transponder Surveillance Unit. The surveillance-based 

applications of ADS-B IN currently under development would also be hosted in this avionics system, and 

AFR was considered by the aviation community to be just an application of ADS-B IN. This software 

application (and possibly the hardware it resides on) might be called the Air Traffic Unit (ATU). Other 

cockpit systems would connect to the ATU, most in a "read only" mode, but the AFR outputs, which 

carry the importance of an Air Traffic Control (ATC) clearance, would go to the Multi-Function Display 

or Navigation Display, the cockpit audio system and the Multifunction Control Display Unit or other pilot 

control interface. Additionally, a data communications system, either broadband internet equipment or 

other data radio, would be used to send the near-term intent trajectory, including conflict resolutions, to 

the ground ATC system for information only. The necessary degree of independence of the surveillance 

systems and redundancy of the cockpit avionics was determined to be an output of the system safety 

study, which must be accomplished before these operations can take place. For each of the four airspace 

user classes, avionics architectures were constructed representing the best and worst case outcomes of the 

safety study, from an avionics cost standpoint. 
iii 

The cost categories making up the total cost of AFR implementation are equipment acquisition, 

equipment installation, training, and operations and maintenance. The factors influencing these costs were 

considered for each user class, with the most important discriminator being the operating category, Part 

91 of the Federal Aviation Regulations or Part 121 or 135. The expected requirements in each of the cost 

categories come primarily from this "airline" versus "GA" distinction. Acquisition was found to be the 

largest cost item followed by installation. In general, the older the existing avionics, the more expensive 

the installation. Training of pilots can be a substantial cost item, and as a result, all operators plan to use 

computer-based training techniques as they do when introducing other new systems to control these costs. 

Operations costs would include any necessary upgrades to the flight planning system to take advantage of 

the operational freedoms permitted by AFR, and any feedback mechanism the company might need to 

monitor the transition to the new procedures. Maintenance of the ATU and related new equipment was 

found to be a relatively small cost, often completely hidden in the routine maintenance of the parent 

surveillance unit. 

Many factors must be considered when calculating the expected cost of AFR implementation by any 

specific operator. In this study, all the factors were listed for each user category with representative costs 

associated with them and the rationale for determining these costs. The cost estimating method is 

presented so that an operator can substitute his own numbers for each cost factor to arrive at an estimate 

of his own implementation cost. An example is provided in each user category for illustration of the cost 

estimation method. Some of the variables in operator’s costs include whether they contract out or do their 

own installations, pay for training or have the pilots do it on their own time, etc. In the example 

calculations, these assumptions were described such as the existing equipment on the airplane when 

upgrading for AFR, who did the installation, how training was accomplished, and who did the 

maintenance. The template permits any operator to compute his/her own cost estimates. For the examples 

presented in this report, a summary of "typical" cost estimates on a per aircraft basis is given in the 

following table, with a range reflecting possible variation. 

Airline Fractional GA UAS 

Total Costs $200 to 600K $50 to 200K $10 to 50K $10 to 45K 

Cost ranges reflect both the variation in needed equipment, in installation, and the certification 

requirements that are expected to vary the cost by a factor of two to three. The estimated user cost of 

implementing AFR is comparable to navigation system upgrades for all four airspace user classes and 

therefore generally within reach for most operators. 

Estimating the costs of implementation provides only one half of the information needed for a 

business case decision on whether to implement AFR. The other half is the benefit to be derived from 

using the procedures. This study did not contain a quantitative assessment of these benefits but does 

include a description of the benefit mechanisms from which those with operations experience can obtain a 

feel for the magnitude of the benefits. AFR is strong in this area compared to other ADS-B IN 

applications since the first to equip gets all the benefits, without waiting for a “critical mass” of the user 

population to equip or for any substantive change to the supporting ground services. Most of the benefits 

from AFR operations are a result of exemption from flow management constraints that are artifacts of 

human-centered air traffic control, but would be unnecessary when using automated separation. While 

AFR flights would participate in destination airport traffic flow management, they would be exempt from 

departure fix restrictions, airspace-related ground delay programs, overhead slot restrictions, miles-in-trail 

at Center boundaries, en route severe weather re-routes, terminal area departure procedures, and ATC 

preferred routes. Of course, the efficiency obtained by being able to operate on ad hoc trajectories and not 

waiting for approval to change the trajectory when optimizing the flight is also available in the AFR 
iv 

concept. These and other benefits are described as they would be experienced by each class of airspace 

user. 

Aircraft operators with large fleets would necessarily require several years to implement AFR in the 

whole airline. Thus, the strategy for implementation is important to minimizing costs while maximizing 

the achieved benefits during the implementation period. Done right, the benefits derived from the first 

equipped airplanes can pay for the balance of the transition. In the information gathering efforts, a number 

of common strategies emerged to optimize this aspect of the business case. The chosen first fleet to be 

modified would operate domestically to maximize the opportunity for benefit, already contain much of 

the required avionics so that software upgrades would comprise the bulk of the modification, and the 

installations would occur during regular maintenance visits without lengthening the scheduled “out of 

service” time for each airplane. A relatively small sub-fleet would maximize the exposure of pre-trained 

pilots to modified airplanes, especially if those pilots were not cross-qualified so that their numbers per 

aircraft was minimized. As the benefits can be used to offset the costs of implementation, it is important 

to achieve a high rate of implementation. This can be done by modifying several fleets simultaneously 

rather than doing it all sequentially. As soon as actual AFR operations validate the achievement of 

monetary benefits, every effort should be made to accelerate the transition, consistent with minimizing 

implementation costs. On the flip side of this argument, airplanes soon to be retired may not pass the 

cost/benefit test within the required, short return-on-investment period. This would be especially true if 

the older fleet required major hardware upgrades to participate in AFR operations, raising the 

implementation cost with only a limited time to recoup the payback. Analog avionics and Cathode Ray 

Tube (CRT) displays are examples of equipment that would be very expensive to replace to participate in 

AFR. 

A byproduct of the information gathering meetings with many members of the aviation community 

was the feedback received from these people on the AFR concept itself. All of the airspace users felt it 

was important to continue the development of the AFR capability and make it an operational reality. 

Some called it the most important thing to come out of ADS-B. Among the recommendations for further 

work on the concept are performing a quantitative AFR benefit study and conducting the safety case to 

determine avionics requirements. 
v 

Table of Contents 

Preface i

Executive Summary ii

Table of Contents v

1. Introduction 1

2. Background 3

3. Methodology 4

4. Findings Regarding AFR Avionics Architecture 5

5. AFR Airborne Architecture Alternatives 8

5.1. Proposed Airline Aircraft AFR Architecture 10

5.2. Proposed Fractional Jet Operator AFR Architecture 11

5.3. Proposed General Aviation Aircraft AFR Architecture 12

5.4. Proposed UAS AFR Architecture 13

6. Cost Categories 14

7. Development of Cost Estimate Model 16

7.1. Airline Cost Estimation Example 17

7.2. Fractional Operator Cost Estimation Example 18

7.3. General Aviation Owner/Pilot Cost Estimation Example 19

7.4. UAS Cost Estimation Example 20

8. Description of Benefit Mechanisms 21

8.1. Airline Benefit Mechanisms 21

8.2. Fractional Operator Benefit Mechanisms 22

8.3. General Aviation Benefit Mechanisms 22

8.4. UAS Benefit Mechanisms 23

9. Considerations for Implementation Strategies 24

9.1. Airline Strategy Considerations 25

9.2. Fractional Operator Strategy Considerations 26

9.3. General Aviation Strategy Considerations 27

9.4. UAS Strategy Considerations 28

10. Other Feedback from Outreach Interviews 30

11. Conclusions and Recommendations 32

12. References 33

Appendix A. AFR End to End Flight Scenarios 34

A1. Air Carrier Scenario Example 34

A2. Fractional Ownership Operator Scenario Example 36

A3. General Aviation Scenario Example 37

Appendix B. Organization Interviews 40
vi 

B1. Example presentation 40

B2. Interview Questions 43

B3. Organizations and companies interviewed 44

Appendix C. Abbreviations 45

Author Biographies 46
1 

1. Introduction 

NASA's Airspace Systems Program and its predecessor projects span more than three decades of 

research and development of systems using automation in air traffic control functions. This research has 

led to important tools for air traffic management that were transferred to the Federal Aviation 

Administration (FAA) and placed into operational service. During the same period of time, air traffic has 

continued to grow and the delays and inefficiencies experienced by airspace users have grown along with 

it. The FAA has kept operations safe throughout this growth period by employing traffic flow 

management initiatives that limit the aircraft demand on constrained resources (runways, control sectors) 

to manageable levels. These limits on demand represent constraints to operations that are manifested in 

many ways in the current Air Traffic Control (ATC) paradigm. Departure fix restrictions, red sector 

limits, miles-in-trail "passbacks," ATC preferred routes, and bulk weather re-routes are examples of these 

constraints. 

NASA's research has always focused on removing or reducing the impact of these constraints which 

are part of the very structure of today's ATC system. Most often, the approach has been to automate 

certain manual functions to reduce the controller's workload so that more aircraft will be accepted in any 

given sector. In some cases, the focus was on permitting more efficient flight profiles to be used without 

changing the number of aircraft accepted. In others, assistance was provided to de-randomize the flow of 

aircraft into a major airport, helping to get the aircraft spaced properly to achieve a more regular arrival 

interval. As such, NASA's goal has been to improve the capacity, efficiency, and safety of the National 

Airspace System (NAS). 

The Next Generation Air Transportation System (NextGen) program, now a decade old, brought all 

the concerned federal agencies together in furtherance of the same goal, and was designed to be a 

transformative roadmap for Air Traffic Management (ATM) of systems and procedures to meet much 

higher targets for capacity, safety, and efficiency. A few of the enablers to achieve the goals have been 

implemented during the last decade, among them Required Navigation Performance (RNP) procedures to 

shorten arrival paths to some runways and the ground-based Automatic Dependent SurveillanceBroadcast (ADS-B) network - a backbone for NextGen surveillance. Additionally, a mandate to equip 

aircraft for ADS-B OUT (i.e., transmit) was established to take effect in 2020, that will transform the 

surveillance function. It also will enable applications of ADS-B IN (i.e., receive), permitting aircraft to 

share in separation responsibilities in an important new way. 

The most transformational aspect of NextGen is automation of the separation function. Automated 

separation has the potential to eliminate those constraints to flights that have been established to ensure 

safety in a human-centered system for traffic separation. The regimentation of traffic flows and limits on 

the number of aircraft in a sector, for example, would not be necessary in an automated separation system. 

However, this important feature of NextGen, originally targeted for operational readiness by 2025, has 

been dropped from the FAA's current implementation plan. That decision has put responsibility for 

developing the automation necessary to overcome the majority of shortfalls in ATC capacity and 

flexibility back into NASA's Airspace Systems Program. 

Specifically, automation of the separation process has been pursued in both the NASA Langley and 

Ames Research Centers, one examining an airborne implementation and the other a centralized groundbased solution. The airborne solution studied at the Langley Research Center has evolved into what is 

now called Autonomous Flight Rules (AFR).1,2 AFR takes advantage of the surveillance available in 

aircraft resulting from the ADS-B mandate by placing the automated separation responsibility in the 

aircraft. The research done to date on AFR has established the feasibility of the concept in mixed 

IFR/AFR operations.3

 That was a major finding as it enables a viable transition path for the automated 
2 

capability. Additional AFR research will test the operations in the presence of various system failures 

and external anomalies, such as adverse weather. Another aspect of the AFR investigation is the business 

case for the concept - the cost associated with airspace users flying under AFR and the benefits accruing 

to its use. The present study is an examination of the costs to airspace users of AFR. 
3 

2. Background 

The AFR concept is formally described in Reference 1. This description is the result of more than a 

decade of Langley research into airborne self-separation, beginning with Distributed Air/Ground Traffic 

Management in the late 1990s. Creating the capability to perform the traffic separation function from the 

cockpit consumed most of this research effort. The research included writing and refining the conflict 

detection and resolution (CD&R) algorithms, creating the pilot interfaces and procedures to effectively 

use the surveillance and the CD&R tools, and testing the validity of the concept against simulated traffic 

using much higher traffic densities and complexities than currently exist, for robustness to real world 

failures and to measure sub-system performance. 

Once it was proven that airborne self-separation was a viable concept, the means for employing this 

capability for operational benefit in the NAS was examined. It was recognized that segregating airspace 

specifically for self-separation operations was untenable because it is neither fair to deny access to the 

unequipped nor reasonable to expect a large proportion of the traffic to equip for new operations prior to 

receiving any benefits. 

Accordingly, self-separation would have to work in mixed airspace with other IFR and Visual Flight 

Rules (VFR) operations to see the light of day. The other essential principle for incorporating selfseparation into the airspace was determined to be non-interference with existing operations. To meet this 

principle, it is necessary for the self-separating aircraft to give right of way to all IFR flights whenever a 

conflict would develop. In this way, conventional air traffic control procedures could be used with IFR 

aircraft while the AFR share the same airspace, similar to VFR with IFR. 

Finally, the use of self-separation in mixed airspace was given its own set of proposed standards, 

procedures and rules for use under a separation name - Autonomous Flight Rules, or AFR. The use of a 

separate set of rules permits the clear delineation of the requirements for equipment, the procedures for its 

use, and the rules for pilot training and flight operations under AFR. 

The next step in the research is to determine what it would cost for an airspace user to participate in 

AFR operations and what they would produce as benefits. This report is an examination of the first part 

of this cost/benefit exercise, the costs of AFR. While a comprehensive and quantitative benefit study for 

AFR remains as future work, the benefit mechanisms for each of the airspace user classes studied are also 

set forth in this report to provide context for the cost items. The Air Navigation Service Provider (ANSP) 

costs of implementing AFR are not part of this study. AFR was designed to minimize the impact on the 

ANSP in accommodating AFR aircraft, and so the primary expense is expected to be borne by the 

operators. 
4 

3. Methodology 

The costs to equip and operate aircraft using AFR is highly dependent upon what equipment will be 

required, what avionics already exist in the airplane to be used, and the nature of the flight operations 

themselves. In other words, one size does not fit all. One way to divide this problem so that meaningful 

results can be obtained is to separate the analysis by airspace user class. In this study, four user classes 

were selected: airlines, fractional ownership operators, General Aviation (GA), and Unmanned Aircraft 

Systems (UAS) operators. Of course there are many distinctions possible within each of these but for this 

first cut at the costs of AFR participation, the airspace users have been generalized in this fashion. 

Military flying was not analyzed in this study but as that represents a major airspace user class, they 

should be considered in future studies of AFR operations. 

It was decided to use the interview process, interviewing those with domain expertise garnered 

through personal experience and involvement, to gather information specific to the cost categories and the 

airspace user categories in this study. Knowing that the biggest cost drivers would be the acquisition cost 

of the avionics for AFR and the installation of that equipment into the aircraft, it was decided to meet with 

the avionics manufacturers first. From these discussions it would be possible to postulate representative 

avionics architectures needed by each class of airspace user in their aircraft. Armed with the avionics 

architectures, the following discussions with representatives of the airspace users would be more 

productive as they would have a better feel for what their installation, training and operating costs would 

likely be. 

Some of the interviews were held face-to-face as this method provides more effective communication 

and produces better and more complete results from the information gathering effort. To interview more 

representatives and to economize on travel costs, some of the interviews were conducted by conference 

telephone and internet, using WebEx to assist with PowerPoint presentations and other written materials 

used in the discussions. At least one face-to-face meeting was to be held with a representative of each 

user class. Confidential reports of each of the meetings have been delivered to the NASA technical point 

of contact. 

For each meeting, a one-page read-ahead explanation of AFR and the objective of the meeting in 

relation to its support for the current NASA research was sent to those who would be attending. A 

tailored, PowerPoint presentation was created for each representative meeting that explained the AFR 

concept and the relationship of the meeting to the current research. Then a prepared page of structured 

questions was used in each meeting to solicit specific cost-related information needed by the project as 

well as general feedback on the AFR concept and the research performed so far. 

With the results of those meetings (interviews), a representative aircraft-operator example was created 

in each user category for use in defining the costs and preferred implementation strategy that would 

maximize the savings and other benefits from the use of AFR in each of their operational paradigms. To 

protect the competition-sensitive information provided by those interviewed, averages were used in the 

representative examples provided in the report for specific expected costs. Additionally, the factors that 

influence each of the cost items are identified so that variations from the average can be computed by 

anyone wishing to apply the method to their own operations. 

In some cases, the dollar value costs were unknown to those interviewed or were considered so 

premature that they declined to quote a figure that could later be used against them. Whenever this 

occurred, cost estimates were created in consultation with those interviewed that were based on very 

similar experience with other avionics, training, etc. The results arrived at in this report thus represent the 

best possible estimate of costs available at this writing based upon consultation and honest input from 

those in the best position to know. In other words they are not "catalog" prices, but good enough to 

support initial investment planning. 
5 

4. Findings Regarding AFR Avionics Architecture 

The cockpit systems used by the pilots in flying AFR are comprised of five functional elements: 

surveillance, computation, control and display, communication, and guidance. The Autonomous 

Operations Planner (AOP) developed at NASA Langley during their research into the AFR concept 

served as the initial model for the cockpit avionic systems.4

 

In the Langley implementation, the surveillance function was simulated by ADS-B IN supplemented 

with Traffic Information Service Broadcast (TIS-B). The computation function that took surveillance 

data and modeled the projected positions of both "ownship" and the other nearby aircraft was the heart of 

the AOP software and operated in parallel with the simulated Flight Management System (FMS). This 

location made sense because that is where the navigation function currently resides and the ownship state, 

intent and performance information is also available there. Control and display of the separation function 

resided primarily in the in the Multi-function Control Display Unit (MCDU) in the AOP implementation 

with the addition of an AOP hard key and dedicated AOP pages on which to view, select and execute 

strategic resolution options. The status of the system and traffic situation was displayed on a separate, 

small alphanumeric display called the SNAPI (Status Notification and Planning Information). 

Communication of the ownship trajectory to the Air Navigation Service Provider (ANSP) and 

surrounding aircraft was through the ADS-B OUT link, with Trajectory Change Points (TCPs) assumed 

to be activated. This communication is to provide intent information from ownship to the ANSP and 

other nearby aircraft. Finally, the flight guidance function was split among the SNAPI and FMS displays, 

the Primary Flight Display (PFD) and the Navigation Display (ND). Aural annunciation of tactical 

separation commands was simulated through the aural alerting system on the active audio channel and/or 

over the flight deck speakers. For a detailed description of the AOP, see Reference 4. 

As all the previous research had used this experimental setup to enable pilots to simulate flight under 

AFR, the current study looked at the practicality and feasibility of this AOP implementation and 

alternative avionics architectures considering costs and certification difficulties inherent in integrating the 

AFR functions into existing cockpits and forward-fit installations for new aircraft. One of the major 

considerations was the impact of re-certifying complex avionics already resident in the aircraft to 

accommodate the AFR functions. From a cost-to-implement standpoint, this obviously needed to be 

minimized. Another consideration was the certification level, determined by the criticality of the AFR 

functions. This level should match that of the avionics box in which the function will reside. The need to 

add additional boxes in the radio rack or additional displays on the instrument panel is another important 

consideration. Space is at a premium in both areas, weight is always a factor, and the need to run 

additional wiring to and from the new equipment is always a major cost factor. Finally, the avionics 

changes taking place in the near-term to implement other functions either required or desired will alter the 

existing suite of avionics prior to the introduction of AFR and should be considered baseline to the AFR 

changes. This would include ADS-B OUT and any near-term ADS-B IN applications like In-Trail 

Procedures (ITP), Flight-deck Interval Management (FIM), Pairwise Traffic Management (PTM) or 

Traffic Aware Strategic Aircrew Requests (TASAR) that might be implemented first. 

To address the avionics architecture questions, meetings were held with four of the primary avionics 

manufacturers in the US: Honeywell/ Bendix/King, Rockwell Collins, ACSS, and Garmin. The meeting 

with Rockwell Collins was in person at their Cedar Rapids headquarters. The others were conducted by 

conference call using WebEx to make the presentation, discuss the architecture graphics, and conduct the 

question and answer session regarding cost considerations. The first three manufacturers produce 

primarily for the transport aircraft market and Garmin produces primarily for GA, but there is some 

overlap reflected by Bendix/King of Honeywell and Rockwell Collins producing significant avionics 

lines for the high-end GA market (i.e., business jets and fractional ownerships), and Garmin is about to 

make some higher end offerings for larger jet aircraft. 
6 

In the meetings, the AFR operational concept was described and discussed in sufficient detail that the 

manufacturers were very aware of the AFR functions to be performed and the necessary integration with 

other system and displays. They were shown how the AOP implementation worked but were not 

constrained in their thinking to that particular architecture. 

Probably the most significant finding from these meetings was the degree to which all the 

manufacturers are already integrating "surveillance-based functions" in their product offerings. The first 

foray into airborne surveillance was the Traffic Alert and Collision Avoidance System (TCAS) followed 

by TIS-B, and with the ADS-B mandate coming, ADS-B IN and OUT offerings are already available 

from many manufacturers as shown in Section 7. 

The surveillance explosion has resulted in integrated box offerings to replace/combine the TCAS and 

Mode S Transponder boxes with a single "Surveillance Box" containing those two functions, amongst 

others, and also incorporating ADS-B radios for both IN and OUT. A number of ADS-B IN applications 

have been certified. The combination of ADS-B, TIS-B, and TCAS targets detected by any means are 

correlated so that only one target is displayed per aircraft, with the best source of information being used 

to display its position. For some applications, in certain conditions, ADS-B targets must be validated 

with active interrogation. 

The adequacy of TIS-B to serve as back-up surveillance for AFR was also discussed. Since TIS-B 

targets are generally of lower quality than ADS-B,a TIS-B target aircraft could be avoided using a larger 

separation zone. For TCAS-equipped aircraft, active interrogation could be used to more accurately 

measure the distance to the target. In general, that distance will be more accurate than the ADS-B 

calculated distance. Another technique would be to track targets by fusing ADS-B, TIS-B, and active 

interrogation. The safety case will dictate which of those techniques is an acceptable minimum, as 

required for the AFR function. 

 Several manufacturers are already offering a surveillance box containing TCAS, TIS-B and ADS-B 

with one or more ADS-B IN applications. 

The computation function is the heart of AFR, using the surveillance and intent information to do 

trajectory modeling, conflict detection and resolution and the communications of the executed resolutions 

to the ANSP and surrounding aircraft. This function is called the Air Traffic Unit (ATU). The NASA 

AOP (described earlier) is a research prototype of an ATU. The ATU function is expected to reside on a 

computer board in the surveillance box and is considered by the TCAS manufacturers to be just a TCAS 

upgrade, even though it is using primarily ADS-B information. 

For aircraft without TCAS, the ATU is expected to reside in an integrated navigation system. Many 

GA aircraft have installed a Wide Area Augmentation System (WAAS) navigation system with a moving 

map that additionally displays terrain, weather, and traffic. Avionics manufacturers expect that a Cockpit 

Display of Traffic Information (CDTI) with AFR functions could be hosted in such a system. The major 

cost factor will be the level of certification required for AFR. In addition, if the FAA were to require a 

Letter of Authorization for AFR operations for certain user categories, the training and administrative 

burden might prevent some of these operators from participating in AFR. The key will be ensuring that 

the AFR implementation is intuitive enough so that extensive training is not required, such as was done 

for WAAS Localizer Performance with Vertical guidance (LPV). That may require limiting AFR to 

tactical resolutions only where the aural and visual resolutions mimic controller voice instructions. 

The conflict detection and resolution function is divided into two modules, strategic and tactical, that 

are differentiated in several ways. The strategic module has a longer look ahead time; probably out to 10 

minutes in the future. The tactical module would have a look ahead time of four minutes until projected 

loss of separation. Another distinction is that the strategic algorithms may produce several available 

resolution options from which the pilot may choose one to execute. The tactical logic produces a single 

directive resolution which must be followed, just like an ATC clearance or instruction. The tactical 
7 

CD&R algorithms are more safety critical and their implementation in hardware and software will have to 

be FAA-tested and approved. The avionics manufacturers will be incorporating the RTCA Minimum 

Operational Performance Standards (MOPS) compliant CD&R algorithms into their software and the 

pilots will be following their output, just like an IFR clearance, so traffic separation under AFR is still an 

FAA controlled and approved function. 

There was a near universal opinion that "you should never break into a certified box that you don't 

need to" as it incurs the expense not only of certifying the new function but also re-certifying the old. For 

this reason, none of the manufacturers favored using the FMS to host the AFR functions in a retrofit 

scenario. The MCDU was chosen as the best place to control the AFR functions on airline aircraft and 

host the status display system including traffic conflict status. On general aviation aircraft the control and 

status display may be a part of the traffic/surveillance unit, or the crew interface device to the navigation 

system could be modified to accommodate AFR. 

Traffic situational awareness was felt to be properly located on the ND / Multi-Function Display 

(MFD) in some aircraft. This is in the forward field of view and CDTI functions are already fairly well 

understood because of TCAS and are being further developed through ITP, FIM and CDTI-Assisted 

Visual Separation (CAVS). The additional symbology needed for AFR could be relatively easily added 

as long as a digital flat panel display is used, not a symbol generator-driven Cathode Ray Tube (CRT). 

Breaking into the PFD, however, was not considered desirable. If flight director guidance for resolution 

maneuvers is a wanted function, it would likely be requested as an option on a new delivery aircraft. 

However, speed commands and altitude changes can be shown on the PFD just as FMS and Mode 

Control Panel (MCP) changes are displayed. 

Other systems that are integrated with the AFR functions either provide information to the ATU 

computer, take information from it, or both. The FMS is foremost in this category but unlike using the 

FMS to host the ATU function, it merely supplies information on planned trajectory and aircraft 

performance to the ATU and accepts routes, altitude and speed modifications from the ATU for execution 

by the pilot. Similarly, the MCP sends information on active flight mode, heading, altitude target, speed 

and vertical speed target information to the ATU for use in ownship trajectory modeling. On a few 

aircraft, the ability to accept an ATU output on the MCP will also be available, but it is not necessary 

where it can't now be done (see figure 1). 

All manufacturers accepted that both 1090 Megahertz Extended Squitter (1090ES) and Universal 

Access Transceiver (UAT) receivers would be included in the surveillance package and that an antenna is 

available that accommodates both frequencies. 

The issues of redundant equipment, independent sources of data and equipment, and software 

certification levels were discussed at length with all parties. Those issues all relate to the safety of the 

systems used to conduct AFR and the answers cannot be known until the conclusion of the NASA/ FAA 

safety case study for AFR. Because the certification level is unknown at this point, the true costs, 

especially the certification costs and risks, cannot be accurately determined a priori. None of the parties 

interviewed thought that Level A certification would be required. Level A certification is typically 

required only for aircraft control systems that ensure safety of flight such as autoland systems. For this 

analysis, two representative architectures were derived for each of the four airspace user categories as 

examples. The more stringent one assumed that complete redundancy of equipment and Level B 

certification of the software containing the CD&R algorithms would be required. The less stringent (and 

less expensive) option assumed redundancy of some elements, but not all, and that Level C certification 

of the software would be sufficient. Where a range of estimated costs is shown, it reflects these two 

options. In the section below, the avionics suites to support AFR are shown for each of the four studied 

classes of airspace users: 

1. Airlines 
8 

2. Fractional ownership operators 

3. General Aviation owner/pilot 

4. UAS operator 

5. AFR Airborne Architecture Alternatives 

Below are architecture alternatives for airborne equipment to implement an ATU as a retrofit on 

legacy aircraft in the 2020 time frame. A typical airline architecture is shown in Figure 1, and an airline 

ND showing notional AFR symbology is shown in Figure 2. 

Figure 1 Typical airline AFR architecture. Arrows indicate information flow. 

Mode Control panel

Audio Panel

TCAS  

Control Panel

Broadband

FMS FMS

MCDU MCDU CM

MFD or

Navigation

Display

CDTI

MFD or

Navigation

Display

CDTI

Primary

Flight

Display

Primary Flight

Display

1090 ES

978 UAT

ATU

TCAS/Transponder

Surveillance Unit

[in radio rack]
9 

Figure 2 Navigation Display showing AFR Symbology 

Architectures are proposed for each of the four classes of aircraft. It is assumed that a safety study 

will be accomplished that will determine a number of performance parameter requirements. In these 

preliminary architectures the design assurance and redundancy levels are presumed to be the major cost 

drivers. In each case, two architectures are described. One is considered worst case and the other, a 

“realistic” alternative. The assumed time frame is post 2020 when the current ADS-B OUT mandate is in 

place. It is also assumed that MOPS compliant and certified ATU CD&R algorithms (both strategic and 

tactical) and Traffic Flow Management (TFM) software are in place. Joint US/European Minimum 

Aviation System Performance Standards (MASPS) and Minimum Operational Performance Standards 

(MOPS) are assumed to be in effect, and International Civil Aviation Organization (ICAO) Standards and 

Recommended Practices (SARPS) for the ATU function are assumed to be in effect. Note: In the 

following, *indicates equipage assumed in the great majority of aircraft by 2020.
10 

5.1. Proposed Airline Aircraft AFR Architecture 

o Dual FMS with: 

 intent bus providing own aircraft four-dimensional (4D) trajectory to the ATU* 

 ability to accept 4D trajectories from ATU* 

 airspace information (sector boundaries, Special Use Airspace (SUA), ATC frequencies) 

in the navigation data base, and aircraft performance limitations available 

o CDTI on ND with AFR and other ADS-B IN applications (Figure 2) 

 ability to display heading, airspeed, and altitude resolution guidance from the ATU*. 

o MCP with status (horizontal and vertical navigation modes, heading, airspeed, altitude) output to 

ATU 

 heading, airspeed, and altitude from ATU if that feature is implemented under Controller 

Pilot Data Link Communications (CPDLC).* 

o TCAS and/or Transponder Line Replaceable Unit (LRU) which includes: 

 hybrid surveillance* 

 independent ADS-B IN system which includes UAT receiver, processes TIS-B and Flight 

Information Service Broadcast (FIS-B), hosts air traffic unit for strategic and tactical 

AFR, and perhaps other applications 

 receives and outputs to Communication Management Unit (CMU) and/or broadband 

and/or Overlay (weather, System Wide Information Management (SWIM), ownship and 

other aircraft trajectories, etc.) 

 outputs to FMS (and MCP if implemented) in Data Comm format ( or CPDLC or Airline 

Operational Control (AOC) formats) 

 outputs to aural alerting system* 

 interfaces with MCDU or other input/output (I/O) device 

o Upgrade 1090 antennas to 1090/UAT antennas 

o Dual Very High Frequency (VHF) Data Radio* 

o Dual MCDU* 

 ATU status, CD&R information pages and pilot interface 

Architecture 1: dual TCAS as described above, Level B software 

Architecture 2: single TCAS as described above, second Air Traffic Unit in TCAS LRU with 

independent power source and 2nd 1090/UAT receivers (share 1090/UAT antennas), Level C software 

(but without the TCAS function) 
11 

5.2. Proposed Fractional Jet Operator AFR Architecture 

The architectures proposed for Fractional Jet Operators are twofold. The first is similar in functional 

capability to the airline equipment listed above. The second is more in line with high-end GA, described 

below. It is expected that the choice between these (or something in between) would be driven by the type 

of aircraft under consideration (size and installed equipment) and the nature of the operations such as the 

percentage of flights into the top 30 United States (US) airports. 

o Dual FMS with: 

 intent bus providing own aircraft 4D trajectory to the ATU* 

 ability to accept 4D trajectories from ATU* 

 airspace information (sector boundaries, SUAs, ATC frequencies) in the navigation data 

base, and aircraft performance limitations available 

o CDTI on large format Nav Display with AFR and other ADS-B IN applications 

 ability to display heading, airspeed, and altitude resolution guidance from the ATU*. 

o MCP with status (horizontal and vertical Nav modes, heading, airspeed, altitude) output to ATU 

o TCAS and/or Transponder LRUs which includes: 

 independent ADS-B IN system which includes UAT receiver, processes TIS-B and FISB, hosts air traffic unit for strategic and tactical AFR, FIM, closely spaced parallel 

approaches and other applications 

 receives and outputs to CMU and/or broadband and/or Overlay (weather, SWIM, 

ownship and other aircraft trajectories, etc.) 

 outputs to FMS in Data Comm format ( or CPDLC or AOC formats) 

 outputs to aural alerting system* 

 interfaces with MCDU or other I/O device 

o Upgrade 1090 antennas to 1090/UAT antennas 

o Dual I/O device* 

 ATU status, CD&R information pages and pilot interface 

Architecture 1: dual TCAS as described above, Level B software 

Architecture 2: Single FMS and second navigation system with display capable of accepting traffic 

information to support AFR.* Single TCAS as described above, second Air Traffic Unit in Traffic 

Advisory System (TAS) LRU with independent power source and 2nd 1090/UAT receivers (share 

1090/UAT antennas), Level C software (but without TAS function) 
12 

5.3. Proposed General Aviation Aircraft AFR Architecture 

The following proposed architecture for GA aircraft includes an ATU in which the CD&R software 

uses "tactical resolution" algorithms only, provided and certified by the FAA. 

 Minimum required IFR equipment plus: 

 Dual Global Positioning System (GPS) navigation system with: 

o ND capable of accepting traffic information to support AFR* 

o Ability to display airspace information (sector boundaries, SUAs, ATC frequencies) from 

nav database or FIS-B 

 I/O device with ability to display commanded heading, airspeed and altitudes from ATU* 

 TAS/surveillance unit which includes: 

o independent ADS-B IN system which includes UAT and 1090 receivers, processes TIS-B 

and FIS-B, hosts air traffic unit for tactical AFR 

o Interfaces with I/O device 

o aural alerting system or outputs to existing aural system where installed 

 Upgrade 1090 or UAT antennas to 1090/UAT antennas 

 Broadband internet connection* (higher end GA. State vector provided over ADS-B is sufficient 

for others.) 

Architecture 1: Dual TAS surveillance units with Technical Standard Order (TSO) compliance. 

Broadband internet connection. 

Architecture 2: Single TAS surveillance unit as described above and second ATU in TAS LRU with 

battery power and independent 1090/UAT receivers. 
13 

5.4. Proposed UAS AFR Architecture 

 Dual GPS Navigation System 

 TAS/surveillance unit which includes: 

o independent ADS-B IN system which including both UAT and 1090 receivers, 

processes TIS-B and FIS-B, hosts air traffic unit for tactical AFR 

o Interfaces with I/O device 

 Upgrade 1090 or UAT antennas to 1090/UAT antennas 

 Communications unit to communicate to remote operator and send velocity vector or 

trajectory to ANSP. 

Architecture 1: Dual TAS surveillance units with TSO compliance. Broadband internet connection. 

Architecture 2: Single TAS surveillance unit as described above and second ATU in TAS LRU with 

battery power and independent 1090/UAT receivers. 

The four classes of airspace users represent a wide range of vehicles and operators in each class. 

"Airlines" include the remaining majors ( e.g., United, American, Delta), the so-called low cost carriers 

(e.g., Southwest, JetBlue, Virgin America, Alaska), and the regional carriers performing express service 

for the major carriers under their logos (e.g., United Express), using regional jet aircraft. The "Fractional 

Ownership" category includes the on-demand carriers using small to medium and some large business jet 

aircraft, such as NetJets, FlightOptions, etc. The General Aviation category is the largest comprising both 

personal and commercial services in all kinds of aircraft from small single-engine piston aircraft through 

piston twins, turbo-prop and light jets to specialized operations using transport category aircraft. 

Similarly, UAS encompasses an even wider range of vehicles and types of operations. Most private and 

commercial UAS uses in the NAS are still "proposed" as they don't yet have the freedom of access needed 

to accomplish most of the missions. The kinds of UAS that would be using AFR are in the medium to 

large vehicle category, used almost exclusively today by the military. The proposed architectures are 

based upon a "representative" example aircraft in each of the four categories. The chosen aircraft 

representatives used in the example cost calculations in Section 7 are, for the airlines, the 737-900; for the 

fractional operator, the Embraer Phenom; for the GA aircraft, the Piper Meridian; and the UAS, the 

Predator drone. 
14 

6. Cost Categories 

This AFR cost analysis, performed with the aid of interviews with airspace user representatives, 

determined that the costs associated with AFR fall into four categories: 1) Equipment acquisition; 2) 

Equipment Installation; 3) Training; and 4) Operations and maintenance. The factors that influence the 

cost of each of these items are presented next, and actual cost examples appear in Section 7. 

Equipment Acquisition 

The equipment acquisition cost will be based on what items of new or upgraded avionics are needed, 

what certification level was approved by FAA, how many items are being purchased (how many shipsets) 

and how many competitors are in the market selling this equipment. In a monopoly market, the 

manufacturers try to understand what the item will produce in the way of benefits for the customer, then 

price the item to get a substantial percentage of that value rather than relate it to development and 

production costs. If there is competition, the price quickly returns to a cost of production basis. In the 

equipment lists shown above under "Avionics Architecture", the starred items are assumed to be on the 

aircraft in the 2020 time frame and don't need to be purchased to support AFR. It can be seen that the 

primary purchase item is the TCAS/Transponder (Surveillance) LRU upgrade to include the necessary 

ADS-B radios and ATU software application. Software upgrades will also be needed for the FMS 

navigation data base to include additional airspace information, for the ND to include AFR specific traffic 

symbology, and the MCDU to incorporate control and display of ATU system information. As an 

alternative to an FMS data base upgrade, since the airspace sector boundaries and frequency information 

are in an FAA database, it may be necessary for manufacturers to have access to this database to include it 

as part of the AFR software and to update it periodically as the FAA makes changes to these parameters. 

Avionics Installation 

The avionics installation is a major driver of AFR implementation costs. It could be as much as the 

acquisition cost of the hardware and software equipment itself but will generally be much less if only 

software upgrades are required. The variables associated with installation cost include availability of 

space, integration with other systems, wiring changes required and where the work is accomplished. The 

ATU "card" including the surveillance radios will likely fit into the latest TCAS/Transponder surveillance 

"boxes" or LRUs without modification. Therefore, they might not take up any room on the radio rack, or 

in or behind the instrument panel. However, to retrofit the capability on older aircraft it might be 

necessary to install a completely new box. Depending on the aircraft, this could take up space in the 

equipment bay or on and behind the instrument panel itself. In general, the older and less sophisticated 

the cockpit to be modified, the more expensive the AFR installation will be. Sample installations in an 

aircraft from each user category will be detailed in the next section. One of the biggest installation costs 

is to re-wire the aircraft for the new equipment. Wiring is required for power, for control, for antennas, 

and for connections to and from other systems used to provide information to the ATU or to accept and 

display or transmit the output from the ATU. The degree to which new wires require the airplane interior 

to be removed, other parts to be removed for access, passing through the pressure bulkhead or external 

skin of the airplane all directly affect the cost of the installation. Other avionics systems that the ATU 

"talks to" may be accessed on a standardized bus, but in some installations, they may require discreet 

wires to be run between them. The final variable for installation cost is who is doing the installation and 

how long does the aircraft need to be out of service to do the installation. Work done "in-house" can 

usually be combined with other installations and timed to coincide with routine maintenance. Often the 

technicians are salaried and this specific installation might not be traceable in their costs, but lumped 

together with all changes. On the other hand, it has become commonplace for aircraft operators to 

outsource maintenance and installation work to overseas locations to take advantage of lower wages and 
15 

other overhead costs. So the installation cost will be related to both the difficulty of accomplishing it and 

the accounting system used for the work done. 

Training 

Training is needed, primarily for the pilots who will operate the AFR equipment, and to a lesser 

degree, the technicians who will maintain it. Pilot training on new avionics systems is typically done with 

computer-based technologies (CBT) either on company computers at the flight office, or, more commonly 

today, comp any-owned tablet devices like the iPadTM. Today's computer-based training is usually 

interactive, enabling testing for system knowledge, comprehension and correct procedural actions at the 

time the pilot is engaged in the training. This has proven to be much more effective training than a flight 

manual bulletin only, or a bulletin accompanied by a short multiple choice quiz. A minority of those 

interviewed felt that the FAA might require some AFR training to be performed in a full flight simulator. 

If this were the case, training costs would be much higher. Even though many companies pay their pilots 

for time spent on required Computer Based Training (CBT) training, the fact that they don't have to travel 

to the simulator base and involve simulator instructors and technicians results in tremendous savings. One 

other training and checking tactic - the line check - might also be employed. In this, the pilot new to AFR 

would be paired on a flight with a pilot who has experience with the system. The experienced pilot might 

be a Line Check Airman, which complicates the crew scheduling, or any other pilot who has used the 

equipment before. The operational approval from FAA will specify the specific training techniques that 

may be used. 

Operations and Maintenance 

Actual AFR operations don't have any specific additional costs associated with them. There are two 

things that may be used to get the most in benefits from these operations, however, and these are the flight 

planning system and the pilot reporting and feedback system. AFR flights would be exempt from many 

delay-causing restrictions, preferred routes, and traffic flow management initiatives. Many of these 

constraints are built in to the flight planning software so that flight plans have a high likelihood of being 

accepted by the ANSP. For AFR flights to achieve their operating benefits, they must be planned to use 

optimum wind routes, speeds, and altitudes, disregarding the structure required for IFR flight until they 

are re-integrated with these flights near the destination runway. Some flight planning systems may have to 

be modified to disregard these IFR structures, which bears a cost. Many operators subscribe to flight 

planning services and contracts may have to be modified or re-negotiated to ensure the plans delivered 

permit AFR flights to maximize their flexibility benefits. In a similar fashion, the Collaborative Decision 

Making (CDM) used during flow programs must recognize the special status of AFR with respect to these 

delays. 

During the start-up of AFR operations, it will be important to hear from the pilots how the system is 

working and if there are any procedural or equipment problems that need to be addressed. An information 

feedback system is thus important to the AFR implementation. It was determined that many companies, 

especially the airlines, already have such information feedback mechanisms in place that are well suited 

to fulfilling this task for AFR. There are others that don't have such a system, however, and there would 

be administrative costs associated with establishing and using such a system. 

Maintenance of the avionics equipment that is added to perform AFR was found to be minimal and 

would probably be lumped in with the maintenance of the parent "black box" such as the surveillance unit 

that will be common on many aircraft. Another finding regarding maintenance is that service agreements 

are often negotiated with the avionics manufacturer at the time of equipment purchase. These agreements 

provide for lifetime maintenance of the equipment. If a unit fails or has a problem, it is simply swapped 

out with an exchange unit and no money changes hands. 
16 

7. Development of Cost Estimate Model 

The purpose of this section is to present what has been learned during this study about the costs of 

implementing the capability to participate in AFR, in a manner that is truly useful to anyone in the 

selected user categories. To accomplish this, a list relating the items of identified avionics architecture 

supporting AFR and their projected costs, based on information obtained during the information gathering 

process, is presented first. Then, an example operation and an example aircraft is chosen in each airspace 

user category that is fictitious, but representative of the class. The baseline avionics for each example 

aircraft is assumed to be all the equipment expected to be installed and operational post 2020 so that the 

additions to use AFR represent the upgrade costs. Then, for each representative aircraft, the additional 

equipment and estimated costs for each item that might not already be present is given, so that any 

potential user can create a list that pertains to him/her, and arrive at a total cost estimate for their own 

aircraft/operation. The cost estimates shown represent the best forecast the authors could make in 2013 

dollars on the basis of information obtained during the interviews and their own airline and GA years of 

operating and planning experience. Except for current product offerings in Table 1 and other kinds of 

implementation costs, no real data on the cost of an ATU and its peripherals exists yet, so these are by 

their very nature, projected costs, but they do represent very educated guesses. 

Table 1 General Aviation ADS-B avionics offerings with capabilities and prices (2013) 

Manufacturer Product Features Current List Price 

Garmin GDL 88 ADS-B IN and OUT, 1090 and UAT $3,995 

 GDL 39 ADS-B IN $875 

Avidyne AXP340 ES ADS-B OUT (DO 260B) $5,995 

 TAS 600 A ADS-B IN, XPDR TAS $8,490 

 VeriTAS 605A, 615A, 620A ADS-B ADS-R XPDR active 

passive 

$10,990 to 

$20,990 

Aspen ARX 100 ADS-B IN $1695 

 ATX 200 ADS-B IN and OUT $3995 

 ATX 200G ADS-B IN and OUT plus GPS rcvr $4995 

Dynon SV-ADSB-470 ADS-B IN UAT only $995 

FreeFlight 

Systems 

FDL 978-TX ADS-B OUT ES $1,995 

 FDL 978-RX ADS-B IN $1,200 

 FDL-978-XVR ADS-B IN and OUT $3,495 

The following subsections present a cost buildup per user class, followed by an example calculation 

given for a "typical" installation to illustrate the use of the template. 
17 

7.1. Airline Cost Estimation Example 

Example Airline: 

500 aircraft, domestic and international 

150 B-737s of all types 

60 B-737-900 selected to receive AFR first 

AFR-Enabling Equipment Projected Unit Cost 

AFR upgrade to surveillance unit $40,000 to $120,000 

New surveillance unit with AFR $80,000 to $200,000 

Display software for CDTI features on Nav display $20,000 to $100,000 

UAT/1090 antenna upgrade $3000 to $30,000 

AFR software load for MCDU $0 to $20,000 

VHF Data radios $10,000 to $30,000 

Equipment already installed in Example fleet of B737-900 

Dual FMS with intent bus 

CDTI on large format Navigation Display (PTM, FIM and TASAR applications) 

MCP with active modes on bus 

Dual 1090 antennas 

Dual VHF Data Radio 

Dual MCDU 

Simple TCAS/ Transponder surveillance unit 

Needed equipment for the example aircraft Cost 

AFR upgrade to TCAS/Transponder Surveillance Unit $60,000 

Second AFR/ Surveillance unit /without TCAS $140,000 

UAT/1090 antenna upgrade $10,000 

AFR software pages for MCDU $20,000 

Total equipment cost per aircraft $230,000 

 

As is common industry practice, the example airline performs its own installations during regular 

maintenance visits, so it is assumed in this example that there is no additional unproductive downtime for 

the AFR installation. The second surveillance unit fits as a new "card" in the same box and does not 

require additional wiring. The example airline also develops its CBT programs in-house. They have a 

pilot reporting and feedback program in place. 

Installation cost per unit Cost per Airplane 

100 man hours @ $50/hr $5,000 

Unit Training Cost Cost per Airplane 

5 pilots per airplane 

2 hours per pilot @ $120/hr $1200 

Course development cost (non recurring) Amortized cost per airplane (60 total) 

160 man hours @ $75/hr = $12,000 $200 

Example implementation cost per aircraft for B737-900 $236,400 
18 

7.2. Fractional Operator Cost Estimation Example 

Baseline Fractional Company 

150 aircraft, domestic and International 

40 Embraer Phenoms selected to receive AFR first 

AFR-Enabling Equipment Projected Unit Cost 

FMS with intent bus or Navigation system with intent bus $20,000 to $60,000 

Display software for AFR CDTI features on Navigation 

Display $8000 to $20,000 

TAS Transponder unit with AFR capability $20,000 to $80,000 

UAT/1090 antenna upgrade $1000 to $3000 

AFR software pages for pilot I/O device $5000 to $20,000 

Broadband internet connection $20,000 to $40,000 

Equipment already installed in the example Embraer fleet 

FMS and second navigation system, each with intent bus 

CDTI with ADS-B traffic for awareness and TAS on ND 

MCP with flight mode status output to ATU 

Simple TAS/Transponder Air Traffic Control Radar Beacon System (ATCRBS) 1090 ES / 978 receivers for 

ADS-B IN and TIS-B 

UAT/1090 antenna upgrade 

Broadband internet connection 

Needed equipment for the example aircraft Cost 

AFR upgrade for existing TAS/Transponder unit $15,000 

Second Surveillance unit without TAS feature $40,000 

Display software for AFR CDTI features on ND $15,000 

AFR software pages for pilot I/O device $10,000 

Total equipment cost per aircraft $80,000 

The example fractional company has a contractual arrangement with an avionics shop for installation 

and maintenance on all its aircraft. The AFR installations will be done during maintenance downtime and 

no additional out of service time is required for the installation. In this example, the second surveillance 

unit does require additional wiring, and the installation cost is higher. The company also develops its own 

CBT programs for pilot training to be accomplished on their pilot-owned iPads, on their own time. The 

example company has a pilot feedback program to the flight office using their cell phones. 

Installation cost per unit Cost per airplane 

240 man hours @ $50/hr. $12,000 

Unit Training Cost 

Pilots are to accomplish training on their own time $0 

Course development cost (non recurring) 

150 man hours @ $75/hr amortized over 40 aircraft $281 

Example implementation cost per aircraft for Phenom $92,281 
19 

7.3. General Aviation Owner/Pilot Cost Estimation Example 

Baseline is a business owner/operator with one airplane that (s)he flies both for business and personal 

transportation, a Piper Meridian. 

AFR-Enabling Equipment Projected Unit Cost 

Dual GPS navigation system capable of displaying 

traffic information and symbology to support AFR $14,000 

TAS/ Surveillance unit with UAT IN and OUT, 1090 IN., 

Host ATU tactical software $8000 

Second surveillance unit without TAS function $4500 

Controls and status information integral with panel 

mounted surveillance unit $0 

1090/UAT antenna upgrade $500 

Equipment already installed in Piper Meridian 

Dual GPS Navigation System with flat panel displays capable of supporting traffic. 

TAS/Surveillance unit with UAT ADS-B OUT and both 1090 and UAT ADS-B IN, TIS-B 

Dual frequency 1090/UAT antenna 

Needed equipment for the example aircraft Cost 

AFR upgrade for the TAS/Surveillance unit $5,000 

Second surveillance unit supporting AFR $8,000 

Second UAT/1090 antenna $500 

Total equipment cost per aircraft $13,500 

The owner pilot has his installations and avionics maintenance performed at a shop at the local FBO. 

The purchase price includes installation (as is common) except for the second antenna. He accomplishes 

his AFR training on-line using a course provided by the avionics manufacturer - free of charge when you 

purchase an AFR surveillance unit. No feedback is required to a company. Problems with the system 

would be reported to the avionics shop or the manufacturer. Operational problems would be reported to 

the FAA General Aviation District Office or the NASA Aviation Safety Reporting System program. 

Installation Cost for second antenna $1,500 

Example implementation cost for the Meridian $15,000 
20 

7.4. UAS Cost Estimation Example 

Example vehicle is a Predator drone equipped for a civilian surveillance and monitoring role, 

operated by the US Environmental Protection Agency. 

AFR Enabling Equipment Projected Unit Cost 

Dual GPS Navigation System $14,000 

TCAS/Surveillance unit containing tactical AFR function $8000 

Interfaces with flight control system and communications unit $2500 

UAT/1090 antenna upgrade $500 

Equipment already installed in example UAS 

Dual GPS Navigation system 

Detect-and-avoid (DAA) system including TCAS, ADS-B IN and OUT and ATCRBS 

Interfaces from DAA to flight control system, ATSU and remote operator 

Dual frequency antennas 

Needed Equipment for the Example Aircraft Cost 

DAA system upgrade to include tactical AFR function $5,000 

Second surveillance system with tactical AFR function 

but without TCAS or non-cooperative surveillance $8,000 

The government is purchasing the UAS new with the needed equipment installed by the 

manufacturer. Remote pilot familiarization with the AFR function is integral with the initial training for 

its entire operation. 

Example marginal AFR cost for Predator $13,000 

The current operator of most large UAS is the US military. As a very significant user of the US 

airspace and provider of air traffic services, representatives of the military should be familiarized with the 

AFR concept and discuss its potential for their US domestic operations of both manned and unmanned 

aircraft. 
21 

8. Description of Benefit Mechanisms 

This report does not contain a comprehensive, quantitative assessment of the AFR benefits available 

to the identified airspace users. That activity is reserved to a future study. This section describes the 

benefit mechanisms that would be available to each of the users, emphasizing those that are most 

important to each user category. The benefits may be grouped into the following three broad areas: 

1. Exemption from certain traffic flow management initiatives and procedures 

2. Exemption from constraints in the IFR airspace structure 

3. Improved access to airspace and freedom of operation within the airspace 

The traffic flow management initiatives from which AFR flights would be exempt include airspace 

(red sectors and defined congestion areas) ground delay programs, miles-in-trail restrictions on departure 

and en route, and en route severe weather re-routes. The constraints associated with the IFR airspace 

structure include departure fix restrictions, overhead slot restrictions, terminal area departure procedures, 

and ATC preferred routes. The final benefit category includes the ability to depart at will, without 

waiting for a clearance to be coordinated with the Center, and to operate along ad hoc trajectories, not 

declared in advance. 

8.1. Airline Benefit Mechanisms 

The airlines would derive the majority of their AFR benefits from mechanisms one and two. The IFR 

system has been designed around the needs of the scheduled air carriers so their access to airspace and 

most commonly used routings is accommodated. Improvements to ATC procedures are geared to 

obtaining greater efficiency for point to point transportation flights. The adoption of RNP terminal arrival 

procedures is an example of this kind of improvement. But the greatest causes of delay and inefficiency 

for the air carriers are the flow constraints and structural rigidity of flight paths established to maintain a 

manageable workload for human controllers, and thus ensure the safety of IFR operations. 

When multiple flights are routed over the same departure fix, often from multiple airports in the same 

metropolitan area, the needed distance between flights at the fix causes takeoff delays to be issued to each 

of the flights. AFR flights would not be subject to this delay and could depart from an intersection or 

another runway to avoid the queue. At many airports, flights are delayed at takeoff to wait for a slot in 

the overhead stream of traffic on the filed airway. AFR flights would be exempt from these delays. 

As air traffic has increased through the years, individual en route sectors in the airspace become 

"overloaded," in that the number of aircraft in the sector is projected to exceed that which can be safely 

handled by a human controller. An automation tool has been employed to predict when these overloads 

will occur and impose ground delays for takeoff on those aircraft whose flight plans traverse the impacted 

sector. As the overload is a human limitation rather than a lack of airspace, the AFR flights would be 

exempt from these delay programs. 

In the en-route airspace, it is common practice to require a minimum miles-in-trail spacing, regardless 

of altitude, between aircraft crossing the center boundary. This may be 20, 30, or even 40 miles at times 

if two flows of traffic are to be merged in the next sector. The effect of this practice is to prevent normal 

passing from taking place between aircraft with different cruising speeds. There is not room in one 

Center's airspace to catch up, pass, and get 20 to 40 miles ahead before crossing the next Center 

boundary, so the flights are slowed and vectored to maintain spacing in the flow behind the slowest 

aircraft in line. AFR flights would be exempt from this as they are not under IFR control en route and 

merge with the IFR flights in the destination terminal area using RTA, where available, or a separate 
22 

arrival fix elsewhere. It should be noted that AFR flights are sequenced equitably with IFRs in a 

destination airport delay program, but would be free to meet the arrival time on their own rather than 

through an imposed takeoff time upstream, thus can fly more optimal routes and altitudes. 

In the continental US, "convective activity" (thunderstorms) exists somewhere during at least nine 

months of the year. It is a common practice for the FAA Command Center to create mass re-routes for 

flights that would traverse an area of forecast convective activity to prevent flight diversions around cells 

that increase controller workload. The re-routes can add hundreds of miles to a route of flight, and 

sometimes the weather either doesn't materialize, or shows up at a different location or time. AFR flights 

would be exempt from these re-routes and free to fly around the actual weather encountered in real-time 

using airborne and ground-based radar and "now-cast" products, and dispatch services, when available. 

ATC preferred routes abound, especially east of the Mississippi, between all major city pairs. Those 

routes are established to force traffic into major flow patterns that assist human controllers in managing 

the traffic. Preferred routes commonly add 10-20 and often up to 50% increases in route mileage over the 

great circle route between the cities. In addition, there are standard terminal departure routes that add 

additional miles. Those in the larger metropolitan areas are quite circuitous, adding significant mileage to 

the flight, and they also contain altitude constraints that prevent the ability to use an efficient 

(uninterrupted) climb profile. AFR flights are free to find and fly a "wind-optimized" route to destination, 

again, merging with the IFR flow in the destination terminal area. 

8.2. Fractional Operator Benefit Mechanisms 

The majority of the flights flown by the fractional operators experience the same sorts of delays and 

inefficiencies as the airlines, with an increased bias away from benefit number 1 toward benefit number 2. 

This bias stems from the greater use of the non-hub airports by the fractionals, while still frequenting the 

largest population centers in the country. Fractionals are particularly hard hit by IFR airspace structural 

constraints because terminal airspace structures favor the major airport and frequently add additional 

penalty for those using the satellite airports. But the fractionals take a double hit from structural 

inefficiency since many of their operations are range-limited and the route penalties can force a fuel stop 

en route when the same trip could be flown nonstop using AFR without the route penalty. 

8.3. General Aviation Benefit Mechanisms 

The benefits of AFR for the majority of GA flights come from mechanisms 2 and 3. GA flights have 

the same route mile penalties as the fractionals when operating from satellite airports in the major 

terminal areas. They also have an even bigger problem when trying to fly IFR from airports not in the 

major metropolitan areas - a problem of gaining access to the airspace. At most of these airports, an IFR 

clearance cannot be received on the ground by radio because there is no radio coverage to the ground. 

Procedures call for obtaining an IFR clearance from these airports over the telephone from a Flight 

Service Station. The coordination between the Flight Service Station and the Center takes time, of 

course, and the Center may be busy with other traffic and place this clearance on a low priority. Once the 

clearance is finally received, it comes with a void time. "Clearance void if not airborne by...". After the 

delay in getting the clearance, there is often a rush to get airborne before the void time, which is a 

situation that does not enhance the safety of the operation. Once in the air on the IFR clearance, the same 

issues of inefficiency described for the fractional operators hold equally true for GA operators. 

There is a high percentage of GA operations that are not point to point transportation. Among them, 

flight training, sport and recreational flying and a myriad of "surveillance missions" of sorts like real 
23 

estate, power line and pipeline patrol, and other surveys of all kinds. These flights do not go from A to B, 

but return instead to A. Furthermore, they cannot specify the trajectory to be flown because it is not 

known in advance, and it depends on what is encountered or occurs after takeoff. Most helicopter flights 

face similar IFR delays. VFR makes these flights possible today but when any portion of such a flight 

might encounter Instrument Meteorological Conditions (IMC) today, the flight must be scrubbed. With 

the AFR option available, these flights could continue to operate and provide their benefits with much 

greater reliability. 

8.4. UAS Benefit Mechanisms 

In a similar fashion, many of the proposed UAS civil operations depend on access to the airspace, not 

from the major airports, but from secondary or even private facilities for launch and recovery. UAS 

operations will benefit from mechanisms 2 and 3 with an emphasis on 3. The large, unmanned vehicles 

have the capability to fly using IFR, if necessary, to accomplish their missions. But the IFR constraints 

are cumbersome, time consuming, wasteful of fuel, and worse for the environment. The ability to perform 

these missions using AFR would provide very substantial savings, and in many cases, make the mission 

possible at all. 

Civil use of UAS is very small right now, but in the time frame that AFR could be approved, there are 

solid proposals for a large number of operations that would truly be additional flights in the airspace, not 

just existing (manned) flights shifting from IFR to AFR. The scalability of AFR supports this projected 

increase in flights that may occur with regular use of UAS in the NAS. In this sense, AFR not only eases 

access to the NAS, it actually enables access to the NAS when it might otherwise have been denied. 

Obtaining access to the airspace is essential, of course, but just as important is the ability to conduct 

the mission once airborne. The myriad of GA operations that are not point to point transportation is 

eclipsed by those planned for UAS. From law enforcement to survey to surveillance, fire and disaster 

relief, communications, environmental monitoring, even tethered power generation - the list is as long as 

the imaginations of the futurists. The need to operate through periods and locations of IMC during these 

missions is paramount and AFR provides the practical means for achieving this. AFR, therefore, is not 

just a financial benefit for these operations, it is truly an enabler of them. 
24 

9. Considerations for Implementation Strategies 

All airspace user classes face a period between first installation and regular, complete use of AFR in 

their entire fleet. It is important to create a strategy to minimize the costs during implementation while 

maximizing the operating benefits. Although our proposed implementation is after the effective date of 

the ADS-B OUT rule, there may be some operators who had not planned on flying in ADS-B airspace 

who will choose to do AFR and thus will have to implement ADS-B OUT to participate in AFR. 

To enable AFR, FAA certification, operational approval, and flight procedures will need to be 

approved and in place. This will ensure that the mechanisms for individual operational approvals will be 

in place for applicants to meet the operational, equipment, and training standards. The flight procedures 

need to include transition to AFR (“after take-off cleared to proceed under AFR”) and integrating the 

aircraft into the IFR arrival flow at high density airports. For arrivals, the current concept is that the AFR 

aircraft will be given an arrival fix and a required time of arrival (if needed) to that fix. When the aircraft 

is flying “direct to” that fix and conflict free (about 10 minutes prior) the pilot will call ATC and ask for 

an IFR clearance (possibly a FIM clearance). It is assumed that lower traffic density will permit the 

assigned arrival fix to be closer to the airport. Procedures for equipment failure will also need to be 

approved. In the vast majority of cases, the aircraft will be conflict free at the time an equipment failure 

occurs, thus there will be time for the aircraft to call ATC and request an IFR clearance (the aircraft 

intended route of flight will already be available to the controller). 

The equipment to be purchased for AFR will comply with AFR MOPS created in the RTCA, and for 

airlines, the boxes will have to meet a TSO. The installation of even TSO'd equipment has to be done 

according to an approved Supplemental Type Certificate (STC). The pilot training requirements will vary 

by operator type but at a minimum there will likely be a new FAR Part 61 set of rules regarding 

acceptable training and checking for AFR operations. Airlines will have their AFR training program 

approved by their Principal Operations Inspector (POI). All of these things must be in place before the 

transition begins. When it is possible to buy approved equipment for AFR, train pilots to use it and 

operate it using established AFR rules in the national airspace, then it is time to purchase and install the 

equipment, train the pilots to use it and begin flying AFR. The implementation strategy is a transition plan 

from being totally unequipped to participate to a final state of being completely capable of using AFR in 

all operations. At each stage of the transition, the strategy should ensure maximum payback from the 

investments made (benefits minus costs). Until the first aircraft is equipped and the first crew trained, 

there will only be costs, of course, but the strategy is to turn this equation positive in the shortest time and 

continue to grow it during the transition. What follows are the more detailed implementation strategy 

considerations by airspace user class. 
25 

9.1. Airline Strategy Considerations 

The strategy for airline implementation of AFR includes these cost considerations: 

 1. Fleet and sub-fleet size 

 2. Existing avionics 

 3. Purchase price 

 Delivery rate, maintenance agreement, favored customer status 

 4. Installation opportunities 

 Installation vendor 

 5. Training program and schedule 

 6. Flight Planning systems 

 7. Operational feedback 

The benefit considerations during implementation are: 

 1. Aircraft routing 

 2. Flight planning 

 3. CDM treatment 

An airline fleet is defined by the aircraft type, e.g., B-757. Each fleet may be divided into sub-fleets 

for many reasons, usually having to do with installed equipment, operating regions (domestic, overwater), 

or pilot qualification. For AFR, these are all important distinctions. The sub-fleet that has the most 

required avionics already installed will have the smallest equipment acquisition cost. As this is the largest 

cost item, it should be used in appraising the starting choice. Next, look at where the fleet spends most of 

its flying time, as AFR will initially only be available in the US domestic airspace. The first fleet to 

receive equipment and training should operate domestically and make a preponderance of its departures 

from major airport terminals where IFR delays and constraints are high. A secondary consideration 

would be fleets that fly city pairs which currently experience the greatest distance penalty over the great 

circle distance. 

The equipment cost per unit in any given sub-fleet is nearly always subject to negotiation. Things that 

affect this cost are number of units purchased, the delivery schedule, other revenue connected to the 

purchase such as additional, unrelated avionics equipment, maintenance agreements for the equipment 

and perhaps, a favored vendor status that exists prior to the purchase. As long as there is competition in 

the equipment supplier marketplace, the costs will be in line with other avionics of similar complexity and 

certification criticality. An exception to this may be the aircraft that have all their electronic functions 

bundled into a single proprietary "cabinet". This represents more of a monopoly supplier situation that can 

impact equipment cost significantly since the price may be set according to the expected benefits to be 

enjoyed by the user rather than production costs plus margin. This has become a common practice in the 

industry during the last few decades. For an AFR system, the cost impact could be significant because of 

the high benefits available from its use. 

It is common practice among the airlines to install systems while the airplane is "down" for routine 

scheduled maintenance visits. This prevents adding "out of service" revenue loss to the cost of 

installation. The maintenance visits in question are normally "heavy maintenance" when much of the 

airplane's interior is already being removed, creating access for necessary wiring changes. These visits 

usually occur about once in five years, however, so it could take a very long time to equip a sub-fleet for 

which the pilots have all been trained but only get a few opportunities to fly the airplanes that have been 

modified. Thus it is important to find the shortest fleet wide installation time and pair it with more routine 

maintenance visits in order not to stretch out the transition too long, thus delaying the accumulation of 

benefits. Sometimes this favors doing the installation in-house as the opportunities are more frequent. On 

a large fleet, however, the savings in installation cost by outsourcing might outweigh the benefit of a 
26 

more rapid conversion. In addition, with all crews trained, each aircraft will receive the full benefit as 

soon as the aircraft is converted thus enticing airlines to expedite the equipage. This will also accelerate 

the benefits from other ADS-B IN applications that require a high percentage of equipped aircraft. 

 Any fleet that shares a common pilot type rating with another fleet has a larger number of pilots 

assigned to fly it. As the number of pilots that might fly the airplanes is increased, the total training costs 

go up. This is a cost consideration that will go into the payback equation but will probably not determine 

which sub-fleet to equip first by itself. Development of the training program will be about the same for 

each fleet regardless of fleet size, so amortization of that cost favors starting with the largest fleet. 

However, the training development cost is usually small compared to the pilot pay for training, so it is a 

minor consideration. Once the installations begin on any sub-fleet, the pilot training to use the equipment 

for benefit should proceed immediately so that every equipped airplane will have a trained crew on board 

to use it for benefit. As long as the training can be accomplished by CBT, it can proceed simultaneously 

among all the effected pilots. All can be trained within a matter of weeks. 

The flight planning system used for the chosen initial AFR fleet should be modified as necessary to 

disregard ATC preferred routes and procedural constraints when calculating a wind-optimized flight plan. 

This modification should be timed for completion prior to the first AFR-equipped aircraft entering service 

as the cost will be the same whenever it is done, but it must be accomplished to receive maximum AFR 

benefits on the first flight. CDM is a term applied to the airlines collaboration with the FAA Command 

Center during the use of TFM initiatives. These initiatives occur daily in at least some part of the 

country, so the airlines have created sophisticated automation tools to assist in the handling of their IFR 

flights to limit the delay impact of TFM initiatives as much as possible. The ground delay programs 

associated with adverse weather at a destination airport causing a reduced acceptance rate will include 

both IFR and AFR flights, but the AFRs will be exempt from the other local and enroute initiatives, and 

the airlines CDM tools should be able to automatically exempt them from participation, from the time of 

the first AFR flight onward. 

The feedback system to let pilots inform management about the AFR experience and any part of the 

system or procedures that need attention should likewise be in place at the time of the first AFR flight. 

Any reported AFR incident should be immediately flagged for analysis and lead to remedial action, if 

necessary. Flight planning and CDM modifications and information feedback systems represent one-time 

costs, non-recurring, but essential to obtaining the maximum benefits from AFR. These fixed start-up 

costs argue for making the initial AFR sub-fleet relatively large to begin re-cooping these costs as soon as 

possible. 

9.2. Fractional Operator Strategy Considerations 

The primary differences between airlines and fractional operators are: The size of the aircraft is 

smaller; the operations are not regular nor scheduled far in advance; the costs of avionics are a much 

higher proportion of the total value of the aircraft; the operating regulations (Part 135 vs. 121) are less 

stringent; the use of major hub airports is less. The ways in which they are the same include: fairly large 

fleet size; point to point transportation; use of professional pilots with contractual flight rules and pay; 

centralized dispatch organizations and flight planning systems. Thus much of what was said above for 

the airlines holds true of the fractional operators as well. 

Most of the fractional companies operate more than one fleet type. The most recently purchased 

aircraft will likely have the most modern avionics and could integrate the AFR additions with the least 

cost. Fractionals are caught between the airlines and General Aviation in terms of avionics requirements 

and costs. They want to have (and be able to advertise) the reliability and safety of airline equipment but 

the cost of getting an AFR equipment STC for some of these small fleets of aircraft can be prohibitive. 
27 

The greater the number of aircraft types, the worse this problem becomes. Large avionics manufacturers 

will be more likely to obtain STCs for their equipment installations in the large airline fleets than for 20 

or so "business jet" sized aircraft. The offerings from Garmin, Bendix/King, and Avidyne could make a 

lot more sense for AFR retrofit in the fractionals' market. 

AFR benefits for the fractionals are often related to exemption from the IFR routings and procedures 

in place for a major hub airport, that must be flown even when the flight is operating to or from another 

airport in the same terminal area. These terminal procedures and other parts of the ATC preferred routing 

structure can spell the difference between a non-stop flight and having to make a fuel stop. Accordingly, 

other things being equal, the most range-limited fleet should be considered as the first to be equipped for 

AFR. 

Installation costs will again be the second highest category for the fractionals and timing the 

installation to occur with maintenance visits is common in these companies as well. The correct strategy 

would be to equip the fleet first that requires the least in upgrades for lower purchase and installation 

costs so that those aircraft can be producing operating savings while the balance of the fleet gets 

equipped. The issue of in-house installation versus outsourcing should be decided by the existing 

capability to perform this work. If such exists, that is likely the best option. If not, it may make the most 

sense to look for a purchase agreement that includes the installation at a reputable (and capable) avionics 

mod shop. Like the airlines, the fractionals can negotiate deals that may combine equipment purchase 

and installation and perhaps even continuing maintenance under one contract. 

Also like the airlines, pilot training for those pilots in the chosen first fleet should be accomplished by 

the time the first airplane is equipped for AFR. CBT should be used if such a program will be approved 

by the FAA. The company's local FAA oversight office should be included in the installation and 

training planning from the start so that the rationale behind all decisions is understood going in. This will 

help prevent costly mistakes and time consuming delay in achieving the operating benefits of AFR. 

The flight planning systems used by the fractionals are frequently outside services available under 

contract. The implementation strategy for fractionals must include consultation with their flight planning 

service providers to determine whether they are capable of producing a wind-optimized plan for AFR 

flights, free of the IFR preferred ATC structure. If not, it may require looking for an alternative service 

provider to obtain the full AFR benefits. In the event that collaboration with the FAA on flow 

management initiatives is not handled centrally, the pilot training must include information on what types 

of restrictions exempt AFR flights and how to plan and interact with ATC accordingly. 

Fractionals also may not have a formalized pilot feedback mechanism in place. While this is not 

anticipated to be a regulatory requirement, some form of messaging in an easy to use format should be 

established, whether by email, SMS messaging or phone call with an established addressee and an 

internal process for handling the information received. 

9.3. General Aviation Strategy Considerations 

Because of the extreme diversity of GA operations, the strategy to implement AFR will vary widely 

by the type of operator and the mission. The biggest disparities are between very large and very small 

aircraft, and multiple fleet business aviation departments vs. owner/pilot transportation in one airplane for 

business and pleasure. The strategy for major aviation departments is similar to that of the fractionals, but 

the larger number of small owner/pilot aircraft will have a strategy of their own, that is given here. 

There are many General Aviation pilots that only fly VFR. While this helps the efficiency and 

flexibility of their flights, the "see and avoid" practice offers less than perfect mid-air collision safety. 

Many GA pilots have purchased TAS including ADS-B surveillance along with active interrogation on 
28 

the transponder frequency to lower the risk. For many of them, AFR offers additional safety advantages 

and they will want to consider that equipment to get the extra protection. 

All the major manufacturers of general aviation ADS-B equipment already have ADS-B IN offerings 

for traffic awareness and FIS-B weather products. By 2020 when the ADS-B OUT mandate takes effect, 

these manufacturers expect to include an AFR software upgrade with these offerings, assuming the FAA 

has approved the system standards and created operational rules for its use. Thus the acquisition strategy 

for a GA owner /pilot is simply to survey the offerings and decide if the upgrade is worth the price for the 

operations they either do, or would desire to conduct. It is probable that there will be an upgrade for any 

of the major GA avionics packages that even now contain ADS-B IN applications, and the owner will 

look to the supplier of his currently installed avionics for the upgrade. 

Many GA operations take a huge penalty when conducting a flight under IFR compared to making 

the same flight under VFR. Departing a non-towered airport without radio contact availability on the 

ground can be very frustrating and time consuming doing it over the phone. By contrast, departing AFR 

in IMC in Class G airspace, with an automatic log-on to an ADS-B ground station once airborne, has no 

delay at all. The ability to proceed direct to destination after take-off rather than "fly east to go west" as is 

often required on an IFR departure can also save very significant time and fuel. So the GA strategy 

consists primarily of understanding and evaluating the benefits of AFR in their particular operation and 

comparing that to the cost of an AFR upgrade. It is expected that the training for certification will be 

offered on-line by several of the flight training and re-certification schools that currently provide this for 

other ratings and certificate renewal. The big question is whether the FAA will require any demonstrated 

performance in either a simulator or an aircraft if the pilot being trained is already instrument rated, 

because getting an instruction from the cockpit system that is identical to that given by a controller should 

not require any simulator or airplane demonstrations. A computer-based test to confirm the pilot knows 

the rules and how to operate the equipment should suffice. 

9.4. UAS Strategy Considerations 

UAS operations in the NAS today are very limited because of the restrictions on access and the 

onerous requirements for operational approval. AFR could dramatically alter the access picture and make 

feasible a smorgasbord of UAS domestic missions in civil operations as well as greatly ease the ability of 

the military to operate their UAS in the NAS. For the military, it not only would ease the flights to and 

from military operating areas but could help to reduce the need to restrict the airspace for military 

operations only, thus benefiting all civil users. 

The UAS AFR cost categories are fewer than for manned operations because of the absence of a pilot 

in the cockpit and the expected direct link between the ATU output and the UAS flight control systems. 

The costs are: 

Equipment Acquisition 

Equipment Installation 

Remote pilot familiarization 

Routine maintenance 

AFR avionics for the UAS are considerably simpler than for crewed aircraft because there is no need 

for flight crew interactions and display. It was assumed in the architecture description in Section 4 that 

UAS would only use the tactical separation mode, so the surveillance and the output are simplified to the 

deterministic algorithms. It thus becomes just an upgrade to the DAA system currently under 

development. The upgrade will include an outer layer of standard IFR separation to the collision 
29 

avoidance function already included. Communication of the near term trajectory to both the remote pilot 

and the ANSP will use existing channels and contain the ATU output to show how separation will be 

maintained. An additional benefit for UAS is that operations now conducted only in Visual 

Meteorological Conditions (VMC), to enable the vehicle to remain within the sight of an observer, would 

not need to be concerned with the VMC requirement. Flights could go in and out of clouds under AFR 

with no diminution of safety and eliminate the requirement for an observer while still avoiding the 

restrictions of IFR. 

There are so few UAS operations outside of restricted airspace today that it is unlikely there will need 

to be massive retrofits for AFR use. The capability will be specified at the time of purchase so 

installation by the operator would not generally be required. It will largely be a forward fit situation. 

UAS will also benefit from an ability of DAA equipment to detect non-cooperative targets operating 

under VFR (or IFR) in the lower altitudes of the Class E airspace. Filling this surveillance gap is an 

important step forward. 

As the remote pilot (where used) will not actually control the vehicle through the conflict resolution, 

his training will only consist of familiarization with the function in order to be completely aware of what 

is going on. A training bulletin will likely suffice for this need. 

Maintenance of the ATU is not an additional cost for the UAS operator who already has a DAA 

system installed on the vehicle. It will be accomplished with the maintenance of the parent system. Thus 

the implementation strategy for UAS operators is related solely to the vehicle capability going in. If it is 

equipped to operate under IFR, the upgrade to AFR will quickly pay for itself. If it is currently restricted 

to VMC because IFR restrictions won't permit the intended mission, then adding the AFR capability is 

indicated, and the cost of the system must be justified by the improved utility of the mission. Size, 

weight, power and cost considerations must be weighed against the ATU avionics offerings available, but 

when imbedded in the DAA, these are negligible.
30 

10.Other Feedback from Outreach Interviews 

In the course of information gathering for this study of AFR implementation costs, it was necessary to 

describe the AFR concept of operations as they pertained to each of the airspace user class 

representatives. This engendered a discussion of the value of the AFR option and the expected 

difficulties that might be encountered trying to establish the new operating paradigm. 

Interestingly, the value of AFR operations was perceived as very high by all of the user classes. It was 

not seen as something that "might help out the other guy". Rather, it was described in superlative terms. 

"This is the most important thing ever to come out of ADS-B", and, "this doesn't sound that complicated 

to me." 

After agreeing that it would work in mixed operations, there was usually a discussion of the 

integration with IFR flights in the terminal area. Departure was considered uncomplicated, consisting of 

being released to "proceed under AFR" shortly after takeoff. The arrival scenario depended on the degree 

of automation in existence at the terminal in the time frame of AFR introduction (post 2020). An 

automated airport arrival scheduler is assumed by everyone, upgrading the old Traffic Management 

Advisor system to Time-Based Flow Management (TBFM) or something better with greater sequence 

adjustment flexibility. "FIM" (Flight Deck Interval Management) was seen to be totally compatible with 

AFR and it would pick up the guidance function approaching the terminal just as the IFRs would do using 

this capability. Where FIM is not implemented, a separate arrival fix next to each of those existing for 

IFR could be established with AFR performing any needed metering to this fix so that conventional 

human controller techniques could be easily used to merge the arrivals beyond the arrival fixes. 

The discussion of obstacles to be overcome generally placed the cultural shift at the top of the list, 

and potential resistance by the National Air Traffic Controllers Association (NATCA) to mixed 

operations. While NATCA has not yet been briefed in the AFR outreach, it is planned to do so. The 

AFR concept includes a number of features to make mixed operations acceptable to controllers. AFR 

flights will always give right of way to IFR, so that even though they will appear on the controller's 

display, the controller will not be responsible for them nor have to consider them in the normal course of 

controlling his/her IFR traffic. A separation buffer is in the concept, so that even if an IFR maneuvers 

toward an AFR flight, there is time to resolve the conflict without loss of separation. Additionally, the 

intent of the AFR will be known in almost all cases, beyond the velocity vector to at least the first TCP 

(trajectory change point). And, the AFR flights will be monitoring the active frequency of the sector they 

are in so that contact could be made, if the controller so desired. It may also be possible to reduce the 

redundancy of equipment on the aircraft by implementing procedures where an AFR failure on board an 

aircraft would require the crew to contact ATC for an IFR clearance. Since the aircraft will most likely be 

conflict free for at least ten minutes following such a failure, this procedure should not be burdensome for 

the controller or the crew. 

Another frequently raised point is that AFR is not yet in the FAA's NextGen program, even though 

some aspects of self-separation are (FIM, PTM, corridors). This means formal recognition of AFR and 

specific funding must be found for standards development and rulemaking. Gaining operational 

approvals for the airlines and others, once the concept is accepted, was considered to be routine by some, 

difficult by others. In any case, the FAA's early involvement in bringing about the AFR concept was 

considered both essential and problematic, because it wasn't part of the ADS-B IN Aviation Rulemaking 

Committee, and the list of applications coming out of that seems to be the total focus of FAA right now. 

The airlines, in particular, thought the big "airframers" Boeing and Airbus should be included in the 

outreach soon, even though they worried about them taking ownership of the avionics and sending the 

prices sky high. For those aircraft with a high degree of avionics integration during the initial 
31 

manufacture, the addition of the AFR function could be more complex as a re-certification problem 

because of the number of connected systems and the manner in which those systems would be impacted. 

Overall, the feedback was very positive toward AFR, recognizing that it is not just the "ultimate 

ADS-B IN application, but the way all the airspace users ultimately wished to operate in NextGen. 
32 

11. Conclusions and Recommendations 

This study has estimated the user cost of implementing AFR, and findings indicate the cost to be 

comparable to navigation system upgrades for all four airspace user classes and therefore generally within 

reach for most operators. The AFR equipment is very similar to avionics already being purchased, or 

planned for future purchase by most operators. As the primary element of AFR, the ATU is just a 

software upgrade using information from inside the aircraft and from external surveillance that is already 

defined and in increasing use. Neither installation, training nor operations are seen to be major obstacles 

as they will all follow normal and accepted practices, and the safety of the operations is assumed from the 

start as pilots will still be following clearances and instructions just as they always have, emanating from 

a new source. 

Typical costs for each of the four classes of airspace user to implement AFR on a "per aircraft" basis 

were projected to be: 

User Class Average Range 

Airline $236,400 $210,000 to $603,000 

Fractional Operator $92,281 $50,000 to $200,000 

General Aviation $15,000 $10,000 to $50,000 

UAS $13,000 $10,000 to $45,000 

These cost projections include purchase and installation of the necessary avionics equipment, training 

of the pilots to use it in manned aircraft, and operations and maintenance of the equipment on an on-going 

basis including optimizing the flight plans for maximum beneficial use (and payback) of AFR. The 

projected range figures show the difference between expected (hoped for) safety case outcome and a more 

onerous result. They also reflect the difference between a few upgrades to existing equipment and all new 

equipment and new wiring on very old aircraft. 

For owners of large fleets of aircraft, necessitating an extended period for implementing the capability 

throughout the entire fleet, there are strategies which can begin producing operating savings very quickly 

while the investment is still quite low. This result of benefits accruing to the first adopter makes the 

business case for AFR even stronger. 

Recommendations include the following: 

 NASA should conduct a comprehensive and quantitative AFR benefit study to complete the 

necessary information needed in the investment decision equation. It was found in this study that 

the airspace users intuitive feel for the value of the benefits showed them to be very substantial, 

supporting a short payback period. 

 Perform research on failure modes 

 Assist FAA with the AFR safety study 

 Test and refine CD&R algorithms - especially tactical 

 Investigate simpler pilot interfaces with the system and procedures for its use 

 Engage with the UAS research community to integrate DAA with AFR 

 Expand the concept to the runway, both departure and arrival 

A final, but major, recommendation is to engage in a joint development program for AFR with the 

FAA so that work on standards and rules can proceed in parallel with the remaining research. 
33 

12.References 

1

Wing, David, and Cotton, William. Autonomous Flight Rules: A Concept for Self-Separation in U.S. 

Domestic Airspace. NASA/TP-2011-217174; 2011

2

Wing, David, and Cotton, William. For Spacious Skies: Self-Separation with "Autonomous Flight 

Rules" in Domestic Airspace. NASA/AIAA 2011-6865; 2011

3

Wing, David; Prevot, Thomas; Lewis, Timothy; Martin, Lynne; Johnson, Sally; Cabrall, Christopher; 

Commo, Sean; Homola, Jeffrey; Sheth-Chandra, Manasi; Mercer, Joey; and Morey, Susan. Pilot and 

Controller Evaluations of Separation Function Allocation in Air Traffic Management. Tenth 

USA/Europe Air Traffic Management Research and Development Seminar (ATM2013), Chicago, 

Illinois, June 2013.

4

Karr, David, Vivona, Robert, Roscoe, David A., and DePascale, Stephen, Wing, David. Autonomous 

Operations Planner: A Flexible Platform for Research in Flight-Deck Support for Airborne SelfSeparation. NASA/AIAA-2012-5417; 2012 
34 

Appendix A. AFR End to End Flight Scenarios 

A1. Air Carrier Scenario Example 

The year is 2020. Transcon flight 657 is a regularly scheduled flight from Phoenix (PHX) to 

LaGuardia (LGA). It departs PHX at 1050 PDT and on this day in July is scheduled to arrive at 1745 

EDT. The airline's flight planning system has recently been upgraded with optimization logic that can 

ignore structural route preferences except for the RNP Standard Terminal Arrival Route procedures at 

major terminals, such as LGA. The winds at altitude are typically light for the summertime but definitely 

favor flying north of the great circle route today. The flight planning system picks a lateral track that is 

slightly S-shaped and defined by 15 waypoints between PHX and the LGA arrival fix. The vertical path 

includes three 1000 foot step climbs between top of climb and top of descent. The cruise speed varies 

some throughout the flight as fuel is burned but averages about .01 less than standard Mach number 

because of slightly favorable winds. There is possible thunderstorm activity forecast from the Ohio valley 

northward through the Great Lakes but cells are expected to be scattered. Nevertheless, the ATCSCC has 

already begun Severe Weather Avoidance Plan (SWAP) route assignments for most IFR traffic that 

would otherwise fly through this area. The Transcon dispatcher and pilot assigned to this flight agree with 

the computer generated plan and add just 800 pounds for possible detours around cells during the final 

hour before descent into the New York area. The AFR flight plan is transmitted to both the FAA and the 

aircraft as the pilots go to the airplane to make ready for the flight. 

Following a routine cockpit setup which includes verifying the expected route loaded in the FMS, the 

first officer logs in to the ANSP automation with the flight number, origin and destination for 

human/automation verification of the flight plan. The aircraft mode S code, Flight ID and the route of 

flight and initial cruise altitude from the FMS are automatically sent with the log in message to complete 

the verification process. Because the mode S transponder code is used and communications will be via 

CPDLC for this AFR flight, no pre-departure clearance is necessary. As soon as the flight indicates 

"ready" via data link, the route to follow from Terminal 3 to runway 8R is shown on the Electronic Flight 

Bag (EFB) display of the airport surface. When ready to enter taxiway Charlie from the ramp, the aircraft 

to follow is also shown on the display. When nearing the end of the departure runway, the taxi route 

indicates use of the runway intersection at Charlie 2, that is 500 feet from the runway end. This is done to 

bypass other IFR flights with departure fix restrictions, eliminiating a few minutes wait before departure. 

Takeoff clearance is received as soon as the preceding departure is 6500 feet down the runway with a 

restriction to remain separated from that aircraft during departure. The IFR intent information available to 

Flt 657 shows the preceding departure will be turning to a heading of 060 after liftoff climbing to 8000 

feet and proceeding direct to DRYHT when out of 4000. The ATU, knowing the two aircraft types will 

experience a slight overtake directs an initial heading of 045 to our AFR crew which will be used until 

standard lateral or vertical separation is established. This, and all subsequent flight guidance given to the 

AFR crew will also be sent to other AFR aircraft and the ANSP for use in the ground system safety 

monitoring functions. 

As Flt 657 is leaving 4300 feet Mean Sea Level, standard lateral separation is achieved when the 

preceding departure heads direct for DRYHT and the message "Proceed under AFR" is received by our 

crew. This version of the FMS software continuously adjusts the entered route to begin at present position 

on the current track while flying in heading or track mode, so the pilots merely engage FMS lateral 

navigation and are on their way to LGA using the most current optimized trajectory available. The 

airline's flight planning system runs a new trajectory search from present position to destination right after 

liftoff and every subsequent half hour using the latest met information and sends a new plan to the 

airplane if it saves either a minute or 100 pounds of fuel. During the climb, the ATU detects a conflict 

with an IFR flight descending toward PHX and, because the vertical separation buffer is quite large while 

neither aircraft is in level flight, creates a slight adjustment to the right to pass behind this aircraft at a 
35 

distance of four miles, one more than the current ubiquitous three mile separation from IFR aircraft. At 

this point in time, even though the three largest US airlines have announced their intentions to go all 

AFR, only 5% of the fleet is equipped. This results in most conflicts being with IFR aircraft in which the 

AFR is burdened with the resolution responsibility. However, overall traffic has only grown 15% since 

2012 and with the three mile standard, this is the only conflict encountered during the whole flight to the 

LGA arrival fix. The cold front in the eastern half of the country has progressed southeastward more 

quickly than forecast altering the winds used during initial flight planning and two flight plan 

amendments are received by the AFR crew, one resulting in earlier step climbs due to lower temperature 

and the other because of the shifting wind direction resulting in a trajectory closer to a great circle direct 

to the arrival fix. Destination fuel is shown increasing from both changes so they are immediately 

executed by the crew. 

Throughout the flight, vectors and speed control instructions given to IFR flights in order to maintain 

miles in trail at boundary crossings are an amusement to our crew which is exempt from those constraints. 

Just before entering Indiana, the crew picks up the current convective activity from both their airborne 

and ground sensed radar, the latter being sent through their broadband connection. The place to be 

avoided at this point is further south than anticipated and several IFR aircraft are detouring on vectors 

around the south side of the weather even though this was expected to be clear and on their SWAP routes. 

The ATU had also chosen to go this way but based on the existing radar and visual observations of the 

weather, the crew "draws" a new route on the Nav Display just skirting the north side of the weather and 

then going direct to LIZZY on the Milton 4 arrival. The new touch screen display allowed the pilot to 

"grab and pull" the route to a new desired location, eliminating a lot of typing. They then Execute and the 

new plan is sent to other AFR aircraft and the ground. This new trajectory is used by the ground 

automation to define flight 657's Coded Departure Route to LIZZY, even though it is not on one of the 

charted transitions. The sent trajectory also contains an estimated LIZZY crossing, which is used in the 

TBFM automation to merge Flt 657 with the other arrival traffic to LGA. Two of the aircraft that deviated 

south of the weather in Indiana were also going to LGA and are now slightly behind their previous 

estimates so the TBFM has altered the sequence and now needs Flt 657 to cross LIZZY 24 seconds earlier 

than its estimate. This time is entered into the FMS at the fix and a new descent profile is calculated, 

leaving cruise altitude a little later and using a higher speed in descent. Even though several aircraft are 

converging at small angles toward LIZZY, their time separation at the fix keeps them separated 

longitudinally as they lose lateral separation due to the convergence. 

Throughout the flight, the AFR crew had received data link messages updating the voice guard 

frequency for their location and they listened to the IFR communications, but none were required for Flt 

657 and none were made. Nearing the LIZZY arrival fix, the ground-based IM software sends a message 

to Flt 657 containing the aircraft to follow and the desired time interval to use. After confirming this data, 

the crew accepts it, confirming the plan to the ground and allowing the FMS to provide flight guidance to 

the autopilot and flight director to establish and maintain the interval to the runway threshold. LIZZY is 

still 71 miles from LGA and during that arrival, several building cumulus clouds were present on the 

charted path. The crew of Flt 657 was able to clear the airspace and deviate around the bumpy clouds 

while still maintaining the interval on the aircraft ahead with a slightly increased speed, taken care of by 

the autothrottles. Any aircraft following 657 at a prescribed interval simply maintained the time to its 

abeam position on the common route. The more precise inter-arrival interval made possible by FIM 

permits an increase of 7 arrivals per hour from 34 to 41 when using the ILS to 4R. This increase has made 

it possible to eliminate the slot restrictions at LGA during almost the entire day. Flt 657 gets landing 

clearance on the datalink while just outside the DNNIS final approach fix and crosses the threshold 68 

seconds behind the preceding arrival, two seconds early. 
36 

 The taxi route to the gate is already on the EFB surface map and the "hold short" intersections and 

aircraft to follow clearly indicated. As the airplane pulls into the gate and sets the parking brake, the flight 

completion/logoff message is created and sent when the main cabin door is opened. 

A2. Fractional Ownership Operator Scenario Example 

The year is 2021. YourFlight, Inc. is a fractional ownership operator that uses three types of jets 

ranging from the five seat successor to the Eclipse called the Penumbra to an eight seat Citation XX and 

several long range Bombardier 500 Globals. A call has just come in to take a family of three from 

Manchester New Hampshire to Fort Lauderdale Executive Airport in Florida. The Penumbra is the right 

fit for the job except that the IFR preferred route is to fly west to Wilkes-Barre, PA before turning south 

toward Florida. This adds 85 miles to the route and puts the destination just out of non-stop range. 

Fortunately, YourFlight has just installed the equipment and trained their crews to operate AFR in the 

Penumbra primarily because of the range limitation. A late autumn nor’easter is moving up the coast and 

the flight planner shows that a route just off the coast east of the New York metro area saves 35 minutes 

over going around to the west over Pennsylvania, enabling the flight to proceed non-stop. The AFR flight 

plan is loaded into the FMS and filed with the FAA for their reference. 

After the airplane is loaded with the family and their luggage, the cockpit setup is completed 

including the AFR login with the FAA, confirmation of the filed flight plan, and initialization of the ATU 

computer that will manage flight optimization and traffic separation during the flight. Manchester does 

not yet have CPDLC so routine voice communications are used with the tower for taxi and takeoff 

clearance. The only difference is that even though the weather is IMC, the takeoff clearance sounds like 

the flight was VFR. “YourFlight 23, cleared for takeoff on Runway 35, left turn on course, monitor 

departure on 124.9”. No wait is required to get a release from the Center, and no charted departure routing 

to conform to Boston traffic flows is needed. The flight plan keeps our flight initially at 14,000 feet for 

the first hour because it is above the mechanical turbulence and below the higher turbulence caused by 

high altitude wind shear associated with the storm system. It also provides a rare northeast tailwind that 

further speeds our flight toward Florida. 

A conflict is detected by the ATU with a flight westbound to Westchester County airport, and the 

ATU computes a 10 degree left turn to pass clear behind. Crossing Long Island, the ATU indicates that 

climbing is not available because of a flight above descending for landing at Kennedy. Even though we 

had not planned to climb for another 45 minutes anyway, giving way to an occasional IFR flight is more 

cost effective than flying the additional 85 miles under IFR. Several other flights appear on the display 

while flying southwestward off the New Jersey coast, but none result in a conflict. Further south the 

winds aloft gradually shift around to favor the higher altitudes where the true airspeed is also higher. The 

optimization function of the ATU indicates a gradual climb to FL340 is available and will save fuel. A 

cruise climb is begun, and the trajectory is broadcast to other AFR’s and the FAA over the ADS-B and to 

the company via the Broadband link . 

Over the east coast of South Carolina, the customer gets a call from her sister asking if they could 

meet in Boca Raton rather than Fort Lauderdale as they had gotten delayed at Grandma’s house. Quickly 

inquiring of our Captain, she is told, “no problem”. Entering the Boca Raton airport in the FMS results in 

a new trajectory, optimized from the present position. Pushing “Execute” sends the new route to the 

others as before for use in their strategic planning systems. The ATU automatically checks the status of 

the offshore Warning Areas and, as they are hot, keeps the flight west of that airspace. The CPDLC 

routinely provides the voice frequency to monitor as the flight progresses through ATC sectors on the 

way south. No calls from ATC are required, nor made. Just off the Georgia coast, the flight begins to pick 

up light chop. The meteorological data suggested it would be smooth as high as Flight Level (FL) 330 so 
37 

the lower altitude is checked for conflicts and seeing none, FL330 is selected in the FMS and a descent 

begun. 

Since the Boca Raton airport is in Class D airspace, it is not necessary to fly any of the charted arrival 

routes, thus saving additional miles. The Automatic Terminal Information Service (ATIS) indicates 

runway 05 is in use so the FMS connects the descent trajectory to a standard left turn into the final 

approach fix TANAH. This plan is sent to the Terminal Radar Approach Control (TRACON) as soon as 

it is executed. An idle descent from FL 330 begins 91 miles out as computed by the FMS which had 

loaded the current winds for the altitudes to be traversed along the way. Slight differences between the 

forecast winds and those encountered are accommodated by small pitch changes that increase and 

decrease the speed slightly around the target 260 knot descent speed. 

At 35 miles from the airport, a message is received to extend the Final Approach Fix (FAF) out one 

and a half miles on the final approach course to accommodate another arrival that was a little later than 

forecast. Pulling the FAF into the scratchpad, "plus 1.5" is typed in, selected and executed. The execute 

key triggers the return message confirming the new clearance. The 1 degree right turn is almost 

imperceptible as the aircraft adjusts to the new course. The Approach Descent checklist is completed and, 

just prior to the turn to final, landing clearance is received. The desired parking area at Signature Flight 

Support had been sent earlier, prior to descent, so after landing, the taxi route to that location via the ramp 

taxiway appears on the iPad EFB with no interfering traffic showing to yield to. The welcoming party is 

standing at the fence outside the Fixed Base Operation (FBO), cheering our passengers as they leave the 

airplane in the warm sunshine, just three hours, but worlds away from the storm they had left behind in 

New England. The flight took just 3 hours and 11 minutes. More than an hour of flight time, additional 

fuel and lots of hassle and turbulence was avoided by going AFR non-stop vs. IFR with an enroute stop. 

A3. General Aviation Scenario Example 

In 2020 when the ADS-B mandate took effect, AFR flights were allowed for the first time and Clyde 

Snodgrass was planning a business trip in his Piper Meridian, N280KTS. Mr. Snodgrass understood the 

value of AFR to his flying and had purchased the equipment a year earlier to be ready. He had taken and 

passed the FAA's required online training making it legal to fly AFR once the rules were effective. In the 

interim, he routinely operated the system while in VMC and flying under VFR to take advantage of the 

extra safety it provided. 

Mr. Snodgrass is a marketing executive with a major tractor and farm implement manufacturer in 

Rock Island Illinois. However, he lives in his hometown of Altamont, TN on the Piney Creek Airpark 

(88TN) and keeps his airplane in his hanger, which is part of his house. It was Sunday night when Clyde 

checked the weather for his Monday morning flight to the office and found it was forecast to be clear in 

Tennessee but with low surface visibilities due to haze. During the flight to the Quad Cities airport (MLI), 

multiple layers of clouds would be encountered between 4000 and 18,000 feet. MLI was expected to have 

a ceiling of 4,000 and visibility of 5 miles at the proposed arrival time. The forecast wind increased 

rapidly out of the west at altitudes above FL240 so he decided to fly over at FL200, to be above all clouds 

during cruise in smooth air. 

Clyde took out his electronic notebook and logged into his favorite third party flight planning 

provider to create his flight plan and file it with the FAA - as an AFR flight Plan! As his airplane's 

performance is already stored in the planner, Clyde just put in his preference for FL200 and requested the 

most fuel efficient route. Because of wind circulation patterns and wind gradient during climb and 

descent, the best wind route is almost never the great circle from origin to destination. This day was no 

exception and the flight planner produced a plan with the initial track during climb to the west of the 

direct track, the cruise portion drifting back across the track to the east and the descent gradually arcing 
38 

back in to Moline. Taking advantage of the wind gradient saved two minutes compared to the great circle, 

resulting in a 1 hour 44 minute flight plan. To go IFR would have meant a route over Nashville and Saint 

Louis, arriving from the southwest for an increased distance of 62 miles and additional 15 minutes of 

flight time. 

Departing IFR from an uncontrolled airport can be a very time consuming process if the nearest tower 

can't be contacted by radio while on the ground. The clearance must be received over the telephone, good 

for a small window of time during which you must take off before the "void time". Sometimes this may 

only take an extra 10 minutes. Often, especially on busy Monday mornings, it can take a half hour or 

more. AFR flights are exempt from this process. Thus, the combination of shorter flight time and 

simplified departure allows Clyde to get an extra hour of sleep before the flight, leaving at 0700 Central 

time. 

Fueling and preflight inspections had been completed the night before, so after pulling the airplane 

out of the hanger, Clyde gets in, starts the engine, turns on the radios and taxis out for takeoff. The pretakeoff checklist is completed, his departure at Piney Creek is announced on 122.8 and he is on his way in 

less than 4 minutes since getting into the airplane. At 700 feet above the ground as he enters the Class E 

airspace, the ATU has logged in through the nearest ADS-B ground station and its annunciator shows that 

the initial frequency to monitor is Nashville Approach. During his cruise climb, Clyde can hear two 

aircraft being worked into the landing pattern at Nashville. They are also displayed on the ND, but are "no 

factor" as indicated on the ATU, being well below the climb path of N280KTS. The seven waypoints in 

the flight plan between Piney Creek and Moline that define the S - shaped lateral path are being followed 

by the autopilot and have also been sent to ATC via the Broadband link. The frequency to monitor has 

switched to Memphis Center, then Indianapolis Center and back again as the flight track cuts across the 

boundaries of their respective airspace. 

Near the top of the climb, a northeast bound IFR flight is converging from the left at 17,000 feet. The 

ATU shows that a fifteen degree turn to the left will pass behind the traffic. Clyde turns the heading bug 

to the left, satisfying the ATU. This information is also sent via ADS-B from his newly purchased 

transponder unit. Even though the ADS-B mandate does not require sending this information, AFR rules 

do. As the method for including commanded headings and altitudes is already in the MOPS, some 

manufacturers have been including it in their new units, along with the next two TCPs, for competitive 

reasons, even though it is not mandatory. The traffic crossing takes place just 2 minutes after the new 

heading was established and Clyde redirects his navigation system to proceed direct to the next waypoint. 

Clyde is flying in the clouds now and picking up light rime ice. The anti-ice system is keeping most 

of it off but the residual is costing about 5 knots of indicated airspeed. Upon reaching FL 200, the airplane 

is still going in and out of the cloud tops so Clyde continues the climb to FL210 and is now in the bright 

sunshine, where the residual ice will shortly sublimate. Near the Central City VHF Omnidirectional 

Range (VOR), IFR traffic appears at the edge of the display co-altitude and nearly head-on. The ATU 

shortly shows a projected conflict 45 miles ahead and indicates that a slight deviation to the right will 

resolve it. This is accepted and executed, and the conflict is cleared. 

Other aircraft appear on the display during cruise, but no conflicts result, as most of them are at 

higher altitudes. The flight planning service uses more recent wind data and sends an updated plan to 

Clyde via the Broadband link. There is minimal change to the lateral track but the descent begins earlier, 

75 miles from Moline, so it is accepted and executed. During the descent, a south bound airline flight is 

climbing on a converging course from the right and the ATU instructs that the descent rate should 

increase to pass well below the traffic. As soon as the vertical speed reaches 2000 feet per minute down, 

the conflict clears. The rest of the descent is routine and no other conflicts are encountered. 

As soon as the communications monitor frequency calls for Quad City Approach, Clyde makes the 

standard IFR call in, "leaving 8000 feet 30 miles southeast with information Bravo". The AFR flight plan 
39 

has triggered an electronic flight strip in the TRACON so the controller has been expecting N280KTS and 

she responds with, "proceed direct to PCITY and plan an Area Navigation (RNAV) Runway 31 approach. 

You are number three to land but traffic is no factor". Clyde pulls the speed brakes briefly to get down to 

the 2,500 foot crossing altitude and sets up for the straight in approach and landing. Not having to fly a 

pattern to an opposite direction runway saves another five minutes thanks to the wind direction. Clyde is 

cleared to taxi via runway 23 and Delta to the ramp, where his assistant is waiting with the car. The 

fifteen minute ride to the office has him at his desk by 0900 Central time, just two hours after leaving his 

home in rural Tennessee. 

 
40 

Appendix B. Organization Interviews 

B1. Example presentation 

Cotton

Aviation

AFR Implementation for Airlines

NASA investigation ofAFR Implementation Issues

Cotton

Aviation

Background

 Airline operations are hindered by IFR

procedures

 Human centered separation paradigm requires

regimentation, limits numbers of operations

 TFMI have replaced efforts to expand capacity

 NextGen no longer transformational

 NASAAFR concept is designed to overcome

the limitations of IFR

Cotton

Aviation

Purpose of Discussion

 Explain theAutonomous Flight Rules (AFR)

concept for self separation

 Review benefit mechanisms

 Present enabling assumptions

 Discuss avionics architecture issues

 Address airline specificAFR adoption costs

Cotton

Aviation

Origins of IFR Flight

Restrictions

Procedural Separation

Radar Separation

• Early IMC navigation limited to a few radio airways

– Surveillance by position reports, communications through 3rd party

– Led to ATC procedural separation by assignment of route/alt/speed

• By 1960s: radar, direct pilot/controller comm., RNAV

– New technologies enabled reduced separation standards

– But assignment of route/alt/speed still the norm

• Recent decades: Airspace “sector” controller has become the

limiting factor

– Limitations of human cognition demands “orderly” traffic flows

– Airways, “preferred” routes, cardinal altitudes, “pass back” of delays

– Sectors, human capabilities limit aircraft simultaneously handled

• Restriction, delay, inflexibility the norm for IFR

– Necessary to enable ATC to maintain responsibility for separation

– Inefficient routing, non-optimum altitudes, reduced speeds

– Miles-in-trail spacing, ground delay programs due to en route 

“congestion”

– En masse rerouting for weather

Cotton

Aviation

Solution – AFR Operations

 Self separation from all other traffic, weather

and airspace hazards

 Airborne surveillance and separation

algorithms provide safe trajectory guidance

 Pilots follow approved guidance just like

following an ATC clearance

 Flights are free to optimize within the

constraints of the automated guidance

Cotton

Aviation

AFR Benefit Mechanisms

 Exemption from departure fix delays

 Exemption from airspace ground delay

programs

 Exemption from Miles‐in‐Trail passbacks

 Exemption from use ofATC preferred routes

 Exemption from en mass weather re‐routes

 Continuous trajectory optimization in

accordance with individual business case
41 

Cotton

Aviation

Research & Development History

 Concept of Operations

 “Distributed Air‐Ground Traffic Management” (~2000)

 “Autonomous Flight Rules” (2011)

 Flight‐Deck Technology Development (AOP)

 Algorithms, displays & procedures, avionics integration (~2000 ongoing)

 Human‐in‐the‐Loop Research

 Intent information (2001)

 High‐hazard scenarios (2002)

 Basic mixed operations and scalability (2004)

 Air vs. ground separation assurance comparison (2010)

 Mixed operations w/ ground‐based NextGen (2012a, 2012b)

 Controller‐focus and pilot‐focus experiments

 Batch Research

 Traffic density (2007)

 Pilot response time (2008)

 Wind uncertainty (2009)

 ADS‐B surveillance limitations (2010)

 Weather/traffic avoidance integration (2010)

 Intent information (2011)

Cotton

Aviation

AFR Descriptive Papers

 NASA/TP‐2011‐217174 “Autonomous Flight Rules

– A Concept for Self Separation in U. S. Domestic

Airspace”

 AIAA‐2011‐6865 “For Spacious Skies: Self

Separation with ‘Autonomous Flight Rules’ in

U.S. Domestic Airspace”

 AIAA‐2012‐5417 Paper “Autonomous Operations

Planner:A Flexible Platform for Research in

Flight Deck Support forAirborne Self‐

Separation”

Cotton

Aviation

Enabling Assumptions

 User demand forAFR Operations

 Successful completion of safety case forAFR

 FAA approval of mixedAFR, IFR,VFR

operations

 FAA approved conflict detection and

resolution algorithms publically available

 Liability issues no different thanTCAS

Cotton

Aviation

Why New Flight Rules?

 Permits continuity of service to IFR andVFR

 Gives flexibility in definingAFR and its

integration with other operations

 Permits uniquely defined training, equipment

and certification requirements

 Clarifies operator responsibility with clearly

delineated operating rules

Cotton

Aviation

ATU Functional Description

 Trajectory modeling – ownship and nearby traffic

 Conflict detection out to established time

horizon

 Calculate conflict resolution(s) and prevention

 Communicate resolution to crew, (UAS

Autopilot), to theANSP and nearby aircraft

 Participate in destination airportTFM

 Perform ownship business trajectory

optimization

Cotton

Aviation

Required New Enabler Systems

 AirTraffic Unit (ATU) software application

 ADS‐B “In and Out” on ownship and ADS‐B

“Out” on all others

 TIS‐B (enhanced) backup surveillance

 Basic Data Comm between ownship and

ANSP

 Interfaces with some existing cockpit systems

Cotton

Aviation

Automation Technology for AFR NASA “Autonomous Operations Planner” (AOP)

Integrated avionics system enabling self‐separation

 Traffic separation in FMS and MCP flight modes

 Optimization of trajectories (integrated with de‐confliction)

 Conformance with trajectory constraints

 Provisional probing for conflict‐free trajectory changes

 Implicit coordination with “traffic aircraft” actions

Cotton

Aviation

Sample AFR Architecture

 AirlineAircraft

 Dual FMS with:

 intent bus providing own aircraft 4D trajectory to theATU*

 ability to accept 4D trajectories fromATU*

 airspace information (sector boundaries,SUAs,ATC frequencies) in the navigation data base, and aircraft performance limitations available

 CDTI on large format Nav Display with AFR and other ADS‐B "In" applications

 ability to display heading, airspeed, and altitude resolutions from ATU*.  

 MCP with status (horizontal and vertical nav modes, heading, airspeed altitude) output to ATU

 heading, airspeed, and altitude fromATU if that feature is implemented underCPDLC.*

* expected to be present in 2020
42 

Cotton

Aviation

Sample AFR Architecture (cont.)

 TCAS and/orTransponder LRUs which includes:

 hybrid surveillance*

 independentADS‐B “In” system with 1090 andUAT receivers, processesTIS‐B and FIS‐B, hosts air traffic unit forAFR, IM, closely spaced parallel approaches  and other applications

 receives and outputs to CMU and/or broadband and/or

Overlay (weather,SWIM, ownship and other aircraft trajectories, etc.)

 outputs to FMS (and MCP if implemented) in Data Comm format ( or CPDLC orAOC formats)

 outputs to aural alerting system*

 interfaces with MCDU or other I/O device *expected to be present in 2020 Cotton

Aviation

Sample AFR Architecture (concl)

 Upgrade 1090 antennas to 1090/UAT antennas

 DualVHF Data Radio*

 Dual MCDU*

 ATU status, CD&R informationand pilot interface

 Architecture 1:  dual TCAS as described above, level B software

 Architecture 2: singleTCAS as described above, second AirTraffic Unit in TCAS LRU with independent power source and 2nd 1090/UAT receivers (share 1090/UAT antennas), level C software (but without TCAS function)

* expected to be present in 2020
43 

B2. Interview Questions 

Installation 

1. What fleet types do you operate? 

2. How many aircraft in each fleet? 

3. What plans are in place for aircraft additions and retirements? 

4. Have you made plans to equip for the ADS-B mandate? 

5. Do you perform avionics installations in-house? 

6. Do you have your own DAS authority for avionics STCs? 

7. Do you plan installations to coincide with regular maintenance visits? 

8. How are costs allocated for avionics installations? 

9. What was your experience with the TCAS change 7.2 upgrade? Did you include hybrid 

surveillance? 

10. On which fleets do you have flat panel NAV Displays, versus CRTs? Do you have plans for 

replacing CRTs? 

11. How are simulator modifications made to reflect aircraft changes? 

Training 

5. To what extent do you train your pilots using individualized CBT techniques? 

6. What training programs have you had approved by your POI using CBT? 

7. What costs are associated with CBT? 

Course development? 

Pilot pay for training time? 

8. What costs are involved in incorporating new procedures into: 

Recurrent training? 

Initial/Transition training? 

Operations 

1. What do you see as obstacles to obtaining operational approval? 

2. What formalized procedures do you have to receive operational feedback from pilots? 

3. What costs are associated with administering feedback programs? 

4. Is your flight planning system capable of ignoring ATC constraints while optimizing plans? If 

not, how hard would it be to modify for this capability? 

5. Do you optimize flight plans of airborne aircraft? 

Maintenance 

1. Do you perform your own avionics maintenance? 

2. If avionics maintenance is outsourced, to whom? 

3. What are typical costs to maintain TCAS and Transponders? 
44 

B3. Organizations and companies interviewed 

 Name 

Airlines for America 

Aircraft Owners and Pilots Association 

Air Line Pilots Association 

National Business Aircraft Association 

General Aviation Manufacturers Association 

American Airlines 

Delta Airlines 

JetBlue Airlines 

Southwest Airlines 

United Airlines 

VirginAmerica Airlines 

General Atomics 

Northrop/Grumman 

Honeywell/Bendix/King 

ACSS 

Garmin 

Rockwell Collins 

ITT/Excellis 

Federal Aviation Administration 
45 

Appendix C. Abbreviations 

1090ES 1090 Megahertz Extended Squitter 

4D Four Dimensional 

ADS-B Automatic Dependent Surveillance Broadcast 

AFR Autonomous Flight Rules 

ANSP Air Navigation Service Provider 

AOC Airline Operational Control 

AOP Autonomous Operations Planner 

ATC Air Traffic Control 

ATCRBS Air Traffic Control Radar Beacon System 

ATU Air Traffic Unit 

CBT Computer Based Training 

CD&R Conflict Detection and Resolution 

CDM Collaborative Decision Making 

CDTI Cockpit Display of Traffic Information 

CMU Communication Management Unit 

CPDLC Controller Pilot Data Link Communications 

CRT Cathode Ray Tube 

DAA Detect And Avoid (also referred to as Sense And Avoid, SAA) 

EDT Eastern Daylight Time 

EFB Electronic Flight Bag 

FAA Federal Aviation Administration 

FAF Final Approach Fix 

FAR Federal Aviation Regulations 

FBO Fixed Base Operator 

FIM Flight-deck Interval Management 

FIS-B Flight Information Service Broadcast 

FL Flight Level 

FMS Flight Management System 

GA General Aviation 

GPS Global Positioning System 

I/O Input/Output 

ICAO International Civil Aviation Organization 

IFR Instrument Flight Rules 

IMC Instrument Meteorological Conditions 

ITP In-Trail Procedures 

LRU Line Replacement Unit 

MASPS Minimum Aviation System Performance Standards 

MCDU Multifunction Control Display Unit 

MCP Mode Control Panel 

MFD Multi-Function Display 

MOPS Minimum Operational Performance Standards 

NAS National Airspace System 

NATCA National Air Traffic Controllers Association 

ND Navigation Display 

NextGen Next Generation Air Transportation System 

PDT Pacific Daylight Time 

PFD Primary Flight Display 

POI Principal Operations Inspector 

PTM Pairwise Traffic Management 

RNP Required Navigation Performance 

SARPS Standards and Recommended Practices 

SNAPI Status Notification and Planning Information 
46 

STC Supplemental Type Certificate 

SUA Special Use Airspace 

SWAP Severe Weather Avoidance Plan 

SWIM System Wide Information Management 

TAS Traffic Advisory System 

TASAR Traffic Aware Strategic Aircrew Requests 

TBFM Time-Based Flow Management 

TCAS Traffic Alert and Collision Avoidance System 

TCP Trajectory Change Points 

TFM Traffic Flow Management 

TIS-B Traffic Information Service Broadcast 

TRACON Terminal Radar Approach Control 

TSO Technical Standard Order 

UAS Unmanned Aircraft Systems 

UAT Universal Access Transceiver 

US United States 

VFR Visual Flight Rules 

VHF Very High Frequency 

VMC Visual Meteorological Conditions 

WAAS Wide Area Augmentation System 

Author Biographies 

William B. Cotton 

Captain Cotton is known worldwide as the “Father of Free Flight”, the ATM operating concept for the future that 

would simultaneously increase safety, capacity, and operating efficiency in the air traffic system. As the chief 

technical pilot at United Airlines, he directed all of their air traffic control and flight systems related efforts. Mr. 

Cotton managed numerous projects from concept through development and implementation and has been a key 

innovative participant in many aviation industry activities to bring new technologies to fruition, such as TCAS and 

FANS-1. After retiring from United, Captain Cotton was President of Flight Safety Technologies, Inc. creating and 

managing the company’s strategy for developing its air safety technologies. This included creation of the concepts 

of operation and the operational design of its safety systems including the patented Unicorn ground proximity and 

collision alerting system, and the Aircraft Wake Safety Management system for increasing airport capacity. Mr. 

Cotton is currently a consultant working with NASA, the JPDO and FAA on several NextGen development efforts, 

including the investigation of self separation concepts for NASA under their Airspace Systems Program. He 

received a BS in Aeronautical and Astronautical Engineering from the University of Illinois and an MS in 

Aeronautical and Astronautical Engineering from MIT. He is still an active pilot and engineer. 

Robert Hilb 

Captain Bob Hilb is retired from UPS where he headed the Advanced Flight Systems Department which 

recommended and implemented new technologies and systems for UPS aircraft and operations. Among the 

successful programs were a number of industry firsts: GPS autolands, an ASDE-X surface management system, 

CDAs (OPDs), and ADS-B certification and operational approvals. He also participated in numerous aircraft 

acquisitions. Prior to UPS he was a 737 Captain and headed the Operations Computer Department at People 

Express Airlines and he served in the Air Force and Air Force Reserve in various operational and staff assignments. 

Capt. Hilb has a BS degree in Astronautical Engineering, Engineering Sciences, and Computer Science from the 

United States Air Force Academy and a MS degree in Computer Science from Auburn University. He was an airline 

Captain for over 26 years. He participated and chaired various industry groups on ADS-B, Controller Pilot Data 

Link Communications, Flight Management Systems, and Airborne Separation Assurance. He has been a member of 

a number of aviation advisory groups such as the Gore Commission, the National Academies study on NASA, and 

the FAA’s Free Flight Steering and Air Traffic Management Advisory Committees. Bob holds patents on a number 

of aviation technologies and received numerous awards. Since retiring he has been a consultant to airlines, avionics 

companies, the FAA, and NASA. 
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

2. REPORT TYPE 

Contractor Report

 4. TITLE AND SUBTITLE

Autonomous Flight Rules Concept: User Implementation Costs and 

Strategies 

5a. CONTRACT NUMBER

NNL13AA00B

 6. AUTHOR(S)

Cotton, William B.; Hilb, Bob

 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NASA Langley Research Center 

Hampton, Virginia 23681 

 

 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

 8. PERFORMING ORGANIZATION

 REPORT NUMBER

10. SPONSOR/MONITOR'S ACRONYM(S)

NASA

13. SUPPLEMENTARY NOTES

This work was performed by Cotton Aviation Enterprises, Inc., for National Institute of Aerospace under NASA

contract NNL13AA00B. Langley Technical Monitor: David J. Wing 

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

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Availability: NASA CASI (443) 757-5802

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email: help@sti.nasa.gov)

14. ABSTRACT

The costs to implement Autonomous Flight Rules (AFR) were examined for estimates in acquisition, installation, training and 

operations. The user categories were airlines, fractional operators, general aviation and unmanned aircraft systems. Transition

strategies to minimize costs while maximizing operational benefits were also analyzed. The primary cost category was found 

to be the avionics acquisition. Cost ranges for AFR equipment were given to reflect the uncertainty of the certification level 

for the equipment and the extent of existing compatible avionics in the aircraft to be modified. 

15. SUBJECT TERMS

Airspace; Autonomy; Avionics; Costs; Flight rules

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