AC 91-79B

U.

S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Aircraft Landing Performance and Runway Excursion Mitigation Date: 8/28/23 AC No: 91-79B Initiated by: AFS-200/800 Change:

This advisory circular (AC) provides ways for pilots and airplane operators to identify, understand, and manage the risks associated with the landing phase of flight. It also provides information that both certificated and noncertificated operators may use to develop personal or standard operating procedures (SOP) to mitigate a runway excursion. The contents of this document do not have the force and effect of law and are not meant to bind the public in any way, and the document is intended only to provide information to the public regarding existing requirements under the law or agency policies.

Wesl ey L. Mooty Acting Deputy Executive Director, Flight Standards Service

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CONTENTS Paragraph Page

Chapter 1. Introduction1-1

1.1 Purpose of This Advisory Circular (AC)1-1

1.2 Audience1-1

1.3 Where You Can Find This AC1-1

1.4 What This AC Cancels1-1

1.5 Background1-1

1.6 Content of This AC1-2

1.7 Related Documents (current editions)1-3

1.8 Definitions1-4

1.9 Training Considerations1-6

1.10 AC Feedback Form1-6

Cha pter 2. Predeparture Flight Planning2-1

2.1 B ackground2-1

Table 2-1. Regulatory Planned Dispatch Destination Airport Requirements2-3

2.2 AFM Landing Distance Data2-3

Ch apter 3. Time of Arrival (TOA) Landing Distance Assessment3-1

3.1 B ackground3-1

3.2 General3-1

3.3 Conducting the Assessment3-1

Table 3-1. Landing Distance Factors3-3

3.4 Runway Condition Considerations3-3

3.5 Risks Associated With Moderate or Heavy Rain3-4

3.6 Risk Associated With Standing Water3-4

3.7 A ircraft Performance Considerations3-5

3.8 Autobrake and Manua l Brake Usage3-5

3.9 Touchdown Point3-6

3.10 Crosswind Considerations3-6

3.11 Assessment Based on Preflight (Dispatch) Criteria3-6

3.12 Risk Management Considerations3-7

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3.13 Technical Considerations for Understanding Landing Performance

and the RCAM3-7

T able 3 -2. Pilot/Operator Runway Condition Assessment Matrix (RCAM)3-11

Cha pter 4. Braking Action Reports4-1

4.1 G eneral4-1

4.2 Understanding Aircraft Deceleration4-1

4.3 Classifying Wheel Braking Action4-1

4.4 Braking Action Reports4-1

4.5 “Braking Action Advisories Are in Effect.”4-2

4.6 How to Use the RCAM4-3

4.7 Criteria for Making Observations4-3

4.8 Recommended Method for Classifying Pilot Observations4-4

F igure 4-1. An Expectation of Good, Medium, and Poor Braking4-6

4.9 P ilot or Pilots Reporting Conventions4-6

4.10 Comparison of Braking Action Reports: PBAR vs ABAR4-7

F igure 4- 2. Precision and Accuracy4-7

F igure 4-3. Comparison of Various Braking Action Reports4-8

4.11 R ecommended Action4-8

Cha pter 5. Runway Overrun Hazards5-1

5.1 B ackground5-1

5.2 Overrun Hazards5-1

F igure 5-1. Effects of Compound Factors5-4

5.3 R isk Mitigation5-4

Appendix A. Aircraft Braking Action Report (ABAR) SystemsA-1

1-1 CHAPTER 1. INTRODUCTION

1.1 Purpose of This Advisory Circular (AC). This AC provides ways to identify, understand, and manage the risks associated with the landing phase of flight. It describes braking action reports and the Runway Condition Assessment Matrix (RCAM), discusses the hazards associated with runway overruns and excursions, reviews the requirements for predeparture flight planning, and provides procedures for completing a time of arrival (TOA) landing distance assessment. It also provides operators with information they may use to develop standard operating procedures (SOP), training programs, policies, and briefing guides in order to mitigate landing risks. The contents of this document do not have the force and effect of law and are not meant to bind the public in any way, and the document is intended only to provide information to the public regarding existing requirements under the law or agency policies.

1.2 Audience. This AC is intended for pilots, check airmen, dispatch examiners, flightcrews, airplane operators, certificate holders, program managers, training providers, pilot examiners, and other support personnel.

1.3 Where You Can Find This AC. You can find this AC on the Federal Aviation Administration’s (FAA) website at https://www.faa.gov/regulations_policies/advisory_cir culars/ and the Dynamic Regulatory System (DRS) at https://drs.faa.gov.

1.4 What This AC Cancels. AC 91-79A, Mitigating the Risks of a Runway Overrun Upon Landing, dated September 17, 2014, is canceled. Safety Alert for Operators (SAFO) 19001, Landing Performance Assessments at Time of Arrival, dated March 11, 2019, and SAFO 19003, Turbojet Braking Performance on Wet Runways, dated July 2, 2019, are canceled.

1.5 Background. Heavy snow was falling on a frigid day in December 2005 when a Boeing 737 ran off the runway at Chicago’s Midway Airport. Although the aircraft touched down normally, thrust reverser activation was delayed. On a wet runway, this would have resulted in approximately a 180-foot (ft) increase in stopping distance.

Although the braking action was reported as “good” by previous aircraft, National Transportation Safety Board (NTSB) analysis had in fact shown it to be poor. As a result, the stopping distance for the accident aircraft was increased by approximately 2000 ft, and the aircraft ran through the airport fence onto Central Avenue, and struck two cars. A dozen people were injured and a child inside one of the cars was killed.

1.5.1 In response to that accident, it was determined that there were no standardized means to observe and predict landing performance on runways whose condition were worse than wet, and the FAA convened the Takeoff and Landing Performance Assessment (TALPA) Aviation Rulemaking Committee (ARC). Because regulations do not include dispatch requirements for landing on runways other than wet or dry, exposure to the risks associated with other runway conditions during TOA had not been formally addressed.

The FAA adopted several committee recommendations and implemented them on October 1, 2016.

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1.5.2 TALPA standardized runway condition reporting and set the conditions within a matrix that compared airport observations, engineering-based landing performance calculation methods, vehicle observations, and runway friction measuring ranges. The matrix was called the “Runway Condition Assessment Matrix (RCAM).” This guidance is now set out in three separate ACs for airports (AC 150/5200-30, Airport Field Condition Assessments and Winter Operations Safety), aircraft certification (AC 25-32, Landing Performance Data for Time-of-Arrival Landing Performance Assessments), and aircraft operators (this AC).

1.5.3 TALPA recommendations served as the basis for the International Civil Aviation Organization (ICAO) standards. Known collectively as the Global Reporting Format (GRF), this series of publications became applicable in 2021. A complete list of publications can be found on the ICAO website at https://www.icao.int/publications/Page s/default.aspx. International operator s should be familiar with the ICAO GRF to ensure proper understanding of terms, procedures, and policies.

1.5.4 The RCAM forms the basis of the FAA’s TALPA initiative as well as the ICAO GRF.

While the levels of predicted aircraft wheel brake performance were set in these documents, there was no guidance for how actual aircraft performance could be used to provide standard reports. In 2017, the Society of Aircraft Performance and Operations Engineers (SAPOE) convened a special task group to address this issue. The result was published as two ASTM standards (ASTM E3188, Standard Terminology for Aircraft Braking Performance, and E3266, Standard Guide for Friction-Limited Aircraft Braking Measurements and Reporting) that set formalized definitions and minimum standards for braking action reports derived directly from aircraft data. These documents described how braking action reports should be structured, the intended precision of the reported braking action, and how accuracy should be applied to the RCAM scale.

1.5.5 According to FAA and NTSB information, runway overruns during the landing phase of flight account for approximately ten incidents or accidents every year with varying degrees of severity, including fatalities. As a result, the NTSB recommended that a means be developed for aircraft to have the capability to record and report braking performance.

This was later published in Safety Recommendations A-16-23 and A-16-24 after another runway excursion in 2015. This AC revision incorporates guidance on this capability.

1.6 Content of This AC. This guidance incorporates the recommendations from the TALPA ARC and the material from SAFOs 19001 and 19003, and references guidance from ASTM E3188 and E3266.

1.6.1 Braking Action and Braking Action Reports. To effectively manage landing risk, it is critical that the effect of wheel braking is understood, as it plays a vital role in both dispatch and TOA landing distance assessments. While these risks are commonly associated with transport category aircraft and operations, this AC provides the knowledge, skills, and techniques that may be used by other aircraft with similar designs.

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1.6.2 Runway Overrun Hazards. In addition to wheel braking, proper airmanship based on a foundation of knowledge regarding other overrun risk factors is essential. These risks, which are generic to all aircraft, are discussed as well as their consequences.

1.6.3 Pr e departure Flight Planning. This AC provides a brief introduction to the regulations and recommended practices concerning preflight runway requirements for large transport aircraft.

1.6.4 T ime of Arrival (TOA) Landing Distance Assessments. Upon arriving at the destination airport, prior to top of descent, the flightcrew obtains the runway’s reported condition and assesses if the aircraft can safely land with reference to the wet contaminated runway landing data if available in the pilot’s operating handbook (POH)/Airplane Flight Manual (AFM).

1.6.5 Aircraft Braking Action Report (ABAR). Appendix A provides detailed background information on ABAR systems and their use.

1.7 Related Documents (current editions).

1.7.1 ASTM International Standards.

• E3188, Standard Terminology for Aircraft Braking Performance.

• E3266, Standard Guide for Friction-Limited Aircraft Braking Measurements and Reporting.

1.7.2 A dvisory Circulars (AC) .

• AC 23-8, Flight Test Guide for Certification of Part 23 Airplanes.

• AC 25-7, Flight Test Guide for Certification of Transport Category Airplanes.

• AC 25-31, Takeoff Performance Data for Operations on Contaminated Runways.

• AC 25-32, Landing Performance Data for Time-of-Arrival Landing Performance Assessments.

• AC 60-22, Aeronautical Decision Making.

• AC 120-71, Standard Operating Procedures and Pilot Monitoring Duties for Flight Deck Crewmembers.

• AC 121.195-1, Operational Landing Distances for Wet Runways; Transport Category Airplanes.

1.7.3 F AA Handbooks.

• FAA-H-8083-3, Airplane Flying Handbook.

• FAA-H-8083-25, Pilot’s Handbook of Aeronautical Knowledge.

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1.7.4 Safety Alerts for Operators (SAFO). SAFO 10005, Go-Around Callout and Immediate Response.

1.7.5 A dditional References .

• Approach and Landing Accident Reduction (ALAR)/Runway Excursion Risk Reduction (RERR) Toolkits.

• Flight Safety Foundation (FSF) ALAR Tool Kit.

• FSF’s Reducing the Risk of Runway Excursions Report.

• Safety Targeted Awareness Report (STAR) 007, Overruns on Landing, from the European Regions Airline Association (ERA) Air Safety Work Group.

• Flight Test Harmonization Working Group (FTHWG) Topic 32, Codification of Part 25 Takeoff and Landing Performance Assessment (TALPA) (Recommendation Report, July 20, 2022).

1.8 Definitions. The following definitions are used in this AC:

1.8.1 Advisory Data. Aircraft performance data that applies standard engineering factors to certified data to produce nonmandatory guidance for runway conditions other than wet or dry.

1.8.2 A ircraft Braking Action Report (ABAR). A braking action report generated by an automated system designed to provide a standardized indication of the aircraft’s braking performance.

1.8.3 A pproved Data. Aircraft performance data that is approved for use by the FAA.

1.8.4 Autobrakes. An automated aircraft control system that normally allows the pilot to select a targeted deceleration rate for the landing rollout.

1.8.5 B raking Action. T he method for describing the maximum capability of a vehicle’s braking system on a wet or contaminated surface that references a standardized scale (the RCAM).

1.8.6 C ertified Data. Aircraft performance data that is required to be provided by regulation and is derived from flight testing. This data is provided by the manufacturer as AFM landing distance.”

1.8.7 F actored Landing Distance. The AFM landing distance adjusted by the applicable Title 14 of the Code of Federal Regulations (14 CFR) preflight factors.

1.8.8 F riction -Limited Braking. A condition of aircraft braking performance where the amount of deceleration force that can be applied by the aircraft brakes is limited by the friction level of the runway surface. For aircraft so equipped, any increase in command to the brake system will be limited by the anti-skid system.

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1.8.9 Global Reporting Format (GRF). The format used by ICAO to denote standard runway condition reporting and aircraft braking performance. This format is based on and largely similar to current FAA guidance.

1.8.10 O perational Land ing Distance. A calculation of landing distance based on actual landing weight, aircraft configuration, runway and meteorological conditions, including braking action reports that are used by the flightcrew to make an assessment at the TOA. This calculation normally references advisory data supplied by the manufacturer and may include recommended air distances and safety margins and is used in the TOA assessment.

1.8.11 O perator. For the purpose of this AC, any air operator, foreign air operator, or private operator.

1.8.12 P ilot Braking Action Report (PBAR). A braking action report based on observations from the pilot. In some countries, PBARs may be referred to as a Pilot Report (PIREP) or an Air Report (AIREP).

1.8.13 P orous Friction Course ( PFC). A thin layer of porous asphalt that allows water to drain vertically away from the surface of the runway.

1.8.14 R eliable Pilot Braking Action Report (PBAR). A PBAR whose precision and accuracy can be justified and can therefore be reasonably used to create a time of landing performance assessment for the aircraft receiving the report. The following should be considered when determining if the braking action report is reliable:

1. Similar types of aircraft (e.g., transport category jet aircraft with fully modulating anti-skid systems).

2. Time since braking action report was given (e.g., stable conditions with cold temperature and no active precipitation will likely be reliable for a longer time than reports provided during an active precipitation event with temperatures near 0 ºC).

3. Pilot education and training in the principles of braking action and braking action reporting.

1.8.15 Runway Condition Code (RwyCC). A number from 0 to 6 that represents the slipperiness of a designated portion of a runway (i.e., a specific one-third of the runway); a rating of 0 indicates extremely slippery and a rating of 6 indicates a dry runway. (See Table 3-2, Pilot/Operator Runway Condition Assessment Matrix (RCAM).)

1.8.16 T akeoff and Landing Performance Assessment (TALPA) Aviation Rulemaking Committee (ARC). The FAA body formed to reduce the risk of runway overruns by developing a series of guidance materials for runway conditions and aircraft performance.

These procedures have since formed the basis of the ICAO GRF.

1.8.17 T ime of Arrival (TOA) Assessment . Upon arriving at the destination airport, prior to top of descent, the flightcrew obtains the runway’s reported condition, assesses if the aircraft

1-6 can safely land, with reference to the wet contaminated runway landing data if available in the POH/AFM.

1.8.18 T orque- Limited Braking. A condition of aircraft ground deceleration performance where the amount of deceleration force that can be generated by the aircraft brakes is limited by the maximum torque capability of the wheel brakes.

1.8.19 Unfactored A irplane Flight Manual (AFM) Landing Distance. The landing distance provided by the AFM without any factors applied.

Note: F or some operations, t hese landing distances may be determined in a way that represents the maximum performance capability of the airplane, which may not be representative of normal operations. (See Chapter 2, Predeparture Flight Planning.)

1.8.20 Wheel Braking Coefficient. Th e ratio of the deceleration force from the braked wheels/tires relative to the sum of the vertical (normal) forces acting on the braked wheels/tires. The wheel braking coefficient is the result of the combination of all functioning braked wheels.

1.9 T raining Considerations. We recommend operators include the information in this AC in their SOPs for operations of aircraft in their pilot training programs.

1.10 AC Feedback Form. For your convenience, the AC Feedback Form is the last page of this AC. Note any deficiencies found, clarifications needed, or suggested improvements regarding the contents of this AC on the Feedback Form.

2-1 CHAPTER 2. PREDEPARTURE FLIGHT PLANNING

2.1 Background.

2.1.1 D ispatch Requirements . Large transport category airplanes are subject to specific regulations with the intent of ensuring that a flight does not begin that cannot be safely concluded. Title 14 CFR parts 91 subpart K (part 91K), 121, and 135 operators must not plan to arrive at either the destination or the alternate airport at a weight that would require them to use more runway than is available (and 14 CFR part 125, § 125.49(a) requires part 125 operators to only use an airport if it is adequate for the proposed operation). These predeparture planning procedures are also recommended, although not required, for part 91 operators.

Note: D uring a discussion of predeparture flight planning requirements, it is important to keep in mind that the regulations specify flight-planning requirements, not landing requirements. In other words, upon arrival, all (100 percent) of the runway available may be used for landing.

2.1.2 T itle 14 CFR Compliance . It is not the intent of this AC to provide all the predeparture landing distance regulatory requirements. However, pilots must be knowledgeable of the regulations applicable to their type of operation, so they can both comply with such regulations and fully understand regulatory shortcomings. Parts 91K, 121, and 135 require operators of large transport category airplanes to comply with certain landing distance requirements at the time of takeoff. These requirements are sometimes referred to as “dispatch requirements.” The requirements limit the allowable takeoff weight to that which would allow the airplane to land within a specified percentage of the Landing Distance Available (LDA) on: (1) the most favorable runway at the destination airport under still air conditions; and (2) the most suitable runway in the expected wind conditions. Part 91, § 91.1037(e); p art 121, § 121.195(e); and part 135, § 135.385(d) further require an additional 15 percent be added to the landing distance required when the runway is wet or slippery, unless a shorter distance can be shown using operational landing techniques on wet runways.

2.1.2.1 S ections 91.1037(b), 121.195(b), and 135.385(b). Regulations require that during preflight planning, the flightcrew may not depart on the flight unless it has been determined that the aircraft will be able to perform a full stop landing within 60 percent of the effective length of the runway. To determine the landing distance required, multiply the AFM approved landing distance by 1.667 or divide the AFM approved landing distance by 0.60. This factor assumes a dry runway condition at TOA.

Example: AFM approved landing distance = 3000 ft (3000’ x 1.667 = 5000’ or 3000’ ÷ 0.60 = 5000’.) In this example, to comply with the 60 percent rule, the runway LDA at the planned destination would need to be at least 5000 ft long.

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2.1.2.2 Sections 91.1037(e), 121.195(e), and 135.385(d). If weather reports or forecasts indicate that the runways at the destination airport may be wet or slippery, unless a shorter distance can be shown using operational landing techniques, that the aircraft may not depart unless the operator can show that the effective runway length at the destination airport is at least 115 percent of the runway length required for a dry runway (as calculated above).

Example: If it was determined that the runway at the planned destination would need to be 5000 ft to comply with the 60 percent rule in dry conditions (as in the first example, above), then in forecast wet conditions, the runway LDA would need to be at least 5750 ft long (5000’ x 1.15 = 5750’).

Note 1: The additional 15 percent increase required by the regulations above is based only on the previously calculated distances used for a dry runway. Caution: The increase is not based on demonstrated wet runway stopping performance; therefore, wet runway factored landing distance may not provide enough runway for the aircraft to stop.

Note 2: There exists a common misconception that grooved runways or runways covered in PFC are considered dry for predeparture-planning calculations. Pilots and dispatchers must remember that the 15 percent increase is still required if the runway will be wet on landing, even if it is grooved or PFC.

2.1.2.3 Sections 91.1037(c), (d), (e), and 135.385(f). Parts 91 and 135 operators that are authorized via operations specifications (OpSpecs) or management specifications (MSpecs) to use a Destination Airport Analysis program (such as a part 135 eligible-on-demand operator) may depart on a flight if preflight planning indicates that the aircraft will be able to perform a full stop landing within 80 percent of the effective runway length available. To determine the landing distance required, multiply the AFM approved landing distance by

1.25 or divide the AFM approved landing distance by 0.80. This factor assumes a dry runway condition at TOA.

Example: AFM approved landing distance = 3000 ft.

(3000’ x 1.25 = 3750’ or 3000’ ÷ 0.80 = 3750’.) In this example, to comply with the 80 percent rule, the appropriately authorized operator would need to confirm that the runway LDA at the planned destination is at least 3750 ft long.

Note: The 80 percent factored distance in most cases will not provide a safe landing margin if the runway is either wet or contaminated.

Operators must exercise extreme caution when preflight planning if the destination airport runway is either wet or contaminated.

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2.1.3 Overview. Table 2-1 below provides an overview of predeparture landing distance requirements.

Table 2-1. Regulatory Planned Dispatch Destination Airport Requirements Regulation Type of Airplane Runway Condition Percentage of Effective Runway Length § 121.195(b) § 135.375(a) § 135.385(b) § 91.1037(b) Large turbine/Large reciprocating engine powered Dry 60% § 121.195(c) § 135.385(c) Turboprop, Large turbine engine powered (excluding turbojet) Dry 70% § 121.195(d) § 135.385(d) § 91.1037(d) Turbojet without an approved AFM wet runway landing technique Wet/Slippery 115% of § 121.195(b) or § 135.385(b), or § 91.1037(d) AFM factored dry landing distance § 135.385(f) § 91.1037(c)(2) Large turbine powered, eligible on demand OpSpecs/MSpecs Authorized 80% § 121.197 § 135.387(a) § 91.1037(b) Large turbine engine powered, alternate airport Dry Turbojet airplanes: 60% Turbo-propeller: 70% § 121.197 § 135.387(a) § 135.375(b) Large turboprop/Large reciprocating engine, alternate airport Dry 70% § 135.387(b) § 91.1037(d) Large turbine powered, eligible on demand, alternate airport OpSpecs/MSpecs Authorized 80%

2.1.4 Part 91 Recommendations. Preflight planning requirements for part 91 operators are governed by §§ 91.103 and 91.605. (Section 91.1037 is only applicable to part 91K operators.) Although not required by regulation, we recommend that part 91 operators and pilots calculate predeparture landing distance performance requirements based on the guidance contained in their AFM.

2.2 AFM Landing Distance Data. Operators and pilots should flight plan using the best available information concerning expected destination runway conditions. The regulatory requirements referenced in this chapter are intended to represent a minimum level of compliance. Compliance with preflight planning regulations is accomplished by using approved data from the AFM.