9. RISK MITIGATION.
a. SOP. Specific SOPs to prevent a runway overrun are a primary risk mitigation tool.
Once SOPs are developed, it is imperative that the pilot/flightcrew execute them faithfully to mitigate a runway overrun. As a minimum, the SOPs should contain the factors presented in this AC.
b. Runway Overrun Mitigation Training Curriculum. An effective training program is the next tool that provides academic knowledge and skill to increase the pilot’s awareness of the factors that can cause a runway overrun. At a minimum, the operator’s training program should include the same elements contained in their SOP. Also, the go-around maneuver and the reasons to initiate a go-around maneuver must be part of their training. (Refer to SAFO 10005.)
NOTE: Operators should also incorporate this training into their pilot and dispatcher training for operations conducted in accordance with 14 CFR parts 91, 91 subpart K (part 91K), 121, 125, 135, 141, and 142. Further, all independent certificated flight instructors (CFI) should also provide this training to the pilots they train.
c. Flight Checking and Recurrent Training. Checking, testing, and recurrent training that emphasizes airplane landing performance are essential tools to mitigate runway overruns.
Designated Pilot Examiners (DPE), flight and ground instructors, check airmen, and dispatch examiners should specifically stress ADM, runway overrun risk management scenarios, and the elements within this AC as they qualify, train pilots, flightcrews, and dispatchers to exercise the privileges of their certificate. Trainers and examiners must include runway overrun mitigation strategies during training and checking to ensure the pilot/applicant can apply the principles in a real-world environment.
NOTE: The following appendices provide additional information for operators and pilots to develop SOPs, training programs, pilot techniques, and a case study.
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.
Par 9 Page 11 (and 12)
Appendix 1 APPENDIX 1. SUGGESTED PROCEDURES AND TRAINING INFORMATION
1. ORGANIZATION. This appendix divides the discussion of runway overruns during the landing phase of flight into the following broad categories:
• Definitions;
• The necessity to fly a stabilized approach to the touchdown aiming point;
• A discussion of landing performance data; and
• Landing and braking techniques.
2. DEFINITIONS. The following, though not all inclusive, are definitions of landing elements that form the foundation for a successful landing.
a. Declared Runway Distance. Declared distances for a runway represent the maximum distances available and suitable for meeting takeoff and landing distance performance requirements. All Title 14 of the Code of Federal Regulations (14 CFR) part 139 airports report declared distances for each runway. For runways without published declared distances, the declared distances may be assumed to be equal to the physical length of the runway unless there is a displaced landing threshold. (Refer to the Aeronautical Information Manual (AIM) for more information.)
b. Landing Distance Available (LDA). The length of the runway declared available for landing. This distance may be shorter than the full length of the runway due to a threshold displacement.
c. Actual Landing Distance. The landing distance for the reported meteorological and runway surface conditions, runway slope, airplane weight, airplane configuration, approach speed, use of autoland or a Head-Up-Guidance System (HGS), and ground deceleration devices planned to be used for the landing. It does not include any safety margin, and represents the best performance the airplane is capable of for the conditions. (Refer to Safety Alert for Operators (SAFO) 06012, Landing Performance Assessments at Time of Arrival (Turbojets), for more information.)
d. Braking Action Reports. When available, air traffic control (ATC) furnishes pilots the quality of braking action received from pilots. The quality of braking action is described by the terms “good,” “good to medium,” “medium,” “medium to poor,” “poor,” and “nil.” When pilots report the quality of braking action by using the terms noted above, pilots should use descriptive terms that are easily understood, such as “braking action is poor the first/last half of the runway,” and include the type of airplane. When tower controllers have received runway braking action reports which include the terms “medium,” “medium to poor,” “poor,” or “nil,” or whenever weather conditions are conducive to deteriorating or rapidly changing runway braking conditions, the tower will include on the Automatic Terminal Information Service (ATIS) broadcast the statement, “Braking Action Advisories are in Effect.” (Refer to the AIM for more information.) See Table 1-1, Pilot/Aircraft Operator Operational Runway Condition Assessment Matrix (RCAM) Braking Action Codes and Definitions. (See the notes below Table 1-1 for clarification and information of terms and addition of codes.)
Appendix 1 TABLE 1-1. PILOT/AIRCRAFT OPERATOR OPERATIONAL RUNWAY CONDITION
ASSESSMENT MATRIX (RCAM) BRAKING ACTION CODES AND DEFINITIONS Assessment Criteria Control/Braking Assessment Criteria Runway Condition Description RwyCC Deceleration or Directional Control Observation Pilot Reported Braking Action
• Dry 6 --- ---
• Frost
• Wet (Includes damp and 1/8 inch depth or less of water) 1/8 Inch (3mm) Depth or Less of:
• Slush
• Dry Snow
• Wet Snow 5 Braking deceleration is normal for the wheel braking effort applied AND directional control is normal.
Good -15 ºC and Colder Outside Air Temperature:
• Compacted Snow 4 Braking deceleration OR directional control is between Good and Medium.
Good to Medium
• Slippery When Wet (wet runway)
• Dry Snow or Wet Snow (any depth) over Compacted Snow Greater Than 1/8 Inch (3 mm) Depth of:
• Dry Snow
• Wet Snow Warmer Than -15 ºC Outside Air Temperature:
• Compacted Snow 3 Braking deceleration is noticeably reduced for the wheel braking effort applied OR directional control is noticeably reduced.
Medium Greater Than 1/8 Inch (3 mm) Depth of:
• Water
• Slush 2 Braking deceleration OR directional control is between Medium and Poor.
Medium to Poor
• Ice 1 Braking deceleration is significantly reduced for the wheel braking effort applied OR directional control is significantly reduced.
Poor
• Wet Ice
• Slush over Ice
• Water over Compacted Snow
• Dry Snow or Wet Snow over Ice 0 Braking deceleration is minimal to nonexistent for the wheel braking effort applied OR directional control is uncertain.
Nil Note 1: The unshaded portion of the RCAM (Assessment Criteria columns) is associated with how an airport operator conducts a runway condition assessment.
Note 2: The shaded portion of the RCAM (Control/Braking Assessment Criteria columns) is associated with the pilot’s experience with braking action.
Note 3: The Pilot/Aircraft Operator Operational RCAM illustration will differ from the RCAM illustration used by airport operators.
Note 4: The RCAM illustration used by airport operators in AC 150/5200-30, Airport Field Condition Assessments and Winter Operations Safety, is not intended for use by pilots and/or aircraft operators.
Note 5: Runway condition codes (RwyCC), one for each third of the landing surface (e.g., 4/3/3), represent the runway condition description as reported by the airport operator.
Appendix 1
e. Aiming Point. The aiming point is the point at which the airplane would contact the ground if it maintains a constant glidepath and does not execute the round out (flare) maneuver for landing.
f. Maximum Braking Effort. Maximum braking effort is defined as maximum brake application by the pilot and/or autobrakes.
g. Adjusted Landing Distance. The actual landing distance adjusted for a landing safety margin in accordance with the operator’s standard operating procedures (SOP). This should not be confused with the landing distance associated with the dispatch requirements.
h. Target Touchdown Point. As discussed in FAA-H-8083-3, Airplane Flying Handbook, the target touchdown point is defined as a touchdown point approximately 1,000 ft down the runway. Additionally, the operator may define the desired target touchdown point in their SOP.
i. Touchdown Zone (TDZ). As referenced in FAA-S-8081-5, Airline Transport Pilot and Aircraft Type Rating Practical Test Standards for Airplane, the TDZ is referred to as a point 500-3,000 ft beyond the runway threshold not to exceed the first one-third of the runway.
This reference is not used in landing distance performance calculations.
j. Unfactored or Certified Landing Distance. The landing distance determined during certification as required by 14 CFR part 23, § 23.2130, and part 25, § 25.125. The unfactored landing distance is not adjusted for any safety margin additives. The unfactored certified landing distance may be different from the actual landing distance because not all factors affecting landing distance are required to be accounted for by certification regulations. For example, the unfactored certified landing distances are based on a dry, level (zero slope) runway at standard day temperatures, and do not normally take into account the use of autobrakes, autoland systems, HGS, or thrust reversers. This is considered the baseline landing distance from which all subsequent user calculations emanate.
k. Factored Landing Distance. For applicable operations, the dispatch landing distance allows the airplane to land and stop within 60 percent of the available runway when the runway is dry. The factored landing distance is the certified landing distance multiplied by 1.67, which can then be compared directly to the available landing distance. When the runway is wet, the certified distance is multiplied by 1.92 to account for the 15 percent additional runway requirement.
3. STABILIZED APPROACH TO THE TOUCHDOWN AIMING POINT. A stabilized approach is the safest profile, and it is one of the most critical elements to ensure a safe approach to a landing operation.
Appendix 1 FIGURE 1-1. STABILIZED APPROACH
NOTE: The approach descent rate will vary given the airplane’s groundspeed as a result of the required approach speed per the Airplane Flight Manual (AFM), weight, and wind additives.
a. Landing Configuration. The airplane should be in the landing configuration early in the approach. The landing gear should be down, landing flaps selected, trim set, and fuel balanced per the AFM or pilot’s operating handbook (POH). Landing checklist items should be completed. Ensuring that these tasks are completed will help keep the number of variables to a minimum during the final approach.
b. Stabilized on Profile. The airplane should be stabilized on profile before descending through the 1,000-ft window or through the 500 ft above touchdown zone elevation (TDZE) window in visual meteorological conditions (VMC). Configuration, trim, speed, and glidepath should be at or near the optimum parameters early in the approach to avoid distractions and conflicts as the airplane nears the threshold window. The electronic or visual glidepath or an optimum glidepath angle of 3 degrees should be established and maintained. For the purposes of this AC, approaches that require a glidepath angle greater than 3 degrees are a “special case.”
The airplane must be in the proper landing configuration, on the correct lateral track, the correct vertical track and at the proper airspeed. It should be noted, as it applies to stabilized approaches, that following lateral and vertical tracks should require only normal bracketing corrections.
NOTE: An approach that requires abnormal bracketing does not meet the stabilized approach concept, and a go-around should be initiated.
c. Descent Rate. The optimum descent rate for a 3-degree approach path is based upon the airplane’s groundspeed. A pilot must exercise discipline and situational awareness to maintain the airplane’s target approach speed. The following is a method to estimate the appropriate P age 4
Appendix 1 descent rate for a 3-degree descent path: Multiplying the groundspeed in knots (kts) by 5 provides a usable target 3-degree descent rate in feet per minute (fpm). Combined with disciplined airspeed control, slight adjustments in the rate of descent to maintain the glidepath will ensure flying the descent/instrument landing system (ILS) glidepath. For example, see Table 1-2 below and refer to the ILS approach chart.
TABLE 1-2. RATES OF DESCENT ESTIMATE CONCEPT FOR 3-DEGREE GLIDEPATH VS. GROUNDSPEED Groundspeed kts 70 90 100 120 140 160 Published 3° GS fpm 372 478 531 637 743 849 5×GS estimated fpm 350 450 500 600 700 800
d. Indicated Airspeed. Indicated airspeed should be not more than VREF + 5 or the POH published approach airspeed, with appropriate adjustments for wind or other factors, and never less than VREF or the appropriate airspeed in order to avoid the loss of aircraft control. There is a strong relationship between trim, speed, and power, and it is important to stabilize the speed in order to minimize those variables.
e. Turbojet Engine Speed. The engine speed should be at a setting that allows best response when and if a rapid power increase is needed. The stabilized approach parameters should be confirmed at 500 ft (VMC) or 1,000 ft (instrument meteorological conditions (IMC)) above airport TDZE. This is approximately 1 to 2 minutes from touchdown. If the approach is not stabilized at that altitude, a go-around/balked landing should be executed.
f. Touchdown Point. Approach speed, flare, and runway slope are factors that affect pilot control of the touchdown point. Turbine airplanes should be flown onto the runway rather than being held off the surface as speed dissipates. A firm landing is both normal and desirable.
The typical operational touchdown point is in the first third of the runway, and it may be farther down the runway than the 1,000-ft. aiming point. This additional distance should be accounted for in the landing distance assessment at time of arrival (TOA).
g. Downhill Runway Slope. Additionally, a negative runway slope affects the touchdown point. According to the Flight Safety Foundation (FSF) Approach and Landing Accident Reduction (ALAR) Briefing Note 8.3, Landing Distances, each 1 percent of downhill runway slope increases the landing distance by 10 percent. Depending upon the airplane’s manufacturer, runway slope may be included in the AFM/POH landing performance data.
Appendix 1 TABLE 1-3. SAMPLE INCREASE IN LANDING DISTANCE COMPUTATION
IF RUNWAY SLOPE IS NOT INCLUDED IN THE AFM/POH LANDING PERFORMANCE DATA, WITH A RUNWAY LENGTH OF 7,000 FEET Elevation of Approach end of runway 1,310’ Elevation of Rollout end of runway -1,240’ 70’difference between approach end of runway and roll out end of the runway.
Example: Per the AFM, the landing distance for this runway is 3,500 feet. Therefore, Runway gradient = 70’/7,000 × 100% = 1% downhill gradient.
• A 1% downhill gradient = 10% increase in landing distance required. (Each 1% of down slope increases the landing distance by 10%.)
• Adjusted runway landing distance is: 3,500’ × 1.1 = 3,850 feet (a landing distance increase of 350 feet).
• However, if the downhill slope were 3%, then the downhill gradient increases the landing distance by 30%, which equates to: 3,500 × 1.3 = 4,550 feet (a 1,050 foot landing distance increase).
NOTE: Per FSF ALAR Briefing Note 8.3, this effect is accounted for in landing performance computations only if the downhill runway slope exceeds 2 percent. Be sure to check your aircraft’s AFM/POH to determine if runway slope is included in the landing distance performance computation.
NOTE: When computing runway gradient, every 1 percent grade equals approximately 10 percent change in effective runway length. Also, for shorter runways, it does not take as large an elevation difference between runway ends to result in a 3 percent gradient. For example, for a 3 percent gradient for a 3,000-ft runway, the elevation difference between the runway ends would only be 90 ft.
h. Factors That Contribute to an Unstabilized Approach.
(1) An ATC clearance that requests an airspeed in excess of those airspeeds normally flown in the terminal area, and/or clearances that require an airplane to remain at altitude to a point where intercepting the normal glidepath is difficult to achieve, pilots should be aware that if they cannot achieve a stabilized approach profile, to advise ATC.
NOTE: A stabilized approach to landing is key to mitigating the risk of a runway overrun. If the pilot determines that a stabilized approach cannot be flown, the approach should not be accepted and a go-around should be initiated.
(2) It is paramount that the airplane arrives at the approach threshold window on speed.
If the pilot has planned to carry additional airspeed beyond the threshold due to gusty surface Page 6
Appendix 1 wind conditions, then the effect of this additional airspeed/groundspeed should be included in the actual landing distance. A balked landing maneuver should be executed if the airplane does not cross the runway threshold at the planned airspeed.
NOTE: A 10 percent excess landing speed causes at least a 21-percent increase in landing distance. The excess speed places a greater working load on the brakes because of the additional kinetic energy to be dissipated.
Also, the additional speed causes increased drag and lift in the normal ground attitude, and the increased lift reduces the normal force on the braking surfaces. The deceleration may suffer during this range of speed immediately after touchdown, and it is more probable for a tire to be blown out from braking at this point.
4. DISCUSSION OF LANDING DATA.
a. Landing Performance Assessment. Landing performance assessment is influenced by a multitude of variables. Airplane weight and configuration, use of deceleration devices, airport elevation, atmospheric temperature, wind, runway length, runway slope, and runway surface condition (i.e., dry, wet, contaminated, improved, unimproved, grass, etc.) are all factors in determining landing performance. The condition of airplane tires, brakes, and systems installed/operative/inoperative (e.g., antiskid braking, propeller reversing, thrust reversers, etc.), and pilot abilities/technique all have a direct impact on the airplane’s ability to come to a full stop after touchdown. However, there is no one standard format in which airplane manufacturers are required to provide this additional data. The pilot must be aware of the airplane’s landing data/performance. The pilot must also obtain the most current runway condition information within a reasonable time before initiating the approach phase of flight in order to assess the airplane operational landing distance to ensure that it does not exceed the LDA. To begin the assessment process of landing performance, we need to first address some basic principles of landing performance.
b. Data Provided. The data provided in the AFM/POH may only provide unfactored landing data, which does not reflect operational landing distances. The AFM landing data for most large airplanes operated in accordance with 14 CFR part 121 provide factored landing distances. Some manufacturers provide advisory or supplemental performance data in the AFM/POH which may account for conditions such as a dry runway, a wet runway, ground spoilers operative/inoperative, thrust reversers operative/inoperative, antiskid operative/inoperative, propeller reverse, tailwind, and/or headwind. Also, it is very important to understand that the factors that affect the stopping ability of an airplane are cumulative.
c. AFM Performance Section. The following includes general examples of aircraft performance factors required for certification, and inclusion in the airplane’s AFM. Landing performance is of primary interest in operating an airplane because it is a factor in defining the runway length requirements. In addition to the importance of proper piloting technique, any factor that affects the landing velocity or deceleration during the landing roll will affect landing distance.
Appendix 1
(1) Factors Required to be Included in the Performance Charts:
• Pressure altitude,
• Standard temperature,
• Gross weight,
• Wind, and
• Airplane configuration.
(2) For Small Airplane Operation on Unpaved Runway Information. For airplanes less than 6,000 pounds (2,730 kg) maximum weight, the factors given below may be quoted in the flight manual as an alternative to the scheduling of data derived from testing or calculation.
It should be noted that these factors are intended to cover the range of airplane types in this category and are necessarily conservative (refer to AC 23-8, Flight Test Guide for Certification of Part 23 Airplanes).
TABLE 1-4. SMOOTH, FLAT RUNWAY Takeoff Landing Dry Grass 1.2 1.2 Wet Grass 1.3 1.6 NOTE: If the runway is not smooth, or the grass is very long or very short, higher factors may be warranted. Very short grass = golf course length. Very long grass = unmowed field or high interstate highway median grass length.
(3) Landing Distances for Large Transport Airplanes. Landing distances for large transport airplanes determined during certification tests are aimed at demonstrating the shortest performance distances for a given airplane weight with a test pilot at the controls. In addition, they are established with full awareness that operational rules for normal operations require the addition of factors to determine minimum operational field lengths. Therefore, the landing distances determined for large airplanes under § 25.125 are much shorter than the landing distances achieved in normal operations. For small airplanes, § 23.2130 prescribes the requirements to certify a small airplane landing performance (refer to AC 23-8). Though the factors of weight, speed, and pressure altitude are considered, the factors that extend the landing distance are not included. Therefore, given the factors that increase the airplane’s required landing distance, the pilot/operator should seriously consider the consequence of not assessing the landing distance required.
(4) Air Carriers and 14 CFR Part 91 Subpart K (Part 91K) Operators. To mitigate the risk of a runway overrun, air carriers and part 91K operators are required by regulation to multiply the airplane’s actual landing distance by a specified factor associated with a destination or alternate airport. All operations must mitigate the risk of a runway overrun by considering all the elements that affect the unfactored landing distance provided in the AFM/POH. This is to ensure that at the TOA, the landing distance required will not exceed the LDA. (For examples, Page 8
Appendix 1 refer to the applicable part 91, § 91.1037; part 121, § 121.195; and part 135, § 135.385 for more information.)
NOTE: It is strongly recommended that operators adopt a factored landing distance methodology.
d. Minimum Landing Distance Prediction. In the prediction of minimum landing distance from the AFM/POH data, the following should be addressed (see paragraph 4 above and the sample cumulative landing distance worksheets in Appendix 3, Operational Awareness of Wet and Contaminated Runways Landing Distance Data, for more information):
• High airport elevation or high Density Altitude (DA), resulting in increased groundspeed;
• Landing weight;
• Excess airspeed over the runway threshold;
• Landing beyond the intended touchdown point;
• Runway slope;
• Excessive height over the runway threshold;
• Delayed use of deceleration devices;
• Tailwind landing; and
• A wet or contaminated runway.
e. The Effect of Wind on Landing Performance. Figure 1-2, Effect of Wind on Landing Performance, illustrates the general effect of wind by showing the percent change in takeoff or landing distance as a function of the ratio of wind velocity to takeoff or landing speed.
For example, a tailwind velocity that is 10 percent of the landing airspeed produces a general effect of a 21-percent increase in the landing distance. (Refer to FAA-H-8083-25, Pilot’s Handbook of Aeronautical Knowledge, Chapter 11, Aircraft Performance.)
NOTE: If the wind direction is variable and a range is given, the value that provides the most negative condition must be used in performance calculations. If no range is given, the full value of the wind velocity must be considered a tailwind, since the possibility of this exists on landing.
Appendix 1 FIGURE 1-2. EFFECT OF WIND ON LANDING PERFORMANCE 80 Percent increase in takeoff or landing distance 40 Ratio of wind velocity to takeoff or landing speed 10 30% 20% 10% Lailwind Head wind 10% -20% -30÷% 10 Ratio of wind 20 velocity to takeoff or landing speed 30 Percent decrease 50 in takeoff or 60 landing distance FIGURE 1-3. BASIC LANDING DISTANCE CHART Flaps lowered to 40° LANDING DISTANCE Power off Hard surface runway Zero wind Gross weight Approach speed IAS. MPH Ground roll At sea level & 59 °F Total to clear 50 ft OBS Ground roll At 2,500 ft & 59 °F Total to clear 50 ft OBS Ground roll At 5,000 ft & 41 °F Total to clear 50 ft OBS Ground roll At 7,500 ft & 32 °F Total to clear 50 ft OBS 1,600 60 445 1,075 470 1,135 495 1,195 520 1,255
1. Decrease the distances shown by 10% for each 4 knots of headwind croperation on a dey grass runway, Increase distances born ground roi and total to clear so ff obstacle by 20% of the "total to clear so ff obstacle figur or operation on a dry, grass runway, Increase Page 10
Appendix 1 FIGURE 1-4. CUMULATIVE TYPE OF LANDING CHART PLOTTING
DENSITY ALTITUDE, LANDING WEIGHT, HEADWIND/TAILWIND,
AND OBSTACLE CLEARANCE 3,500 Associated conditions line Weight at 50 feet Speed Reference line Power Retarded to maintain (pounds) Kts MPH - 3,000 900 feet/on final approach Flaps Down 2,950 70 80 Referer Landing gear Down 2,800 68 78 Runway Paved, level, dry surtace 2,600 65 • 2,500 Approach speed IAS as tabulated 2,400 63 Braking Maximum 2,200 60 69 2,000 1,500 1,000 500 C -40°-30° -20°-10° 0° 10% 20° 30° 40° 50= 2,800 2,600 2,400 2,200 0 10 20 30 0 50 Outside air temperature Weight Wind component Obstacle (pounds) (knots) height (feet) F -40° -20° 0° 20° 40° 60°
f. Stabilized Approach. Without the benefit on an AFM/POH performance chart that accounts for the variables this AC is discussing, the concept in Figure 1-1, Stabilized Approach, provides an appreciation of the factors that increase the airplane's landing distance, and it keeps the pilot engaged in landing distance assessment.
(1) Figure 1-2 illustrates the general effect of wind by showing the percent change in takeoff or landing distance as a function of the ratio of wind velocity to takeoff or landing speed.
(2) Figure 1-4, Cumulative Type of Landing Chart Plotting Density Altitude, Landing Weight, Headwind/Tailwind, and Obstacle Clearance, provides the manufacturer's airplane performance data accounting for DA, landing weight, wind, and Obstacle Clearance Height (OCH). It also illustrates a performance chart which plots the cumulative effect of each condition as the pilot progresses to obtain the landing distance.
g. Airplane Landing Weight. Calculate the anticipated landing weight by starting with the airplane gross takeoff weight (GTOW) at departure and subtracting the anticipated normal consumption of fuel required to arrive at the destination airport. If the en route fuel burn is less than planned, the airplane will arrive at its destination at a weight heavier than expected.
Therefore, relative to the airplane's actual landing weight, a recalculation of the airplane's landing performance is essential prior to attempting a landing maneuver to validate the dispatched LDA.
h. Extended Flaps. Flaps may be fully extended to give the airplane a lower stalling speed during the approach to landing. This also allows the airplane to land in a shorter distance.
The higher lift and drag associated with fully extended flaps produces greater drag, permitting a steeper approach. The greater lift permits a lower landing speed to the landing site but imposes Page 11