Study guide
9.1 Takeoff Performance Speeds & Balanced Field Concept
FAA Aircraft Dispatcher Certificate ADX
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1 Chapter 1: Regulations, Certification & Operational Control
1.1 Part 65 Subpart C: Certification, Eligibility & Currency 1.2 Operational Control & Dispatcher-PIC Joint Responsibility 1.3 Domestic, Flag & Supplemental Operations Framework 1.4 Dispatch Release Elements, Signatures & Recordkeeping 1.5 Regulations, Manuals, Crew Qualifications, and Source Control
2 Chapter 2: Atmospheric Physics, Pressure Systems & Fronts
2.1 Atmospheric Structure, Standard Atmosphere & Altimetry 2.2 Air Masses, Frontal Systems & Frontogenesis 2.3 Atmospheric Stability, Lapse Rates & Cloud Formation 2.4 Earth Motion, Regional Weather, Local Winds, and Water Phase Changes
3 Chapter 3: Aviation Weather Hazards & Severe Weather Avoidance
3.1 Structural and Induction Icing: Types, Accretion & Operations 3.2 Thunderstorms, Squall Lines, Microbursts & Low-Level Windshear 3.3 Clear Air Turbulence (CAT), Mountain Waves & Jet Streams 3.4 Low Ceilings, Fog Types & Visibility Restrictions 3.5 Hurricanes, Typhoons, Tornadoes, and Tropical Dispatch Hazards
4 Chapter 4: Weather Observations, Forecasts & Advisories Decoding
4.1 METAR and SPECI Surface Observations: Decoding & Operations 4.2 Terminal Aerodrome Forecasts (TAF): Groups & Timing 4.3 Pilot Weather Reports (PIREP): Coding, Severity & Urgent Alerts 4.4 In-Flight Advisories: AIRMETs, SIGMETs & Convective SIGMETs 4.5 Weather Collection, NWS Facilities, GFA, and EWINS
5 Chapter 5: Aviation Weather Charts & Upper-Air Analysis
5.1 Surface Analysis & Radar Summary Charts 5.2 Constant Pressure Analysis & Winds Aloft (FB) 5.3 Significant Weather Prognostic Charts (SIGWX) 5.4 Satellite Imagery, Moisture-Stability Analysis, and Forecast Integration
6 Chapter 6: Air Navigation, Airspace Architecture & Route Structure
6.1 National Airspace System: Classes, Rules & Special Use 6.2 Ground-Based Navigation Aids & Standard Service Volumes 6.3 Area Navigation (RNAV), GNSS/GPS, PBN & RNP Fundamentals 6.4 En Route Airways, SIDs, STARs & Chart Interpretation 6.5 Earth Coordinates, UTC, Chart Projections, and Flight Instruments 6.6 North Atlantic, Pacific, RVSM, and Global Navigation Differences
7 Chapter 7: Instrument Approaches, Minimums & Airport Operations
7.1 Precision Approach Systems: ILS Categories & Tolerances 7.2 Non-Precision Approaches, RNAV & Decision Minimums (MDA/DA) 7.3 Takeoff Minimums, Lower-Than-Standard & Takeoff Alternates 7.4 Holding Procedures: Patterns, Speed Limits & Timing
8 Chapter 8: Subsonic Aerodynamics & Jet Aircraft Performance
8.1 Subsonic Jet Aerodynamics: Lift, Drag & Flight Regimes 8.2 High-Altitude Flight: Mach Number, Buffet & Coffin Corner 8.3 Transport Turbine Engines: Thrust, Specific Fuel & Bleed Air
9 Chapter 9: Transport Category Takeoff & Landing Runway Analysis
9.1 Takeoff Performance Speeds & Balanced Field Concept 9.2 Takeoff Climb Segments & Obstacle Clearance Gradients 9.3 Landing Performance: Field Lengths, 60% Rule & Contamination
10 Chapter 10: En Route Performance, Driftdown Profiles & ETOPS Operations
10.1 One/Two-Engine-Inoperative En Route Net Profiles & Driftdown 10.2 Extended-Range Operations (ETOPS): Philosophy & Regulations 10.3 ETOPS En Route Alternates: Adequate vs. Suitable & Critical Fuel
11 Chapter 11: Aircraft Weight & Balance, Center of Gravity, and Loading
11.1 Transport Aircraft Structural Weight Limits: Definitions & Rules 11.2 Center of Gravity Computations: Datum, Arm, Moment & Index 11.3 Mean Aerodynamic Chord (%MAC) Computations & Stability 11.4 Payload-Range Analysis, Zero Fuel Weight Tradeoffs & Loading
12 Chapter 12: Destination Alternate Airport Selection & Weather Rules
12.1 Destination Alternate Selection: 91.169 & Part 121 1-2-3 Rule 12.2 Flag & Supplemental Operations Destination Alternate Rules 12.3 Derived Alternate Minimums: 1-Nav and 2-Nav Facility Rules
13 Chapter 13: Part 121 Fuel Planning, Reserves & En Route Re-Release
13.1 Part 121 Domestic Fuel Requirements: Reserves & Calculations 13.2 Part 121 Flag Fuel Requirements: 10% Reserve & Island Rules 13.3 Supplemental Fuel Requirements & Holding Fuel Management 13.4 Redispatch and En Route Re-release Procedures
14 Chapter 14: Transport Systems, Pressurization & MEL/CDL Procedures
14.1 Transport Jet Auxiliary Power, Electrical, Hydraulic & Pneumatic Systems 14.2 Cabin Pressurization, Rapid Decompression & Oxygen Requirements 14.3 Master Minimum Equipment List (MMEL), MEL & CDL Procedures 14.4 Flight Controls, Autoflight, Fuel, Oil, Brakes, and Fire Protection
15 Chapter 15: Hazardous Materials, Duty Regulations & Emergency Procedures
15.1 Dangerous Goods Carriage by Air (49 CFR Part 175) & NOTOC 15.2 Dispatcher Duty Limitations, Rest Requirements & Fatigue 15.3 Emergency Authority, Declaration & Diversion Decision-Making 15.4 NTSB Part 830 Accident Reporting & Wreckage Preservation 15.5 Security, Overdue Aircraft, and FAA Emergency Services
16 Chapter 16: Communications, ATC, and Flight Plan Procedures
16.1 Voice, Data Link, Position Reports, and Lost Communications 16.2 ATC Facilities, Separation, ICAO Flight Plans, and Traffic Management
17 Chapter 17: Human Factors and Practical Dispatch Applications
17.1 Dispatch Resource Management, Human Error, and Risk Decisions 17.2 Manual Flight Planning, PIC Briefing, Flight Watch, and Postflight Closeout
9.1 Takeoff Performance Speeds & Balanced Field Concept
Key Takeaways Explain This Topic AI
§ 25.107 requires VEF ≥ VMCG and accounts for speed gained during the engine-failure recognition/action interval in the V1 lower bound.
VR is not less than V1 or 1.05 VMC, subject to additional approved takeoff constraints.
V2 stall-speed factors vary with the configurations specified in § 25.107; use the applicable AFM.
TORA, TODA, ASDA, and LDA have distinct purposes and must all be applied correctly.
Reduced thrust and fixed derates require the approved aircraft performance data and restrictions.
Last updated: October 2026
Takeoff Speeds and Runway Analysis
Transport-category takeoff planning uses approved AFM data to demonstrate both stopping and continuing capability under the applicable certification assumptions. The dispatcher compares the computed performance with runway declared distances, obstacles, weather, airplane configuration, and maintenance restrictions. A mnemonic such as “balanced field” describes one calculation concept; it does not replace the approved analysis or the crew's aircraft-specific rejected-takeoff procedure.
Define the speeds before using them
VEF is the speed at which the critical engine is assumed to fail for the performance calculation. V1 is the maximum speed by which the first action to stop must begin within accelerate-stop distance, and also relates to the minimum continuation speed after the assumed engine failure. VR is rotation speed. V2 is takeoff safety speed. VMCG and VMCA are minimum-control speeds on the ground and in the air. VMBE represents the brake-energy limitation used in applicable approved performance analysis.
Section 25.107(a) requires VEF not less than VMCG, and V1 not less than VEF plus the speed gained during the demonstrated interval between engine failure and the pilot's first stopping action. Thus the familiar VMCG ≤ V1 relationship is not a complete description of the lower bound. Section 25.107(e) makes VR no lower than V1 or 1.05 VMC, with further liftoff and screen-height requirements. Use the applicable AFM's speeds rather than calculating an operational V1 from only these two inequalities.
- Speed Planning significance
- VEF Assumed engine failure and subsequent recognition/action interval
- V1 Approved stopping/continuation decision framework
- VR Start of rotation, with control and liftoff constraints
- V2 Engine-inoperative takeoff climb safety speed
- VMCG / VMCA Ground / airborne controllability bounds
- VMBE Brake-energy restriction on the applicable rejected-takeoff calculation
Section 25.107(b) sets different V2min stall-speed factors for specified aircraft configurations, including 1.13 VSR in some cases and 1.08 VSR in others, together with the 1.10 VMC requirement and other constraints. Neither V2 = 1.13 VSR nor V2 = maximum L/D is a universal dispatch formula. Certification basis and aircraft design matter.
Engine failure and rejected takeoff
The certification model includes an assumed engine failure before V1 and the recognition/action interval. Consequently, “every failure before V1 means abort” is an inadequate training rule. Crews apply their approved rejected-takeoff policy, including whether the airplane can safely fly and whether a stop can be completed. A failure exactly at a particular displayed speed does not guarantee either an overrun or safe continuation regardless of other circumstances.
The dispatcher's task is to supply correct, applicable data and restrictions, not improvise cockpit memory actions. If the approved analysis cannot satisfy the applicable stopping, continuing, obstacle, or brake-energy requirements, change weight, runway, configuration, or the plan before departure. Do not infer that adding thrust alone cures every limiting condition.
Declared distances and screen height
TORA is takeoff run available. TODA adds the available clearway to TORA. ASDA adds a stopway to TORA. LDA is landing distance available. They may differ from the physical pavement length. A clearway is not stopping pavement; a stopway is not automatically landing runway. Check current airport data and NOTAMs before assigning credit.
Approved dry-runway takeoff-distance data generally include engine-inoperative distance to 35 feet and the applicable all-engine factor. Wet-runway data can use a 15-foot engine-inoperative screen-height provision with its associated requirements, including the required V2 achievement and subsequent obstacle analysis. This is not permission to discard the net takeoff flight path's obstacle clearance. Reverse-thrust credit also depends on the certification condition and approved data; do not import wet-runway credit into a dry-runway chart.
A clearway's usable credit is limited by the applicable operational rule and AFM analysis. The definition in § 1.1 describes its dimensions and obstacle plane; the statement that § 1.1 itself universally caps its usable length at 50 percent of TORA is incorrect. Identify the actual operational limit when applying clearway credit.
Balanced and unbalanced fields
A balanced field uses a decision speed for which the limiting accelerate-stop and engine-inoperative accelerate-go requirements are equal under the stated assumptions. Raising V1 generally increases the stopping distance and reduces the continuing distance; lowering it does the reverse. The optimum for a runway with unequal declared distances or significant obstacles may be unbalanced.
For an illustrative analysis, suppose approved data at a proposed weight give 7,000 feet accelerate-stop and 7,400 feet takeoff distance, while ASDA is 7,200 and TODA 7,300 feet. The stop requirement fits, but the takeoff-distance requirement does not. The flight is not acceptable merely because one comparison passes. A permitted V1 adjustment, weight reduction, or another runway must satisfy all applicable limits, including TORA and obstacles.
Reduced thrust and fixed derates
The assumed-temperature method selects thrust appropriate to an assumed temperature higher than actual temperature, within approved limitations. FAA AC 25-13 supplies certification guidance, including a maximum 25 percent reduction for reduced thrust relative to the approved takeoff thrust basis. A fixed derate is an approved lower rating with its own performance and control-speed data. The two methods are distinct and may be combined only as authorized.
Do not universalize airline-specific prohibitions about anti-skid, contamination, or windshear without consulting the AFM and approved procedures. These conditions can make reduced thrust unavailable or inappropriate; the controlling restriction is the approved aircraft/operation data. A fixed derate does not mean the crew is physically incapable of selecting higher thrust. Higher thrust can invalidate the lower control-speed assumptions, so follow the approved limitation and emergency procedures.
Practical verification
Before accepting a runway-analysis result, verify the airplane variant and engine rating, weight, pressure altitude, temperature, wind and gust treatment, runway slope and condition, flap setting, bleed/anti-ice configuration, inoperative equipment, and obstacle procedure. Confirm the output speed units and whether the data are dry, wet, or contaminated. A correct arithmetic result using the wrong configuration remains an incorrect dispatch decision.
Official References
Source check: 2026-10-12 . Transport performance certification ; Part 121 performance rules . For operational use, apply current issued authorizations and the assigned aircraft’s approved data.