Calculation-Source Register
Every calculator on FlightCalculators.com is backed by a published, authoritative source. This register lists each calculator’s primary source, the exact edition or effective date we consulted, the formula method used, the key assumptions or limitations, and the date we last validated it. It is generated from the same data that drives our methodology and sources pages, so the three always stay in sync.
Showing 29 of 29 calculators.
| Calculator | Primary Source | Edition / Date | Formula Method | Assumptions | Last Validated |
|---|---|---|---|---|---|
| Density Altitude Calculator Atmospheric & Performance | Manual of the ICAO Standard Atmosphere (extended to 80 km) | Doc 7488/3, 3rd Edition (1993) | ISA lapse-rate derivation with NWS density-altitude approximation; optional Bolton 1980 humidity correction | Standard lapse rate (1.98 °C/1000 ft); approximation less exact at temperature/altitude extremes. | 2026-08-03 |
| Pressure Altitude Calculator Atmospheric & Performance | Manual of the ICAO Standard Atmosphere (extended to 80 km) | Doc 7488/3, 3rd Edition (1993) | Standard-atmosphere altimeter-setting correction (1 inHg ≈ 1000 ft) | Assumes standard pressure lapse near sea level; field elevation entered by the user. | 2026-08-03 |
| True Airspeed (TAS) Calculator Atmospheric & Performance | Manual of the ICAO Standard Atmosphere (extended to 80 km) | Doc 7488/3, 3rd Edition (1993) | Density-ratio method: TAS = CAS / √(density ratio) from the standard-atmosphere model | CAS approximated from IAS plus a user calibration correction; compressibility ignored at low speeds. | 2026-08-03 |
| Crosswind Calculator Navigation & Magnetic Models | Wind-triangle (vector) navigation method | Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Ch. 16 (2023) | Trigonometric decomposition: headwind = V·cosθ, crosswind = V·sinθ | Steady wind; angle measured between runway heading and wind direction. | 2026-08-03 |
| True Altitude Calculator Regulatory | AC 91-105 / AIM 7-2 — altimeter procedures and cold-temperature error | Current as of 2026-07-30 | Non-standard-temperature altitude correction (ICAO cold-temperature method) | Correction grows with height above the reporting station; based on reported station temperature. | 2026-07-30 |
| Mach Number Calculator Atmospheric & Performance | Manual of the ICAO Standard Atmosphere (extended to 80 km) | Doc 7488/3, 3rd Edition (1993) | Local speed of sound from OAT; Mach = TAS / a, solved in both directions | Speed of sound depends on temperature only; assumes dry air. | 2026-08-03 |
| Pilot Currency Calculator Regulatory | 14 CFR Part 61 — Certification: Pilots, Flight Instructors, and Ground Instructors | e-CFR, current as of 2026-07-30 | Rule-based date arithmetic against FAR 61.56 / 61.57 recency windows | Reflects Part 61 as of the review date; does not track individual logbook endorsements. | 2026-07-30 |
| Medical Certificate Expiration Calculator Regulatory | 14 CFR Part 61 — Certification: Pilots, Flight Instructors, and Ground Instructors | e-CFR, current as of 2026-07-30 | Rule-based date arithmetic per 14 CFR 61.23 class/age rules and BasicMed validity | Based on 14 CFR 61.23 as of the review date; age on exam date governs duration. | 2026-07-30 |
| Standard Atmosphere Calculator & Table Atmospheric & Performance | Manual of the ICAO Standard Atmosphere (extended to 80 km) | Doc 7488/3, 3rd Edition (1993) | ICAO standard-atmosphere equations for temperature, pressure, density, density ratio, and speed of sound | Standard-day conditions; troposphere model below 36,089 ft. | 2026-08-03 |
| Fuel Burn Calculator Atmospheric & Performance | Pilot’s Handbook of Aeronautical Knowledge | FAA-H-8083-25C (2023) | Fuel = burn rate × time, plus reserve and contingency allowances | Constant burn rate entered by the user; does not model climb/cruise/descent phases separately. | 2026-08-03 |
| Endurance Calculator Atmospheric & Performance | Pilot’s Handbook of Aeronautical Knowledge | FAA-H-8083-25C (2023) | Endurance = usable fuel / burn rate, with reserve-adjusted safe endurance | Constant burn rate; usable fuel entered by the user. | 2026-08-03 |
| Reserve Fuel Calculator Regulatory | 14 CFR Part 91 — General Operating and Flight Rules | e-CFR, current as of 2026-07-30 | FAR 91.151 / 91.167 reserve requirements applied to a user-entered burn rate | Reflects Part 91 as of the review date; day VFR / night VFR / IFR selected by the user. | 2026-07-30 |
| Aircraft Range Calculator Atmospheric & Performance | Pilot’s Handbook of Aeronautical Knowledge | FAA-H-8083-25C (2023) | Range = groundspeed × (usable−reserve fuel) / burn rate, with optional wind comparison | Constant cruise groundspeed and burn; wind applied as a steady component. | 2026-08-03 |
| Weight & Balance Calculator Aircraft Data | Cessna 172S Skyhawk SP Pilot’s Operating Handbook | Revision 4 (2006), Part No. 172SPHBUS-00 | Moment method: CG = Σ(weight × arm) / Σ weight, per aircraft profile | Built-in arms/limits are representative POH values — verify against your airplane’s weighing record. | 2026-07-30 |
| CG Envelope Checker Aircraft Data | Cessna 172S Skyhawk SP Pilot’s Operating Handbook | Revision 4 (2006), Part No. 172SPHBUS-00 | Point-in-polygon test of the loaded CG against the published envelope | Envelope coordinates are representative POH values — verify against your airplane’s POH. | 2026-07-30 |
| Useful Load & Payload Calculator Atmospheric & Performance | Pilot’s Handbook of Aeronautical Knowledge | FAA-H-8083-25C (2023) | Useful load = max gross weight − empty weight; full-fuel payload derived from fuel weight | Empty weight and max gross entered by the user from their weighing record. | 2026-08-03 |
| Wind Correction Angle Calculator Navigation & Magnetic Models | Wind-triangle (vector) navigation method | Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Ch. 16 (2023) | Wind-triangle solution for WCA, true heading, and groundspeed | Steady wind; true course and TAS entered by the user. | 2026-08-03 |
| Digital E6B Flight Computer Navigation & Magnetic Models | Wind-triangle (vector) navigation method | Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Ch. 16 (2023) | Digital E6B aggregating TSD, fuel, TAS, wind, density altitude, and unit methods | Each tab inherits the assumptions of its standalone calculator. | 2026-08-03 |
| Time-Speed-Distance Calculator Navigation & Magnetic Models | Wind-triangle (vector) navigation method | Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Ch. 16 (2023) | Algebraic solution of distance = speed × time for any unknown | Constant groundspeed over the leg. | 2026-08-03 |
| Magnetic Variation Calculator Navigation & Magnetic Models | World Magnetic Model (WMM) | WMM2025, epoch 2025.0, valid 2025.0–2030.0 | World Magnetic Model field evaluation at the entered coordinate/date | WMM2025 valid 2025.0–2030.0; a warning is shown if the model epoch is expired. | 2026-07-30 |
| Top of Descent Calculator Atmospheric & Performance | Pilot’s Handbook of Aeronautical Knowledge | FAA-H-8083-25C (2023) | Descent geometry from altitude to lose, descent rate/angle, and groundspeed | Constant descent rate and groundspeed; still-air geometry. | 2026-08-03 |
| Required Rate of Climb/Descent Calculator Atmospheric & Performance | Pilot’s Handbook of Aeronautical Knowledge | FAA-H-8083-25C (2023) | Required rate (ft/min) and gradient (ft/nm) from altitude change, distance, and groundspeed | Constant groundspeed; ODP/climb-gradient guidance is advisory only. | 2026-08-03 |
| Airspace Calculator Regulatory | National Airspace System Resource (NASR) subscription data | 28-Day NASR Subscription, effective 2026-08-01 | Point-in-geometry test against NASR Class B/C/D/E boundaries with MSL/AGL interpretation | Reflects the 28-day NASR cycle effective on the review date; not a substitute for current charts. | 2026-08-01 |
| Flight Category Checker Weather & Meteorology | Flight-category (VFR/MVFR/IFR/LIFR) ceiling and visibility thresholds | AIM and NWS Aviation Weather Center definitions, current as of 2026-07-30 | Threshold comparison of ceiling and visibility against VFR/MVFR/IFR/LIFR limits | Uses standard AIM/NWS thresholds; ceiling and visibility entered by the user. | 2026-08-03 |
| Cloud Base Calculator Weather & Meteorology | Convective condensation level (Espy’s) approximation for cumulus cloud base | Standard meteorological approximation (≈ 400 ft per °C of temperature–dewpoint spread) | Convective condensation approximation: base ≈ spread × 400 ft | Applies to convective (cumulus) cloud only; not valid for stratiform or frontal cloud. | 2026-08-03 |
| METAR Decoder Regulatory | Aeronautical Information Manual (AIM) | Basic dated 2024, Change 1 (current as of 2026-07-30) | Text parsing of METAR fields into plain-language output | Decodes standard FAA/ICAO METAR format; not a substitute for an official briefing. | 2026-08-03 |
| Relative Humidity Calculator Weather & Meteorology | Bolton, D. — “The Computation of Equivalent Potential Temperature” (saturation vapor pressure formula) | Monthly Weather Review, Vol. 108, No. 7, pp. 1046–1053 (1980) | Relative humidity from temperature/dewpoint via Bolton 1980; carburetor-icing risk from the AC 61-23C chart | Vapor-pressure approximation; icing indicator is advisory. | 2026-07-30 |
| Freezing Level Calculator Atmospheric & Performance | Manual of the ICAO Standard Atmosphere (extended to 80 km) | Doc 7488/3, 3rd Edition (1993) | Linear extrapolation of surface temperature to the 0 °C level using a lapse rate | Assumes a constant lapse rate; actual inversions and moisture layers not modeled. | 2026-08-03 |
| Precipitation Type Estimator Atmospheric & Performance | Pilot’s Handbook of Aeronautical Knowledge | FAA-H-8083-25C (2023) | Vertical-temperature-profile heuristic for rain / snow / ice pellets / freezing rain | Educational estimator from a simplified profile — not a forecast. | 2026-08-03 |
Density Altitude Calculator
Atmospheric & Performance
- Primary Source
- Manual of the ICAO Standard Atmosphere (extended to 80 km)
- Edition / Date
- Doc 7488/3, 3rd Edition (1993)
- Formula Method
- ISA lapse-rate derivation with NWS density-altitude approximation; optional Bolton 1980 humidity correction
- Assumptions
- Standard lapse rate (1.98 °C/1000 ft); approximation less exact at temperature/altitude extremes.
- Last Validated
- 2026-08-03
Pressure Altitude Calculator
Atmospheric & Performance
- Primary Source
- Manual of the ICAO Standard Atmosphere (extended to 80 km)
- Edition / Date
- Doc 7488/3, 3rd Edition (1993)
- Formula Method
- Standard-atmosphere altimeter-setting correction (1 inHg ≈ 1000 ft)
- Assumptions
- Assumes standard pressure lapse near sea level; field elevation entered by the user.
- Last Validated
- 2026-08-03
True Airspeed (TAS) Calculator
Atmospheric & Performance
- Primary Source
- Manual of the ICAO Standard Atmosphere (extended to 80 km)
- Edition / Date
- Doc 7488/3, 3rd Edition (1993)
- Formula Method
- Density-ratio method: TAS = CAS / √(density ratio) from the standard-atmosphere model
- Assumptions
- CAS approximated from IAS plus a user calibration correction; compressibility ignored at low speeds.
- Last Validated
- 2026-08-03
Crosswind Calculator
Navigation & Magnetic Models
- Primary Source
- Wind-triangle (vector) navigation method
- Edition / Date
- Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Ch. 16 (2023)
- Formula Method
- Trigonometric decomposition: headwind = V·cosθ, crosswind = V·sinθ
- Assumptions
- Steady wind; angle measured between runway heading and wind direction.
- Last Validated
- 2026-08-03
True Altitude Calculator
Regulatory
- Primary Source
- AC 91-105 / AIM 7-2 — altimeter procedures and cold-temperature error
- Edition / Date
- Current as of 2026-07-30
- Formula Method
- Non-standard-temperature altitude correction (ICAO cold-temperature method)
- Assumptions
- Correction grows with height above the reporting station; based on reported station temperature.
- Last Validated
- 2026-07-30
Mach Number Calculator
Atmospheric & Performance
- Primary Source
- Manual of the ICAO Standard Atmosphere (extended to 80 km)
- Edition / Date
- Doc 7488/3, 3rd Edition (1993)
- Formula Method
- Local speed of sound from OAT; Mach = TAS / a, solved in both directions
- Assumptions
- Speed of sound depends on temperature only; assumes dry air.
- Last Validated
- 2026-08-03
Pilot Currency Calculator
Regulatory
- Primary Source
- 14 CFR Part 61 — Certification: Pilots, Flight Instructors, and Ground Instructors
- Edition / Date
- e-CFR, current as of 2026-07-30
- Formula Method
- Rule-based date arithmetic against FAR 61.56 / 61.57 recency windows
- Assumptions
- Reflects Part 61 as of the review date; does not track individual logbook endorsements.
- Last Validated
- 2026-07-30
Medical Certificate Expiration Calculator
Regulatory
- Primary Source
- 14 CFR Part 61 — Certification: Pilots, Flight Instructors, and Ground Instructors
- Edition / Date
- e-CFR, current as of 2026-07-30
- Formula Method
- Rule-based date arithmetic per 14 CFR 61.23 class/age rules and BasicMed validity
- Assumptions
- Based on 14 CFR 61.23 as of the review date; age on exam date governs duration.
- Last Validated
- 2026-07-30
Standard Atmosphere Calculator & Table
Atmospheric & Performance
- Primary Source
- Manual of the ICAO Standard Atmosphere (extended to 80 km)
- Edition / Date
- Doc 7488/3, 3rd Edition (1993)
- Formula Method
- ICAO standard-atmosphere equations for temperature, pressure, density, density ratio, and speed of sound
- Assumptions
- Standard-day conditions; troposphere model below 36,089 ft.
- Last Validated
- 2026-08-03
Fuel Burn Calculator
Atmospheric & Performance
- Primary Source
- Pilot’s Handbook of Aeronautical Knowledge
- Edition / Date
- FAA-H-8083-25C (2023)
- Formula Method
- Fuel = burn rate × time, plus reserve and contingency allowances
- Assumptions
- Constant burn rate entered by the user; does not model climb/cruise/descent phases separately.
- Last Validated
- 2026-08-03
Endurance Calculator
Atmospheric & Performance
- Primary Source
- Pilot’s Handbook of Aeronautical Knowledge
- Edition / Date
- FAA-H-8083-25C (2023)
- Formula Method
- Endurance = usable fuel / burn rate, with reserve-adjusted safe endurance
- Assumptions
- Constant burn rate; usable fuel entered by the user.
- Last Validated
- 2026-08-03
Reserve Fuel Calculator
Regulatory
- Primary Source
- 14 CFR Part 91 — General Operating and Flight Rules
- Edition / Date
- e-CFR, current as of 2026-07-30
- Formula Method
- FAR 91.151 / 91.167 reserve requirements applied to a user-entered burn rate
- Assumptions
- Reflects Part 91 as of the review date; day VFR / night VFR / IFR selected by the user.
- Last Validated
- 2026-07-30
Aircraft Range Calculator
Atmospheric & Performance
- Primary Source
- Pilot’s Handbook of Aeronautical Knowledge
- Edition / Date
- FAA-H-8083-25C (2023)
- Formula Method
- Range = groundspeed × (usable−reserve fuel) / burn rate, with optional wind comparison
- Assumptions
- Constant cruise groundspeed and burn; wind applied as a steady component.
- Last Validated
- 2026-08-03
Weight & Balance Calculator
Aircraft Data
- Primary Source
- Cessna 172S Skyhawk SP Pilot’s Operating Handbook
- Edition / Date
- Revision 4 (2006), Part No. 172SPHBUS-00
- Formula Method
- Moment method: CG = Σ(weight × arm) / Σ weight, per aircraft profile
- Assumptions
- Built-in arms/limits are representative POH values — verify against your airplane’s weighing record.
- Last Validated
- 2026-07-30
CG Envelope Checker
Aircraft Data
- Primary Source
- Cessna 172S Skyhawk SP Pilot’s Operating Handbook
- Edition / Date
- Revision 4 (2006), Part No. 172SPHBUS-00
- Formula Method
- Point-in-polygon test of the loaded CG against the published envelope
- Assumptions
- Envelope coordinates are representative POH values — verify against your airplane’s POH.
- Last Validated
- 2026-07-30
Useful Load & Payload Calculator
Atmospheric & Performance
- Primary Source
- Pilot’s Handbook of Aeronautical Knowledge
- Edition / Date
- FAA-H-8083-25C (2023)
- Formula Method
- Useful load = max gross weight − empty weight; full-fuel payload derived from fuel weight
- Assumptions
- Empty weight and max gross entered by the user from their weighing record.
- Last Validated
- 2026-08-03
Wind Correction Angle Calculator
Navigation & Magnetic Models
- Primary Source
- Wind-triangle (vector) navigation method
- Edition / Date
- Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Ch. 16 (2023)
- Formula Method
- Wind-triangle solution for WCA, true heading, and groundspeed
- Assumptions
- Steady wind; true course and TAS entered by the user.
- Last Validated
- 2026-08-03
Digital E6B Flight Computer
Navigation & Magnetic Models
- Primary Source
- Wind-triangle (vector) navigation method
- Edition / Date
- Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Ch. 16 (2023)
- Formula Method
- Digital E6B aggregating TSD, fuel, TAS, wind, density altitude, and unit methods
- Assumptions
- Each tab inherits the assumptions of its standalone calculator.
- Last Validated
- 2026-08-03
Time-Speed-Distance Calculator
Navigation & Magnetic Models
- Primary Source
- Wind-triangle (vector) navigation method
- Edition / Date
- Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25C, Ch. 16 (2023)
- Formula Method
- Algebraic solution of distance = speed × time for any unknown
- Assumptions
- Constant groundspeed over the leg.
- Last Validated
- 2026-08-03
Magnetic Variation Calculator
Navigation & Magnetic Models
- Primary Source
- World Magnetic Model (WMM)
- Edition / Date
- WMM2025, epoch 2025.0, valid 2025.0–2030.0
- Formula Method
- World Magnetic Model field evaluation at the entered coordinate/date
- Assumptions
- WMM2025 valid 2025.0–2030.0; a warning is shown if the model epoch is expired.
- Last Validated
- 2026-07-30
Top of Descent Calculator
Atmospheric & Performance
- Primary Source
- Pilot’s Handbook of Aeronautical Knowledge
- Edition / Date
- FAA-H-8083-25C (2023)
- Formula Method
- Descent geometry from altitude to lose, descent rate/angle, and groundspeed
- Assumptions
- Constant descent rate and groundspeed; still-air geometry.
- Last Validated
- 2026-08-03
Required Rate of Climb/Descent Calculator
Atmospheric & Performance
- Primary Source
- Pilot’s Handbook of Aeronautical Knowledge
- Edition / Date
- FAA-H-8083-25C (2023)
- Formula Method
- Required rate (ft/min) and gradient (ft/nm) from altitude change, distance, and groundspeed
- Assumptions
- Constant groundspeed; ODP/climb-gradient guidance is advisory only.
- Last Validated
- 2026-08-03
Airspace Calculator
Regulatory
- Primary Source
- National Airspace System Resource (NASR) subscription data
- Edition / Date
- 28-Day NASR Subscription, effective 2026-08-01
- Formula Method
- Point-in-geometry test against NASR Class B/C/D/E boundaries with MSL/AGL interpretation
- Assumptions
- Reflects the 28-day NASR cycle effective on the review date; not a substitute for current charts.
- Last Validated
- 2026-08-01
Flight Category Checker
Weather & Meteorology
- Primary Source
- Flight-category (VFR/MVFR/IFR/LIFR) ceiling and visibility thresholds
- Edition / Date
- AIM and NWS Aviation Weather Center definitions, current as of 2026-07-30
- Formula Method
- Threshold comparison of ceiling and visibility against VFR/MVFR/IFR/LIFR limits
- Assumptions
- Uses standard AIM/NWS thresholds; ceiling and visibility entered by the user.
- Last Validated
- 2026-08-03
Cloud Base Calculator
Weather & Meteorology
- Primary Source
- Convective condensation level (Espy’s) approximation for cumulus cloud base
- Edition / Date
- Standard meteorological approximation (≈ 400 ft per °C of temperature–dewpoint spread)
- Formula Method
- Convective condensation approximation: base ≈ spread × 400 ft
- Assumptions
- Applies to convective (cumulus) cloud only; not valid for stratiform or frontal cloud.
- Last Validated
- 2026-08-03
METAR Decoder
Regulatory
- Primary Source
- Aeronautical Information Manual (AIM)
- Edition / Date
- Basic dated 2024, Change 1 (current as of 2026-07-30)
- Formula Method
- Text parsing of METAR fields into plain-language output
- Assumptions
- Decodes standard FAA/ICAO METAR format; not a substitute for an official briefing.
- Last Validated
- 2026-08-03
Relative Humidity Calculator
Weather & Meteorology
- Primary Source
- Bolton, D. — “The Computation of Equivalent Potential Temperature” (saturation vapor pressure formula)
- Edition / Date
- Monthly Weather Review, Vol. 108, No. 7, pp. 1046–1053 (1980)
- Formula Method
- Relative humidity from temperature/dewpoint via Bolton 1980; carburetor-icing risk from the AC 61-23C chart
- Assumptions
- Vapor-pressure approximation; icing indicator is advisory.
- Last Validated
- 2026-07-30
Freezing Level Calculator
Atmospheric & Performance
- Primary Source
- Manual of the ICAO Standard Atmosphere (extended to 80 km)
- Edition / Date
- Doc 7488/3, 3rd Edition (1993)
- Formula Method
- Linear extrapolation of surface temperature to the 0 °C level using a lapse rate
- Assumptions
- Assumes a constant lapse rate; actual inversions and moisture layers not modeled.
- Last Validated
- 2026-08-03
Precipitation Type Estimator
Atmospheric & Performance
- Primary Source
- Pilot’s Handbook of Aeronautical Knowledge
- Edition / Date
- FAA-H-8083-25C (2023)
- Formula Method
- Vertical-temperature-profile heuristic for rain / snow / ice pellets / freezing rain
- Assumptions
- Educational estimator from a simplified profile — not a forecast.
- Last Validated
- 2026-08-03
Want to check a result yourself? See How to Verify Our Calculations. Aircraft-specific figures always come from the aircraft’s own POH/AFM — verify against your documents before flight.