What is a METAR and how do I read it?

A METAR (Meteorological Aerodrome Report) is a routine aviation weather observation. It includes wind direction and speed, visibility, weather phenomena, cloud layers, temperature, dew point and altimeter setting. AviationCalcs provides a free METAR decoder that translates any METAR string into plain English.

What is density altitude and why does it matter?

Density altitude is pressure altitude corrected for non-standard temperature. High density altitude means the air is less dense, reducing aircraft lift, engine power and propeller efficiency. It is critical for takeoff performance calculations, especially at hot or high-elevation airports.

How do I calculate cloud base height?

Cloud base height can be estimated using the surface temperature and dew point: cloud base (ft) ≈ (Temperature − Dew Point) × 400. This formula gives the approximate height of the lifting condensation level above the aerodrome elevation.

How do I calculate wind correction angle (WCA)?

Wind correction angle is calculated using the triangle of velocities: given the desired track, true airspeed (TAS), wind direction and wind speed, the WCA gives the heading to fly so that the aircraft tracks along the desired course. AviationCalcs computes WCA and ground speed automatically.

What is the difference between IAS and TAS?

IAS (Indicated Airspeed) is the raw reading from the airspeed indicator. TAS (True Airspeed) is the actual speed of the aircraft through the air mass, corrected for altitude and temperature. TAS increases with altitude for the same IAS because air density decreases.

How much fuel do I need for a VFR flight?

For VFR day flights, EASA regulations require trip fuel plus a final reserve of 30 minutes at cruise power. For VFR night, the final reserve is 45 minutes. AviationCalcs calculates trip fuel, alternate fuel, contingency fuel and final reserve automatically based on the rules selected.

What is the ISA standard atmosphere?

The International Standard Atmosphere (ISA) is a reference model defined by ICAO that specifies standard values of temperature, pressure and density at each altitude. At sea level, ISA conditions are 15°C and 1013.25 hPa. Temperature decreases at 6.5°C per 1000 m up to the tropopause at 11,000 m.

How do I determine the correct holding pattern entry?

ICAO defines three holding pattern entries based on the angle between your inbound heading and the hold course: Direct entry (within 70° on the non-holding side), Parallel entry (within 110° on the holding side), and Teardrop entry (the remaining sector). AviationCalcs visualizes the entry sectors automatically.

Is AviationCalcs free to use?

Yes, AviationCalcs is completely free. There is no signup, no subscription and no ads. All calculations run entirely in your browser — no data is sent to any server.

Can I use AviationCalcs for real flight operations?

AviationCalcs is designed for educational and reference purposes. Results should always be cross-checked with official sources: aircraft POH/AFM, AIP, NOTAMs and licensed aviation professionals. Do not use as the sole source for operational flight decisions.

AviationCalcs — Aviation & Aerospace Engineering Tools

PPL · Weather

METAR / TAF Decoder

Free online METAR and TAF decoder. Paste any ICAO aviation weather report to get a plain-English breakdown of wind, visibility, ceiling, temperature and flight category (VFR / MVFR / IFR / LIFR). Live fetch by airport ICAO or IATA code supported.

Search by airport to auto-fetch live METAR & TAF — or enter strings manually below.

🛜 Requires internet connection · Data: NOAA

METAR

METAR string

Runway in use — optional (for wind components)

TAF

TAF string

PPL · Weather

SIGMET Decoder

SIGMET (Significant Meteorological Information) — Meteorological report describing significant en-route phenomena that may affect the safety of aircraft operations. Supports WS (En-Route), WV (Volcanic Ash), and WC (Tropical Cyclone) formats per ICAO Annex 3.

Full SIGMET string (ICAO format)

Ejemplos rápidos

PPL · Weather

Cloud Base Estimator

Estimate cloud base height from surface temperature and dew point spread. Based on the lifting condensation level formula used in PPL training: cloud base (ft) ≈ (T − Td) × 400. Optionally add aerodrome elevation to get altitude MSL.

Temperature (°C)

Dew Point (°C)

Aerodrome Elevation (ft MSL) optional

PPL · Weather

Density Altitude

Calculate density altitude from QNH, pressure altitude and temperature. Essential for takeoff and landing performance calculations at hot, high-elevation or humid airports where aircraft performance is significantly reduced.

Field Elevation (ft)

QNH / Altimeter (hPa)

Temperature OAT (°C)

PPL · Weather

Cloud Base + Density Altitude

Search by airport to auto-fill conditions — or enter values manually below.

🛜 Requires internet · Data: NOAA

Temperature OAT (°C)

Dew Point (°C)

Aerodrome Elevation (ft MSL)

QNH (hPa)

PPL · Weather

ISA Atmosphere

ISA atmosphere calculator (ICAO 1993). Compute standard temperature, pressure, density and speed of sound at any altitude. Referenced to sea-level conditions of 15 °C and 1013.25 hPa. Used in PPL training, performance calculations and aerospace engineering.

Altitude ft m

PPL · Navigation

Headings — True / Magnetic / Compass

Convert between true heading, magnetic heading and compass heading. Apply magnetic variation (declination) and compass deviation to find the heading to steer. Essential for PPL cross-country navigation and flight planning.

True Heading (°)

Magnetic Variation (°E +, W −)

Compass Deviation (°E +, W −)

PPL · Navigation

Wind Correction Angle (WCA) & Ground Speed

Calculate wind correction angle (WCA) and ground speed using the triangle of velocities. Enter desired track, true airspeed (TAS), wind direction and wind speed to find the heading to fly and actual ground speed over the ground.

Desired Track (°)

TAS (kt)

Wind Direction (°)

Wind Speed (kt)

PPL · Navigation

Great Circle Distance

Calculate the great circle distance (orthodrome) and initial bearing between any two airports or coordinates. The shortest path between two points on Earth — used in long-range flight planning and navigation.

Origin (ICAO / IATA)

Destination (ICAO / IATA)

PPL · Navigation

Holding Pattern

Holding pattern entry calculator — determine the correct entry procedure (Direct, Parallel or Teardrop) based on inbound heading and hold course, per ICAO standard. Visualizes the pattern with entry sectors. Supports right and left-hand turns.

Direct

Parallel

Teardrop

Aircraft Heading (°)

Hold Course

Turn Direction

Compass View

Inbound Course

270°

Outbound Course

090°

Inbound Heading

270°

Outbound Heading

090°

Entry Type

—

PPL · Performance

IAS ↔ TAS

Convert between indicated airspeed (IAS) and true airspeed (TAS). Accounts for pressure altitude and outside air temperature (OAT). Also converts TAS back to IAS for flight planning and performance calculations.

Mode

IAS (kt)

Pressure Altitude (ft)

OAT (°C) ISA ↙

PPL · Performance

Takeoff & Landing Distance

Estimate takeoff and landing distance for common PPL training aircraft. Accounts for pressure altitude, temperature, wind and runway slope. Based on published POH data under standard conditions.

⚠️ Reference only. These values are approximate estimates based on published POH data under standard conditions (paved, level, dry runway). Always consult the official POH/AFM of your specific aircraft before any flight. Performance varies with aircraft configuration, weight, surface condition, and other factors.

Search by airport to auto-fill elevation, QNH, OAT and calculate wind component.

🛜 Requires internet · Data: NOAA

Aircraft

Field Elevation (ft)

QNH (hPa)

OAT (°C)

Wind Component (kt) + head / − tail

Runway Surface

Data sources (pre-loaded aircraft):
Cessna 172S — POH §5 (BEFA / Cessna, Rev. 2019)
Cessna 152 — POH §5 (Wayman Aviation / Cessna)
PA-28-161 Warrior II — POH §5 (Basic6Aviation / Piper, VB-1180, 1982)
PA-28-181 Archer III — POH §5 (FoxFlying / Piper, VB-1563, 1994/1998) — values interpolated from charts
Diamond DA40 — Tables extracted from official POH §5 (diamondaviators.net)
Robin DR400/180R — POH Supplement §5 Tablas 5-2/5-13 (Robin / EASA, Issue 3, Jul 2014)
SOCATA TB10 Tobago — POH §4 via euroga.org ⚠️ no direct PDF available — verify against aircraft POH
Tecnam P2002 Sierra MkII — Flight Manual §4 (Delta Aviation / Tecnam, Rev.4, 2008) · Base conditions: dry/firm grass (POH standard); paved runway ≈ 6% less ground roll

PPL · Performance

Fuel Requirements

Calculate total fuel requirements for VFR and IFR flights per EASA/ICAO regulations. Includes trip fuel, alternate fuel, final reserve and contingency fuel. Supports both litres and US gallons.

Rules

Fuel unit

Trip distance (NM) optional

Groundspeed (kt) optional

Trip time (min)

Burn rate (L/h)

Start, Taxi & Run-up (min)

Fuel to Alternate Airport (min) advisory for VFR

Final Reserve (min)

Extra fuel (min) optional

Aerospace · Aerodynamics

Mach Number

Calculate Mach number, true airspeed (TAS) and equivalent airspeed (EAS) from calibrated airspeed (CAS) and pressure altitude. Includes compressibility corrections valid through the subsonic and transonic regimes.

Mach reference — critical speeds

Aircraft	Type	Cruise	MMO / Max
Airbus A320	Narrowbody jet	M0.78	M0.82
Boeing 737	Narrowbody jet	M0.79	M0.82
Airbus A330	Widebody jet	M0.82	M0.86
Boeing 787	Widebody jet	M0.85	M0.90
Airbus A350	Widebody jet	M0.85	M0.89
Boeing 747	Widebody jet	M0.85	M0.92
Boeing 777	Widebody jet	M0.84	M0.89
Concorde	Supersonic airliner	M2.02	M2.02
F-16 Fighting Falcon	Fighter jet	—	M2.05
F-22 Raptor	Fighter jet	—	M2.25
SR-71 Blackbird	Recon aircraft	M3.2	M3.3
X-15	Experimental	—	M6.7
Source: Wikipedia

Mode

Velocity m/s kt km/h mph

Mach Number

Altitude m ft

OAT (°C) — leave blank to use ISA conditions

Aerospace · Aerodynamics

Reynolds Number

Calculate the Reynolds number for a given chord length, airspeed and altitude. A dimensionless parameter that characterises the flow regime (laminar vs. turbulent) — fundamental in airfoil selection and aerodynamic analysis.

NACA Profile — optional preset

Velocity m/s kt km/h

Chord / Length m cm ft

Altitude m ft

OAT (°C) — leave blank to use ISA conditions

Aerospace · Aerodynamics

Lift & Drag

Compute lift and drag forces for a wing or body using the fundamental aerodynamic equations. Enter lift/drag coefficients, wing area, airspeed and altitude to get forces in Newtons or pounds-force.

Aircraft preset

Velocity m/s kt km/h

Altitude — ISA density m ft

Wing Area S (m²)

C_L — Lift coefficient

C_D — Drag coefficient

Weight W — optional, for load factor kg N

Aerospace · Aerodynamics

Stall Speed

Calculate stall speed (Vs) for any aircraft configuration. Accounts for weight, wing area, maximum lift coefficient, load factor and bank angle. Essential for V-speed analysis and manoeuvre envelope studies.

Aircraft preset

Weight W kg N

Altitude — ISA density m ft

Wing Area S (m²)

CL_max

Load Factor n — optional

Aerospace · Aerodynamics

ISA Atmosphere

International Standard Atmosphere (ICAO 1993) — standard temperature, pressure and density at altitude, referenced to sea-level conditions of 15 °C and 1013.25 hPa.

Altitude m ft

Aerospace · Orbital Mechanics

Hohmann Transfer

Two-impulse transfer between two coplanar circular orbits. Calculates Δv burns, transfer time, and orbital velocities.

Input mode:

Initial orbit radius r₁ (km)

Final orbit radius r₂ (km)

Celestial body

Aerospace · Orbital Mechanics

Vis-Viva — Orbital Parameters

Full orbital characterization from semi-major axis and eccentricity. Computes periapsis/apoapsis velocities, orbital period, specific energy, and more.

Semi-major axis a (km)

Eccentricity e (0 = circular)

Celestial body

Aerospace · Propulsion

Multi-Stage Rocket Staging

Applies the Tsiolkovsky equation independently to each stage. Stage 1 fires first (bottom of rocket); Stage N fires last, carrying only the payload.

ms (structural mass) = dry mass of that stage only — tanks, engines, interstage structure. It does not include propellant or upper stages.

Model assumptions: ideal vacuum, instantaneous burns, constant Isp per stage. Real launches add ~1.5–2 km/s of gravity & drag losses not accounted for here.

For single-stage analysis → Tsiolkovsky Rocket Equation

Rocket preset (auto-fills all parameters)

Number of stages

Payload mass (kg)

Aerospace · Propulsion

Tsiolkovsky Rocket Equation

Apply the Tsiolkovsky rocket equation to calculate delta-v, propellant mass or final mass for a rocket stage. The fundamental equation of astronautics, relating exhaust velocity (Isp) to mass ratio and achievable velocity change.

For multi-stage analysis → Multi-Stage Staging calculator

Scenario preset (auto-fills fields, leaves one blank to solve)

Δv (m/s)

Isp (s)

Initial mass m₀ (kg)

Final mass mf (kg)

Thrust F (N) optional — burn time

Structural mass (kg) optional — ε efficiency

Aerospace · Propulsion

Specific Impulse (Isp)

Trajectory analysis → Tsiolkovsky · Multi-Stage Staging

Engine / propellant preset (auto-fills fields, leaves one blank to solve)

Specific Impulse Isp (s) leave blank to solve

Thrust F N kN lbf

Mass flow rate ṁ (kg/s) leave blank to solve

Rocket total mass m (kg) optional — TWR

Aerospace · Performance

Breguet Range Equation

Apply the Breguet range equation to estimate the maximum range of an aircraft. Relates lift-to-drag ratio, specific fuel consumption (SFC), cruise speed and fuel fraction — the key tool in aircraft preliminary design.

Related → Specific Impulse · Tsiolkovsky Δv

Aircraft preset

Cruise speed V m/s kt

TSFC (kg/N·s)

Lift-to-Drag ratio L/D

Initial mass m₀ kg lbs

Final mass m_f (kg)

Aerospace · Performance

Load Factor

Calculate load factor (g) for banked turns, pull-ups and manoeuvres. Determine stall speed in manoeuvre, limit load factors and structural margins. Includes V-n diagram analysis for any aircraft category.

Related → Stall Speed · Lift & Drag

Aircraft category

Bank Angle φ (°)

Speed V — for turn kinematics kt m/s km/h

V_s1 1g stall — optional kt

Weight W — optional kg lbs

Reverse — bank angle from target n

Target n (g)

PPL · Navigation

Alternate Airports

Find all airports within a given radius. Select an airport or enter coordinates manually, set the radius, and apply optional filters.

Reference Airport (ICAO / IATA)

Radius: NM

25100200300400500600

Min. runway length ft m

Exclude reference airport

Pre-Flight

Flight Briefing Generator

AIRPORTS

✈ Departure

🏁 Destination

🔄 Alternate (optional)

AIRCRAFT & MISSION

Aircraft (TOLD data)

Flight Rules

Cruise Altitude (ft)

TAS (kt)

Fuel Burn

Runway Surface

WINDS ALOFT (at cruise altitude — enter manually)

Wind Direction (°T)

Wind Speed (kt)

Magnetic Variation (°E/W)

DEPARTURE TIME (for sunrise/sunset analysis)

Departure Time UTC Local

:

🗺️ Route Map

☁️ Weather

🧭 Navigation

⛽ Fuel Requirements

📊 Takeoff & Landing Performance

🌅 Sunrise & Sunset

⚠️ NOTAMs

🌩️ SIGMETs & AIRMETs

📄 Text Summary

Includes METAR, TAF (when loaded) and pasted NOTAMs.

⚠️ For training and reference only. Always verify data against official sources (AIP, NOTAMs, aircraft POH/AFM) before flight.

About

About AviationCalcs

AviationCalcs is a free, browser-based suite of precision calculators for PPL students and Aerospace engineering students. No sign-up, no ads, no tracking — just the tools.

PPL & Pilot

Tools for the Private Pilot Licence and aerial navigation

METAR / TAF Decoder
SIGMET Decoder
Cloud Base & Density Altitude
ISA Standard Atmosphere
Headings (True / Magnetic / Compass)
Wind Correction Angle & Ground Speed
Great Circle Distance
Holding Pattern
Alternate Airports
IAS ↔ TAS Converter
Takeoff & Landing (TOLD)
Fuel Requirements
Flight Briefing Generator

Aerospace

Engineering calculators for aerodynamics, propulsion & orbital mechanics

Mach Number
Reynolds Number
Lift & Drag
Stall Speed
Load Factor
Breguet Range Equation
Specific Impulse (Isp)
Tsiolkovsky Rocket Equation
Multi-Stage Rocket Staging
Hohmann Transfer Orbit
Vis-Viva Orbital Parameters

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Free & open No paywalls, no account required. Always.

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Zero cookies No tracking, no analytics, no cookies. Ever.

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Fast & lightweight Vanilla HTML, CSS and JS. No frameworks. Works offline.

✈️

Orientative use only Results are for study and reference — not for operational flight planning.

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Questions or suggestions? contact@aviationcalcs.com