Aircraft Takeoff Distance & Obstacle Clearance Calculator
Calculate takeoff ground roll and distance to clear a 50 ft obstacle with CASA safety margins.
Last reviewed by the myCalculator Editorial Team
Input Parameters
C172S standard sea level ground roll ~960 ft (PA28 ~1,190 ft, DA40 ~1,250 ft)
C172S sea level distance over 50ft ~1,630 ft
Enter positive for headwind, negative for tailwind
Positive for uphill (+7% per 1% slope), negative for downhill
Calculation Results
Next: related Aviation calculators
E6B Flight Computer
Interactive digital E6B — fuel burn, ground speed, wind correction angle, density altitude.
E6B Whizz Wheel
Analogue E6B flight computer — turn the circular slide rule and work the wind side, with a full how-to guide.
Density Altitude Calculator
Pressure and density altitude from elevation, QNH and OAT — °C/°F and ft/m support.
Formula & How Aircraft Takeoff Distance & Obstacle Clearance Calculator Works
Takeoff distance is the base ground roll scaled for weight, density altitude, wind and the surface, then increased by a safety margin. With a 960 ft sea-level base roll, a weight of 1,100 kg against a 1,157 kg maximum gives a factor of (1,100 ÷ 1,157)² = 0.90. At 2,000 ft pressure altitude and 25°C, which is ISA +14, the altitude and temperature factor is 1 + 0.1 × 2 + 0.01 × 14 = 1.34. The still-air ground roll is then 960 × 0.90 × 1.34 = about 1,163 ft, and with the 1.25 margin about 1,453 ft. Headwind shortens the roll, while tailwind, a soft or wet surface and a slope lengthen it. Always use the aircraft's flight manual for real operations.
- Enter Sea Level Base Ground Roll (ft): Input your target parameter value.
- Enter Base Distance over 50 ft Obstacle (ft): Input your target parameter value.
- Enter Takeoff Gross Weight (kg) (kg): Input your target parameter value.
- Enter Maximum Takeoff Weight / MTOW (kg) (kg): Input your target parameter value.
- Enter Pressure Altitude (ft) (ft): Input your target parameter value.
- Enter Outside Air Temperature / OAT (°C) (°C): Input your target parameter value.
- Enter Headwind Component (kts) (kts): Input your target parameter value.
- Enter Grass Runway Surface (+15%): Input your target parameter value.
- Enter Runway Slope Gradient (%) (%): Input your target parameter value.
- Apply Formula: Calculate using
TODR = BaseRoll × (Weight/MTOW)² × [1 + 0.1(PA/1000) + 0.01ΔISA] × WindFactor × SurfaceFactor × 1.25 CASA Margin. - Review Results: View exact computed answers, metrics, and worked mathematical proofs.
Need this calculator for your blog, publication, or client portal?
Get pre-formatted embed codes, Markdown citations for forums (Reddit/Whirlpool), or HTML anchor tags free.
Frequently Asked Questions (FAQs)
How does density altitude affect takeoff distance?
High density altitude reduces engine power output, lowers propeller efficiency, and increases the true airspeed needed for liftoff, dramatically lengthening the takeoff ground roll.
What is the CASA takeoff distance safety factor?
Under Australian CASR Part 91 MOS / AC 91-15 guidelines, a 1.15 safety factor is applied to ground roll and 1.25 (or 1.33 for private operations) is applied to total distance over a 50 ft obstacle.
How much does a grass runway increase takeoff distance?
Dry short grass typically increases takeoff ground roll by 15% to 20%, while wet long grass or soft soil can increase ground roll by 25% to 40%.
Embed Aircraft Takeoff Distance & Obstacle Clearance Calculator on Your Site
Offer your readers, students, or clients interactive calculations. Fast, responsive, and 100% free with no login required.
Widget Customizer
Recommended for publishers & educational portals to provide source citation.
Authoritative Standards & Verified Reference Citations
Calculations and mathematical logic on this page are grounded in published statutory rules, regulatory standards, and official government data published by the following bodies:
CASR Part 91 general operating and flight rules, Part 121 fuel reserves, and flight crew licensing standards.
Aviation weather services, standard atmosphere (ISA) profiles, METAR/TAF aerodrome weather reports.
Aeronautical Information Publication (AIP), En Route Supplement Australia (ERSA), and airspace procedures.
CASA Navigation theory practice for RPL, PPL and CPL students, including compass, variation, track, wind and flight-planning topics.
Jandakot-based rotary and fixed-wing operations unit — real-world reference for helicopter performance and mission profiles.
Australia's largest aeromedical operator — 79 aircraft across 23 bases delivering emergency and primary healthcare to remote Australia.
NSW Police airborne support unit operating Bell 429 and Bell 412EPI helicopters for search, surveillance and rescue operations.
Victoria Police's aviation support unit, operating since 1975.
QPS Aviation Capability Group — police helicopter and fixed-wing operations across Queensland.
AW139 rescue helicopter fleet operating from Belmont, Tamworth and Lismore bases across Northern NSW.
Queensland-based rescue helicopter and aeromedical retrieval service, operating since 1979.
South Australia's specialist emergency medical retrieval and aeromedical service.
Operational Scenario
Operational Scenario: Coastal VFR Passage Approaching Deteriorating Stratus
You are planning a day VFR flight from Moorabbin (YMMB) to Latrobe Valley (YLTV) via the coastal visual corridor. The GAF indicates broken stratocumulus at 2,500 ft with localised coastal drizzle lowering the cloud base to 1,000 ft AMSL. The forecast freezing level is 4,500 ft with moderate mountain waves over the Strzelecki Ranges.
Practical Decisions
- •Compare the GAF area by area against your personal minimums, and decide before departure the cloud base at which you will turn back.
- •Check whether an alternate is required (CASR Part 91 MOS 8.04; AIP ENR 1.1 para 10.7.2): for an aeroplane, if you will arrive during, or up to 30 minutes before, forecast cloud of more than SCT below 1,500 ft or visibility below 8 km at the destination, you must provide for a suitable alternate — unless flying day VFR within 50 NM of the departure point.
- •Know what CAVOK means (AIP GEN 3.5): visibility 10 km or more, no cloud below 5,000 ft or the highest minimum sector altitude (whichever is higher), no cumulonimbus or towering cumulus, and no significant weather.
- •Set a fixed turn-back point before terrain traps or coastal cloud banks, and brief it as a decision already made.
Knowledge Check
Need Equipment for Your CASA Flight Test?
While this digital E6B suite is great for pre-flight calculation and theory practice, tablets and phones are restricted in official CASA exams. Pilots must carry approved mechanical instruments into the cockpit.
ASA Color E6B Metal Flight Computer
The gold standard physical slide rule for CASA RPL, PPL, and CPL navigation exams. Indestructible aluminum alloy, zero battery reliance, with wind component grid.
- Meets CASA Part 61 exam rules
- Crosswind component grid
- Dual-sided time & speed scales
David Clark H10-13.4 Aviation Headset
The legendary benchmark headset trusted by student pilots worldwide. Certified 23dB noise reduction, ultra-durable build, and crystal-clear ATC transmission.
- Certified 23dB passive noise reduction
- Standard dual GA twin plugs (PJ-055 / PJ-068)
- M-7A noise-canceling electret microphone
Aviation Kneeboard (iPad Mini Adaptable)
Essential in-flight organizer holding your VFR nav log, charts, and iPad Mini for OzRunways & AvPlan EFB. Includes heavy-duty leg strap and pen holders.
- Fits iPad Mini & standard VFR notepads
- Adjustable elastic cockpit leg strap
- Printed VFR visual reference cheatsheet
Independent recommendation. As an Amazon Associate, purchases through verified partner links may earn a small referral commission at no additional cost to you.
Flight school or avionics partner? Sponsor this spot
Studying to be a pilot?
AeroAcademic — CASA exam prep & ground school for RPL, PPL and CPL, fixed-wing and helicopter. Currently in beta, free to try.
Dedicated Australian home loans, borrowing capacity, mortgage repayments & refinance modeling.