Between 2014 and 2024, the SIPAER dashboard recorded 289 runway excursions in airplane accidents in Brazil. It is the second most frequent type of occurrence, behind only system failure or malfunction, and ahead of in-flight loss of control (275). Added to loss of control on the ground (144), the runway accounts for more than 430 accidents in ten years.
Worldwide, the business aviation picture is even sharper. The Flight Safety Foundation counted 79 runway excursions with corporate jets between 2017 and 2022, about 41% of all accidents in the segment over the period: more than the next two types combined. Six were fatal, with 18 deaths.
None of these events starts on the runway. It starts with a calculation that was not done, or was done with the numbers from the day the airplane was new.
Why the calculation disappears
Every pilot learned to calculate takeoff and landing distance. Few do the calculation on every flight, and the reason is simple: the runway "has always been enough." An aircraft that operates from a 1,500 m aerodrome with a manual that calls for 700 m has so much to spare that the chart becomes a formality.
The surplus is real, but it has three problems:
- It belongs to the home runway. The operation changes aerodromes, and the margin that existed in São Paulo does not exist on a 1,100 m regional runway at 900 m elevation on a 34 °C afternoon.
- The manual's numbers are certification numbers. New airplane, engine delivering rated power, test pilot, exact technique, dry, level runway of known surface. The real fleet is not like that.
- The factors multiply, they do not add. Weight above plan, a "light" tailwind, a wet runway and a long touchdown are each a small increase. Together, they consume the entire runway.
RBAC 91 does not leave this to discretion. Section 91.103 requires the pilot in command, before beginning a flight, to become familiar with the runway lengths and the takeoff and landing distances: the data from the approved flight manual, when it is required to contain them, or, for other aircraft, "other reliable information" on performance according to aerodrome altitude, runway gradient, gross weight, wind and temperature. The rule lists exactly the variables that physics charges for.
The physics, in the FAA handbook's numbers
The Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25), in its performance chapter, gives rules that hold for any airplane, from a single to a jet. The percentages below are the handbook's own.
Weight. Takeoff distance varies, at a minimum, with the square of the weight. A 10% increase in takeoff weight produces about 5% more rotation speed, at least 9% less acceleration and at least 21% more takeoff distance. On landing, 10% more weight means 5% more approach speed and 10% more landing distance.
Ten percent is small. On a 2,000 kg light twin, it is 200 kg: two passengers with baggage that "wasn't on the list" or the extra fuel "just to be safe."
Speed. Taking off or landing at 10% more speed than the manual's increases the distance by about 21%. On landing, it is the most common error: the approach "with a few extra knots for safety" is in fact the decision that consumes the most runway. Energy grows with the square of speed, and everything that comes in excess has to be dissipated by the brakes or by the grass past the threshold.
Wind. A headwind equal to 10% of takeoff speed reduces the distance by about 19%. A tailwind of the same intensity increases the distance by about 21%. The asymmetry matters: the tailwind costs more than the headwind saves. Accepting a runway with a tailwind to shorten the pattern or avoid a long taxi is trading minutes for meters of runway, and the calculation is rarely done.
Density altitude. High altitude, high temperature and low pressure produce thin air. The airplane needs the same indicated airspeed to fly, but that corresponds to a higher true airspeed, and the naturally aspirated engine delivers less power with each foot of density altitude. The result is a longer run to reach a higher ground speed, with less acceleration. A plateau runway at midday in summer can have a density altitude one or two thousand feet above its elevation, and the manual only covers this if the pilot enters the chart with the real temperature.
Gradient and surface. An uphill runway lengthens the takeoff; a wet, contaminated, grass or dirt runway lengthens the landing and reduces braking effectiveness. The manual of many light aircraft gives corrections only for dry grass; for everything else, the information is up to the operator.
Business aviation: the problem is the landing
For the business jet, takeoff is calculated as an obligation: dispatch requires weight, runway and conditions. Landing is where the margin evaporates, because it is decided in flight, with data that has changed since dispatch.
That is what the FAA acknowledged after the Chicago Midway accident in December 2005, when it issued SAFO 06012, "Landing Performance Assessments at Time of Arrival (Turbojets)". The recommendation, addressed to turbojet operators, is that the crew reassess landing distance at the time of arrival whenever weather, runway condition, weight or braking systems have changed since dispatch, applying a safety margin of at least 15% to the actual landing distance.
Practice shows where the 15% gets lost:
- Short regional aerodrome, chosen for passenger convenience, with a 1,400 m or 1,500 m runway and no overrun area.
- Wet runway from a shower that passed ten minutes earlier, with the briefing done for the dry condition.
- Tailwind accepted to land straight in without a pattern, because "it's only five knots."
- Unstabilized approach and touchdown beyond the zone, with the airplane still fast. In a jet, every second of float is tens of meters.
- Go-around seen as a failure, when it is the only procedure that gives the margin back.
RBAC 135 brings its own performance limitations for air taxi airplanes, and the operator's general operations manual must say how the assessment is done. The question for the manager is not whether the procedure exists, but whether the crew did the calculation on yesterday's flight, with yesterday's wind, runway and weight.
General aviation: the problem is the takeoff
On the light aircraft, the statistics point to the other end of the runway. Takeoff from a short, grass or dirt runway, with a full airplane, in the heat and at altitude is the classic scenario for excursion and loss of control on the ground.
The ingredients repeat:
- Unknown real weight. Passengers and baggage estimated, tank full "because the fuel stop is far away," and takeoff weight above what the pilot thinks.
- Ignored temperature. The chart was read once, on a mild day; the calculation is not redone on the 35 °C afternoon.
- No abort point. Without a mark on the runway where the speed must have been reached, the decision to abort comes too late.
- Aircraft without complete data in the manual. This is the case provided for in 91.103(b)(2): the rule asks for "other reliable information," and that means responsibility for the estimate rests with the operator.
Rules of thumb common in general aviation, such as adding 50% to the manual distance on light aircraft, exist because the difference between the certification airplane and the fleet airplane is real. They are not regulation. They are the recognition that the manual describes the best case.
What changes in the routine
- Do the calculation on every flight that departs from routine: new aerodrome, different weight, high temperature, wet runway, tailwind. Any one of these invalidates the known surplus.
- Enter the chart with the day's data: actual takeoff and landing weight, aerodrome temperature, elevation, wind on the runway in use.
- Define and apply the margin: at least 15% on turbojet landings, as the FAA recommends; larger margins where the manual is incomplete.
- Establish the abort point before lining up, and respect it.
- Treat tailwind and a wet runway as multipliers, not as details to tolerate.
- Stabilized approach, touchdown in the zone, go-around without blame. The procedure that saves the most runway is the one practiced the least.
- Record threats by aerodrome: short runway, nonexistent overrun area, uneven surface. The knowledge of those who have already operated there is worth more than the chart.
Where Alis comes in
The distance calculation belongs to the manual and the pilot in command. Alis puts the data next to it and keeps the record. The Flight Kit gathers, for each flight, the runway dimensions and aerodrome elevation, the weather and NOTAMs, and the weight and balance with estimated takeoff and landing weight, the margin to MTOW and an explicit warning when the estimate exceeds it. The FRAT crosses this with the threats reported by other operators at the same aerodrome, anonymously, so that the short runway or poor surface enters the risk assessment before the airplane leaves the hangar. After the flight, hours, cycles and landings go straight to the digital logbook and to maintenance tracking.
For those who want to go deeper into the risk assessment method, the article on FRAT and PAVE describes how the decision is structured before the flight; and the overview of LOC-I and CFIT in general aviation shows what happens when the margin runs out after takeoff.
Want to see the Flight Kit with weight, runways and FRAT in the same document? Book a demo.
This article is informational. The performance percentages are those published by the FAA in the Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25) and are an order of magnitude; each aircraft's data are those of its approved flight manual. The statistics cited are from the SIPAER/CENIPA dashboard (airplanes, 2014–2024) and the Flight Safety Foundation (corporate jets, 2017–2022), as published at the date of publication. The text does not replace consulting RBAC 91, RBAC 135, SAFO 06012 or the guidance of the person responsible for operations.