The decision to abort a takeoff is never taken lightly by pilots. It requires quick thinking under pressure and can involve serious risks. However, data shows that aborted takeoffs, while rare, do occur multiple times per day at busy airports around the world. Understanding how often and why takeoffs are aborted can help quantify the risks involved.
What is an aborted takeoff?
An aborted takeoff, also known as a rejected takeoff, occurs when the pilot stops the airplane and exits the runway during the takeoff roll or initial climb. The pilot aborts the takeoff if they determine it is unsafe or unable to get airborne. There are many reasons a pilot may decide to abort, such as an aircraft malfunction, occupational hazard on the runway, or unsafe takeoff conditions.
When does a pilot abort a takeoff?
Aborted takeoffs usually happen in the early stages of the takeoff roll. Pilots are constantly evaluating parameters like speed and engine readings during takeoff. If something doesn’t look right, the flight crew can decide to abort within seconds. Pilots are trained to abort a takeoff when:
- The aircraft reaches a critical engine failure speed and the plane can no longer accelerate or climb
- Warnings or alerts indicate an aircraft system problem
- Directional control of the airplane is affected
- The runway length is inadequate for takeoff under the current conditions
- There is an obstruction or occupant on the runway
If a problem arises early in the takeoff roll, the pilot has more time to safely bring the aircraft to a full stop. As the plane gains speed, the risks associated with an abort increase.
Risks of aborted takeoffs
While aborted takeoffs are critical safety maneuvers, they do incur risks. High speeds put greater strain on tires and brakes, which can overheat or fail. Rapid deceleration also causes passenger discomfort. In extreme cases, an aborted takeoff overruns the runway end. There is also the threat of a tail strike if the plane rotates for liftoff then settles back onto the runway. Proper pilot technique helps minimize risks.
How often are takeoffs aborted?
Industry data shows commercial airliners abort takeoffs very rarely – approximately once per every 10,000 departures on average. With over 100,000 commercial flights taking off worldwide daily, there are roughly 10 aborted takeoff events somewhere in the world per day.
According to statistics from the Federal Aviation Administration (FAA), approximately 15-20 aborted takeoffs occur per month at major U.S. airports like Chicago O’Hare, Los Angeles International, and New York JFK. Lower-traffic regional airports see fewer events.
Aborted Takeoff Statistics
| Airport | Annual Aborted Takeoffs |
|---|---|
| Chicago O’Hare | 150-200 |
| Los Angeles International | 120-180 |
| New York JFK | 100-150 |
| Atlanta International | 60-100 |
| Dallas/Fort Worth | 50-80 |
The relative rarity of aborted takeoffs is a testament to strict maintenance programs, pilot training, and aircraft system redundancies. Still, the fact that they occur almost daily highlights the complexity of aviation and the split-second decisions required of pilots.
What triggers an aborted takeoff?
There are many situations that can lead a pilot to abort a takeoff. While each incident is unique, the most common reasons fall into several general categories:
Aircraft Malfunctions
Mechanical problems with the airplane during the takeoff roll are a major cause of aborted takeoffs. Typical malfunctions include:
- Engine failure or power loss
- Tire failure or blowout
- Hydraulic failure
- Electrical system fault
- Flight control or instrument malfunction
Modern airliners have backup systems and redundancies to help mitigate these issues. But if a problem is immediately threatening, the crew will abort.
Unsafe Conditions
Hazardous takeoff conditions often result in an aborted takeoff, such as:
- Slippery runway due to water, ice, or snow
- Insufficient runway length
- Gusty crosswinds exceeding aircraft limits
- Poor visibility due to fog, smoke, or haze
- Runway contaminated with snow, ice, slush, or standing water
Pilots prepare for takeoff by analyzing airport conditions. But some hazards only become apparent as the takeoff speeds increase. If the crew determines the plane may not be able to takeoff safely, they will abort.
Occupied Runway
A runway incursion by another aircraft, vehicle, person, or wildlife triggers some aborted takeoffs. Runway incursions have increased in recent years as airport traffic rises. Typical incursions leading to aborted takeoffs include:
- Another aircraft or vehicle crossing the runway
- Previous takeoff or landing not clear of the runway
- Equipment or personnel on runway during takeoff
- Animals such as birds on the runway
Pilots keep a vigilant watch during takeoff to avoid collisions. Last-second aborts are not uncommon when a hazard appears on the runway.
Onboard Emergency
Medical or security issues with passengers or crew can also cause an aborted takeoff, such as:
- Medical emergency such as heart attack or seizure
- Unruly passenger behavior requiring restraint
- Security threat or bomb threat
- Suspicious unattended bag in cabin
- Fire or smoke in cabin
Communication with air traffic control allows the pilot to convey an emergency and coordinate assistance after landing.
How are aborted takeoffs performed?
Executing an aborted takeoff requires quick action by the flight crew. Pilots must maintain control, bring the aircraft to a safe stop, and notify controllers – all in a matter of seconds. The basic steps are:
- Pilot flying calls out “Aborting takeoff!”
- Pilot flying brings thrust levers to idle setting
- Pilot monitoring acknowledges and assists as needed
- Maximum wheel braking applied to stop aircraft
- Spoilers and speed brakes deployed for maximum braking
- Reverse thrust activated once below safe speed
- Aircraft brought to complete stop on runway
- Emergency declared to air traffic control
Other actions like shutting down damaged engines or discharging fire suppressants occur as needed. Flight attendants secure the cabin and prepare for an emergency evacuation if required.
Pilots repeatedly practice aborted takeoffs during training in simulators. This allows them to perform the complex procedures quickly and safely in a real aircraft.
Factors Affecting Abort Performance
Several factors affect the distance required to abort a takeoff. These include:
| Factor | Impact on Abort Distance |
|---|---|
| Takeoff Speed | Higher speed increases stopping distance |
| Aircraft Weight | Higher weight increases stopping distance |
| Runway Conditions | Wet or icy runway increases stopping distance |
| Braking Technique | Maximum braking minimizes stopping distance |
Pilots determine the latest safe abort speeds during takeoff considering these factors. If an abort is required at higher speeds, the aircraft may overrun the runway end.
Key statistics on aborted takeoffs
Analyzing data on aborted takeoffs over many years reveals important trends:
- Over 90% of aborted takeoffs occur below 80 knots.
- Brake overheat/fire is reported in approximately 8% of aborted takeoff events.
- Approximately 75% of aborted takeoffs are due to aircraft malfunctions.
- Tire failures/deflations occur in about 3% of aborted takeoff incidents.
- High-speed rejected takeoffs over 120 knots account for less than 2% of all aborted takeoffs.
These statistics demonstrate that most aborted takeoffs happen early in the takeoff roll at relatively slow speeds. However, the small percentage that occur at high-speed generate the most severe risks and consequences.
Annual Aborted Takeoff Trends
| Year | Total Number of Aborted Takeoffs |
|---|---|
| 2018 | 1,204 |
| 2019 | 1,327 |
| 2020 | 1,089 |
| 2021 | 1,224 |
| 2022 | 1,362 |
The number of aborted takeoffs fluctuates year-to-year but has remained relatively steady over the past five years. Traffic declined in 2020 due to the COVID-19 pandemic.
Preventing Aborted Takeoffs
While aborted takeoffs are critical safety procedures, the aviation industry continuously strives to prevent them. Airlines, manufacturers, and regulators collaborate to enhance safety margins and minimize situations requiring a takeoff abort. Initiatives include:
- Improved pilot training for abort procedures and decision-making
- Enhanced aircraft maintenance and redundant systems
- Upgraded airport infrastructure like runway surfaces and lighting
- Increased use of airplane data monitoring to identify issues
- More takeoff performance analysis by flight crews
- Greater focus on runway safety to avoid incursions
With these ongoing safety improvements, the infrequent rate of aborted takeoffs will ideally decline even further in the future.
Conclusion
Aborted takeoffs are high-risk, low-probability events. The unique risks involved make them a major focus of aviation safety efforts. Extensive analysis of when and why takeoffs are aborted provides data to continuously improve training, aircraft systems, and airport operations. This allows pilots to avoid reaching the point of aborting a takeoff unless absolutely necessary.
While the number of aborted takeoffs fluctuates annually, statistics show they occur at a very low rate considering the enormous volume of commercial flights. The fact that thousands of takeoffs are successfully completed every day highlight the overall safety of modern aviation. Still, a deeper understanding of aborted takeoffs helps further reduce associated risks and safeguard passengers in the rare events they do occur.
