Much like go-arounds, aborted takeoffs happen from time to time. An aborted takeoff is when an aircraft begins accelerating down the runway in order to takeoff. However, before the end of the runway it will come to a halt.
Aborted takeoffs happen to all aircraft large and small. However, much planning is needed to ensure an aircraft can stop in time once it starts accelerating down the runway. After all, the aircraft needs to stop before it reaches the end of the runway. Simple Flying investigates the aborted takeoff.
Why do pilots abort takeoff?
There are a number of different reasons why a pilot may choose to abort a takeoff. These can range from engine problems to something just not feeling quite right. After all, it’s better to be safe and to err on the side of caution.
Usually, after a rejected takeoff, the aircraft will return to the gate for checks depending on why the takeoff was aborted. However, if an aircraft has had to brake particularly hard, the brakes can get hot. This can result in the brake needing to cool down before a second attempt.
ASDA (not the supermarket)
The first important variable to consider when looking at aborted takeoffs is the ASDA or Acceleration Stop Distance Available. This is the distance between where the aircraft commences its takeoff, and the point at which it must have stopped by should the takeoff be rejected.
When the aircraft is at rest, its speed is zero, or V0. Next, the aircraft will reach Vs, or the stall speed of the aircraft.
V1 – decision speed
V1 is arguably the most important speed when taking off. It is known as the decision speed, as beyond it a takeoff should not be aborted if anything goes wrong. Why? Because the aircraft will struggle to stop by the end of the runway if it manages to at all.
If an engine were to fail on takeoff, the pilot would likely have begun to abort the maneuver before V1 was reached. The aircraft’s brakes would be applied and reverse thrust could be utilized.
How are the speeds calculated?
All of the speeds are calculated by the aircraft’s onboard computer. Using everything from the weather to flap settings, the FMS calculates exactly what speed the pilot should decide on aborting takeoff, and when to start to lift off. These speeds are then overlayed on the speed ribbon in the cockpit.
Thankfully, the vast majority of flights take off without incident, however, technology is there to help should an aborted takeoff be necessary.
Have you been on an aircraft that aborted its takeoff? How did you find the experience? Let us know in the comments.