Rejected Takeoff: When Stopping Becomes Critical

Every takeoff begins with a fundamental question: at what point does continuing become safer than stopping? The rejected takeoff procedure exists to answer this question systematically, providing pilots with clear decision-making criteria when something goes wrong during the most dynamic phase of flight. Understanding RTO isn't just about memorizing speeds—it's about grasping the physics, psychology, and operational realities that make these decisions life-critical.

The Physics of Stopping: Why Speed Changes Everything

A rejected takeoff transforms your aircraft from an accelerating machine into a massive braking challenge. The energy that must be dissipated increases with speed—doubling your speed quadruples the energy your brakes, reversers, and spoilers must absorb. This fundamental physics principle explains why RTO procedures are built around specific speed regimes, each with distinct risk profiles and decision criteria.

Below 100 kt, you have flexibility. The relatively low energy levels mean your braking systems can handle the stopping task with reasonable runway requirements. Here, the captain can evaluate ECAM warnings and cautions more deliberately, weighing whether the malfunction truly compromises flight safety or can be managed airborne.

Between 100 kt and V1 represents the critical decision zone. Energy levels are climbing rapidly, but you still have sufficient runway to stop safely—if you act decisively. This regime demands strict criteria: fire warnings, severe structural damage, sudden engine thrust loss, or malfunctions making safe flight impossible. Notice what's excluded: EGT red line exceedances or nose gear vibration don't justify RTO above 100 kt because these conditions, while concerning, don't prevent safe flight.

Above V1, physics takes over. The energy is simply too high, and the runway remaining too short, for safe deceleration. This isn't a suggestion—it's an aerodynamic reality that makes continuing takeoff the only viable option.

Decision-Making Under Pressure: The Human Factor

RTO decisions occur in seconds, not minutes. Warning inhibition from 80 kt to 1500 ft (or 2 min after liftoff) ensures that only critical warnings reach you during this high-workload phase. Any warning that breaks through this filter demands immediate attention—the aircraft's computers have determined it's serious enough to interrupt your takeoff focus.

The captain maintains physical contact with thrust levers until V1, regardless of whether they're pilot flying or monitoring. This isn't about control authority—it's about decision speed. When milliseconds matter, the person making the RTO decision must be able to act instantly. The "STOP" call confirms the decision and transfers control without the usual "I have control" exchange, streamlining the process when every second counts.

Managing the Energy: How Your Aircraft Stops

Understanding your deceleration systems helps you maximize stopping performance and recognize when something isn't working normally. Ground spoilers deploy automatically when the main gear touches down and one thrust lever moves to reverse, destroying lift and transferring weight to the wheels, where your brakes can use it effectively. Reverse thrust provides maximum effectiveness at high speeds—use REV MAX initially, then reduce to REV IDLE below 70 kt to prevent engine stall while maintaining deceleration assistance.

Autobrake MAX during RTO provides consistent, maximum braking without the risk of uneven pedal application. Avoid pressing brake pedals when A/BRK MAX is active—you'll only interfere with the system's optimized pressure control. The DECEL light indicates when you're achieving 80 % of the selected deceleration, but on contaminated runways, it might not illuminate even when the autobrake is working correctly due to antiskid cycling.

When Systems Fail: Backup Procedures

If normal braking fails during RTO, the LOSS OF BRAKING memory items must be executed immediately. This procedure switches you to alternate braking without antiskid—you lose nosewheel steering (requiring rudder control at higher speeds and differential braking at lower speeds), but you maintain stopping capability. If alternate braking also fails, the parking brake becomes your final option, applied in short bursts to minimize brake onset asymmetry and tire burst risks.

For tire failures between V1 - 20 kt and V1, continuing takeoff is generally safer than attempting to stop. The energy levels and runway remaining make a successful RTO unlikely, while a controlled flight to a suitable airport with full runway length provides better safety margins.

Risk Factors and Mitigation

RTO carries inherent risks even when procedures are followed correctly. Tire damage, worn brakes, incorrect weight calculations, wrong runway lineup, or contaminated surfaces can all compromise stopping performance. Pre-flight planning becomes critical: verify takeoff data calculations, confirm runway conditions, and ensure brake temperatures are within limits before accepting takeoff clearance.

The oversteer technique during lineup maximizes your acceleration-stop distance by minimizing field length loss. Don't accept takeoff clearance or attempt intersection takeoffs until you're fully prepared and performance is verified for actual conditions.

Post-RTO Considerations

After stopping with A/BRK MAX, disarm ground spoilers before taxiing to release the brakes. Remain on the runway until confirming evacuation isn't required and taxi is safe. If planning another takeoff attempt, reset both flight directors, reconfigure the Flight Control Unit (FCU), and restart procedures from the AFTER START checklist—essentially treating it as a new departure.

For subsequent takeoffs, recalculate performance data if conditions have changed. The RTO may have affected brake temperatures, runway conditions might have deteriorated, or the wind could have shifted. Each takeoff attempt deserves fresh performance calculations based on current conditions.

The Bigger Picture

RTO procedures represent a carefully balanced system where physics, human factors, and aircraft systems work together to provide escape options when takeoffs go wrong. The speed-based decision criteria aren't arbitrary—they reflect the mathematical reality of energy management and stopping distances. Understanding these principles helps you make confident decisions under pressure, knowing that your actions are backed by sound engineering and operational experience.

Remember: the goal isn't to avoid RTOs at all costs, but to execute them safely when conditions warrant. A properly executed RTO, even if ultimately unnecessary, is always preferable to continuing a takeoff when flight safety is genuinely compromised.

The physics and decision-making behind A320 rejected takeoffs – speed regime criteria, deceleration systems, loss of braking backup, and what to do after stopping.