United Boeing 737 MAX at Orlando on 26th April 2024 – Runway Incursion and Rejected Takeoff

On 26th April 2024, a serious runway incursion took place at Orlando International Airport (MCO), involving a United Airlines Boeing 737-9 MAX and a Southwest Airlines Boeing 737-8 MAX. This incident, while not resulting in any physical damage or injuries, posed a significant safety risk and necessitated immediate corrective actions, highlighting the importance of precise communication and strict adherence to operational procedures.

Incident Overview

The United Airlines Boeing 737-9 MAX, registered N37540, was performing flight UA-1929 from Newark Liberty International Airport (EWR) in New Jersey to Orlando, Florida. Upon landing on runway 18R at Orlando, the flight crew was instructed by air traffic control (ATC) to vacate the runway via taxiway E and hold short of runway 18L. Holding short is a routine part of taxiing after landing, where aircraft must stop before entering an active runway to avoid conflicts with other traffic, whether taking off or landing.

Simultaneously, a Southwest Airlines Boeing 737-8 MAX, registered N8875B and operating flight WN-5777 from Orlando to Dallas Love Field in Texas, had been cleared for takeoff from runway 18L. The Southwest flight was in the midst of its takeoff roll, rapidly accelerating down the runway. However, at approximately 110 knots, the flight crew was instructed to abort the takeoff as the United Airlines aircraft had inadvertently crossed the hold short line of runway 18L, entering the active runway without clearance.

Runway Incursion – A Serious Aviation Hazard

A runway incursion is defined by the International Civil Aviation Organization (ICAO) as any occurrence at an airport involving the incorrect presence of an aircraft, vehicle, or person on a runway that is being used for aircraft operations. Runway incursions are among the most serious hazards in aviation because they can lead to collisions between aircraft, particularly during critical phases of flight such as landing or taking off. Even a minor miscommunication or error during these phases can escalate rapidly, as aircraft operate at high speeds and pilots have limited time to react.

In this case, the incursion occurred when the United Airlines flight crossed the hold short line and entered an active runway while the Southwest Airlines aircraft was taking off. Given that the Southwest aircraft was already accelerating at a high speed (about 110 knots), the situation could have escalated into a catastrophic collision. Fortunately, the swift decision by ATC to cancel the takeoff clearance, combined with the Southwest crew’s timely response in executing a rejected takeoff, prevented a potentially fatal accident.

The Importance of Holding Short and ATC Instructions

Holding short of a runway is a critical safety measure that ensures aircraft do not enter active runways unless cleared to do so by ATC. When an aircraft lands and vacates the runway, it is common for the aircraft to be instructed to hold short of another active runway that it might need to cross during taxiing. In this incident, the United flight was instructed to vacate via taxiway E and hold short of runway 18L, meaning the crew should have stopped before crossing the hold short line and awaited further instructions from ATC before proceeding.

However, there was a breakdown in communication between the United flight crew and ATC. The flight crew incorrectly read back the instruction, indicating they were going to cross runway 18L, and this incorrect readback went unchallenged by ATC. In such situations, ATC is required to catch and correct any miscommunication, but in this case, the tower did not notice the error. This allowed the United aircraft to proceed across runway 18L, creating a conflict with the Southwest aircraft that had already commenced its takeoff roll.

Human Factors and Communication Errors

One of the key elements in this incident is the role of human factors, particularly in the area of communication between the flight crew and ATC. Aviation relies heavily on precise, standardised communication to ensure that all parties have a clear understanding of instructions and procedures. In this case, the misunderstanding between the United crew and the tower controller could have been the result of a variety of factors, such as fatigue, distraction, or stress.

Human factors such as pilot workload after landing, ATC workload during peak airport operations, and even the possibility of similar-sounding instructions can contribute to communication errors. This is why it is crucial for ATC to confirm the correct readback of all instructions, especially in busy or complex airspace environments like Orlando International, where multiple runways are in use.

The United crew’s incorrect readback and the subsequent failure of ATC to correct it underline the critical importance of maintaining high levels of situational awareness and communication clarity in aviation. The need for strict adherence to standard operating procedures (SOPs) by both flight crews and ATC cannot be overstated. SOPs are designed to minimise the risk of such misunderstandings and ensure that all instructions are accurately conveyed and followed.

Rejected Takeoff – A Critical Safety Manoeuvre

In response to the runway incursion, the Southwest Airlines crew was instructed to abort their takeoff. A rejected takeoff (RTO) is a safety procedure where the flight crew discontinues the takeoff roll, usually in response to an emergency or other unforeseen event. The decision to reject a takeoff is a critical one, as it must be made within a narrow time window – typically before the aircraft reaches V1, the decision speed, which is the point at which the aircraft is committed to taking off.

In this case, the Southwest flight was travelling at approximately 110 knots when ATC cancelled the takeoff clearance. Given that the aircraft’s V1 speed would likely have been around 130 to 140 knots, the decision to reject the takeoff was made in a timely manner, with the aircraft safely slowing to a stop well before reaching the United aircraft that had crossed the runway.

Rejected takeoffs are high-stress situations for flight crews, as they require precise coordination between the pilots to safely stop the aircraft without overrunning the runway or causing damage to the brakes and tyres. The successful execution of the RTO in this incident reflects the professionalism and skill of the Southwest flight crew, who responded quickly to the situation and followed established procedures to avoid a collision.

Post-Incident Actions and Investigations

Following the incident, the Southwest Airlines flight returned to the hold short line of runway 18L, where it awaited clearance to depart. After a delay of approximately 25 minutes, the flight departed without further issues, continuing its journey to Dallas Love Field. The United Airlines aircraft, which had completed its arrival into Orlando, later departed on schedule for its return flight to Newark.

While there were no injuries or damage as a result of the incident, it is likely that both the Federal Aviation Administration (FAA) and the National Transportation Safety Board (NTSB) would have initiated an investigation into the runway incursion. These investigations typically involve a detailed review of ATC recordings, flight data, and cockpit voice recordings, as well as interviews with the flight crews and ATC personnel involved. The aim is to identify the root causes of the incident and implement corrective actions to prevent similar occurrences in the future.

Conclusion

The runway incursion and subsequent rejected takeoff involving United Airlines flight UA-1929 and Southwest Airlines flight WN-5777 on 26th April 2024 serve as a reminder of the critical importance of clear communication, adherence to procedures, and vigilance in aviation operations. While no harm was done, the incident could have had far more severe consequences, highlighting the need for continuous improvement in both human and procedural factors.

From an aircraft engineering and accident investigation perspective, this incident offers valuable insights into the complex interplay between technology, human factors, and operational protocols. Both the ATC and the flight crews demonstrated the need for rapid decision-making and the reliance on well-rehearsed safety procedures like the rejected takeoff to mitigate potentially dangerous situations.

The aviation industry continually strives to enhance safety, but as this incident shows, even routine operations can quickly turn hazardous when communication breaks down. The lessons learned from incidents like this drive ongoing efforts to improve training, communication protocols, and technology in order to prevent future runway incursions and ensure the safety of all those involved in air travel.