Why Did Technology Fail to Prevent the Fatal Air Collision Over Washington?

On Wednesday night (U.S. time), a passenger jet and a U.S. Army helicopter collided at low altitude near Ronald Reagan Washington National Airport, crashing into the Potomac River.

A total of 60 passengers, including U.S. and Russian champion figure skaters, along with four crew members, were aboard American Airlines flight AA5342 from Wichita, Kansas. The helicopter, carrying three military personnel, was on a routine training flight. Authorities confirmed that no one on either aircraft survived.

Recent Aviation Disasters Raise Global Safety Concerns

This crash occurred just over a month after a passenger jet went down in South Korea—possibly due to a bird strike—leaving only two survivors out of 181 passengers. These incidents have heightened global concerns about aviation safety.

In the latest U.S. tragedy, pilots had access to technology designed to prevent midair collisions: the Traffic Collision Avoidance System (TCAS).

So, how does TCAS work? And why might it have failed to prevent this disaster?

A TCAS is a safety system that scans the surrounding airspace for other aircraft equipped with transponders, which detect and respond to electronic signals.

The TCAS, also known as the Airborne Collision Avoidance System (ACAS), operates independently from external air traffic control systems. Its primary function is to alert pilots to nearby aircraft and potential collision risks.

Since its development in 1974, the technology has evolved.

TCAS I: Monitoring and Traffic Advisory Alerts

The first generation, TCAS I, monitors the aircraft’s surroundings, providing information about the bearing and altitude of nearby planes. If a collision risk is detected, it generates a “Traffic Advisory” (TA). While the pilot is alerted to the threat, they are responsible for deciding the appropriate evasive action.

The second generation, TCAS II, takes it a step further by offering specific instructions on avoiding collisions—whether by descending, climbing, turning, or adjusting speed. These systems can also communicate with one another to ensure coordinated advice is provided to all involved aircraft.

Under international regulations, particularly the Chicago Convention, all commercial aircraft are required to be equipped with a TCAS. While the convention includes provisions for noncommercial aircraft, military helicopters are exempt from these rules, though they must comply with domestic laws and regulations. Reports suggest that the military helicopter involved in this incident lacked a TCAS system.

Even if the military helicopter involved in the crash had a TCAS, the technology has limitations, particularly at altitudes below approximately 300 meters.

The last recorded altitude of American Airlines flight AA5342 was around 90 meters, while the military helicopter was at an altitude of about 60 meters when the collision occurred.

The TCAS’s limitations at low altitudes are by design.

Accuracy Issues at Low Altitudes

This is mainly because the system relies on radio altimeter data, which measures altitude but becomes less accurate as the aircraft nears the ground, potentially leading to unreliable collision-avoidance guidance.

Additionally, at such low altitudes, an aircraft has limited options for descending further to avoid a collision.

Ronald Reagan Washington National Airport is among the busiest airports in the U.S., with commercial, military, and private aircraft sharing limited airspace and flight corridors.

There have been several near misses at the airport in recent years.

For instance, in April 2024, a commercial flight pilot had to take evasive action while landing to avoid a helicopter located about 100 meters below. In the incident report, the pilot stated:

Many, including Democratic U.S. Senator Tim Kaine, cited this near miss as a reason to oppose the proposal to allow more flights into Ronald Reagan Washington National Airport. Despite the concerns, the plan was approved the following month.

The National Transportation Safety Board will undoubtedly review all of this as part of its investigation into the disaster.

Read the original article on: Science Alert

Read more: Ancient Ship Found in Ecuador Jungle After 10,000 Years: Evidence of Lost Technology?