Pilots got 100 collision warnings for helicopters near D.C. airport in past decade

Airline pilots received more than 100 cockpit warnings over the past decade that they were in danger of a midair collision with a helicopter near Reagan National Airport, according to flight-tracking and government incident data, a record of repeated risks compiled by air traffic controllers before the Jan. 29 crash that killed 67 people.

A Washington Post examination of the records reveals the potential for an airborne collision was more frequent near the airport than has been previously disclosed. Each of the incidents reviewed by the Post triggered an automated cockpit warning advising airliner pilots to take action to avoid a collision - causing them in many cases to abort landings or change flight paths.

The Federal Aviation Administration, which employs the nation’s air traffic controllers, requires such incidents to be documented as part of the agency’s work to analyze safety.

The 104 warnings from the Traffic Alert and Collision Avoidance System add to the volume of evidence suggesting that federal regulators had ample information before last month’s crash that the crowded airspace near the airport carried the risk of catastrophic consequences.

The proximity of planes and helicopters in the airspace near National Airport also generated concern in the control tower. Air traffic controllers told managers about the challenges of maintaining required distances between helicopters and airplanes in writing in 2020, according to government correspondence and interviews with people familiar with operations at the airport. The correspondence and concerns have not previously been reported.

Controllers suggested ways that the FAA could better manage the safety of the busy airspace, including requiring helicopters to hold when airliners approached or moving helicopter routes farther from airline flight paths.

It is unclear what actions, if any, the FAA took in response to the issues documented by air traffic controllers. The FAA kept helicopter flight corridors near the airport with relatively few changes until last month’s tragedy, when an Army Black Hawk helicopter with a crew of three collided over the Potomac River with an American Airlines regional jet from Wichita with 60 passengers and four crew members.

The agency declined to respond to questions about the number of cockpit warnings and concerns raised by air traffic controllers, saying it cannot comment on anything related to an open crash investigation. “The FAA looks into every incident and reviews large volumes of data on a daily basis to try to identify and address potential trends before they become serious issues,” the agency said in an emailed statement to the Post.

In the wake of the Jan. 29 collision, the FAA curtailed helicopter traffic pending the outcome of the National Transportation Safety Board’s preliminary investigation of the accident.

The collision occurred along a helicopter corridor that passes directly under the path of airliners approaching Runway 33 from the southeast, with only a 15-foot margin between the two routes at their closest point.

When former air traffic controller Al Castillo learned of the Jan. 29 collision, his initial shock soon gave way to outrage. He said the site of the catastrophe “is a known hot spot.”

“If they want to prevent this, they have to move that route,” he said of the helicopter path. “Why is that route still there?”

Air traffic controllers have raised concerns to managers within the FAA in the past decade - including in writing, according to two people familiar with operations at National Airport and correspondence reviewed by the Post.

In 2020, controllers outlined the challenges, according to the correspondence: Helicopters could be told to wait for airline traffic to pass, potentially affecting national security and police work. Changing the helicopter corridors along the river could draw noise complaints, a perennial issue around Washington. Taking no action would mean airliners would need to abort landings and conduct “go-rounds” to avoid potential collisions.

One proposal in recent years involved shifting a helicopter route that follows the Potomac River inland to Interstate 295, the people said. That would put it farther from the approach to National Airport’s Runway 33. The route was not changed: The current description for Route 4, the path flown by the Black Hawk helicopter involved in the collision last month, is word-for-word the same as it was in 2012.

“It’s been multiple attempts,” said one of the people, who spoke on the condition of anonymity due to the ongoing investigation. “There was a lot of warning signs.”

Army Col. Mark Ott, at a briefing on efforts to recover aircraft wreckage and human remains from the Potomac this month, said the FAA sets the rules for flying in the area. With the crash investigation in its early stages, Ott said it was premature to decide whether the Army should change its flight procedures around National in the long term.

“The FAA controls those routes, dictates the procedures,” said Ott, the deputy director of aviation at Army headquarters. “It is the FAA that controls how helicopters transit, and the routes that fly around here. And we will certainly be interested to see what, if anything, they decide to do.”

Maj. Montrell Russell, an Army spokesman, said the service investigates violations of FAA rules and the collision warnings did not necessarily indicate any rule had been broken.

The 104 incidents contained in government data involved an alert from airliners’ anti-collision technology, known as a Traffic Alert and Collision Avoidance System, or TCAS. It is designed to prevent midair collisions and is mandatory for passenger planes in the United States. The system automatically communicates with all aircraft equipped with a transponder within about 12 miles, relaying their position and altitude and calculating the trajectories to warn of a possible collision.

If two aircraft are on a collision course, a plane’s TCAS would give pilots a voice warning: “traffic, traffic,” while showing the nearby aircraft on a cockpit display. The system escalates a warning into a “resolution advisory,” instructing the pilot how to avoid a collision, when it projects the aircraft are 15 to 30 seconds from impact.

Nearly a quarter of the warnings identified by the Post involved military helicopters, almost half were medical flights, and the rest involved police departments and private operators.

In at least 24 incidents in the past three years, airplane pilots aborted their landings at National, a maneuver that involves abruptly pulling up and circling around before returning to the airport, flight-tracking data shows. In other incidents, the jets were able to continue on safely to National without changing course, the data shows.

The most recent incident in the data of a TCAS alert logged by controllers occurred the day before last month’s crash, when a Republic Airways flight arriving from Connecticut aborted a landing after receiving a collision warning.

“We had an RA with a helicopter traffic below us,” said a female voice in the cockpit, referring to a resolution advisory, according to archived air traffic control communications. The National Transportation Safety Board is reviewing that incident as part of its crash investigation but has said there was a reasonable amount of space between the aircraft.

The TCAS system has some limitations, experts say. It works by forecasting the paths of nearby aircraft and does not know what other pilots intend or what air traffic controllers are doing to manage airspace by telling aircraft to watch out for one another.

The system is also not designed to provide course corrections below 1,000 feet, so it provides fewer safeguards in the final minutes before a plane lands. The jet that crashed was at about 325 feet, and investigators have said pilots received only an audio advisory stating “traffic, traffic.”

Flight-tracking data shows many of the incidents identified by the Post happened to the north of National, where airliners are still high enough to receive the advisories. That probably means there could be close calls at lower altitudes not reflected in the data, experts said. An incident a week before the collision, previously reported by the Post, in which a jet suddenly abandoned a landing at low altitude because of a nearby helicopter, does not appear in the records.

Not every resolution advisory is a sign of an emergency.

“They range from scary to big nothings,” said Scott Dunham, a retired NTSB investigator. But experts also said the number issued near National in the past decade deserves scrutiny.

“If you wake up in the morning with a headache and it happens to you 100 times in 10 years, you probably need to go to the doctor,” said Michael McCormick, a professor at Embry-Riddle Aeronautical University who specializes in air traffic control.

Concerns about the densely packed airspace and the conflicts between airplanes and helicopters date back decades, and potentially dangerous situations have repeatedly been documented.

The FAA has investigated six near-midair collisions involving helicopters near National since 2013, agency records show. Those records are contained in the FAA’s public Near Midair Collision System and provide only limited details. They are a serious type of incident typically involving aircraft coming within 500 feet. In at least three cases, both of the aircraft involved were helicopters, according to the records, including one in 2016 involving a medical flight helicopter and a Marines helicopter. Investigators rated the incident “critical,” the most serious category of near miss, the records show.

MedStar Health, a regional medical provider, said in a statement that when an official near miss has occurred, which is rare, it has reported the incident as required, thoroughly examined what happened and, when appropriate, made changes to prevent a recurrence.

The TCAS alerts are a different matter, according to MedStar. For example, they can be triggered in cases when a helicopter might appear to be heading toward an airliner but intends to turn away and head in another direction. Flight-tracking data shows MedStar helicopters on a number of occasions heading toward the Potomac as a plane approached, then arcing to the right toward a heliport before reaching the river.

During a flight last February, an American Airlines pilot received a “level off” alert as the plane and a MedStar helicopter seemed to be headed toward the same spot. The aircraft came within roughly 2,500 feet of each other, at altitudes about 600 feet apart, according to flight-tracking data.

“We do not believe resolution advisory alerts indicate unsafe practices, rather they are information that can be used by the pilot to ensure safe operations,” MedStar said in the statement. “No unsafe practices or events occurred in any of these instances.”

In at least 14 cases since 2006, airplane pilots and air traffic controllers have documented near-collisions or registered their alarm about how close an airplane came to a helicopter flying over National Airport, using a voluntary reporting mechanism called the Aviation Safety Reporting System. The Post and other media outlets have previously reported on ASRS reports in the wake of the Jan. 29 crash.

In June 2013, an airplane pilot reporting a close brush with a helicopter said that the sky around National Airport is so full of choppers that cockpit alerts to their proximity are like background noise. “What would normally be alarming at any other airport in the country has become commonplace at DCA,” the pilot wrote.

In 2015, a pilot flying a passenger plane was coming in for a landing on Runway 33, the same approach taken by the American Airlines flight last month, and came “within very close contact” of a helicopter and had to take evasive action. “We were then informed by DCA tower of close traffic although at that point it would have been too late,” the pilot wrote.

The ASRS reporting system is overseen by NASA, which says that when it receives a “report describing a hazardous situation,” it will issue an alert to “organizations in positions of authority.” A spokesman for NASA said ASRS “has not issued an alerting bulletin” about near-midair collisions between planes and helicopters at National Airport between 2006 and 2024, indicating that the standard hadn’t been met.

Castillo, the former controller, said he personally filed a report to the FAA of a near-collision about a decade ago.

A pilot had radioed an air traffic control center that guides planes on approach across the D.C. region, saying that he “almost got knocked out of the sky by a helicopter,” Castillo recalled in an interview. Castillo, who was operations manager, reviewed the radar data, saw how the two aircraft converged and filed a report of a near-midair collision.

Castillo said he believed the incident took place in May 2013, when a passenger plane coming in for a landing on Runway 33 came within 950 feet of a military helicopter at the same altitude. “Passing 900 feet laterally, in the world of air traffic control, is like nothing,” he said. “That’s like a couple seconds of flight.”

Castillo retired from the FAA in 2015 and said he never found out what came of his report.