BOSTON (AP) — A Delta Air Lines jet was roughly 300 feet (90 meters) from an American Airlines plane during a close call at Boston’s airport that forced the Delta aircraft to abort a weekend landing attempt, an aviation expert said Sunday.

The Federal Aviation Administration said it was investigating the incident between two commercial flights that happened Saturday at Boston Logan International Airport.

Todd Curtis, a former safety engineer at Boeing, estimated the distance between the two jetliners using Flightradar24, a website that tracks flights. Curtis now coproduces a podcast about flight safety issues.

“This is a significant incident,” Curtis said, adding that it was particularly concerning because it involved two professional airline crews.

He said federal aviation officials have been concerned about such runway incursions for a while now and will scrutinize Saturday’s close call.

Near-misses and runway incursions at U.S. airports will be the subject of a hearing on Capitol Hill on Tuesday. The Senate Commerce Subcommittee on Aviation, Space, and Innovation will seek ways to strengthen safety across the national airspace system.

The Delta flight from Dallas had to execute a go-around, or aborted landing, to avoid the American plane departing from an intersecting runway, according to the FAA and flight logs.

The crew of Delta flight 2351 coordinated with air traffic control to perform the go-around, an airline spokesperson said. The plane, which had 129 passengers and six crew members on board, landed safely and deplaned normally, according to the spokesperson.

Go-arounds are safe, routine procedures performed at the discretion of the pilot or air traffic controllers, according to the FAA.

The Federal Aviation Administration is investigating a close call between two commercial flights at Boston Logan International Airport on Saturday morning.

Flight tracking data shows the pilots of Delta Air Lines Flight 2351 aborted their approach for landing around 11:30 a.m. as American Airlines Flight 3161 was accelerating for takeoff on an intersecting runway.

Delta pilots performed an evasive go-around maneuver before the Airbus A319 landed safely and passengers deplaned normally, a Delta spokesperson said in a statement.

The two aircraft got within several hundred feet of each other, according to a CNN analysis of tracking data from Flightradar24.

An air traffic controller asked the departing American Airlines flight where it was going, to which its pilot said the tower had cleared the aircraft for takeoff, according to air traffic control audio captured by ATC.com. American Airlines deferred questions from CNN to the FAA.

While experts say flying remains an incredibly safe way to travel, Saturday’s close call is the latest in a recent spate of aviation-related incidents the US, including four dramatic plane crashes, the ever-worsening problem of turbulence and strikingly similar close call and go-around investigations.

A go-around, or aborted landing, is an aviation term for discontinuing a landing and beginning an immediate climb, then following further instructions. The safety maneuver is used to prevent runway incursions – when aircraft, vehicles or people are incorrectly positioned on a runway – as well as to counter other hazards, like sudden wind shifts and less-than-ideal approaches.

While go-arounds can feel jarring to passengers, they are still considered common and happen daily in the US, Michael McCormick, a former FAA air traffic manager and an associate professor in air traffic management at Embry-Riddle Aeronautical University, previously told CNN.

“Passengers aren’t told in advance it’s going to happen, but they’ll recognize it when suddenly they’re coming in to land and the aircraft just starts rising back up again,” McCormick said, again noting go-arounds are routine.

“This is something that pilots practice in flight simulators on a regular basis,” he added.