A near-miss involving two United Airlines jetliners near Houston's George Bush Intercontinental Airport is under investigation.

The incident happened shortly after 9:30 p.m. on May 9 when United says an air traffic controller instructed the pilot of United Flight 601 to make a right turn after departing from a runway. According to the FAA, the controller spotted that the aircraft was heading into airspace normally reserved for another runway, where United Flight 437 had just departed.

The controller issued instructions to both pilots to safely separate the aircraft, the FAA says.

According a transcript of the control tower audio:

Tower: United 601 just stop your heading, stop your turn right there, sir.
United 601: OK, we are heading 2-1-0 now.
Tower: United 437 turn right heading 1-8-0 and maintain 3000 there.
Tower: United 601 stop your turn, stop your climb and stop your turn, United 601.
United 601: United 601 is descending for radar for resolution.

Sources tell Local 2 the controller is experienced, but was receiving training on that position.

Former commercial pilot Joshua Verde explains how he thinks all of this went down.

"The first thing that I noticed was the air traffic control instructed the aircraft that took off on Runway 9 to make a right turn after departure and that's not the normal procedure when all of these runways are being used. I believe he meant to say make a left turn," Verde said.

The FAA says the closest proximity between the two planes was 0.87 miles laterally and 400 feet vertically. It happened around two miles southeast of IAH.

To put that into prospective, 400 feet is just a little more than one football field in length.

"When you consider these aircraft are traveling at 250 knots, if they are headed towards each other, the closure time of less than a mile can be just a matter of seconds," said Verde.

The FAA says it has taken steps to prevent any similar occurrences in the future.

The incident remains under investigation by the FAA.

The FAA issued a statement which read, "FAA air traffic controllers operate the safest and most complex air traffic system in the world. They handle more than 130 million air traffic operations a year, and 99.99 percent of those operations occur normally and in full compliance with FAA safety regulations. The FAA builds robust safety margins into the air traffic system and relies on a series of other safety layers to achieve that high level of safety. The FAA uses sophisticated tools to identify and address safety risks has promoted a non-punitive safety culture that encourages employees to identify safety issues. As a result, the FAA is collecting significantly more data about safety issues than it has in previous years.

The FAA fully analyzes every identified loss of the required separation between aircraft and develops corrective actions to prevent similar events from occurring in the future. Even with the large increase in data collections, the number of events identified as high risk has remained low. In fiscal year 2012, the agency identified 41 high risk events and developed corrective actions that included retraining, procedural changes and outreach to pilots. The FAA monitors incidents across the system on a daily basis to detect and analyze any potential safety trends.

The FAA has identified no specific similarities among any recent events."