The NTSB says air traffic controllers handling a Southwest Airlines Boeing 737-700 and an Atlas Air Boeing 747-400LCF freighter that landed at the wrong airports in January 2014 and November 2013, respectively, did not follow standard procedures in alerting the pilots of other airports “in close proximity” to the intended destination airport, and more needs to be done to prevent issues in the future.

Based on those incidents, the NTSB is calling on the FAA to issue new rules requiring controllers to withhold a landing clearance until after an aircraft has “passed all other airports that may be confused with the destination airport.” A second recommendation, linked to the Atlas incident, calls for the FAA to modify its minimum safe altitude warning systems (MSAWs) in towers to monitor aircraft altitude with respect to the destination airport only. MSAW alerts controllers when an aircraft’s altitude, provided by radar, dips below the approach path to a runway.

In the Southwest incident—for which the NTSB has not yet issued a final report—the Boeing 737 was descending to 16,000 ft. on a visual approach to the Branson Airport in Missouri, when the controller advised the pilot that “the airport” was at his 11 o’clock position—or slightly to the left of the nose—and 15 nm ahead. The NTSB says radar data indicated the airport at that position was actually the Branson Downtown Airport, where the 737 ultimately landed by mistake. Branson Airport at that time was at the 10 o’clock position and 20 nm, the NTSB says.

Eight seconds after the controller’s call, the pilot reported “field in sight,” and the controller cleared the aircraft for a visual approach to Runway 14 at Branson Airport. The pilot, however, ultimately landed on runway 12 at the Downtown Airport—6-nm short of the destination—using 3,109 ft. of the 3,738 ft. runway. Branson Airport’s runway, roughly parallel to Downtown’s runway, is 7,140 ft. long. There was no MSAW warning, as the approach to the airport is below radar coverage.

In the Atlas incident, the Boeing 747-400LCF set up for a GPS approach to Runway 19L at McConnell Air Force Base near Wichita, Kansas, but ultimately landed on the 6,100-ft.-long Runway 18 at the Col. James Jabara general aviation airport, 8-nm short of McConnell’s 12,000-ft.-long runway. While the MSAW system was active, the software was programmed so as to not distinguish between nearby airports and the correct airport, and did not issue an alert even though the 747 was well below the approach path to McConnell.

In both cases, the controllers issuing landing clearances did not alert the crews of nearby airports and that could have caused confusion, as called out in an FAA Air Traffic Control order.

The NTSB says that although the pilots should have more-closely monitored their flight paths, had controllers withheld landing clearances until the aircraft had passed the misidentified airports, “the wrong airport landings may have been avoided.”

An FAA analysis shows that from October 2008 to October 2014, there were a total of 399 wrong-runway takeoffs or landings in the U.S., and 229 taxiway takeoffs and landings.