The control tower had 17 incidents in latest period, FAA data show.
The reasons are unclear, but the numbers may reflect a physical reality. Unlike some larger and newer airports, MSP’s layout and its use of two major runways can increase the complexity of controlling takeoffs and landings. Hemmed in by freeways, homes and a national cemetery, it lacks the space some other airports have for more runways.
“It’s just a different steer to wrangle,” said Sam Tomlin, a veteran air traffic controller at MSP. “There’s a lot of stuff going on.”
Controller mistakes typically involve planes getting too close to each other. Seventeen errors occurred at MSP from late 2010 to early 2012, the most recent period for which such data are available. They are included in reports, covering hundreds of airports, that were released by the Federal Aviation Administration in response to a Freedom of Information Act request by the Star Tribune. The FAA has since changed its method of classifying problems, but has not released those records.
The errors at MSP happened at a faster pace than previously. From late 2006 through late 2010, there were a total of 21 errors.
The FAA acknowledges that intersecting or converging runways at MSP can create complications and opportunities for errors.
“Every time you have an intersection, you have an opportunity for conflict,” said FAA spokeswoman Laura Brown. “It doesn’t mean that you can’t operate safely.” She said comparing traffic control at airports is difficult and that “each airport has its own set of challenges.”
Nationwide, tower errors increased 82 percent over five years. While the FAA has attributed much of the spike to better reporting, the Office of the Inspector General for the U.S. Department of Transportation this year stressed problems.
“[W]e found that the increase in reported errors was linked, in part, to a rise in actual errors rather than increased reporting,” the Inspector General’s Office concluded. The mistakes are “a major air safety concern, particularly in light of dramatic increases.”
Examples of errors
The government sets minimum distances that must be kept between planes to ensure safety. Tower errors typically involve controllers allowing planes to come closer than permitted — often within 3 miles.
One of the 17 errors at MSP ended up in an FAA summary of “untoward events.” The Nov. 11, 2010, episode involved a Delta Air Lines Airbus and a Mesaba Airlines turboprop that were instructed to take off from parallel runways.
The FAA said a controller arranged to have the Mesaba flight follow the Delta one. The controller asked the Mesaba pilot if he “could accept an immediate takeoff and the pilot replied that they were ready.” The controller then told the pilot to “line up … don’t plan on stopping,” and added, “I’ll have a turn at the end.”
After the Mesaba plane left the runway, the controller told its pilot to turn left “without ensuring adequate separation,” according to the National Transportation Safety Board (NTSB). The plane came within 1.84 miles of the Delta Airbus instead of keeping the required 3-mile distance.
The error was one of five category “B” mistakes, the second most serious under the old classification system.
That episode was mentioned in an NTSB investigation of a Sept. 16, 2010, near-collision of a US Airways Airbus and a Bemidji Aviation cargo plane. The NTSB said that the two instances were evidence of a broader problem and that both mistakes involved “lack of awareness between the North and South [runway] local controllers.” It noted that the FAA took steps to lessen the likelihood of a recurrence.
In the September 2010 episode, the Bemidji plane flew 50 to 100 feet below the US Airways jet. The category “A” error was included in an earlier round of mistakes and not with the 17.
The 17 errors included: