Runway incursions a common hazard at U.S. airports

Potentially fatal lapses usually attributed to human errors

Before dawn on Oct. 19, a Delta Air Lines jet with 193 people on board missed its runway and landed instead on a 75-foot-wide taxiway just south of the Hartsfield-Jackson International terminal building.

At peak hours, that taxiway is jammed with jets waiting to depart. This time it was empty, and no one was hurt.

Federal investigators are searching for the reasons behind the potentially disastrous landing. But an examination of federal aviation records by the Atlanta Journal-Constitution shows that while such incidents involving large passenger jets are rare, they are one version of a far more common hazard — a runway or taxiway “incursion” — that occurs hundreds of times a year at the nation’s airports.

Airliners have inadvertently risked collisions, sometimes by landing on runways without permission, getting lost on airport taxiways or crossing runways in front of landing aircraft, the AJC’s review of federal records indicates. The potentially fatal lapses — usually attributed to human errors aggravated by distractions, overwork and fatigue — are prompting aviation authorities to roll out technological and other fixes, but some won’t be in place for years.

The total number of so-called “serious incursions” has dropped in recent years, along with the volume of airline traffic. However, the rate at which they occur — incidents per landing or takeoff — has continued to grow, according to testimony by the U.S. Government Accountability Office in 2008.

Atlanta ranks high

An incursion happens when an aircraft or other vehicle enters a runway or taxiway without permission.

Most of the 957 incursions recorded during the 2008 fiscal year involved private aircraft rather than commercial airliners, a number that amounts to a tiny fraction of the roughly 50,000 flights the Federal Aviation Administration controls each day, according to the GAO.

Still, commercial passenger jets account for about a third of the “serious” incursions — those involving near-collisions — and carry the risk of more deaths or injuries.

Among U.S. airports, Hartsfield-Jackson had the fourth-highest number of incursions from 2001 to August 2008, with 61, though it ranked lower in terms of serious incursions, with three, according to the GAO.

The FAA doesn’t track taxiway landings or takeoffs as a separate category. But federal records indicate that air carriers have been involved in at least seven such incidents since 2004 at airports in Atlanta, Newark, Seattle, Anchorage, Denver, Philadelphia and Las Vegas.

Most incursions happened because of “human factors” such as high work loads, fatigue and confusion among pilots and air traffic controllers, GAO official Gerald Dillingham said last year in testimony to a Congressional subcommittee.

Most incursions ended without collisions or casualties. But crashes were barely avoided in about two dozen incidents during the last fiscal year, Dillingham testified.

Confusion has had deadly consequences, as with the 2006 crash of a Comair commuter jet in Lexington, Ky. Forty-nine of the passengers and crew died after the pilots attempted to take off on a wrong runway that was too short. The regional airline is owned by Delta.

The worst runway disaster happened in 1977, when two Boeing 747s collided in Tenerife, Canary Islands, killing 583.

‘Sidestep’ went wrong

The National Transportation Safety Board and FAA are investigating the Oct. 19 taxiway landing in Atlanta. Officials at each, as well as Delta and its pilots union declined to provide an update on the investigation or to discuss potential causes.

But the distractions of a medical emergency appears to have helped set the incident in motion as the Boeing 767 was arriving at about 6 a.m. after a 10-hour flight from Rio de Janeiro, Brazil.

According to the NTSB’s preliminary report, a supervisory pilot had become ill during the flight and moved out of the cockpit. The flight crew declared a medical emergency.

Flight 60 was initially slated to land on Runway 27L, the active landing runway. People familiar with the incident say air traffic controllers gave the crew permission to be “sidestepped,” or shifted over, for a landing on Runway 27R. The parallel runway is normally used for take-offs, but it’s closer to the terminal, allowing a quicker arrival at the gate.

The sidestep maneuver, commonly used at Hartsfield-Jackson during low-traffic times, requires pilots to be close enough to see the runway — typically within five miles — and to agree to a visual approach. That’s because the instrument landing aids and approach lights are turned off to avoid confusing pilots planning to land on the normal arrival runways. They were off during the incident.

According to the NTSB, the pilots on Flight 60 steered too far to the right. They bypassed the 150-foot-wide Runway 27R for the parallel taxiway about 400 feet to the right.

Even though they are the same length, the taxiway is half as wide as the runway. They are also lighted differently to distinguish them from the air. The runway has white lights on the edges and down its centerline; the taxiway has blue margin lights and green centerline lights.

The NTSB said the weather was clear during the incident, which occurred about an hour before dawn. The pilots have been grounded during the investigation.

Human error prime cause

Investigators haven’t determined a likely cause of the Atlanta taxiway landing, but human error — usually by the pilot — is cited in most such cases. The GAO said FAA statistics show that 57 percent of incursions in 2007 were caused by pilots and 28 percent were attributed to air traffic controller errors.

Many errors seem to be aggravated by the challenges of running around-the-clock airlines and control towers with short staffing at congested airports, suggests an examination of publicly available incident reports.

The first officer of a 2006 flight into Newark, N.J., said he was so busy with a difficult approach at night in rainy, gusty conditions that he didn’t realize he had landed on the taxiway.

“I never noticed the blue [taxiway] lights. Although I thought it was unusual that I was aligning the [aircraft] with the green [centerline] lights, it did not register in my mind that this was the [taxiway],” he said in the report to NASA’s confidential Aviation Safety Reporting System.

According to an NTSB report on the incident, the pilots were flying a Boeing 757 for Continental Airlines with 154 people on board. No one was injured.

The pilot’s comments were among 79 anonymous incident reports reviewed by the AJC. The reports were submitted to NASA’s database by commercial airline pilots, flight controllers and others who were involved in runway or taxiway incursions from 2000 to this year.

Most of the incidents were relatively minor occurrences such as turning on the wrong taxiway but staying clear of active runways or traffic.

But in dozens of cases, pilots and flight controllers confessed to potentially serious mistakes, such as landing on a runway without clearance or crossing an active runway when another plane was landing. In a 2004 incident reported at Miami International Airport, a plane that had just landed narrowly avoided colliding with a second jet landing on the same runway, apparently after an air traffic controller mistakenly gave approval.

Fixes set, but slow

The FAA is pursuing a number of technological and procedural fixes to reduce the risk of incursions.

After the NTSB’s investigation of the Newark taxiway landing, the FAA modified that airport’s flight approach procedures and changed the lighting of the runways and taxiways to make their differences more obvious to landing pilots.

Likewise, after a number of taxiway landings, Seattle-Tacoma airport used paint and different signs and lighting to address the problem, said FAA spokeswoman Laura J. Brown. Before the changes, “from the air, the taxiway looked like a runway,” she said.

Officials declined to say what changes, if any, will be made at Hartsfield-Jackson airport to avoid a repeat of the taxiway landing.

In its report, the GAO said the FAA has installed systems at 39 major airports, including Hartsfield-Jackson, to warn controllers of potential collisions, and is installing flashing lights at 22 airports that will warn taxiing pilots when it is unsafe to enter a runway.

Authorities are also working on other safety measures, such as similar warning lights visible to landing aircraft, new taxiways that don’t cross runways, and bonuses to retain air traffic controllers or encourage them to move to understaffed control towers.

However, the GAO said the FAA appears to be behind schedule on installing some of the new warning systems. Other planned improvements are still being tested and likely won’t roll out for years to come.

“A significant reduction in the number of and rate of incursions may not be realized until the development and installation ... is complete,” the GAO said.

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How we got the story

To get an idea of what may have led to the hazardous landing of a Delta Air Lines jet on a taxiway in Atlanta three weeks ago, the Atlanta Journal-Constitution examined records of past taxiway landings and runway and taxiway incursions during the past decade. Besides sifting through those records, which are maintained on the Aviation Safety Reporting System database by NASA, the AJC also reviewed related reports by the U.S. Government Accountability Office, the National Transportation Safety Board and the Federal Aviation Administration. The AJC also interviewed officials at most of those agencies, Delta Air Lines, and Hartsfield-Jackson International Airport.