Friday, April 05, 2013

Is fatal 2010 crash a harbinger of things to come for air travel?

Nobody in the medical helicopter saw the little Cessna airplane as the helicopter approached Shenandoah Valley Regional Airport.

Skies were clear and visibility excellent the afternoon of Dec. 31, 2010. The airport had no air-traffic controllers, forcing incoming pilots to avoid each other using crude technology: their eyes.

At 2:26 p.m., a nurse sitting in the helicopter felt a sudden bump. On the ground, witnesses saw the helicopter barely touch the four-seat Cessna. But the collision severed the Cessna’s right wing, sending the plane plunging 500 feet to the ground. The pilot and passenger were killed instantly, marking the 20th collision of that year in the United States.

After a probe of the crash, federal investigators blamed a familiar culprit: the “inherent limitation” of pilot observation, “which made it difficult for the helicopter pilot to see the airplane before the collision.”

Starting Sunday, tens of thousands of pilots flying each day will have to rely increasingly on “see-and-avoid” as the Federal Aviation Administration begins to close nearly a third of its air-traffic control towers to cut costs. The 149 affected airports — small facilities in 38 states catering to private and commuter flights — will remain open but without controllers to keep airplanes a safe distance apart and to warn pilots about runway hazards they may not see.

The tower closures are among thousands of steps federal officials are taking to cut $85 billion in spending this year as a 2011 law requires. But unlike furloughs, removing 871 controllers who guide 8 million planes a year around airports raises fears that pilots, passengers and bystanders will be killed.

“You’re putting people’s lives at risk,” said Sen. Jerry Moran, R-Kan., who is trying to restore funding for the control towers, including five in his state. “It’s like taking down the stop signs in your town.”

A few communities are suing to stop the tower closures, saying the FAA has not done a safety analysis.

U.S. airplane collisions have killed an average of 30 people a year since 1982 — a total of 910 deaths, according to a USA TODAY review of federal records. Another 167 people have been seriously injured, and 729 airplanes have been destroyed or substantially damaged in the collisions, the records show.

Pilots flying around airports without towers are at greater risk, the FAA said in a 1990 paper. At airports with towers, “midair collisions are less frequent, and fewer aircraft are damaged in landing accidents,” the FAA wrote in the paper that it used as recently as 2005 to determine which airports need control towers.

The paper says the risk of a midair collision is three times higher around an airport without a control tower than at an airport with a tower. Runway collisions are six times more likely at the “non-towered” airports.

“We wouldn’t have built these towers if we didn’t believe they provided safety,” Moran said.

Transportation Department spokeswoman Sasha Johnson said the FAA paper is no longer used to assess risk and does not reflect safety improvements in the past 25 years.

In its analysis, USA TODAY found that nearly half of the collisions since 1982 occurred at or near non-towered airports. About a quarter occurred around airports with towers, and a quarter occurred far from any airport, in spots where pilots often have no contact with controllers.

Roughly 90 percent of the nation’s 4,880 public airports do not have towers. Typically rural fields with no passenger flights, each has a small fraction of the traffic at major commercial airports with towers.

Transportation Secretary Ray LaHood said in a statement Thursday that the FAA will monitor safety at airports losing controllers and “is committed to maintaining this nation’s extremely safe aviation system.”

The FAA says it had to close towers to reach the savings required of almost every federal agency under automatic budget-cutting, called sequestration. The 149 towers are all operated under contracts that the FAA can break on short notice, providing $33 million of the $637 million the agency must cut by Sept. 30. The FAA also plans to furlough 47,000 employees for up to 11 days over the next six months.

Other contracts could not be cut because they help run the entire air-traffic-control system, the FAA said. An FAA program that gives airports $3 billion a year in grants for capital projects is protected by a 1985 sequestration law, the Congressional Research Service (CRS) said.

The tower closures will have “relatively small but measurable impacts on safety and efficiency,” CRS said.

“Our overall principle has been, How can we protect the maximum number of travelers?” FAA Administrator Michael Huerta told a Capitol Hill hearing in February.

The FAA is closing towers only at airports with fewer than 10,000 commercial flights a year — about 27 per day — and fewer than 150,000 annual arrivals and departures. The closures will not touch the hub and regional airports that handle most commercial traffic, mostly affecting people who fly private planes for business or recreation.

Towers will go dark at 36 airports where small planes operate next to scheduled passenger flights, in cities such as Winston-Salem, N.C., La Crosse, Wis., and Branson, Mo. About 3 million passengers used those airports in 2011. Mixing high-speed jets with propeller planes worries Mark Courtney, manager of Lynchburg Regional Airport in Virginia.

“The safety margin begins to narrow,” Courtney said. US Airways runs six flights a day between Lynchburg and Charlotte on 50-seat airplanes. The Lynchburg tower is set to close May 5, but Courtney is working to find local funding to keep it open.

Although nearly 400 airplanes have collided around non-towered airports since 1982, killing 223 people and seriously injuring 80, safety investigators rarely blame the absence of air-traffic controllers. It’s almost impossible to prove that a controller would have kept two airplanes apart — a point highlighted by the 241 collisions at towered airports.

National Transportation Safety Board (NTSB) investigations often cite the failure of two pilots to see each other when airplanes collide in daylight near non-towered airports.

• In January 2008, two Cessnas collided on a perpendicular angle near Corona Municipal Airport in Southern California as one airplane was descending to land while the other was ascending after takeoff. The collision killed all four people in the planes and a fifth person on the ground, hit by falling plane debris.

• A similar perpendicular collision occurred in February 2010 over Boulder, Colo., killing the pilot and a passenger in a Cirrus airplane that smashed into a Piper, whose pilot also was killed. The NTSB said the pilots would have had trouble seeing the other airplanes because the white Cirrus blended into the overcast sky. The Piper was set against terrain and Boulder’s cityscape.

• In July 2012, a 73-year-old pilot landing in Valentine, Neb., accidentally hit the airplane of his friend and flying companion who had landed moments earlier and was on the runway. The friend, Joseph Andrews Jr. of Puyallup, Wash., died from the crash injuries three weeks later. Surviving pilot Harold Smith said he hadn’t seen Andrews steer his airplane to the side of the runway.

“This accident leaves me with a very heavy heart which will be with me for many years,” Smith wrote in a statement to the NTSB.

Pilots flying in and out of non-towered airports are supposed to fly within established traffic lanes, announce their position using an airport radio channel, and avoid flying in poor visibility unless they are qualified to fly using navigation instruments and have FAA clearance.

Those guidelines are often broken, particularly at non-towered airports, said Gene Benson, an aviation-safety consultant in Hilton, N.Y.

“These airports are magnets for aircraft flying without operating radios,” Benson said, noting that the practice is usually legal. Some pilots fly outside traffic patterns, or in bad visibility when they shouldn’t. “Not everybody does what they’re trained to do in flight school,” he said.

Airport controllers can enforce rules and can notify arriving pilots of runway hazards such as wildlife or a slippery surface. “I’ve been coming in many times and the controller will say, I see three deer or a flock of geese,” Benson said.

On Thursday, the Texas Department of Transportation agreed to pay $2 million to keep open 13 airport towers in the state and a tower in Texarkana, Ark., for 90 days while officials seek a long-term funding source. The airports handle 1,100 flights a week on average.

“The FAA made a determination that we should have the control towers here for the past decade or longer,” DOT Executive Director Phil Wilson said. “We’re trying to maintain that level of safety and integrity.”


NTSB Identification: ERA11FA101A
14 CFR Part 91: General Aviation
Accident occurred Friday, December 31, 2010 in Weyers Cave, VA
Probable Cause Approval Date: 11/26/2012
Aircraft: CESSNA 172H, registration: N2876L
Injuries: 2 Fatal,3 Uninjured.

NTSB Identification: ERA11FA101B
14 CFR Part 91: General Aviation
Accident occurred Friday, December 31, 2010 in Weyers Cave, VA
Probable Cause Approval Date: 11/26/2012
Aircraft: EUROCOPTER DEUTSCHLAND GMBH EC 135 P2, registration: N312PH
Injuries: 2 Fatal,3 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The pilot and both crewmembers of the helicopter recalled routine radio communication as the helicopter approached the destination airport. They established visual contact with two airplanes that had announced their positions in the traffic pattern; one on the downwind leg and one on short final. The airplanes were also identified by the traffic avoidance system onboard the helicopter. The pilot followed behind and north of the second airplane and continued to the west side of the airport to complete a landing at the helipad. During the descent, about 500 feet above ground level (agl), the pilot "saw about 2 feet of white wing right outside." He "pulled power" and then felt contact with an airplane. The airplane's right wing separated before it departed controlled flight and descended to the ground, fatally injuring both occupants. The helicopter subsequently landed with minor damage and no injuries to the 3 occupants.

Interpolation of radar data revealed that the accident airplane departed from the same airport about 21 minutes prior to the accident and completed a right downwind departure, contrary to the established left traffic pattern. The airplane’s transponder appeared to be off for about 3 minutes after takeoff before transmitting the visual flight rules transponder code (1200) for the remainder of the observed flight; the transponder appeared to be on and functioning at the time of the collision. The airplane proceeded north of the airport before reversing course and returning to approach the airport from the northeast. The last target was observed about 1.2 nautical miles north of the airport on a track leading toward the west side of the landing runway at an altitude of 500 feet agl. About 25 seconds later, the helicopter passed northeast of the airport on a modified left base, about 500 feet above traffic pattern altitude (1,500 feet agl), crossed the final approach course, and turned parallel to and on the west side of the runway. Although only the helicopter was observed by radar at the time of the collision, extrapolation of the accident airplane’s previously observed targets and flight path placed the airplane at the accident site about the same time the helicopter was observed there. An analysis of the relative positions of the airplane and helicopter based on radar data indicated that the airplane remained below the helicopter pilot's field of view as the helicopter overtook the airplane from behind and descended upon it from above. Although the data indicated that the airplane would likely have been visible to the pilot of the helicopter, it is important to note that the onboard traffic avoidance system (TAS) did not provide the pilot with any alert of its presence because the system operated on line-of-sight principles. If an intruder aircraft’s antenna was shielded from the TAS antenna, the ability of the TAS to track the target would be affected. If a TAS equipped aircraft was located directly above an intruder, the airframe of one or both of the aircraft could cause the TAS’s interrogations to be shielded, depending on antenna location (either bottom or top-mounted).

All other airplanes in the traffic pattern were acquired visually by the pilot and crew as their positions were confirmed by the helicopter's onboard traffic avoidance system and the position reports provided by the pilots of each airplane. Because of the high-wing structure of the airplane, and its relative position and altitude, the helicopter's image was either blocked from the airplane pilot's view by the left wing, or was above and behind the airplane in the seconds before collision. Further, no radio position reports from the accident airplane were confirmed. The helicopter pilot’s unalerted detection of the airplane against a complex background of ground objects would have been difficult because of both the lack of apparent contrast between the airplane and the ground, its size in the windscreen, its relative lack of movement within the pilot’s field of view, and the position and angle of the sun. In addition, the helicopter pilot’s familiarity with the customary routes used by fixed-wing pilots to fly into and out of the airport also made detection of the airplane less likely, because the airplane was not in a location that normally contained conflicting traffic. Finally, before the helicopter turned and overtook the airplane, the helicopter pilot’s visual attention would have likely been directed toward the landing area, which would also have limited opportunities for detection of the airplane. The airplane's departure and arrival were contrary to published Federal Aviation Administration guidance, the airplane owner's guidance, and the airplane pilot's guidance to his own students with regard to pattern entry at the destination airport.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The inherent limitations of the see-and-avoid concept, which made it difficult for the helicopter pilot to see the airplane before the collision. Contributing to the accident was the airplane pilot’s non-standard entry to the airport traffic pattern, which, contrary to published Federal Aviation Administration guidance, was conducted 500 feet below the airport's published traffic pattern altitude and in a direction that conflicted with the established flow of traffic.

No comments:

Post a Comment