Air traffic controllers who guided a State Police medevac helicopter in the minutes before it crashed in Prince George's County last September were "casual and sloppy" and not always aware of where the helicopter was, according to reports compiled by federal investigators trying to determine what caused the fatal accident.
The reports also show that the pilot might have receive outdated weather information because of technical glitches, including a failed switch at a data center. The helicopter crashed as it tried to land at Andrews Air Force Base, after plans to land at a nearby hospital were aborted because of fog.
None of the revelations, contained in hundreds of pages of documents released yesterday by the National Transportation Safety Board, point to a clear cause of the crash, which killed the pilot, a paramedic, a civilian medic and one of two patients onboard. The documents do state that investigators found no evidence of mechanical failure.
But they also paint a picture of frustration and confusion on several fronts as the helicopter's pilot looked for help to get on the ground, and as controllers and dispatchers slowly realized what happened once they lost radio contact.
A few minutes before the crash, pilot Stephen H. Bunker asked for guidance to land at Andrews but the controller didn't respond for more than a minute, partly because he wasn't wearing a headset, a report from NTSB investigators said. A few minutes later, the controller broadcast a weather report to Bunker that was five hours old, indicating a safe cloud "ceiling" of 1,800 feet even though it had deteriorated to 500 feet, below the safe minimum.
None of the issues were singled out as potential factors in the crash, and air traffic controllers interviewed by investigators said Bunker never indicated he was in trouble.
But one NTSB report questioned the staffing levels at air traffic control centers that handled the midnight flight. Towers at Andrews and Reagan National Airport were each staffed by just one controller, and the regional center in Virginia, which guided the helicopter when it was between airports, had two controllers on duty but one was on an extended break. In an interview with NTSB investigators, the manager of the Virginia tower said he was "surprised" by the performance of his controller on duty, who was assigned to an administrative position after the accident.
In his last radio broadcast, Bunker requested turn-by-turn radar guidance into Andrews, but the controller there said she was not trained to do that. Such requests are frequently denied at Andrews because of staffing at the tower, one document said.
"While the operation here was overall satisfactory, and so far not considered contributory to the accident, the investigation shed light on areas we can all improve on," wrote David S. Mattox, air traffic manager for the Federal Aviation Administration, in a memo distributed to regional air traffic controllers and included among the NTSB documents.
NTSB officials found controller operations at all three towers involved in operations that night to be "casual and sloppy," Mattox wrote.
"The midnight shift is as important as any other shift and must be approached with the same lavel (sic) of situational awareness," Mattox wrote, adding: "Complacency is dangerous."
The papers from the Maryland investigation were part of a large release of NTSB documents related to nine medevac helicopter crashes over the past year that killed 35 people around the country. The board plans to hold a four-day public hearing starting Feb. 3 to explore medevac accidents. Two years ago it recommended several safety improvements to the FAA, including increased oversight and greater use of terrain-avoidance technology, but the suggestions were not fully implemented.
"We have seen an alarming rise in the numbers of EMS accidents, and the Safety Board believes some of these accidents could have been prevented if our recommendations had been implemented," said NTSB member Robert Sumwalt in a statement released yesterday.
The NTSB determined that poor weather and visibility were factors in three of the recent crashes, and much of its work in the Prince George's crash also seems to focus on the weather. Conditions were "marginal" at 11 p.m. on Sept. 27 when Bunker agreed to fly to a car accident scene in Waldorf, and at 8 minutes past midnight, shortly after the crash, an updated weather report determined conditions had deteriorated.
Minutes after he took off from the accident scene in Waldorf, Bunker told air traffic controllers: "we just ran onto some heavy stuff - I don't think we're gonna be able to make it all the way to the hospital."
How much Bunker knew about the conditions before the flight was a subject of the NTSB's investigation. Because of a faulty switch at a data relay center in Nebraska, precise weather data collected by the Air Force at Andrews was not transmitted to the National Weather Service from 6:55 p.m. the night of the crash until 10:55 a.m. the next day. Whether the glitch made any difference in Bunker's understanding of the weather conditions is unclear from the documents released yesterday.