BLOOMINGTON — Loss of control by the pilot, darkness and poor visibility caused the April 7, 2015, plane crash that killed seven men near Central Illinois Regional Airport, investigators said.
"The National Transportation Safety Board determines the probable cause of this accident to be the pilot's failure to maintain control ... which resulted in the airplane exceeding its critical angle of attack and an aerodynamic stall/spin," according to a final report on the crash issued Tuesday.
Pilot fatigue, including cognitive overload; an unexplained disconnected cable; and unbalanced cargo, which dragged the plane down toward its tail, also contributed, investigators said.
The Cessna 414A approached a CIRA runway, but took a turn east, climbed and then descended, crashing into a field east of the airport about 12:06 a.m., according to the NTSB. The men were returning from the NCAA men's basketball national championship game in Indianapolis.
The report concludes a two-year-plus NTSB investigation into the crash that killed seven Twin City area men: pilot Tom Hileman; Torrey Ward and Aaron Leetch of Illinois State University's athletic department; Terry Stralow, co-owner of Pub II in Normal; Scott Bittner, owner of Eureka Locker Co.; Andy Butler, national account manager at Sprint/Nextel; and Jason Jones, senior vice president/investment officer at Secord-Jones Wealth Management Group.
Investigators found "no evidence of (sleep loss) or medical conditions that indicated poor sleep quality for (Hileman)," but "the time at which the accident occurred and the extended hours of continuous wakefulness likely led to the development of fatigue."
"The accident occurred more than 2 hours after (Hileman) routinely went to sleep, which suggests that the pilot's circadian system would not have been promoting alertness," according to the report. "The pilot likely had been awake for 18 hours."
The report also noted Hileman's stress level at the time of the crash.
"It is likely that the higher workload ... and his difficulty maintaining pitch control of the airplane with an aft (center of gravity) contributed to his degraded task performance in the minutes preceding the accident," according to the report.
That stress may have been increased by missing glideslope information — data that helps a pilot track an angle for landing — that investigators couldn't explain.
"(Investigators) determined that the glideslope antenna cable was likely inadequately connected/secured during the flight," according to the report. "There was no history of recent maintenance on the glideslope antenna, and the reason for the inadequate connection could not be determined."
The NTSB also noted declining visibility, light rain and fog at CIRA between 9:56 p.m. April 6 and 12:05 a.m. April 7.
In April, Hileman's widow, Ami, filed a lawsuit seeking unspecified damages in Cook County Circuit Court against five companies allegedly involved in the maintenance, testing or repair of the aircraft. That case is pending.
The men had close ties to ISU athletics, and a memorial to them now stands near Redbird Arena in Normal.
A year after the crash, their families started "Project 7," an effort to honor the men's legacy and encourage Twin City residents to be kind to each other by completing acts of kindness for others.