Power systems failed twice at the air traffic facility at Stevens Anchorage International Airport that guides planes via radar and caused a handful of flight delays.
Larry Lescanec, Alaska vice president of the air traffic controllers union, said the power failures on Sunday at about 7 a.m. and 9 a.m. also took out the software that displays radar information for several minutes.
During both blackouts, air traffic was light.
Lescanec said that during the first instance, an Alaska Airlines jet to Seattle was outbound and control was transferred to another center in Anchorage. In the second, only a small cargo plane landed and the pilot guided the plane in visually.
Lescanec said the complete blackouts at the radar facility were unprecedented.
Allen Kenitzer, an FAA spokesman, said the power problems caused nine departure delays, one of which was for an hour and 39 minutes.
Lescanec accused the FAA of not maintaining batteries in the emergency backup power system that would have restored power right away. The batteries are intended to maintain power until a generator kicks in.
Bob Lewis, a Federal Aviation Administration regional administrator, said the batteries failed in the first blackout and the generator failed a couple of hours later. But he said the situation was handled safely.
Lewis also said the FAA has had batteries on order for some time but had problems with the manufacturer or the supplier.
FAA technicians were aware of the battery problem and took action to procure replacements, Kenitzer said. Delivery was expected Tuesday.
Information from: Anchorage Daily News.