premise: The incident reached the scale that it did due to operator error after the initial rupture. The 8 5/8-inch diameter steel pipeline, which was operated by Enterprise Products Operating L.P., burst at 11:15 a.m. in an agricultural area about 6 miles east of Kingman, Kansas. A drop in pipeline pressure, indicating abnormal conditions or a possible compromise in pipeline integrity, set off alarms displayed on the computerized pipeline monitoring system. Shortly after the first alarm the pipeline controller, in an attempt to remedy the low pressure, increased the flow of anhydrous ammonia into the affected section of pipeline. A total of 33 minutes elapsed between the time when the first alarm indicated a problem with the pipeline and the initiation of a shutdown.
hypothesis: NTSB is responsible for investigating transportation accidents in the United States.