Undetected heart ailment led to fatal I-40 bridge accident, NTSB rules

An abnormal heart rhythm that could not be detected in a physical exam was probably the reason the captain of the towboat Robert Y. Love fainted just before his tug and tow went off course and struck a highway bridge, according to the National Transportation Safety Board.

The bridge piers on either side of the navigation channel had fenders to protect them, but the tug and barge ended up hitting an unprotected pier.
   Image Credit: Images courtesy National Transportation Safety Board

The accident on May 26, 2002, resulted in the deaths of 14 people.

The towboat was pushing two empty barges when the captain lost consciousness. The lead barge then struck a pier on the Interstate 40 bridge over the McClellan-Kerr Arkansas River Navigation System. The impact knocked down a 503-foot-long section of the bridge, and eight cars and three semitrailer trucks hurtled off the bridge and into the water.

The NTSB, which issued its accident report on Aug. 31, 2004, made several recommendations. One of them calls for the U.S. Coast Guard to evaluate the effectiveness of wheelhouse alerter systems on inland towing vessels. These devices would be designed to set off an alarm when an operator ceases to be in control of a vessel.

Three U.S. towing companies are already using wheelhouse alerter systems, according to Ellen Engleman Conners, the NTSB’s chairman: the American River Transportation Co. (Artco), of Decatur, Ill.; Kirby Inland Marine, of Houston; and Magnolia Marine Transport Co., of Vicksburg, Miss., which owns Robert Y. Love.

Other recommendations include asking the Federal Highway Administration to revise its system for rating bridges in need of replacement or repair to take into consideration the risk of impact by a vessel. The NTSB has also suggested that the FAA develop a system to warn motorists so they can stop in case a bridge does collapse.

On the day of the Robert Y. Love accident, the captain of Love suddenly lost consciousness at about 0745, while piloting the towboat and two barges upriver. The lead barge struck a pier in the I-40 bridge, about 200 feet west of the navigation channel. At 0700, the on-duty deck hand had talked with the captain for about 30 minutes. He later told investigators the captain did not seem sick or seem to have anything wrong with him.

The captain said the last thing he remembered before the accident was aligning the tow to go under the bridge and passing a green navigation buoy to port, about a third of a mile from the bridge, according to the report.

The captain told investigators, “I remember looking out to the side of the buoy and then looking back at the bridge, and after that I don’t remember (anything),” according to the report.

Because the tow was traveling at about 6.7 miles per hour; the transit time from the navigation buoy to the bridge was estimated to be about four minutes. The NTSB estimates that this is about how long the captain was unconscious.

That time span is significant, because it suggests that if the boat had been equipped with an alerter system, there would have been enough time for some other member of the crew to respond to an alarm and take control before the tow hit the bridge.

The captain, who was put on disability after the accident, had held an uninspected vessel operator’s license for almost 30 years. He told the NTSB he had passed under the I-40 span “hundreds of times.”

At the time of the accident, the weather was mild and river conditions were calm. The barge tow was small, the barges were empty, and there were no external conditions, such as high wind or rain, that would have affected the captain’s ability to control the tow, according to the NTSB report. Excessive maneuvering was not required to pass through the navigation channel under the bridge, which was 296 feet wide.

The captain, who was 60 at the time of the accident, tested negative for alcohol and drugs. He was working a six-on/six-off shift. In the 72 hours before the May 26 incident, the captain experienced “significant disruption to his work-related sleep patterns,” according to the NTSB report. On May 24, he cut his normal six hours of afternoon sleep by three hours. He stayed awake all night May 24 and all morning May 25. On the morning of May 25, he slept for four hours when he would normally be awake. He also drove for 10 hours to meet Robert Y. Love, missing his afternoon sleep period. In that 72-hour period, the captain had a sleep deficit of 10 to 11.5 hours, according to the NTSB.

Despite that deficit, the NTSB concluded that his loss of consciousness was probably not due to falling asleep. According to investigators, the captain described losing consciousness “all at once,” which is not typical of falling asleep.

Image Credit: Images courtesy National Transportation Safety Board

This chart shows route the vessels took before hitting the bridge.

The captain also said he had taken Benadryl for a sinus headache between 2315 and 2330 just before going to sleep the night before the accident. Benadryl, a trade name for diphenhydramine, is an over-the-counter antihistamine often used to treat allergies. In over-the-counter doses, the medication commonly results in drowsiness and has measurable effects on doing complex motor tasks, according to the report.

Although his performance may have been subtly impaired by the low level of diphenhydramine in his blood and it may have made him more prone to falling asleep, the NTSB does not think the drug contributed to his incapacitation.

The captain’s most recent Coast Guard–required physical was on Nov. 3, 1997, and showed no medication use or medical problems. At that physical, the captain said he did not have a history of heart or vascular disease, dizziness or fainting. After the accident, the captain did state that he suffered some dizzy spells at home, which he thought were caused by overexertion.

He told investigators he felt dizzy and sick on May 22 while on the towboat Jennie Dehmer and that he lay down and felt fine for his next watch.

Extensive testing after the accident did not find a cause for the captain’s loss of consciousness. A stress test after the accident found that the captain’s heart was normal. After an invasive procedure, it was discovered that the captain had coronary artery disease. His doctors then recommended a test that attempts to create an abnormal rhythm in the heart. After that test, the captain had a device implanted that shocks the heart if it goes into an abnormal rhythm.

Given that the captain apparently fainted because of an undiagnosed medical condition, the NTSB concluded that a wheelhouse alerter might have prevented this accident.

“If the Robert Y. Love had been equipped with such a system on the day of the accident, other crewmembers onboard the vessel may have been alerted to a problem in the wheelhouse and may have been able to prevent the accident,” NTSB Chairman Conners wrote in a Sept. 9, 2004, memo to Adm. Thomas H. Collins, commandant of the Coast Guard. “Therefore, the Safety Board concludes that the presence of either another crewmember in the wheelhouse or a wheelhouse alerter system might have resulted in timely action that could have prevented this accident.”

Kirby Inland Marine is using a system to detect physical movement in the wheelhouse, according to Capt. James Scheffer, chief of the Major Investigations Division for the NTSB. If there is no motion in the wheelhouse, the system sounds an alarm to alert the crew. This detection system ignores movement close to the deck, so the alarm will still be sounded if a person falls to the deck and thrashes around.

Artco and Magnolia Marine are using a rudder-monitoring system, in which an alarm sounds if the operator does not attend the helm (see sidebar). Artco put the steering-based system into all 30 of its long-haul towboats and 30 tug or harbor boats, according to the NTSB.

By Professional Mariner Staff