NTSB: Severe winds led to fatal capsizing of SEACOR Power

Written by Nick Blenkey
Capsized SEACOR Power on the evening of the accident, with a Coast Guard response boat in the foreground. [U.S. Coast Guard photograph]

Capsized SEACOR Power on the evening of the accident, with a Coast Guard response boat in the foreground. [U.S. Coast Guard photograph]

Severe winds during a thunderstorm led to a loss of stability and ultimately the capsizing of the liftboat SEACOR Power, the National Transportation Safety Board said Tuesday during a public board meeting. Of the 19 people aboard the vessel, six died and seven are missing, presumed dead. Six people were rescued by the U.S. Coast Guard and other vessels. The SEACOR Power, valued at $25 million, was a total loss.

On April 13, 2021, the vessel, a liftboat supporting offshore work on oil-producing platforms, capsized off the coast of Port Fourchon, La. Vessel operators reported heavy rain, winds exceeding 80 knots and 2- to 4-foot seas at the time of the capsizing.

​The SEACOR Power was destined for an oil and gas lease block in the Gulf of Mexico and got underway shortly after noon. Sometime after 3 p.m., the liftboat was overtaken by a rain squall. The vessel’s mate said a second squall about 10 minutes later caused “white out” conditions. The crew began to lower the vessel’s 265-foot-long legs to the seafloor to allow the vessel to ride out the storm. During the leg-lowering process, the mate turned the SEACOR Power into the wind to slow its speed. As the vessel turned, it heeled over and capsized at around 3:57 p.m.

A National Weather Service report concluded the area of the capsizing was affected by an “unusually intense thunderstorm wind event.”

The NTSB determined the probable cause of the capsizing was a loss of stability that occurred when the vessel was struck by severe thunderstorm winds, which exceeded the vessel’s operational wind speed limits. Contributing to the loss of life on the vessel were the speed at which the vessel capsized and the angle at which it came to rest, which made egress difficult and the high winds and seas in the aftermath of the capsizing, which hampered rescue efforts.

NTSB investigators identified data gaps that prevented the National Weather Service from identifying and forecasting the surface wind magnitudes that the SEACOR Power encountered. The localized wind conditions could not be detected by weather service radars due to their elevation angles.

The final report will be published on the NTSB website in several weeks, however, the executive summary, probable cause, findings, and safety recommendations are in the report abstract available on the investigation web page​.

“We found that the captain’s decision to get underway on the day of the casualty was reasonable and was not influenced by commercial pressure. However, weather information that SEACOR Marine provided to the SEACORPower’s crew was insufficient for making weather-related decisions about the liftboat’s operation,” says the report abstract. “Additionally, due to a Coast Guard broadcasting station outage, the SEACOR Power crew did not receive a National Weather Service Special Marine Warning notifying mariners of a severe thunderstorm that was approaching.

“Even if the SEACOR Power crew had received the Special Marine Warning, data gaps, including a lack of low-altitude radar visibility over the Louisiana coastal areas, prevented the National Weather Service office that issued the Special Marine Warning from identifying and forecasting the surface wind magnitudes that impacted the SEACOR Power. Lowering the angle of the lowest radar beam at select coastal weather radar sites would improve low-altitude radar visibility over coastal waters.

“The capsizing occurred when the SEACOR Power was struck by severe thunderstorm- generated winds that exceeded the vessel’s operational wind speed limits, causing a loss of stability. Other operational factors may have also played a role in the capsizing, including the liftboat’s trim by the stern (the difference between a ship’s forward and aft drafts), its turn to port and speed through the water, a cargo shift, and movement of the vessel’s legs.

“We found that due to the unpredictability of thunderstorm phenomena and the vulnerability of restricted-service liftboats like the SEACOR Power, operating restricted- service liftboats like the SEACOR Power in the afloat mode at any time when a Special Marine Warning has been issued for the vessel’s planned route increases their risk of capsizing. Further, increasing minimum stability criteria for liftboats in restricted service would improve vessel survivability in severe thunderstorms.

“The speed at which the SEACOR Power capsized and angle at which it came to rest made egress difficult and likely contributed to the fatalities. Following the capsizing, the Coast Guard Response Command Center did not effectively use available information to verify the validity of the location of SEACOR Power’s emergency position indicating radio beacon alerts, which led to a delay in dispatching search and rescue units and notifying Good Samaritan vessels of the emergency. Additionally, SEACOR Marine did not have adequate procedures nor did it provide its staff with training for responding to the Coast Guard when contacted regarding emergency position indicating radio beacon alerts, and inaccurate information about the SEACOR Power’s location provided to the Coast Guard by a SEACOR Marine employee contributed to the delayed response.”

RECOMMENDATIONS

As a result, the NTSB recommended the National Weather Service, Federal Aviation Administration, and the Air Force work together to assess coastal weather radar sites to determine if it is safe and appropriate to lower radar angles, which could improve the ability to accurately forecast weather conditions.

The NTSB issued three safety recommendations to the U.S. Coast Guard:

  • develop procedures to inform mariners in affected areas whenever there is an outage at a navigational telex broadcasting site;
  • modify restricted-service liftboat stability regulations to require greater stability for newly constructed restricted-service liftboats; and
  • develop procedures to integrate commercial, municipal, and non-profit air rescue providers into Sectors’ and Districts’ mass rescue operations plans.

The NTSB also reiterated a recommendation to the U.S. Coast Guard to require all personnel employed on vessels in coastal, Great Lakes and ocean service be provided with a personal locator beacon. The NTSB also recommended the Offshore Marine Service Association notify members of personal locator beacons’ availability and value.

“We’ve been waiting five years for the Coast Guard to implement our recommendation on personal locator beacons — a call to action we’re renewing today for the fourth time,” said NTSB Chair Jennifer Homendy. “Mariners’ safety can’t wait, which is why I’m urging employers to invest in personal locator beacons for their crew. As the SEACOR Power tragedy shows, the lifesaving promise of these devices cannot be overstated.”

The first time the NTSB recommended the Coast Guard require personal locator beacons was following the 2015 sinking of the cargo vessel El Faro in which all 33 crewmembers perished. NTSB reiterated the recommendation for the first time after the fishing vessel Scandies Rose sank off Sutwik Island, Alaska, in 2019, which killed five people; and again following the 2020 sinking of the Emmy Rose fishing vessel off the coast of Massachusetts, which killed all four crewmembers.

“None of the people aboard the El Faro, the Scandies Rose, the Emmy Rose, or the SEACOR Power had personal locator beacons. If they did, perhaps more of them would be with us today,” Homendy said. “Instead, 55 people died or were unrecovered in these tragedies — 55 people gone forever.”

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