Two of the 11 people who died in last month’s skydiving plane crash in Mokuleia were solo parachutists who had opted to join the flight at the last minute, according to the National Traffic Safety Board’s preliminary report released Tuesday.

The deadly crash happened moments after takeoff on the fourth of five skydiving flights scheduled June 21 for the Beechcraft King Air plane, operated by Oahu Parachute Center skydiving company, the report stated.

Two prior flights for the plane, registered as N256TA, took place from 9 a.m. to 9:30 a.m. that day, and a third flight — the first of two “sunset” runs — occurred at 5:30 p.m., according to the report.

An Oahu Parachute Center employee reported that the plane’s engines sounded normal as the plane left the operator’s facility southeast of the airfield and taxied west.

Cory Lum/Civil Beat

Once the plane took off, heading east and back toward the Oahu Parachute Center facility, the employee reported that it appeared to turn once it had lifted about 150 to 200 feet off the ground — the plane’s belly facing him, and the top of the cabin facing the ocean, before it nose-dived and crashed into the ground, the report stated.

It burst into flames near a perimeter fence.

The NTSB is slated to release a more comprehensive report into what caused the crash — the worst civil aviation accident in the U.S. since 2011 — sometime in the next 18 to 24 months, investigators say.

The NTSB first raised concerns about inadequate maintenance, pilot training and federal inspections for skydiving flights in 2008 when it issued a series of safety recommendations in a special investigative report.

Despite those efforts, the Federal Aviation Administration has kept skydiving flights under its weakest-possible set of regulations, NTSB officials said during their final press conference on Oahu two weeks ago.

Read a copy of the preliminary report here: