The 27 year old son of a Zoom manager is named the

The 27-year-old son of a Zoom manager is named the fourth victim of the Half Moon Bay plane crash in which a homemade plane plunged into the sea: his girlfriend's body was only recovered after a fishing boat discovered it

The fourth victim of a plane crash off the coast of Half Moon Bay last Saturday has been named as Isaac Zimmern, 27 – the son of a wealthy Zoom executive.

Zimmern was with his long-term girlfriend Emma Willmer-Shiles, known as Pearl, with whom he had been together for more than ten years and was also 27 years old. The two childhood sweethearts lived in nearby San Francisco.

They were killed in the homemade plane flown by Australian Lochie Ferrier, an experimental aircraft pilot who died along with his venture capitalist fiancée Cassidy Petit. Willmer-Shile's body is the only one recovered so far and was spotted by a fishing vessel earlier this week.

Isaac was the son of Johann Zimmern, 59, the head of global education marketing at Zoom in San Francisco, and lives in a $1.1 million home in the Sunnyside neighborhood.

Isaac Zimmern, 27, was with his long-term girlfriend Emma Willmer-Shiles (right), known as Pearl, who was also 27

Isaac Zimmern's body was not found - but he was known to have been on board the light aircraft

Isaac Zimmern's body was not found – but he was known to have been on board the light aircraft

The couple is seen together in 2014 Emma Willmer-Shiles and Isaac Zimmern are seen at a baseball game in May 2015

The couple had been lovers since childhood and had been together for more than a decade

Johann Zimmern, 59, is head of global education marketing at Zoom, based in San Francisco.  His son Isaac died in an experimental plane crash off the coast of California

Johann Zimmern, 59, is head of global education marketing at Zoom, based in San Francisco. His son Isaac died in an experimental plane crash off the coast of California

Isaac's father, Johann Zimmern, 59, lives in a $1.1 million home in the Sunnyside neighborhood

Isaac's father, Johann Zimmern, 59, lives in a $1.1 million home in the Sunnyside neighborhood

Rescuers from the San Mateo County Sheriff's Office continued the search for the other three inmates.

Ferrier was well-known in the “experimental aircraft” community and had graduated from MIT in 2019 with an aeronautical engineering degree.

He worked at Beta Technologies, an electric aircraft company.

He moved to California to work at Magpie Aviation in Hayward, which specializes in electric aircraft.

Emma Willmer-Shiles, pictured.  Her body was recovered as rescuers continued to search for the other three occupants of the experimental aircraft

Emma Willmer-Shiles, pictured. Her body was recovered as rescuers continued to search for the other three occupants of the experimental aircraft

Lochie Ferrier, Cassidy Petit (pictured together) and Emma Willmer-Shiles were named on Tuesday as victims of Sunday's accident in Half Moon Bay, near San Francisco

Lochie Ferrier, Cassidy Petit (pictured together) and Emma Willmer-Shiles were named on Tuesday as victims of Sunday's accident in Half Moon Bay, near San Francisco

Last October, Ferrier – from Armidale, New South Wales – announced his engagement to Cassidy Petit, a venture capitalist at RH Capital who specializes in reproductive and maternal health, with Ferrier proposing to her while on holiday in Baja California.

The couple shared a love of the great outdoors and their social media was filled with scenes of climbing, surfing, snorkeling, hiking and skiing.

Her last Instagram post on January 1 was an engagement photo of the two taken against the snow-capped mountains of Grand Teton National Park in Wyoming.

Horrifying footage showed parts of the wreckage of the Cozy Mark IV – a four-seat light aircraft that can be built from a kit – washed up on the rocks this week.

Horrifying footage showed parts of the wreckage of the Cozy Mark IV - a four-seat light aircraft that can be built from a kit - washed up on the rocks this week

Horrifying footage showed parts of the wreckage of the Cozy Mark IV – a four-seat light aircraft that can be built from a kit – washed up on the rocks this week

The fourth person on board was not named.  The plane took off from Hayward and toured the bay Sunday before landing in Half Moon Bay at 5:04 p.m.  It remained on the ground for two hours, then took off again from Half Moon Bay and crashed shortly afterwards

The fourth person on board was not named. The plane took off from Hayward and toured the bay Sunday before landing in Half Moon Bay at 5:04 p.m. It remained on the ground for two hours, then took off again from Half Moon Bay and crashed shortly afterwards

The aircraft took off from Hayward and toured the bay Sunday afternoon before landing in Half Moon Bay at 5:04 p.m.

It lay on the ground for two hours before leaving Half Moon Bay and crashing shortly afterwards.

Witnesses at Moss Beach Distillery told NBC Bay Area they saw the plane flying “erratically” before losing sight of it.

There was no official indication of what went wrong, but a witness reported hearing an engine lose power and fail.

“They heard the engine sputtering and kept an eye on the aircraft until they lost sight of it just over the horizon,” said Sgt. Philip Hallworth of the San Mateo County Sheriff's Office.

“That triggered a search and rescue operation by the sheriff’s office and the Coast Guard.”

Ferrier, well known in the “experimental aircraft” community, graduated from MIT with an aeronautical engineering degree in 2019 and worked at Beta Technologies – an electric aircraft company

Ferrier, well known in the “experimental aircraft” community, graduated from MIT with an aeronautical engineering degree in 2019 and worked at Beta Technologies – an electric aircraft company

He moved to California to work at Magpie Aviation in Hayward, which specializes in electric aircraft

He moved to California to work at Magpie Aviation in Hayward, which specializes in electric aircraft

The Cozy Mark IV plane crashed into the sea off the California coast last Sunday.  Built piece by piece in a basement, garage and backyard in Michigan over nearly a decade, the small plane is one of tens of thousands of home-built planes that are part of a high-flying hobby flying across the United States

The Cozy Mark IV plane crashed into the sea off the California coast last Sunday. Built piece by piece in a basement, garage and backyard in Michigan over nearly a decade, the small plane is one of tens of thousands of home-built planes that are part of a high-flying hobby flying across the United States

The Coast Guard said a helicopter and boat crew searched for victims in a 28-square-mile area for nearly six hours on Monday before calling off the search around midmorning.

Hours later, a fishing team discovered a woman's body floating in the water.

The unorthodox nature of the aircraft makes an investigation more complicated.

The plane was registered to an Oakland-based company called Winged Wallabies, Inc., according to Federal Aviation Administration records.

“The plane itself has no flight data or cockpit voice recorders because it is such a small, light aircraft,” said Scott Miller, a pilot and instructor at San Jose State University.

He told KTVU, “If there was some sort of mechanical failure, the debris would certainly indicate that.”

“Kit aircraft are flown every day of the week.” “Sometimes it’s a little harder to follow the history of these types of aircraft.”

The NTSB said a preliminary report on the crash will be completed in two to three weeks.

It takes between one and two years to create a cause of damage report. The Federal Aviation Administration is also involved in the investigation.

Thane Ostroth, a retired dentist, started building the plane in 1999 and flew it in 2008. He said he sold the plane last year to a young, experienced and enthusiastic pilot from Australia for around $100,000.  Thane is seen next to his wife Ellen

Thane Ostroth, a retired dentist, started building the plane in 1999 and flew it in 2008. He said he sold the plane last year to a young, experienced and enthusiastic pilot from Australia for around $100,000. Thane is seen next to his wife Ellen

Thane Ostroth, a retired dentist, started building the plane in 1999 and flew it in 2008. He said he sold the plane last year to a young, experienced and enthusiastic pilot from Australia for around $100,000.

The cost is roughly what he estimates has gone into the project over the decades.

Ostroth said the buyer, in his late 20s, knew a lot about airplanes. On his first test flight he landed the plane perfectly, which is not easy.

“I told him, 'That was well done,'” Ostroth recalled. “He said, ‘Thank you. “I’m going to buy the plane.”

Ostroth said he heard about the crash in an online chat group for pilots and manufacturers of cozy planes, a class of aircraft built by individuals rather than mass-produced by companies.

He said it was “traumatic” to know that the plane he had spent so much time on had crashed with people on board.

“It’s just a terrible feeling,” Ostroth said.

Like commercial aircraft, all home-built aircraft must be inspected annually by the FAA for airworthiness.

Cozy planes have the same safety record as commercially built planes of similar size, said aeronautical engineer Marc Zeitlin, who advises the National Transportation Safety Board on crash investigations involving Cozy planes, including this one.

More than 33,000 amateur-built aircraft are licensed by the FAA, a number that has tripled since the 1980s.

The administration refers to all noncommercial recreational aircraft as “experimental aircraft.”

These may include aircraft built from kits with some prefabricated parts, or from plans where the manufacturer purchases or manufactures and assembles all the parts.

The four-seat Mark IV, measuring just over 16 feet long and with a 28-foot wingspan, is a popular aircraft among the growing number of hobbyists building their own aircraft.

Zeitlin owns one himself, which he takes with him on day trips and cross-country trips.

“The misconception is that these are put together by baling wire and glue,” said Zeitlin, CEO of California-based Burnside Aerospace. “But they are built according to the aircraft design.”

The Mark IV has a “canard” design with a small forewing at the front of the main wing, resembling a duck outstretched in flight. It's lightweight, weighing only about 1,050 pounds empty, and the parts are assembled with epoxy resin.

With a top speed of nearly 200 miles per hour, it is fast, stable and fuel efficient, Zeitlin said.

“Like a sports car in the sky,” he said. “It’s a lot of fun to fly.”

Ostroth said he bought the plans for his cozy for about $500 and began putting it together in a friend's basement in Michigan.

Eventually, they moved construction to the home's garage and then built a barn in the backyard for the final steps.

“The plans come with a list of authorized parts suppliers,” said Ostroth, who now lives in Florida. “You buy foam, you buy fiberglass, you buy metal parts from all the manufacturers. And you slowly put it together.”

You can get help from other enthusiasts who post tips and advice in online forums.

Ostroth flew the aircraft regularly for 15 years. He called it “a wonderful little airplane.”