Investigators look through the wreckage of a plane crash at the Trumpf building in Farmington, Connecticut, in 2021.

The Kansas-based company that built the Cessna 560XL that crashed in Farmington in 2021 killing four people knew at least five years before that the aircraft had no parking brake warning system which had been a factor in other accidents, federal documents said.

But Textron Aviation failed to act on recommendations for parking brake safety upgrades after an Australian crash in 2015, according to a National Transportation Safety Board Safety Recommendation Report issued in May.

The NTSB and the widow of Danbury pilot Mark Morrow, who died in the Farmington crash, now want the Federal Aviation Administration to require Textron Aviation to make the safety upgrades they said could avoid future tragedies. A Textron spokesperson said the company is awaiting a recommendation from the FAA.

“This was a death that was 10,000 percent preventable,” said Attorney Douglas Latto, representing Dunja Morrow.

The Farmington crash killed the planes’ two pilots, Morrow, 57, and William O’Leary, 55, of Bristol, and passengers Courtney Haviland, 33, and her husband William Shrauner, 32, both doctors from Boston who were expecting their second child. On the ground, one man was seriously injured and three others suffered minor injuries as a result of the crash, officials said.

The Cessna was cleared to take off from Robertson Airport in Plainville on Sept. 2, 2021, reports said. But the plane appeared to never gain proper altitude and looked like “something was wrong” from the start, according to witnesses who spoke with NTSB investigators.

The plane was exceeding the speed required to take off but went beyond the runway onto a short width of grass, pitched up without gaining altitude, impacted the ground and struck a power line pole before crashing into a Trumpf Inc. building in nearby Farmington, NTSB investigators said in a preliminary report issued in late September. The cockpit, cabin and wings were engulfed in flames, the agency said.

The NTSB, which investigates all types of transportation accidents, pointed out in the preliminary report that the plane’s parking brake was still engaged when the Cessna crashed and that the aircraft’s takeoff configuration warning system “did not incorporate parking brake valve position as part of its activation logic.”

That means that there was no warning light to indicate that the parking brake was still engaged that both pilots could see when they tried to take off and no verbal check list item requiring each to call out to make sure the brake was disengaged, Latto said.

“Even your car has a light if your emergency brake is on,” said Latto whose practice only represents victims of aviation accidents. His client is considering suing Textron Aviation among her options as she continues to struggle with the loss of her husband, Latto said.

At least three other crashes by Cessna 560XLs or Cessna 550s built by Textron Aviation have been investigated since 2015 by the NTSB or similar authorities in Australia and Nigeria, according to the NTSB safety recommendation report issued months ahead of the release of the final report on the Farmington crash.

The NTSB has no regulatory authority and can only make recommendations to the FAA based on investigations into aviation accidents.

The federal agency wants the FAA to issue an “airworthiness directive” which would require Textron Aviation to put warning systems in all existing and newly manufactured Cessna 560XLs or 550s and update pilot take off lists to include a check of whether the parking brake is still engaged. The FAA could also opt to make the changes recommended but not mandatory or adjust the recommendations, Latto said.

The move for an “airworthiness directive” comes six years after Australian authorities recommended that Textron Aviation update parking brake safety systems following a crash in that country in 2015, according to the NTSB report.

But at the time Textron declined to add the features, the NTSB said. In a 2017 response to the Australian investigation report, “Textron stated that the recommended actions were not needed because it was ‘simple airmanship’ to remember to release the parking brake before takeoff,” the NTSB said. As a result, Textron neither updated its pre-takeoff checklists nor added a parking brake warning system, the federal agency said.

The aviation company is now reviewing the NTSB safety recommendations and awaiting a decision from the FAA on whether the proposed safety changes will be required, said Textron Aviation spokeswoman Sarah White.

“Textron Aviation awaits the Federal Aviation Administration’s position and recommendations with respect to the NTSB’s findings,” said White who declined to speak about the crash citing the ongoing NTSB investigation.

The FAA acknowledged Wednesday that the agency is working on the recommendations with the manufacturer but declined to specify a time frame when they would make a determination on whether Textron Aviation would be required to install the parking brake safety features.

The FAA institutes about 80 percent of the safety recommendations issued by the NTSB, said FAA spokesman Eric Weiss.

No one was injured in the Australian crash which occurred in South Wales in September 2015, agency officials said. But the pilot had to reject takeoff when he realized he wasn’t gaining altitude, according to Australian authorities. The plane wound up careening beyond the runway with the nose landing gear detaching, the Australian Transport Safety Bureau said in a 2016 report.

The Australian agency concluded in their investigation that the parking brake, which was still engaged, impeded the acceleration needed for the pilot to properly take off and also impeded the pilot’s ability to safely stop the plane on the runway.

The NTSB stated similar findings, stating that the engaged parking brake only not prevents Cessna 560XLs from gaining altitude, but can also prohibit pilots from safely halting the take off.

The NTSB also investigated a 2019 Cessna 560XL crash in Oroville, California where the plane also overran the runway while the pilot rejected takeoff because he wasn’t gaining altitude, a report said. In that case, the pilot and the passengers were not injured but the plane was destroyed by a “post-impact” fire, the NTSB said.

The cause of that crash was likely the pilot’s “failure to release the parking brake before attempting to initiate the takeoff,” the NTSB said. The fact that the plane had no warning system indicating that the parking brake was engaged and there was no checklist item to ensure the parking brake was “fully released immediately before takeoff” were contributing factors in that crash, the NTSB report said.

In those cases, the pilots and their passengers survived and were not seriously injured, the NTSB said. But the planes were heavily damaged, the agency noted. That’s because the topography beyond the runway in those crashes was flat, allowing the pilots to eventually stop the take off without crashing into any objects including hills, highways or water, the agency said.

Just beyond the runway in Plainville, the ground drops off, Latto said. That created a scenario where O’Leary, the main pilot, was pulling on the yoke very hard to get the plane off the ground but the friction from the tarmac was preventing aircraft from becoming airborn, the attorney said.

At the point when the ground fell away, the friction stopped, likely causing the plane to quickly pitch upward, Latto said. That type of sudden shift can cause the plane to stall, leaving a pilot with no options, he said.

The parking brake warning system “should be in every single airplane,” Latto said. “We’re talking about human lives.”