I read this book in elementary school but pretty sure it was a novel on the longer side targeting at middle schoolers. The main plot was a major airliner, possibly a 747, crashing. I believe it was in the backyard of the house where the main character (a child) lived, and I think the house was a mansion with a big estate. I distinctly remember learning about triage from this book, as the rescuers tag the victims with red, yellow, and green tags. I read this book sometime in the window of 2006-2009.
Could this the Flight 116 is Down! by Caroline B. Cooney?
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The book started out with a young boy named Patrick who was a seventeen year old who was a part of the junior first responder team. Patrick always dreamed about the time he will be able to show everyone that he would be a suitable EMT. Patrick would always sit at the coffee shop downtown. He forced himself to drink the coffee while he listed in on all of the EMT’s stories that they had. His mother and his father were also apart of the Nearing River Emergency squad. There was also a girl named Heidi who lived at the Dove House outside of town about seven miles. Her parents traveled all over the world doing all types of cool things. Heidi went to a boarding school where she did not fit in at all and wished that she could just move home. The Dove house was watched by an elderly woman who took care of the gardens and the home itself.
When Heidi came home from break was when the action started to happen. There was a plane a boeing seven-thirty-seven airplane that was traveling through Connecticut loaded with passengers on it. Off those passengers included two young boys Tuck and Daniel, they were on their way to their dad's wedding. Daniel was the older of the two at the age of fifteen and Tuck was ten. Then there is Darienne a spoiled and smart girl who is very pretty, but because of this, she was very stuck up and snobby. The plane ride was going very smoothly when all of a sudden the plane started losing altitude and shaking out of control. The plane was going down. Panic soon broke out on the plane and people were crying and hugging loved ones. The announcement came over the speaker to take the crash position. The plane crash landed in Heidi’s back yard of the dove house.
The chaos was just beginning for Heidi. She heard a loud crash and took off to the back yard and that is when she saw the plane that had crashed. At first Heidi panicked, she soon got her wit back and called for help, meanwhile help was on the way Heidi helped multiple people to the dove house for warmth and to wait for help. Patrick was the first one on the scene and between himself and Heidi they moved more and more people to the Dove house for safety. They also found people with no serious injuries. Those people also came to help out.
Soon there were multiple ambulances and fire trucks that took up the one lane road to the Dove House. There were so many cars from Nearing River and all surrounding towns of Connecticut that lined the road to the Dove House. All the cars created a little problem when the ambulance crews and fire rescue vehicles were trying to get through to the crash scene, Heidi made a bold move and told them to cut down the ancient rose bushes that were in the front of the Dove House. The crews could then get to the crash scene with ease. The house itself was a command post for all the wounded people and for people to wait for ambulances. The house was a disaster, but Heidi did not care. Heidi was glad that she did the right thing and helped out the people that needed the help.
At the end of the night Heidi knew she could not stay at home, so Patrick and his parents offered a spot for Heidi to sleep while the house got cleaned. Patrick enjoyed having Heidi over and liked spending time with her.
This blog explicitly notes that they learned about triage from the book.
I found it by searching for book 747 crashes in backyard. I was not initially certain it was the right book, but a little more research into the reviews settled it for me.