I have a headcanon that the Tracys all lost a limb or two in some way and are replaced with robotic parts that help them in rescue missions depending on their bird
Scott: Lost his left arm (up to his elbow) and his right leg- replaced with components which are integrated with Thunderbirds One’s system, allowing him to fly the plane in ease, and also has the ability to scan items/compounds with his hands
Virgil: Lost both of his arms, and are replaced with arms that can lift insane amounts of weight
Alan Lost both his legs, and are replaced with legs that have jets in the bottom in his feet which allows him to hover for a limited time on Earth (but can easily move around in space)
Gordon: Sustained heavy damage to his spine and lungs, and are replaced with a spine which can prop up to act like fins and modified lungs which act as gills underwater (there are special slits in neck that part when he’s underwater)
John: Lost all his arms and legs, and has replacements that allows him to integrate into Thunderbird 5′s system. He does this by sitting on a chair and wearing a helmet which reads his brainwaves.
Kayo, lost her hands, feet and most of her joints are damaged. Replaced with hands and feet that pack an insane amount of power and punch, and her new joints allow her to be extremely flexible and quiet at the same time.