With some 42 missions on offer, there's loads for kids to do here. 30 of those missions are "training" missions, which take you at a very steady pace through each character's abilities, and how to use them, while the other 12 see you put the whole team through their paces. From fighting fires in the middle of a thunderstorm, with new blazes being ignited by lightning strikes every few minutes, to rescuing "deer" (basically tractors with antlers strapped to their heads) from an encroaching fire, there's a surprising amount of variety here - and, most importantly, the perfect mix of reality and fantasy to suck kids in. Kids will love being part of the rescue team, and learning how to deal with fires - and the fact you have a limited amount of water to drop, so will have to make regular trips to the lake to fill up, only makes it feel all the more exciting.
In terms of accessibility, for the most part, Planes: Fire and Rescue is absolutely fine. While there are a few strange hitches with waypoint markers not showing, most of the time, the game clearly indicates where you need to go next, and what you need to interact with, even telling you which character you need to switch to next. Perhaps the biggest issue here in terms of younger players is that there's no difficulty level to speak of. With a time limit in place (each fire/incident has a little bar on screen in the top left corner which fills up over time), you'll have to respond to the fires in the right order - however, there's nothing obvious on screen to tell you which fire is which, and which you need to tackle first, which younger children may find confusing.
With nothing in the way of real voice-overs, your child will also need to be a strong reader to understand what they need to do here, and read sentences such as: "There are six small practice fires located throughout Piston Peak. Your challenge is to put them all out without filling up with any extra water." That said, if they're a strong reader, and can cope with the time limits, kids will get a lot out of this - and it should be a game they'll keep coming back to.