Given that cars these days start flawlessly over and over again in all sorts of temperatures and climates, it’s no wonder we’re frustrated that an airplane engine won’t start because it’s a little chilly outside. Or because we just flew it 20 minutes ago. Despite a relatively simple ingredient list of fuel, air, and spark, making that recipe come together takes a bit of knowledge and even more voodoo. Can’t make it work today? Follow our handy flowchart.