I know that. The Stinger also uses an optical sensor that sees UV and IR. Two guys in a boat along the climb out path wouldn't need any extra equipment to see the target. Unlike a miltary plane, commercial flights are well lit like a christmas tree. The takeoff/landing lights are very bright and hot, and they are UV bright as well. From underneath, a Stinger wouldn't need to see the engines.
It would see this nice hot light right in the center of mass (Or this nice bright dot.) making a kill almost guaranteed. That light was right about where the nose came away. The Stinger has a six pound warhead. (Made by Picatinny Arsenal.) It gets within a set distance from the target and blast fraggos the target. Just in case, it also has an impact fuse. Not that it needs one. Now, I don't know about you, but I don't know any plane that can survive getting a belly shot like that while traveling at 300 MPH or so (Or faster.. 500 knots) and not come apart in the slipstream over it's own skin. To all the others out there.. assume the lotus position. Repeat mantra of 'wiring fault' until well brainwashed.
No one saw a fuel/air explosion until at least 20 seconds after the missile impact. A Stinger which is effective would ignite the fuel to create a fuel/air explosion. The actual missile only fragmented the aircraft without a fuel/air explosion. The fuel did not ignite until later. A Stinger has 100% probability if striking an aircraft. But a Stinger without a warhead would only bounce off of a B747 or at least allow the crew to issue a MayDay. This crew was killed on the spot by the violence of the impact. A KKV that is supersonic has both the mass and speed to destroy any aircraft without exploding.