I was building an airplane system which worked fine until....
IT NEVER STOPPED MAKING PLANES!
How to repeat.
1. create a trigger objective
2. Create a command chain of one starting repeat unconditional and the rest chain conditionals
3. /scoreboard players test @a (that objective) 1 1
4./execute @a(that score) ~ ~ ~ /summon (a flying boat)
5. /scoreboard players reset @a(that score) (that objective)
Looks perfect but its not