One command double jump-16w07a+

summon FallingSand ~ ~1 ~ {Block:stone,Time:1,Passengers:[{id:FallingSand,Block:redstone_block,Time:1,Passengers:[{id:FallingSand,Block:activator_rail,Time:1,Passengers:[{id:MinecartCommandBlock,Command:gamerule commandBlockOutput false},{id:MinecartCommandBlock,Command:"/scoreboard objectives add fly stat.aviateOneCm"},{id:MinecartCommandBlock,Command:"/scoreboard objectives add doubleJump dummy"},{id:MinecartCommandBlock,Command:"/scoreboad objectives add OnGround dummy"},{id:MinecartCommandBlock,Command:setblock ~3 ~-2 ~1 chain_command_block 3 replace {auto:1,Command:"/effect @a[score_doubleJump=0] minecraft:levitation 0 0"}},{id:MinecartCommandBlock,Command:setblock ~4 ~-2 ~1 chain_command_block 4 replace {auto:1,Command:"/scoreboard players remove @a[score_doubleJump_min=2] doubleJump 2"}},{id:MinecartCommandBlock,Command:setblock ~5 ~-2 ~1 chain_command_block 4 replace {auto:1,Command:"/scoreboard players set @a[score_doubleJump_min=1,score_doubleJump=1] doubleJump 6"}},{id:MinecartCommandBlock,Command:setblock ~6 ~-2 ~1 chain_command_block 4 replace {auto:1,Command:"/effect @a[score_doubleJump_min=1] minecraft:levitation 1 45 true"}},{id:MinecartCommandBlock,Command:setblock ~7 ~-2 ~1 chain_command_block 4 replace {auto:1,Command:"/clear @a[score_doubleJump_min=1] minecraft:elytra 0 1 {display:{Name:\\\"Double Jump\\\"}}"}},{id:MinecartCommandBlock,Command:setblock ~7 ~-2 ~ chain_command_block 3 replace {auto:1,Command:"/scoreboard players set @a[score_fly_min=1] fly 0"}},{id:MinecartCommandBlock,Command:setblock ~6 ~-2 ~ chain_command_block 5 replace {auto:1,Command:"/scoreboard players set @a[score_fly_min=1] doubleJump 1"}},{id:MinecartCommandBlock,Command:setblock ~5 ~-2 ~ chain_command_block 5 replace {auto:1,Command:"/replaceitem entity @a[score_OnGround_min=1,score_fly=0] slot.armor.chest minecraft:elytra 1 0 {Unbreakable:1,display:{Name:\\\"Double Jump\\\",Lore:[Press space in midair to jump again]}}"}},{id:MinecartCommandBlock,Command:setblock ~4 ~-2 ~ chain_command_block 5 replace {auto:1,Command:"/scoreboard players set @a[] OnGround 0 {OnGround:0b}"}},{id:MinecartCommandBlock,Command:setblock ~3 ~-2 ~ repeating_command_block 5 replace {auto:1,Command:"/scoreboard players set @a[] OnGround 1 {OnGround:1b}"}},{id:MinecartCommandBlock,Command:setblock ~ ~ ~1 command_block 0 replace {Command:fill ~ ~-3 ~-1 ~ ~ ~ air}},{id:MinecartCommandBlock,Command:setblock ~ ~-1 ~1 redstone_block},{id:MinecartCommandBlock,Command:kill @e[type=MinecartCommandBlock,r=1]}]}]}]}