Destroy 2 Air Defense at once

On https://www.reddit.com/r/ClashOfClans/comments/3rjgzi/strategy_destroy_two_air_defenses_at_once_with/ a simple way is detailed to destroy 2 (level 6) air defense:

For this, you must drop between both air defende::

• 2 lightnings (level 5)
• 1 earth quacks
• next a last lightning