How to create a command that enables flight in survival?

Hello. I'm trying to make a custom command which enables flight in survival. I've tried creating a command and putting the "allow entity to fly" procedure, but that doesn't seem to work. Can someone help me with this? Any help would be appreciated.

Here is the code:

package net.mcreator.herocraft;

import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.entity.Entity;

import java.util.HashMap;

@Elementsherocraft.ModElement.Tag
public class MCreatorAllowflightCommandExecuted extends Elementsherocraft.ModElement {
	public MCreatorAllowflightCommandExecuted(Elementsherocraft instance) {
		super(instance, 100);
	}

	public static void executeProcedure(java.util.HashMap<String, Object> dependencies) {
		if (dependencies.get("entity") == null) {
			System.err.println("Failed to load dependency entity for procedure MCreatorAllowflightCommandExecuted!");
			return;
		}
		Entity entity = (Entity) dependencies.get("entity");
		if (entity instanceof EntityPlayer)
			((EntityPlayer) entity).capabilities.allowFlying = (true);
	}
}