Legion Flying Guide

In the upcoming and long awaited Patch 7.2 Legion Flying will be introduced. Just like in WoD you will need to jump through some hoops and grab some achievements to get it. It has been reported that it won't be quite as onerous though.

The two meta achievements you will require are Broken Isles Pathfinder, Part One and Part Two.

Luckily, though, you can get a really good head start now and get Part One.

This consists of:
Broken Isles Explorer - Explore All the Regions
Loremaster of Legion - Do all the Zone Storylines
A Glorious Campaign -Complete Class Order Hall Campaign
Variety is the Spice of Life - Complete 100 Different World Quests
Broken Isles Diplomat - Hit Revered with the 5 Zone Factions

Then when Patch 7.2 hits you just need to do the content there.

Part Two, which awards Legion Flying, consists of:
Part One
Defender of the Broken Isles - Complete the four legion Invasions *UPDATE* as of Hotfix on 06/04/2017 this has now been removed from the meta achievement so is no longer required to get flying
Explore Broken Shore - Explore
Legionfall Commander - Earned Revered with the Armies of Legionfall

There is even a tool on Wowhead that tells you what you still need to do.

Here is my own progress tracker

PART ONE

Broken Isles Explorer - COMPLETE!

Explore Azsuna

Explore Highmountain

Explore Stormheim

Explore Suramar

Explore Val'sharah

Loremaster of Legion - INCOMPLETE

Good Suramaritan 63.6%
Complete the followin Suramar quest lines:
An Ancient Gift
The Waning Crescent
Blood and Wine
Statecraft
Jandvik's Jarl
Eminent Grow-main
Moon Guard Stronghold
A Growing Crisis - finish this by doing The Emerald Nightmare raid, kill Xavius
A Change of Seasons - got to hit 20/21K revered with Nightfallen and done The Emerald Nightmare
(separate from main)
Breaking The Lightbreaker - quest Lyana Darksorrow - Starts at 30.8, 59.1
Tidying Tel'anor - quest: The Lost Advisor - Starts at 45.8, 40.2

Ain't No Mountain High Enough

Azsuna Matata

That's Val'sharah Folks!

Vrykul Story, Bro

A Glorious Campaign - COMPLETE!

Variety is the Spice of Life - COMPLETE!

Broken Isles Diplomat - COMPLETE!

Court of Farondis

Dreamweavers

Highmountain Tribe

The Nightfallen

The Wardens

Valarjar

PART TWO

Part One - INCOMPLETE
Good Sumaraton

Defender of the Broken Isles - COMPLETE

Invasion of Azsuna

Invasion of Highmountain

Invasion of Stormheim

Invasion of Val'sharah

Legionfall Commander - INCOMPLETE
1% Friendly / Revered

Explore Broken Shore
Deliverance Point
Deadwood Landing
Soul Ruin
Broken Valley
The Weeping Terrace
Tomb of Sargeras
Felrage Stand
Felfire Pass