Triggering "I'll Fly Away" Side Mission (Acquiring Iconic Stinger)
I ran into a problem triggering this mission in my second playthrough. While trying to troubleshoot the issue, I found quite a few reports from other players who had difficulties triggering and completing it.
I did manage to eventually figure out what was wrong and get it working, so I decided to put it into a thread with a title that would make it easy to find for people googling the problem.
What's Supposed To Happen
After completing the mission "Riders In The Storm," two separate text message triggers are sent to the player relating to different missions. One is for the follow-up mission in the Panam chain (With A Little Help From My Friends) and one is from Mitch, discussing Scorpion. Mitch's text, when things work normally, places "I'll Fly Away" in the player's journal.
If the player completes the mission before starting Panam's fourth quest "Queen of the Highway," they will be rewarded with Stinger (and a decorative toy.)
What Can Go Wrong
The most common issue is that the text from Mitch is never sent. This is a bug, and it appears to be a very common one. Luckily, if you know the details of the mission, there is a workaround (listed below.)
Having "With a Little Help From My Friends" in your journal moves Mitch from the starting location for "I'll Fly Away," and prevents that mission from being progressed. This particular issue is temporary - at the conclusion of the quest, you can immediately interact with Mitch and begin his side mission. However, if you don't do this right away, advancing Panam's quests can lead to the next major issue.
Completing "Queen of the Highway" will permanenly lock out "I'll Fly Away" from that playthrough. At that point, there is no longer a workaround. The only way to trigger Mitch's quest is to reload to a point before doing "Queen of the Highway."
The Workaround If The Quest Doesn't Trigger
After completing "Riders On The Storm," travel to the Aldecaldo camp (the original one - once they've moved from their original location after "Queen of the HIghway" the quest can no longer be progressed.)
Outside the camp (away from the tents) there is a group of Aldecaldos assembled by cars. Nearby, up a hill, is another small group by a twin rock formation where Mitch is sitting. He will not have a quest marker over his head (unless you received the text from earlier) but you can talk to him. Doing so will trigger "I'll Fly Away" which can be progressed normally. I recommend doing it before anything else, as it is brief.
Stinger can be useful to certain blade builds, so it can be worth the effort to make sure this minor side mission starts properly.