Rail travel between Frankfurt Airport and Munich HBF

Under normal circumstances, 3:20 should be enough to claim luggage, exit customs,
and get to the train. But, the EU has started collecting biometric data for the (eventual)
implementation of the EES system, and this has caused long lines in some situations
as you either need to wrestle with the new machines to get the data recorded, or
stand in a long traditional manual immigration line. If you arrive on a Saturday morning,
it could be much worse than a Tuesday, for example.

Normally, if you miss a connecting train due to some sort of delay, you can just get on
the next one. I'd plug the relevant text about the fare into Google Translate and be sure
you know the rules.

Also, make sure you know you to get to the Fernbahnhof (long-distance station) in the
airport, don't end up on the tracks for the trains that go to downtown Frankfurt and
thereabouts.

Thanks for the input. We arrive on a Thursday morning so I'm hoping/assuming it won't be as crowded as it would be on a weekend. And I am aware of the location of the Fernbahnhof in relation to the main terminal.

Probably will work out, on a trip last year, for me, it didn't, my flight leaving Atlanta was 2 hours late. However, in lots of flights to Europe over the years (maybe 30?), only maybe 3 have been severely late, most early by 30 minutes. If you have the stomach for risk, and don't mind spending a bit more worst case, then go for it. You could also just wait, pay full price and hop on the first train. Not much danger of them selling out seats.

After an overnight and possibly sleepless flight, unless I had to get married in Munich that same afternoon... I would prefer to spend this first day differently.

Rather than spend those first 7+ hours on Thursday in limbo (3.5 probably-wasted hours waiting at the airport, 3.5 on the train, + transfer from Munich station > hotel,) I'd catch the first local train available from FRA to Aschaffenburg (a stop on the train route to Munich, 8:46 - 9:46, for example) and spend the day/night there.

https://tourist-aschaffenburg.de/en/discover-explore/places-of-interest.html

The next morning I'd board an ICE train with my pre-purchased "Super Sparpreis Senior" ticket for Friday's date to Munich, a trip of roughly 2.75 hours.

There may* be an alternate solution. You may be able to book/add a flexible DB Rail & Fly ticket to your airline ticket. This is a joint program between Deutsche Bahn and many partner airlines. The ticket is booked through the airline and is connected to your flight. The beauty of this flexible ticket is that you don’t have to guess what train you might be able to catch - you’ll be asked to “book” a reasonable departure to match your flight arrival, but if you miss that train (or you arrive early), you can use the ticket anytime the day of your arrival. From DBs website:
“…the Rail&Fly ticket can be used flexibly on the selected day of travel on the selected route without being fixed to a specific train.”

I’ve used this program twice, very successfully - once from Frankfurt to Cologne on Lufthansa (added after I purchased my flight) and once from Frankfurt to Munich on Condor (purchased at the same time as my flight). For more info search “Rail & Fly” on your airline’s website, Google “Rail & Fly”, or search the topic on this site or I’d be happy to answer any questions.
*I say “may” because I don’t know if your airline participates or might allow this as an add-on after the original purchase.

Thanks for these suggestions. The fly and rail option sounds good if available. We are flying on United so will have to see if that is an option.

I did a quick search on United’s website and it looks as if United, which is part of the Star Alliance and code shares with Lufthansa, does something called “Lufthansa Rail Express” with Deutsche Bahn, as well as the “Rail and Fly” program. The United website directed me to Lufthansa and I had to scroll down a ways to find the Rail & Fly.

If you’ve already purchased your flights you could try the United app or website to amend your ticket, but I might call United customer service directly to see what’s possible. As a side note: a few years ago, when I added Rail & Fly to a Lufthansa ticket I had already purchased, I had to call CS several times to get to someone who even knew what I was asking about.

"Lufthansa Rail Express" is just a code share between DB and LH. Some DB services get a LH flight number as well, and can be booked through the GDS system. You will get this if you for example book a flight to Cologne via Frankfurt, where you will get a ground level flight added. In this case if you miss your connection due to a delay they rebook you on the next on, and you have reserved seats...
This is of course only available to a limited number of destinations. The nice thing here is that the connection is also protected inbound. So if you eg. book Cologne - FRA - somewhere and a delayed train makes you miss your flight you are protected.

Rail & Fly means that you get free train travel to any destination in Germany added to the ticket. You select a route, and then indeed just board a train of your own choosing. There are no reserved seats, unless you reserve one yourself.
Rail & Fly also allows you to travel to the airport the day before your flight, so you can eg. travel to FRA, stay overnight, and take your flight the next morning...

https://www.lufthansa.com/us/en/rail-and-fly

The two times I tried to take the cheapest train fare after landing in Frankfurt were unsuccessful because my flights were either cancelled or severely delayed. It wasn’t too bad moneywise because the fares were verrry cheap. However I now do as Russ suggeted and take a short ride to a nearby destination, spend the night and continue the next day. Much less stress.

To close out this thread, we were able to cancel our existing United reservation and rebook with the Lufthansa/Deusche Bahn rail connection from Frankfurt to Munich. Because we are extending our stay by another 4 days it actually saved us money! Thanks to the community for the great advice.