Connection time in Frankfurt

One hour will not be enough time. We had a two hour 10m layover 3 weeks ago, which was fine, but I think an hour is cutting it too close . Many planes unload on the tarmac, then you get a bus, ride bus for 10 minutes, walk, have to wait for a kiosk for picture and fingerprints, then stand in line (25 minutes for us) to clear immigration, then walk to your gate,

Although if you miss your flight, Lufthansa will put you on next available flight,

We shouldn't have to go through immigration and security when just changing planes in Frankfurt, should we? We will be coming from a 6-day stay in Iceland.

Hi, Michele.

Yes, KEF-FRA-VIE will be entirely within the Schengen zone. I doubt you even need to leave the secured “airside”. The real issue is the 1-hour connection time. Any combination of a delay leaving KEF, a delay in the airspace on approach to FRA, a delay with the assigned gate not freed with previous plane not having left in a timely manner will make for a very nervy experience.

Schengen to Schengen should, I think, not require an additional security screening in
Frankfurt.

Frankfurt is a large airport, and despite that, many flights arrive and depart from tarmac
"gates". So you could be delayed in two ways; one, you have to deplane and wait for
the bus to fill up before it goes back to the terminal, and two, the last bus for your
connecting flight may leave before the time you could make it on to the plane if it
was parked at the jetway.

Check the next flight to VIE after the 1 hour connection. If it's an hour later, then I would
not worry too much. As noted, LH is obliged to get you to Vienna.

I would add your luggage into the equation? Are you carry-on only for this trip, and do you meet the weight restriction (under 18 lbs)? If you check a bag it may or may not make it, either.
I had a smaller Lufthansa plane a couple years ago from Frankfurt to Berlin. Although my carry on was compliant everyone was forced to check them at the gate. Then the flight was delayed and ultimately cancelled - yes, they rebooked me to another flight later in the day, but the bag of course didn't get the memo!
I was inconvenienced but at least staying in the same arrival city several days. (It took 2 to get the suitcase.) Are you moving on upon landing in Vienna?
Just another aspect to consider. If you're collecting votes I wouldn't take the risk- good luck!

I wouldn’t even be particularly comfortable with a one-hour connection time at a large US airport I’m very familiar with. I definitely would be stressed st an unfamiliar foreign airport, and I like to eliminate as much stress as possible when I travel.

I’d be hesitant based on many experiences at Frankfurt. But check the next flight so you’ll know your options.

Thanks to everyone for providing their knowledge of the Frankfurt airport experience. There are several flights to Vienna later in the day, and it sounds like it would be smart to book one of those rather than the one that only allows an hour connection time. And good point about the luggage. We will be carryon only, but we could be in trouble in the case of a gate-check debacle, as we are going on to Bratislava later in the day and will only be there two nights.