Transiting in ZRH
 

Have a Swiss Air flight Palermo to LAX through ZRH. The ZRH to LAX flight changed leaving an 1:25 connection time, tighter than I like as I think if we miss the ZRH to LAX flight I'm guessing next flight is the next day.

Should I be concerned? I assume we will be able to check bags through and not have to retrieve them but not 100% sure on that. And will we have to go through immigration and additional security check as well?

If it is a single ticket you are definitely able to check bags through, if not, then it is still possible but if agents in Palermo are third-party then they may not know how or want to do it

At ZRH, security no, immigration yes as you are leaving the Schengen area. 1h25m is plenty of time though.

Yes, LX operates one flight per day from ZR but you can be rebooked on other *A flights as well (e.g. LH, OS, UA, etc. - depending on what is still available when you arrive at the transfer service desk).
The connection time is tight but perfectly doable, ZRH is quite efficient to transfer through. I have done VIE-ZRH-BOS with less connecting time and had time to spare.
Yes, if you are travelling on one eTicket LX will check your luggage through to LAX.
Yes (because you are exiting Schengen) and Yes (at the gate).

Safe travel and good luck!

There is a good thread on ZRH connections on the LX board.(I’ve asked a mod to see if they will move this there)

A 1hr 25 connection is plenty of time.

i once had a 55 minute connection and still managed a visit to the lounge to freshen up and have a coffee,

ZRH can be a bit annoying to navigate, in my experience, but the connection time should be fine. Only issue is if the Sicilians cause a delay, which is entirely possible.

Now, why on earth should the Sicilians cause a delay to the LX flight? Turning around a plane at any Italian airport (I've used a few) is not usually "linked" to a delay due to local habits or way of life.

When you arrive in ZRH Swiss Air should have an agent stationed at the end of the ramp. If your flt is a late arrival the agent can assist to expedite your connection; also if you reach the pp check area and there are long lines the line monitor agents can help you in jumping the queue, most likely the pp check lines are populated with lots of people exiting Zurich.

With 1h 25min connecting time on Swiss Air in ZRH, I think that should be manageable. Especially if you are travelling on one ticket, Swiss is usually quite proactive in assisting transit passengers. I once had a connecting on Swiss with just 55mins, and there was a slight delay on my incoming flight to ZRH, there was a Swiss Air staff to assist me, and they even helped to offload my luggage from the plane and brought me to a special immigration checkpoint on a shuttle van. I was connecting to a long haul ZRH-SIN as well, so if it is on one ticket I do not believe there is reason to worry.

As other posters mentioned, ZRH is an easy airport to transfer and 1h25min would be enough.

6 hour layover in ZRH
 

Arriving ZRH at 10:20, flying to KOS at 16:05 on Swiss.

Does this leave me anytime to leave the airport and head into Zurich? Or should I just hang out at the lounge? Anything interesting nearby? How fast/efficient is immigration?

Doable. Assuming no delays coming in, you'll be able to take a train to the Hauptbahnhof around 11 and you'll have to take one back to the airport around 1:30. That leaves you with two hours strolling through the city centre and the lake and grabbing some street food. As for your other questions, a) nothing really interesting to do around the airport and b) Swiss immigration is super-efficient (especially when compared with the US).

Street food? There's not so much in Zürich. However, at the airport, just before you get to the bus terminal, there is a small version of Sternen Grill, where you can get a pretty descent St. Galler bratwurst.

But, me, I'd take the train to Stadlehofen and grab your bratwurst near the lake at the main Sternen Grill, then walk slowly back to the HB along Bahnhofstrasse and then take your train back to the airport and arrive around 13:30. Or just take the train back from Stadelhofen. Price is the same. If you're not in the pointy end of the airplane to KOS, and maybe even if you are, grab a nice dessert at Sprüngli in the main terminal when you're airside, but make sure there isn't a big line downstairs for passports. It's unusual, but it happens.

https://www.sternengrill.ch

Is 55minutes enough connecting time through ZRH?

I am arriving via a Swill flight from LCY, the onwards to MAD via a Helvetic flight. (This means clearing Schengen immigrations at ZRH?)

Should be ok, of a bit rushed. It's on one ticket, right? Worst thing that happens, you take the next MAD flight ans likely pocket € 250 in EU261 compensation.

If it's separate tickets: fugeddaboudit.

Connecting in ZRH
 

I had a connection last week in ZRH. Enroute from YUL to BER.
I found the terminal was a nightmare:
- no agents met the inbound aircraft;
- the transfer desk had no staff at 7 am CET;
- moving from Schengen to non-Schengen gates was problematic due to the absence of staff,
So much for Swiss efficiency,
My re-route took me via STR, Interesting cnx. but why did I have to go there traveling between two European cities?