Flights from Santiago de Compostela to Madrid

Truthfully, I wouldn't risk either. I'd book a flight to Madrid for the previous day. Flights do occasionally get canceled.

You need to go to your transatlantic airline's website and find the suggested check-in time for its international flights from Barajas. The airport's website says to arrive at least 2 or 3 hours before the flight, and I am guessing the 3-hour timeframe is for international flights. In any case, planning to arrive at 11:50 AM would not be a good idea unless you want to buy a replacement one-way ticket home.

I would take the earlier flight. Why risk being late?
I took the train from Santiago from Madrid and enjoyed the 6 hour ride across the landscape I had just walked through. Very relaxing and will do this again rather than fly.

You have to ask yourself what the risk is? The risk is missing the return flight and buying a new ticket. Can you accept that risk?

Ignoring the general advice of checking in two to three early. Take a realistic look at your timeline.

13.10 Departure
12.35 - Check in closes. Most European airline have a fairly strict check-in cut off of 45 minutes especially on international flights.
11.50 - Scheduled arrival in Madrid. You now have 45 mins to get off the plane, get to the check in area, etc. Now a whole bunch of variables kick in that you cannot control. Even if the plane is on time, could take ten minutes or more to deplane. What if the plane is late? Lands on time and delayed getting to the gate? Last gate on the concourse so it is the longest walk. For that flight to work everything has to be perfect and on time. When was the last time you had perfect flight? It is very risky, and I would say - stupid to book that tight a connection.

I would not do the earlier flight either. What happens if that plane is cancelled and back up is the later plane? That is not a good option either. Cancellations happen and it is more frequently with the budget airlines that don't have the backup support that bigger airlines do. Most of the experienced travelers here was go to Madrid the day before.

We did the same connection between Santiago and Madrid 7 months ago. The security measures for boarding the flight from Madrid to the US were really elaborate and time-consuming, so I advise you to give yourself plenty of time to connect.

Jonathan,

I will echo the general consensus...
Why risk missing your Trans- Atlantic flight?
I'd also recommend spending the night before your departure in Madrid.

My daughter & I recently witnessed a very upset/angry traveler in CDG when he missed his flight to JFK (Security had to be called by the airport staff)
The plane was still at the gate, but he arrived once the boarding gate had closed, and he was not allowed to board.

Madrid- Barajas Airport is a huge! I'd suggest arriving 3 hours before your departure.

Enjoy Spain!

Frank's mathematics are overly generous. If you take the later flight from SdC and arrive at 11:50 AM, you'll have just 45 minutes, not 1:45, until check-in closes at 12:35 PM.

If it were me, I would arrive in Madrid the day before my flight. Since these are two separate tickets and possible carriers, I would not risk chancing a delay on the day of my transatlantic flight.

Opps you are correct. I will go back and change it.

You've convinced me. I did the same flight in 2013, but perhaps I got lucky. I'll fly in the day before and spend the day in the Prado and Reina Sofia.