Transiting through CDG on different carriers - some help

The risk is that something might cause your first flight to be delayed or canceled. If anything causes you to miss the second flight, you'll have to buy a replacement ticket at the last-minute fare. Alternatively, you could buy a last-minute train ticket, but that will probably be very expensive.

How much time will you have between your scheduled arrival in Paris and your scheduled departure? Since you won't be on a single ticket, I think you must go through immigration in Paris, and it's unpredictable how long that will take.

Are you traveling on an Indian passport? Do you need some sort of transit visa for France? I have no idea what the requirements are for travelers not on single-ticket itineraries.

The potential visa issue aside, what you're doing is not particularly unusual. However, many of us would not do it, at least not without planning to spend a night in Paris as a sort of insurance against a major delay on the first flight. But a night in Paris would really eat into your flight savings.

Yes it is quite normal to change from an intercontinental flight to a Schengen internal flight. You always go through immigration when you first enter the Schengen Area, but not thereafter.

You need to allow lots of time between the two flights. Like 3 hours+. Immigration could take 1 hour. The big risks are:
1) Your first flight is late.
2) Either flight has its times changed between now and your departure date.

• You will have go through immigration for the Schengen Area in Paris, even if this was on the same ticket. Paris is where you enter the Schengen Area, Paris to Barcelona is inside the Schengen Area so no passport checks (but the airline will want to see your passport as an ID check).
• Your Spanish Student Long-Stay Visa should be OK to get you into the Schengen Area in Paris. But double-check, there is a small risk there is a rule that you must enter Spain first.
• The sequence will be: land - disembark and walk through corridors - Immigration (passport check, show your passport and visa) - luggage pick-up - customs - exit to France - change terminals - check-in for second flight - go through security - wait until gate is shown on screens, then go to gate.

There is a big difference between inbound/outbound flights which are connecting (one PNR) and those which are composed of two separate reservations.

You will not be able to remain airside and take advantage of expeditious passport control and security traveling as you have planned. You will use the same passport control point as passengers with CDG as their final destination and then check in as an originating passenger.

The difference is time and the more you have, the better off you will be. 3 hours between flights would be an absolute minimum.

@Tocard. The OP said in his original post, he knew he would have to go through immigration, pick up his bags, and check in again at a different terminal.
Yes, he needs lots of time
Landing, taxiing, disembark, walk through corridors = 30 minutes+
Immigration = 30-60 minutes
Pick up bags, transfer between terminals = 30 minutes
Minimum check-in time for next flight? Probably 60 minutes, but need to check with airline.
Plus risk first flight may be late landing
Plus risk either flight time may be changed.

Can someone tell me whether what i'm doing is inviting trouble of some kind?

I would suggest a minimum of 4 hours between flights.

Can you check the on time history of your flight to Paris, to give you some idea of what your odds are of an on time arrival and plan accordingly?

When I transit through an airport as opposed to catch a connecting flight, I allow 4 hours between flights.

Thank you for all the responses. It seems that all the flights going to BCN from CDG are either in the morning or the evening. This means I'd be in the airport at least 11-12 hours before my next flight. Not sure if this is worth it.

I presume you tried using your FF miles to book BOM to BCN . ?

It seems that all the flights going to BCN from CDG are either in the morning or the evening.

Have you checked the flights from ORY?

It will take 2 hours by Air France bus to transfer from CDG to Orly. You need to be there 2 hours before the flight. The high-speed train from Paris Gare de Lyon to Barcelona is six hours, or you just wait at CDG for an evening flight.