British Airways to Qatar airways : baggage transfer with separate tickets

As explained on the OneWorld page on baggage:

If you are travelling on connecting oneworld flights, your luggage will be checked through to your final destination at the time of check-in.

If you have a through single ticket for the whole trip, then at checkin they will be able to see your final destination. They should then ask you how far you want your bags checked. If not, let them know. When they give you the little baggage tag receipt, check that that has the final destination on them

If you have two tickets, one for BA and one for Qatar, then they won't know about the onward flights. So, you'll need to have those details to hand at checkin. They will need to know the onward flight numbers, and at least one of the e-ticket number (eg 123-1234567890) and the booking confirmation. I would suggest you have a printout to hand with all of that on at checkin. Then, when you get to the BA checkin desk and they ask "where are you travelling to today", you reply "Heathrow, then on a second ticket onwards to Perth with your OneWorld Partner Qatar". Hand them the details of your onwards flights as well as your passport. Again, check the luggage / baggage receipt to ensure it was correctly tagged to the final destination.

On a single ticket, checking to the final destination will only take a few moments longer than a simple single flight.

On two tickets, they need to spend a bit of time linking / finding the second booking. The printout with flight numbers and ticket details will help, but not all staff know / remember how to do that, so you may have to wait a few minutes while they call someone over to help. So, on two tickets, you should allow an extra 10 minutes just to be safe.

If you are travelling on different airlines, under multiple bookings, then this is referred to as "interlining", rather than connecting.

Almost all major airlines have an interline agreement with each other. This allows baggage to be transferred from one flight to another, regardless of whether the ticket is on a single booking, or whether the airlines are part of the same alliance. The notable exceptions are low cost airlines, such as Ryanair, Easyjet etc (although some of these are starting to seek interline agreements).

Often when you are interlining, one airline may not be able to check you in to your next flight, but they will still be able to transfer your bag over to the next airline. This is due to the separate reservation systems used, and lack of tie-ins between them.

In such a case, they will check you in as far as they can, you then need to visit a transfer desk at the airport, who will check you in for the rest of your flights. You don't need to clear immigration/customs or collect your bag, it will be transferred for you.

This happened to me when flying Air France from Aberdeen to Bali, connecting to Qantas in Singapore. Air France check-in at Aberdeen checked me in as far as Singapore, but tagged my bag for Bali. At Singapore, I just needed to visit the transit desk, and was issued my remaining boarding pass.

However, as you are transferring from one OneWorld carrier to another, they will almost certainly be able to not only take your bag, but also check you in to the next flight.

Enjoy flying Qatar and Perth! I flew them to Perth exactly a year ago, although from Edinburgh. Also, be aware that you will need to change terminals in Heathrow.