Transiting Heathrow
 

I'm flying Delta JFK-LHR, connecting in LHR to Skymiles partner, Tarum Airlines, to Istanbul. Will I be able to check my bags all the way through at JFK? or do I need to clear customs in LHR, claim my bags, recheck, then enter back through LHR Security?

Presuming you mean Romanian carrier Tarom, Delta will be able to check your bags all the way through, if it is all on one ticket. Always check and take a photo of the bag tag applied to your bag though, just to check it includes both the DL flight number and RO (Tarom) flight number(s). If it is not all on one ticket, then you will have to clear customs and recheck.

OP will probably need to provide more information: from LHR only BA and TK appear to operate flights to Istanbul.

I think RO and TK only codeshare on OTP-IST-OTP so it doesn't make sense that OP would have an RO flight number to IST from LHR. Unless this is a super convoluted JFK-LHR-OTP-IST journey.

As others have noted, if all of this travel is on one ticket you will be able to check your bags to your final destination and will not need to claim your bags and recheck them at LHR. You will, however, need to go through LHR Security.

Thankyou

Ticket 1: Delta issued- DL Flight Number- JFK/LHR\

Ticket 2: Delta Issued Milage Ticket- RO Flight Numbers- LHR/IST connecting in Bucharest

Traveling on separate tickets is a very different matter. Others may know more than I, but I have no idea what Delta can and will do at JFK as far as your checked baggage is concerned. In addition, you should be aware that your reservation from London to Bucharest, and any later reservations on that ticket, are subject to cancellation if you do not check in on time for that flight. You would be protected in the event of delays if you were traveling on one ticket with connections, but that's not the case when traveling on separate tickets.

Based on the second enumerated exception listed on Delta's through-check policy, Delta should through-check the baggage all the way to IST, since the OP is traveling on a paid Delta ticket, and on a SkyMiles award ticket. I would advise bringing a hard copy printout of the policy to the DL check-in desk at JFK.

https://pro.delta.com/content/agency...e-policy-.html

("Exceptions

"In cases as noted below, when more than one ticket is presented, Delta will continue to through-check baggage from the origin to the destination

. . . . .


"SkyMiles Award plus a ticket with Delta-marketed / Delta-operated flights"


But I don't know whether DL provides IROPS protection in the OP's situation.

Be aware if you cannot check your bags all the way through, you will have to enter the UK (the e-gates will take US passports) to collect bags landside before checking them further on to IST with Tarom.

If they're checked all the way through, you'll still have a change of terminal from T3 (DL) to T4 (RO).

If you check bags through, you'll be able to take the airside busses (but still have to clear security at T4), otherwise you'll need to take your bags from T3 to T4 via the Elizabeth Line (free between terminals) or Tube (also free, but T4 is one way, so you'll have to to T2/3 to Hatton Cross, cross platforms, then to T4 (if you're doing the same on the return, you can go straight from T4 to T2/3))