I'll soon be taking a flight from Madrid to Victoria Falls, with a scheduled 1-hour connection in JNB. That will be ample time if the incoming flight is on-time or close to it (carry-on bag only, traveling in J so among the 1st off the plane, and transiting so no immigration/customs). However, the incoming flight from Madrid is frequently delayed.

MAD-JNB is operated by IB, and JNB-VFA is operated by BA (Comair). The ticket is an award ticket issued by AA.

If I misconnect due to a late incoming flight, whose responsibility is it to get me to VFA -- IB or BA? Is there a rule regarding the time period to get me to VFA (for example, if the next BA flight is in 20 hours, but another carrier's flight is in 4 hours)?

Probably BA - Comair. If there is no other flight that day, then you'd be put on the next one the next day. Don't know if they'll give you overnight accomodations though.

In the past some airline transits at JNB required clearing immigration/customs -- it depended on the airline pair involved. I know BA-BA does transit airside, but I'm not sure that IB-BA can transit airside -- you may wish to verify this (I think JNB has fixed this problem, but who knows?). Immigration at JNB often takes 2 hours as many 747s arrive simultaneously. It might be wise to verify that you do have a legal connection, meeting BA Comair's published MCT (they have 45 minute cutoff for check-in, for example, so I rather doubt they allow a 1 hour MCT). While BA is responsible for your transportation and lodging if you mis-connect on a valid connection, they are not responsible if the ticket was issued with an illegal connection -- and they will throw it back to AA (often by saying that your ticket is cancelled and cannot be used for future transportation). And AA doesn't have an office or agent in JNB (at least didn't when I needed them a few years ago). So this may be an important point to clarify. Unfortunately BA does not publish MCT times on their web site, and the BA schedule to the once-a-day VFA flight allows several hours connecting time.

You probably know this, but be aware that Iberia is soon entering into a week long strike, with hundreds of cancelled flights every day.

Thanks all for the info. The connection appears to be legal (it's listed in the OW schedule). I am aware of the IB strike coming up; I'm flying in August and will keep a close eye on the goings-on. (Unfortunately, the strike is about a LCC that is planned to begin in October, so additional strikes would certainly be possible.)

I thought IB already was a LCC , at least intra-europe, it definately felt so when I did ARN-MAD when I started this trip, food and bev for purchase...
Long-haul was fine though