I've just returned from doing a transit turnaround in Accra (Ghana) as part of an AONE6 that went very smoothly. A visa was not required for the transit. My routing was HKG-LHR-ACC-LHR on CX/BA.

The LHR-ACC-LHR flight is on a 3-class 767, with two rows of 1-2-1 in First. Biz is 6 rows of 2-2-2 (not NCW). There were 5 people in 1st and only two in Biz for the flight down. The cabin does feel a little cramped and more like office cubicles as the wood trim is a lighter wood (maple?) rather than the burled finish in the 747s. The video screen is also smaller (5") than on the 777/747. The 3000 mile flight is about 6 1/2 hrs each way (good for QF status credit as it is over 2700 miles). The flight departs at 2:10 PM from LHR and is scheduled to arrive at 8 PM. The return flight departs at 10:25 PM and arrives the next morning at 6:25. We were 45 minutes late departing due to slow catering in LHR, but made up some time and arrived in Accra at 8:30 PM. This was still plenty of time to complete the transit. On arrival, you walk across the tarmac into the terminal as there are no jetbridges although the terminal does appear to be fairly new. There is a Transit area off to the right and up the stairs after entering the arrivals area. I didn't have a return boarding pass, so the person at the transit desk escorted me through immigration to the checkin counter and back again. When returning through immigration, make sure to tell the offical that you are in transit otherwise he will look through your passport for 5 minutes looking for an entry stamp like he did with mine. Otherwise, the whole transit process can easily be done within 30 minutes. The transit official who escorted me through immigration did want a tip at this point, a few dollars should suffice. Since I was in First, the checkin counter gave me a pass to the lounge. The VIP lounge is past immigration but before security. It is very basic, free drinks and a few sandwiches. There is a duty-free store across the hall. I sat in the lounge for about 40 minutes before going through security, which can have long lines as there are several flights leaving Accra at the same time and there is only one X-ray machine. Once past security there is only one departure gate, which again gets pretty full. They will call boarding for the BA flight (on a megaphone!) and the process was very orderly, they do enforce boarding by class/row. We started boarding around 10:20 due to the late arrival. You walk down the stairs and across the tarmac to the plane. Sleeper suits were provided for the return trip. All in all though an easy experience, probably much easier than transiting LOS!