Basically there are two airports that you can use from Bangkok to Cape town; 1. Don Muang (DMK) route or 2. the Bangkok direct (BKK) route. Since flights for the DMK route are not usually available we will look at the BKK route.
(BKK) Bangkok to Cape Town
You can make a choice from these cheap flights to Cape Town i.e. Kenya Airways, Ethiopian Airlines, Thai Airways International, Emirates, Cathay Pacific Airways, Malaysia Airways Singapore Airlines or the KLM Royal Dutch Airlines.
Ethopian and Kenyan Airways have the cheapest rates which are about half of the rates being charged by the other airlines.
The Ethiopian airways flight leaves Bangkok at 01:40 and flies to its home country Addis Ababa. It will arrive at 06.35 hrs and is scheduled to leave for Johannesburg at 08.50hrs where it should touch down at 13.15hrs. From there it leaves at 15:00 and heads straight for Cape Town where it arrives at 17:10 the next day.
The total time for this rather cheap flight is 22 hrs and 20 minutes of which 16 hrs and 40 minutes is spent in the air.
Emirates is also the second cheapest flight from Bangkok to Cape Town. It departs from Bangkok at 20.30 hrs headed for dubai . You must be prepared to sleep overnight because it will arrive in Dubai at 23.35 hrs and only leave for Johannesburg at 04.40 hrs the next day.
It will reach Johannesburg at 10.50 hrs and depart for Cape Town. The final journey takes about two hours and by 15:10 you would be in Cape Town.
Other possible flights that you might use are Cathay Pacific, Malaysia and Singapore Airlines. The one with the highest charges and longest journey is KLM.
You can get to check out the latest airfares and other flight related information at any one of these: