A flight from South Africa to New York is epic and arduous, with 1-stop flights taking 24 hours or more. The only direct flights are with South African Airways from Johannesburg to New York (JNB-JFK), which is the 11th longest in the world (the longest flight is from Sydney to Dallas/Fort Worth with Qantas) and is scheduled to take 16 hours and 40 minutes.

South African Airways is the only airline to offer direct flights to New York. They offer a direct service from Johannesburg to New York and return on a daily basis.
Flight SA 203 is scheduled to leave OR Tambo International Airport at 20h45 and arrive at JFK at 06h40 the next morning. The return flight, SA 204, is scheduled to leave JFK at 11h15 and land at OR Tambo International Airport at 08h00 the next morning.
The plane used is an Airbus A340-600, with 275 economy class seats and 42 business class seats.
It's also possible to book SAA flights from Cape Town and Durban, flying via Johannesburg to New York. Other cities in South Africa are possible too, and SAA would draw on the flights of its codeshare partners : Mango Airlines, SA Airlink and SA Express.

The flight covers 12,984km emitting 2031 tonnes of carbon dioxide into the atmosphere.
In 2009 SAA offered a special Economy Class Companion fares between Johannesburg, Windhoek and New York and Washington. You could pay for just one passenger and your companion would pay only the airport taxes applicable to them. This special offer was available for purchase until 16 February 2009 and travel had to be booked between 29 January 2009 and 31 March 2009 or 1 October 2009 to 30 November 2009. Bookings at SAA or by phoning the call centre on 0861 606 606 (+27 11 978 1111).
In a sense, South African Airways actually has no competitors on the route as it offers a unique product - the only direct flights from Johannesburg to New York. However, there are plenty of airlines offering 1-stop flights, so for passengers willing to spend huge amounts of time at airports, there are options. A quick sampling of flight times indicates the following flight times (airlines ordered from cheapest at the top, although this ordering will have subsequently changed):
Etihad : 42 hours via Abu Dhabi
Emirates : 31 hours via Dubai
Turkish Airlines : 23 hours via Istanbul
Cathay Pacific : 31 hours via Hong Kong
El Al : 35 hours via Tel Aviv
Saudi Arabian Airlines : 24 hours via Jeddah
EgyptAir : 24 hours via Cairo
Qatar Airways : 30 hours via Doha
Delta : 21 hours via Atlanta
KLM : 23 hours via Amsterdam
Air France : 22 hours via Paris
British Airways : 21 hours via London
Virgin Atlantic : 24 hours via London
Swiss : 24 hours via Zurich
We can see that the cheapest flight, with Etihad, takes nearly 2 days of travelling! Short of flying direct, the next quickest is with British Airways via London, which is scheduled to take 21 hours (which is not too bad in comparison to SAA's scheduled flight time of 17 hours).
On the flight route from Cape Town to New York SAA faces more competition, as it's 1-stop versus 1-stop with many airlines. For example, all of the following airlines operate 1-stop flights from CPT to JFK:
Emirates : 25 hours via Dubai
Turkish Airlines : 26 hours via Istanbul (not counting technical stop in Johannesburg)
Qatar Airways : via Doha
British Airways : 22 hours via London Heathrow
KLM : 22 hours via Amsterdam
SAA : 25 hours via Johannesburg
As can be seen from the above there are some quicker ways of getting from Cape Town to New York than with South African Airways.
From Durban to New York, it is just South African Airways and Emirates offering 1-stop flight options.
Category : South African Airways