The short story is that there are 2 steps to secure the cheapest flights:
Our top tips for booking cheap flights in South Africa, will help ensure that you get a cheap plane ticket:
Subscribe to the SouthAfrica.TO mailing list - this will alert you to flight specials, and give you a feel for prices.
When booking domestic flights, book your outbound and return flight separately, looking for the best deal on each individually (an exception may be where an airline offers a special which is contingent on you booking a return flight as well, which Mango Airlines used to do). HOWEVER, when booking an international flight, book your outbound and return tickets together with the same airline (it almost always works out more expensive to book the legs seperately on international flights).
When flying to or from Johannesburg, check prices to/from both Johannesburg Lanseria (HLA) and Johannesburg O.R. Tambo International Airport (JNB).
Generally speaking, airlines sell their cheapest tickets first, however, this does not always hold (as if tickets are not selling, airlines sometimes drop their prices and flight prices can get cheaper). Booking a long time before has the added advantage of it being more likely you'll find reasonably priced tickets on the exact dates you want to fly.
Keep track of the Rand price of oil - depending on airlines' pricing power, these will filter through into prices. So if there's been sharp falls in Rand oil prices in the last week, you may want to delay your purchase a bit, but if there's been a sharp increase in the Rand price of oil you may want to accelerate the purchase of your ticket.
If possible be flexible with your leaving and return dates. For domestic flights Saturday afternoon travel is generally cheaper. For international flights leaving South Africa on Sundays to Thursdays and returning Tuesday to Thursday is generally cheaper. Avoid booking on Fridays, Sunday Evenings, on the days before public holidays, and before the start or at the end of school holidays (also keep an eye out for local events, e.g. flying to Cape Town just before the Argus Cycle tour is expensive). August is generally a cheap month in which to fly local South African flights.
When needing to change a booking, check what the costs are of doing it on the internet versus doing it telephonically.
When booking Mango or Kulula flights, use their facility to search for 1-month low rates, to find the cheapest flight price in a month. Mango calls its "1 Month Low Rates". Always use the "Premium" search facility for Mango, as Mango Plus and Mango Flex tickets are sometimes cheaper (the Premium facility also shows the normal price) - especially during high demand dates they are sometimes cheaper than Mango's normal flight prices. Check whether Kulula flexible flights are cheaper (not available online, phone 0861 KULULA).
Where airlines have codeshare arrangements (i.e. they sell tickets on each other's flights) check the prices on all the airlines' websites. For example, SAA sells Qantas Airline tickets for flights from Johannesburg to Sydney - check both the SAA site as well as the Qantas site (the prices are not always the same). Also, Kulula sells British Airways flights on their website, sometimes at a cheaper price than you can book the flights on the British Airways site (you can tell that it's a British Airways flight if the flight number has 4 numbers in it, e.g. MN6313) - we've seen situations where over R1000 can be saved on BA flights by booking them on Kulula's website. We've also seen it happen the other way round, where flights are cheaper on the BA website than on the Kulula website.
When booking domestic South African flights, check the prices of the low cost airlines (Mango & Kulula) , as well as the full service carriers (British Airways & SAA). For international flights, always check the prices of Emirates flights.
Direct non-stop flights are best. With each stop the chances of something going wrong (e.g. being stranded as a result of delayed flights) increases. Especially avoid stopovers in places during their bad-weather seasons (e.g. Chicago is prone to snowstorms in winter).
Get a Kulula credit card - the Kulula moolah you earn can be used to offset the price of Kulula airline tickets. For cheaper Mango flights, get a Vodacom credit card. Where airlines have frequent flyer programmes sign up for them.
After Nationwide's liquidation (& more recently Velvet Sky & 1time) many passengers were stuck with tickets they couldn't use. To reduce this risk, purchase your airline tickets with a credit card that comes with a safeguard that if a supplier fails to deliver, you can turn to your card issuer for a refund (this is usually achieved by choosing the option to pay the full amount before interest rates kick in after a month).
Use the pay later option as a "hedge-bet". It gives you 24-48 hours to look for a better rate and eliminates post purchase dissonance if an airline decides to run a special.
If you're really desperate for a cheap flight, then date a pilot or flight attendant! Or better yet get a job as one - they have loads of flight perks.
Once you've chosen your airline the next challenge is to get the most comfortable seating (In a Skyscanner survey seat 6A was the most popular, as it's close enough to the front of the aircraft to get off early & be served food early, but not too close to the galley/toilet).
Check in & select your favourite seat online. By the time you get around to physically checking-in, all the best seats are taken.
In my experience it is difficult to negotiate an upgrade to business class, but check-in attendants are willing to accommodate requests to be seated at the emergency exits or the front of the plane (not only do these seats have more space, but they are safer in the event of an accident, as you're closer to an emergency exit). At check-in always check whether the seats at the emergency exit and at the front of the plane are available. And don't make the mistake like I once did of asking for seats "next to" the emergency exit, and the SAA check-in lady seated me at the row in front of the emergency exit (which has seats which don't fold back), always ask for the seat "at the" emergency exit.
Note that the Civil Aviation Authority wont allow the following people to sit at the emergency exit row: (1) those who cannot follow & execute instructions in english, (2) those passengers who are largely deaf / blind, (3) kids who are under the age of twelve, including infants, and (4) those who are travelling with another person who would need assistance in the event of an emergency.
If you're travelling in a group (e.g. Mother, Father and daughter), don't just assume that the check-in attendant will seat you together. On occassions I have assumed this, and found myself split from my family on the plane. Rather make sure whilst checking in that you are seated together. If there are no remaining seats together, try to get aisle seats or window seats (and not middle seats) to trade with others on the plane and get yourselves seated together (people are less willing to trade an aisle seat or a window seat for a middle seat. Once on the plane ask the flight attendants to assist you with swapping places to get your group together.
Know the luggage limits, and weigh your luggage before you leave. If you suspect you will be overweight take some of your heavy clothes like coats and jerseys out of your luggage and wear them. Put some heavy items in your pockets. A gent on a China to Kenya flight took this tip to the n'th degree, wearing 70 items of clothing and looking like a sumo wrestler, to avoid extra baggage charges!
If you're still be overweight remember that it's sometimes cheaper to buy coupons for extra luggage online when you book your ticket, rather than at the airport.
If you are traveling with somebody, pack half of your belongings in your travel case, and place the other half in your companion's luggage. In case one person's luggage is delayed, you will both have access to some of your essential items.
Place shoes in plastic bags to prevent them from soiling your clothes
Place shoes & other heavy items at the base of the suitcase near its wheels.
Choose clothing that doesn't require ironing. Roll your clothes rather than folding them - trousers are rolled from the bottom up, and collars should be up & in.
Use your underwear & socks to fill tiny gaps in between luggage.