Mercy Flights were not common in 1929!

Today, mercy flights are an everyday occurrence although it is still a high risk profession.
Consider the obstacles in 1929 in Africa, with no navigation aids, radios, weather reports or airfields.
A female missionary in Angola was bitten by a rabid dog and required serum. The pilot, Rodwell King took off from South Africa in a Gipsy Moth and flew for two days until a faulty compass forced him to land and get a mechanic to fix it. The next day went without a hitch and he reached the beginning of one thousand miles of uncharted wilderness where he would have to land and refuel from the cans he carried.
As his fuel dwindled, he landed by a river and camped for the night to wake up with hundreds of natives surrounding him. With no common language, he persuaded them to carry his, by now dismantled plane through thirteen miles of jungle until he could find a suitable take off area.
Another landing and refuelling was necessary before he had to cross a mountain range in thick cloud. When he descended into the clear, he was over the sea with no land in sight, so he turned east and eventually reached land and landed to get directions. From here, it was a short hop to deliver the package.
Not wishing to return by the same route, he choose an alternative route which put him in the path of a strong storm. He chose to land to avoid the weather and this necessitated a further band of natives clearing a path in the elephant grass so he could take off. During the return flight, he had picked a fare paying passenger wanting to go to Johannesburg.
There were no further problems on his epic flight and he landed at Jo’burg twenty days after starting his six thousand mile mission of mercy. The alternative option of travelling by land would have taken as many weeks as the pilot took days. Pioneering was never easy.