I live in Pinelands, Cape Town. Somebody has to. Pinelands is dull. It is one of two suburbs in Cape Town that do not permit the sale of alcohol or the licensing of bars. If you want a good night’s drinking, Pinelands is not your place. A potential girlfriend broke it off with me because I live in Pinelands.
However, Pinelands does have birds. It has Hadedas and Egyptian geese. The Hadeda call is piercingly horrible. However, they have their uses: Esther Ngowana, the sister of my housekeeper, showed me that, if you throw bread on a vegetable patch, the Hadeda will eat it and all the snails in the vicinity. Egyptian geese, on the other hand, are seldom on the ground. Technically, they do not migrate but they do fly, each day from one place to another. I know this since one goose roosts in my very tall pine tree from about 05:00 and calls out a long wail. Other geese fly towards the goose and wail a different wail and fly over. After the fifth flock of geese passes over, the sole tree goose gives a series of wails and flies after them. Every morning.
The wails by the roosting goose and the flying geese are very different. I have spent many hours working out if the roosting goose is acting as a navigational aid in the form of a directional beacon. This would work like this: (a) The incoming geese flock only has a single goose leader giving out a call (as is the case). (b) The incoming goose emits a series of honks (c). The tree goose, on hearing a honk, honks back (as is the case). (d) Given the speed of sound as 342 m/s, the combination of the incoming honks and the tree honks gives a steady tone to the flying goose, which then stays on track and flies over the tree. I know that the goose honk has a sound power of 105 dBA (yes, I measured it); thus, the incoming goose will hear it from 200 m away. This means that the incoming goose will have a confirmed flight direction from 200 m away and 200 m distant at which location, one imagines, a further goose beacon would exist.
All this brings us to the death of Samora Machel, the former President of Mozambique. He was killed in an aircraft crash. The fact that the aircraft crashed on South African territory raised some questions about the possibilities of the involvement of the apartheid government. It was thought that the South Africans had interfered with a directional radio beacon, causing the pilot to fly off course. As it turns out this is very difficult to do. But, thinking about the geese, all one has to do is to make one honk, briefly, and this would be enough to put the flock off course. For the radio beacon, this would have no effect except for one matter: the identifier for the beacon the aircraft was flying to is Maputo, VMA. The pilot crashed while flying on track to Matsapha, in Swaziland (now eSwatini), identifier VMS.
It occurred to me that one would have no need to do anything other than tune to the Maputo beacon (a simple receiver can do this). Now, the identifier is in Morse Code, so Maputo is VMA or dot dot dot dash dash dot dot dot. Matsapha is dot dot dot dash dash dot dash. It occurred to me that the people doing the interfering would have no need to do anything other than tune to the Maputo beacon (a simple receiver can do this) and transmit a dash to join the last two dots of the Maputo beacon transmission. So, the pilot would tune to Matsapha, assuming it was Maputo and fly on that course. What would then happen one does not know but, in fact, the pilot ignored the low altitude warning and crashed. So. All from thinking about geese. With a hangover. I had.