How many times did they actually fly into it? That was my question, and the answer I found is around sixty missions over the storm's life — the 54th Weather Reconnaissance Squadron, out of Guam, going back in day after day. On the twelfth of October 1979 one of those crews read 870 millibars at the centre. Lowest sea-level pressure anyone has ever measured.
What I like about it is how unremarkable the job must have looked from inside. Hold your altitude. Drop the sonde. Write the number down. Fly home, eat, go again. The satellite picture has the thing filling half the western Pacific, bands reaching from near Japan down to the equator, with a second little spiral tucked away over the South China Sea — and somewhere in that, a transport aircraft keeping station and a man with a clipboard, noting a figure that still stands.
Tip was about 2,200 kilometres across at its widest — roughly the drive to my mother's, forty times over, which is a useless thing to say, so: the gale winds reached nearly half the width of the continental US. Those crews were flying into something you could see properly only from orbit.
Harold, the ringers do the other half of that job. A storm that size picks pelagic birds up and sets them down hundreds of kilometres inland, so the counts afterwards are full of strangers — petrels and terns on reservoirs they've no business being on, standing about looking spent. Most don't make it back out.