Going on a cross-country trip in your light aircraft? Read this first
 

JUDGING THE SURFACE OF A LANDING GROUND
FROM THE AIR
By F.L. Roberts.
An edited version of part 1 of a 2 part series, first published in “Aircraft” in March, 1931

The best surface is generally a paddock where old plough furrows are faintly marked in straight lines, and which has sheep grazing on it. The faint plough furrows are an indication that the surface has been cultivated some time ago—thus evening the surface—and the furrows being straight indicate that there are no stones, large stumps, or other irregularities round which the cultivating machines would have to go.

The presence of sheep is usually an indication that the smaller irregularities on the surface have been trampled down. The small feet of sheep will break down the roughness in the surface without leaving deep imprints—as cattle do—when the ground is wet.

The exception to this rule is, of course the Mallee—but even here paddocks as described above are generally best— but pilots should fly low first to have a thorough inspection. Mallee stumps often look like small patches of horse manure from the air, but when the stumps are thoroughly dried out they give the ground a mottled, grey appearance, and are extremely hard to see.
In the Western District it is necessary to watch for small crab holes and loose basalt stones. The crab holes are clearly seen from the air, as they give the ground a deep mottled appearance. Country of this nature should not be used as a landing ground except in extreme circumstances. Crab holes are often two or three feet deep and close together. They are sure to break the undercarriage of any machine.

Loose basalt stones are hard to see, and may exist even in cultivated paddocks. The only way to play safe in this case is again to fly low and make a careful inspection. Unploughed patches in cultivated paddocks generally comprise piles of loose stones which have been thrown together from the rest of the cultivation.

Centaurus,
Thanks for that post, most of which I understood.

Never having flown in or around the Western Districts though, (why would one?), I'm not familiar with the term 'crab holes'.

Can you enlighten me?

Cheers.


p.s. (why would one?) I must say that anything would be better than doing it by surface transport.
.

there is also the "can of baked beans" test if you suspect mud.

Fitting these will help ....

Crab Holes
 

Years ago, before our airfield had a sealed runway, the grass movement area was beset by crab holes/mounds. During an onsite inspection a DCA Airport Inspector advised that a cure for the problem was to pour copper sulphate down their holes. The groundsman, an elderly chap of Irish persuasion, replied "But who would hold the crabs".