[Petrochemicals (OP)]

If you have a plane that is going to be landing whether you like it or not, what is the best terrain to land it on?

[Bored chemist]

A runway at an airport.

[alancalverd]

Failing which, look for the biggest field you can reach, that isn't crossed by electricity pylons.

Set and maintain your best glide speed until you are certain to make the chosen field. "Flying in" is safer than "stalling in".   

If there's nothing immediately obvious, turn downwind to maximise your search area. Best bet is to fly a glider: if you run out of lift at 1000 ft you might have some 30 - 100 square miles of potential landing spots, preferably near a pub.

Look for sand (beaches are excellent), short crop or bare earth. Beware of golf courses - the grass may look inviting but there are all sorts of traps and gullies and whilst you might squeeze a small high-wing plane onto a fairway, it won't be wide enough for the wings of an airliner. Trees on the approach are bad, but don't worry about trees on the overshoot. Hitting a tree at 60 - 150 mph is usually fatal, 20 - 50 mph may be survivable.

Then, depending on the aircraft, try to approach upwind or upslope, except ploughed field or water waves - land along, not across, the wave crests.

It's a complete lottery at night. Trees and water tend to reflect a bit of moonlight so go for the biggest, blackest area, unless you can find a well-frozen lake. Problem is that low cloud can also look like a big black field if there is no moonlight - entire villages just disappear until you emerge from the mist and see the church spire ahead. 

[evan_au]

Avoidance - don't fly into a flock of ducks.

[alancalverd]

Easier said than done. I recently met a red kite (milvus milvus) who decided to soar into my final approach path. He was climbing at about 200 ft/minute as I was descending at 500 fpm. Fortunately a Cessna 172 at 70 mph is a lot more responsive  than an airliner at 140 mph and the kite is a scavenger rather than a raptor - glider pilots have been deliberately attacked by eagles! - so I was able to dive under him.

A more significant problem was a family of kangaroos who decided to occupy the runway at Caboolture as I was approaching in a very expensive glider. The previous day we had to clear a herd of cattle with a whip before taking off from another strip, but 'roos seem less predictable and asserted their native rights by just ignoring the tractor.

So an addendum to my previous  post - preferably avoid livestock. Horses panic and hurt themselves, and cows like to eat fabric-covered aircraft (they are addicted to nitro dope). Sheep are less of a problem unless you actually hit one.  And every damn animal in Australia wants to kill you.

[Bored chemist]

"What is the best way to crash land a plane?"
Remotely
https://en.wikipedia.org/wiki/2012_Boeing_727_crash_experiment