LAN LANPASS - How do I figure out how many seats are available on a particular flight?

I would like to attempt to book on oversold flights coming in from South America to USA in early Jan for VDB vouchers.

I have tried booking on Lan.com to try to see available seats or something like that, but it never shows up, or at least, I suspect it would happen after purchasing.

Is there any way of doing this otherwise?

I often use www.expertflyer.com
Sign up for free and run your query specifying departure and arrival city, flight number and cabin class.
I am not sure of its reliability but when I boarded on a flight I searched it seemed accurate.

I would like to attempt to book on oversold flights coming in from South America to USA in early Jan for VDB vouchers.

I have tried booking on Lan.com to try to see available seats or something like that, but it never shows up, or at least, I suspect it would happen after purchasing.

Is there any way of doing this otherwise?

You won't ever know the exact number of seats left unless you work for that particular airline. Sites like ExpertFlyer at the most will display 9 seats per bucket or booking class.

ExpertFlyer has a handy seat-map function which shows which seats are taken, blocked or available. Much can be extrapolated from this as far as how many seats have been sold for a particular flight. However much can change at the last minute.

A gamble at best. There are so many things that can change that you won't know if they are oversold until departure time.

I wouldn't do that. If I'm not mistaken, expertflyert etc only shows the booking situation. However, LAN does permit booking seats and paying them for example in local supermarket. Most fares can be put on hold at for days, business class seats for weeks. LAN also has lower change fees and relaxed no-show policy so last minute availability changes are much more likely than with other carriers. By the way, LAN was until last month the only legacy airline with investment grade credit rating so I think that their revenue management department knows very well what they are doing...

Besides that, their route network very exceptional. Most their US routes are operated from most LAN countries. Given that their direct flights are normally more expensive than lets say SCL-LIM-JFK. In case of having oversold LIM-JFK sector, they can proactively offer seats at direct SCL-JFK instead of indirect routing in SCL. Both flights leaves almost at the same time from SCL, shouldn't be difficult to find people willing to take later flight without compensation which arrives earlier than their original flight.

I wouldn't do that. If I'm not mistaken, expertflyert etc only shows the booking situation. However, LAN does permit booking seats and paying them for example in local supermarket. Most fares can be put on hold at for days, business class seats for weeks. LAN also has lower change fees and relaxed no-show policy so last minute availability changes are much more likely than with other carriers. By the way, LAN was until last month the only legacy airline with investment grade credit rating so I think that their revenue management department knows very well what they are doing...
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yes, their revenue management department knows very well what they are doing.... remember about 40% of LAN revenues come from cargo!