Sexy Choccy - ANO 28 route checking but more importantly, a very highly developed personal survival instinct!!!
It is illegal to operate an unpressurised GA aircraft
above LSALT in most parts of PNG! (I didn't say it didn't happen, rather regularly.....)
And think back to the 1950s when most PNG operators were operating under powered DH84 Dragons and Avro Ansons and a variety of single engine aircraft - and the accident rate was still low by any standards.
Woomera