Here is something a bit different.

        On 3 July 1963, a NAC Douglas DC-3 crashed into the Kaimai Ranges in New Zealand's North Island while flying in clouds and turbulence. The aircraft was flying from Whenuapai Airport, in Auckland, to Tauranga.

       The crash happened when the aircraft struck a vertical rock face after encountering a strong downdraft. The aircraft may also have commenced an early descent with the pilots unaware of the true position of the aircraft, on the wrong side of the ranges. All 23 people on board were killed. The wreckage remains on the hillside to this day, with a small memorial cairn beside it.

The NAC DC 3 at it was in 1963, partly covered by trees. You can see how damaged it is. Today the aircraft is totally covered by trees and impossible to see from the air.
       

Cover from the wreck of  NAC DC3 ZK-AYZ "City of Hastings."

        During recovery of the bodies and personal items, reportedly 168 pieces of mail were salvaged, but only a few of them were ever seen again. Above we can see one of these letters, damaged and partly burnt. What I like about this cover is the clear post mark showing 2nd July, 1963 and the three 1d stamps from the 1960 definitive series. It is a really interesting Postal History item.

Certificate confirming it came from the crash.

          When the letter was finally delivered it was accompanied by this certificate from the postmaster explaining why the letter was in such a damaged state. It reads - "The enclosed letter has been recovered from the plane which crashed on the Kaimai Range on 3rd July. I am sorry for the damaged condition." 
Of course today the certificate supports and proves the claim that this letter did in fact survived the plane crash and eventually reached the person it was addressed to mid July. I think that is still fairly quick considering what this poor little letter has been through.