On 31 March 1975, a Pilatus PC-6 Porter (registration number 9N-AAZ, and serial number 727),[2] operated by Royal Nepal Airlines crashed in Nepal en route from Tribhuvan International Airport to Phaplu Airport on a domestic charter flight.

The flight was chartered by Sir Edmund Hillary to bring his wife Louise and daughter Belinda to Phaplu, where he was building a hospital.

[7] The aircraft turned towards the right but was unable to make a landing, crashing into a ditch behind the northern end of the runway.

[3] In her biography Keeper of the Mountains, Elizabeth Hawley describes that the pilot Peter Shand did not do a walk-around,[3] failing to see that an aileron was still fixed by a ground lock pin, because he was late to the airport and this caused the accident.

[7] The Nepali Times reported that the pilot was hired by Royal Nepal Airlines despite losing his previous job due to "carelessness".