Chavalit Punthong, PTT's executive vice-president for retail marketing, said the three engineers were travelling to Laos to carry out a mission to expand petrol stations and depot in the neighboring country.
They were identified as Yangyoung Apaanan, Nipol Mengsee and Vilathep Vivavong, a Laotian.
Chavalit said the three were valuable staffs of the PTT and the PTT would take good care of their families and pay to the families more than the welfare as stated in the PTT rules regarding to deaths of the staffs.
The PTT will also assign its agency concerned to coordinate with the families to seek compensations from the airline, Chavalit said.