Three minutes. That is the time frame to deliberately switch off a plane’s transponder and remain invisible on radar without arousing any suspicion if they are flying between Malaysian and Vietnamese airspace, pilots say.
One pilot familiar with the route said there is a point over the Igari navigational waypoint in the South China Sea where commercial pilots have to use radio to communicate with air traffic controllers as the planes would be out of reach of civilian radars.
Malaysia Airlines Flight MH370 carrying 239 people on board disappeared over the Igari area last Saturday while en route to Beijing. It never arrived and there has been no trace of the aircraft since it vanished seven days ago.
“There is three-minute window to do this, and the transponder can only be switched off manually,” the pilot told The Malaysian Insider on condition of anonymity.
He said that the transponder carried all information about the aircraft’s identity or Ident, altitude, location and other data that air traffic controllers need to ensure planes fly on dedicated corridors.