- The fatal crash of a Bell 212 helicopter flying the President of Iran, Ebrahim Raisi and Foreign Minister, is one more accident involving high-profile passengers, in mountainous terrain and very poor visibility.
- In fog and heavy rain, the visual illusions are plenty and depth perception induced by rainwater flowing down the aircraft/helicopter windscreen makes a huge impact.
- Several accidents have been caused due to misjudgements induced by optical illusions.
- Navigation in poor visibility has become easier with the use of the Global Positioning System (GPS) with an accuracy as close as a metre.
- The accuracy takes a hit if one uses a different system where the datum shifts.
- Military aircraft, to avoid enemy interception or identification, tweak the system. Worldwide, it is the WGS 84 which is the base datum. The Indian Air Force uses a system called EVER-MD.
- Datum shift can result in an error of between 10 metres and 3,000m. a vertical datum is used to measure the elevation or depth relative to a standard origin, such as mean sea level (MSL).
Dig Deeper: What are the recent technological advancements to avoid flight accidents?
