Toronto law firm Thomson, Rogers announced on Monday that it will represent 95 people who were on board Air Canada Flight 878 from Toronto to Zurich in January, 2011.
Sixteen people were injured after the Boeing 767 plane dipped about 120 metres from its assigned altitude before the captain was able to pull it up again.
A Transportation Safety Board report conducted last month said the plane began its abrupt descent after a first officer spotted an oncoming aircraft and mistakenly perceived it to be on a collision course with the Air Canada flight.
The first officer, who had just woken up from a scheduled nap, took action to avoid what was thought to be a potential collision.
The pilot also initially mistook the planet Venus for another plane, the report said.
Fourteen passengers and two flight attendants, who were not wearing seatbelts, were injured during the brief but turbulent incident.
According to the lawsuit, the 46-second plunge tossed several passengers out of their seats, catapulting them into the ceiling, and projected various objects through the cabin.
An Air Canada spokesman said afterward that the sudden drop was caused by turbulence, rather than pilot error. The actual cause of the drop was not reported until the Transportation Safety Board report was released on April 16, 2012.
Some passengers have complained that they were given indemnity waivers to sign without knowing what had happened.
The class action lawsuit claims Air Canada covered up the true cause of the terrifying episode and demands punitive damages for the company's handling of the incident.
