But till early 1920, the now-prevalent pre-flight routines (seatback upright, seatbelt securely fastened, etc.) were non-existent.
And air travel was considerably risky—in commercial flights, there was a death for every 22,000kms flown.
At the same time, for the government-owned Air Mail service (inaugurated in 1918), there was a death for every 1.3 million kms flown.
It turned out that the Air Mail System had a high focus on safety, and that made the difference.
E.g., it had a 180-point inspection checklist for every flight, pilots were selected after careful medical examination, and engines were checked once for every 100-hours flight.
The airline industry took notice, and by 1935, the aviation regulator in the US imposed some safety rules on the airlines.
E.g., the requirement of co-pilots, planes to have multiple engines but the ability to fly on one engine in case of emergency.
Since then, the safety rules are monitored closely and upgraded as and when required.
One such upgrade happened in the 1960s when all airlines were asked to include oxygen masks, floating devices, emergency markings, and informing passengers of the closest exits.
All these changes were a part of a more extensive rule called the 90-seconds rule.
The 90-seconds rule mandates all airlines using planes with a capacity of 44 people or more to demonstrate the ability to conduct an emergency evacuation in 90 seconds or less.
And for people to successfully evacuate the plane, their eyes should adjust to the dark that may be caused because of the lights going off during an emergency.
Research suggests that most accidents happen during landing (48% of the total) and take-off (13%).
And so, to better prepare the passenger for these comparably high-risk events, the airlines dim the cabin lights during take-offs and landings.
