Dope smokers in charge of machines where judgement is critical have been regularly found to be seriously lacking in ability to judge time accurately - and suffer from an inability to respond quickly to dangerous events, where a quick response is needed to avoid disaster.
Marijuana ingestion slows response and reflex times and compresses time for the user. The greatest single public transportation disaster that was sheeted directly home to marijuana use, was the 1987 Maryland Amtrak/Conrail smash.
Two dope-smoking engineers were detailed on Jan 4 1987, to move a consist of three Conrail locomotives from Bayview Yard just east of Baltimore bound for Enola Yard near Harrisburg, PA.
These engineers knew the route well and ignored several red signals, merely trusting on their view of elapsed time to reach a mainline junction at Gunpow Interlocking, just before the Gunpowder River bridge.
However, the engineers use of marijuana compressed the time they thought had elapsed, and they arrived at Gunpow Interlocking well ahead of time.
The engineers braked hard at Gunpow Interlocking junction when they realised they didn't have a green to enter the mainline - but they failed to stop the three locomotives in time and ended up stopped on the mainline, directly in the path of passenger train Amtrak #94, which was doing 125mph.
The engineer in control of Amtrak #94 braked hard in a desperate attempt to avoid a collision and reduced #94's speed to 108mph before #94 collided with the three Conrail locos at that speed.
The collision resulted in a colossal amount of destruction and the deaths of 16 people. The Amtrak engineer was one of those killed, but both Conrail engineers survived.
By sheer good fortune, the cars behind the Amtrak locos were nearly empty, as these car seats were booked by passengers who were to get on further North. It has been estimated the death toll would have been well over 100, otherwise.
One Conrail engineer was jailed for 5 yrs, and one was given immunity from prosecution, on the basis he testified against the other engineer.
This smash was the driver for the introduction of drug and alcohol testing for many industries involved in public transportation.
It seems that NZ is lagging in world standards when it comes to introducing alcohol and drug testing, and strict regulations against drug and alcohol use, for anyone piloting balloons, that are transporting paying members of the public.
Pilot who smoked cannabis before flight caused New Zealand balloon crash that killed 11, investigators say - ABC News (Australian Broadcasting Corporation)
Carterton balloon tragedy caused by errors of judgment - National - NZ Herald News