When a Bell 206 helicopter carrying a family of Spanish tourists crashed into the Hudson on Thursday I, like so many others, watched in helpless horror.

I spent six years flying Black Hawk helicopters with the US Army as a crew chief.

We prepared for just this is the sort of nightmare scenario, hanging upside down in a helicopter, strapped into a five-point harness and submerged under the pitch-black water of a ‘dunk tank’ swimming pool.

Without that military training, you’d stand no chance of getting out alive. And, indeed, all five members of the Escobar family and the pilot, former Navy SEAL, Sean Johnson were tragically killed.

It’s terrifying to know that the family and pilot would have been fully aware of what was happening.

Video of the incident shows the aircraft’s rotor ripping off in mid-flight. That would have been incredibly loud. Then the helicopter fell, like a rock, from 1,000 feet into the frigid water below, landing upside down.

There are a handful of explanations for what could have gone wrong.

First the rotor broke off then it took the tail boom – the slender structure that connects the tail rotor to the main fuselage – with it.

I’m a former Black Hawk helicopter crew chief and flight instructor. I know how quickly a routine flight can turn into a terrible tragedy. (Pictured: Mark McEathron on X as @Mark_McEathron)

This could have been caused by a phenomenon called, ‘mast bumping.’ This is when the blades tilt too far down, striking the body of the helicopter which can cut off the tail entirely.

It happens when the helicopter experiences low G force – during rapid descents or the sort of drops caused by hitting pockets of turbulence, for example – which is characterized by a feeling of ‘weightlessness’ or free-falling.

If a pilot over-corrects in these moments it can prove fatal.

A second scenario could be a straightforward mechanical failure.

The mast is attached to a transmission – the mechanism which works like a gear box rapidly transferring power from the engine to the blades.

This is then connected to a long pipe running back to a second transmission which transfers power to the tail rotors.

All of this is spinning incredibly fast and if there’s anything wrong it just shreds.

Agustín Escobar, the president of the Spanish branch of the technology company Siemens, and his wife and three children (pictured) were killed in the crash

Wreckage of the Bell 206 helicopter is pulled from the Hudson (pictured). The family and pilot would have been fully aware of what was happening.

A child’s pink trainer is clearly visible floating amidst the helicopter wreckage. The Escobar family were celebrating the birthday of one of their three young children.

 A third and final possibility is a bird strike.

That’s what brought down ‘Miracle on the Hudson,’ Delta Flight 1086 back in 2009. Captain ‘Sully’ Sullenberger famously landed that aircraft in an incident that took place on the same stretch of river into which the tourist helicopter plummeted on Thursday.

Birds are just as dangerous for helicopters as they are for planes. If a bird hits the rotor and knocks it off kilter even a little bit then you have a flapping rotor.

That’s the main rotating blade assembly that generates lift and provides the force for flight, propulsion and directional control, so any malfunction is a serious problem.

It may not have helped that the weather conditions were somewhat challenging, with winds of 10-12 miles an hour and gusts of up to 30.

In my Black Hawk that wouldn’t be a problem – we’d fly in 60mph winds – but that’s a much bigger beast.

The gusts on Thursday wouldn’t have been enough to mandate a grounding of helicopters – that would be at the discretion of individual pilots, owners or operators.

But reports have suggested that some news crews and other charter operators did take the decision not to fly that afternoon.

Some people have picked up on the fact that the pilot radioed to say he was running low on fuel.

That’s not alarming. This was a helicopter used for short rides, 16 minutes into a 20-minute flight. The pilot was simply alerting the ground staff to be ready for refueling on landing.

Having said that the low fuel level would have made the helicopter lighter and therefore less stable.

It’s going to take many weeks for the truth to emerge.

When it does, I’ll be interested in the cockpit recordings which will reveal how the pilot was reacting to what may have been going on with the aircraft and whether he made any mistakes.

The digital data recorded by the onboard operating systems should also prove illuminating.

I stopped flying Black Hawks in 2007. The day I finished I said I’d never go in a helicopter again.

I’d done over 3,000 hours in the Black Hawk by that point and had some pretty close scrapes. I knew I’d reached the moment to stop rolling the dice.

But, for all that, this shocking tragedy doesn’t change the fact that, statistically, helicopter tourism is safe.

In New York City, 32 people have died in helicopter accidents since 1977. How many died from falling down stairs in that same period?

As grim as it is, accidents make us safer. There will be an investigation and there will be lessons learned.

Nothing can change what took place on Thursday, but we might prevent it from happening again.