I can understand how low visibility will cause a crash during landing or take off. I can also understand how it could lead to collisions with tall structures like masts and trees. However, in many of these cases it doesn’t seem like they collided with anything. They seem to drop out of the sky “due to low visibility”.
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> They seem to drop out of the sky “due to low visibility”.
Just because officials dont know the actual events and are still investigating they state that the ceasg was due to bad visibility.
Nl, helicopters dont just crash mid air agains fog.
And i have no idea what you mean with often, can you name more than one case?
Because you can’t see anything out of the window the only way you know what angle you’re at is to very carefully watch your instruments. Turbulence can also make it feel like you’re turning or speeding up or slowing down differently to how you actually are (Somatogravic illusions)
So if you stop paying extremely close attention to instruments then, say, wrongly feel you’re suddenly turning hard left you might jam the control stick hard right to “correct” and go into a hard right turn instead, falling because the rotors aren’t pointing downward, and hit the ground in seconds before you realize your mistake.
The most recent example of this happening was when Kobe Bryant’s helicopter crashed.
In that case, the pilot was supposed to be flying under visual flight rules (required to be able to see where you’re going). The pilot was certified to fly instrument only, but was no longer proficient. He flew into the clouds, became disoriented, radioed into ATC that he was climbing but was actually banking and descending towards the hills.
It would seem like most instances where this has happened was due to pilot error.
The fog alone is usually not a real issue.
The FIM-92 Stinger Shoulder Mounted Anti Air Missile coming out of it, much more so.
The modern collision avoidance systems (primarily EGWPS and TCAS) are very expensive and still “relatively” new (coming out in 1996). Older aircraft don’t have it and therefore can’t use the benefits it provides.
Also, if you don’t know how to fly in instrument flight rules (aka you can’t see), you die very quickly.
Stats show that if you fly into clouds without proper training, you will probably hit the ground after 178 seconds.
You go from looking outside 90% of the time to not being able to see anything. You can’t see, you end up pointed down, and you end up suffering a tragic collision with the ground. Often at high speed.
Source: the aircraft owners and pilots association
https://www.aopa.org/news-and-media/all-news/2022/june/pilot/asi-tips-178-seconds
When everything is gray and there’s no horizon, which way is up? Kobe’s pilot did the same thing. Loss of situational awareness and your inner ear tricks you into not believing the instruments.
There’s a phenomenon called the [Graveyard Spiral](https://en.m.wikipedia.org/wiki/Graveyard_spiral) that is a high risk when flying without visual cues – eg in fog.
The gist is that without instruments (equipment that tells the pilot how level the aircraft is on all axis and which direction it’s going in) and knowing how to use them (harder than it sounds) it is very easy to end up going in a curve, but you don’t realize because the plane/helicopter is at an angle and the centripetal forces from its circular motion make you feel like you’re still vertical. This can very quickly deteriorate to put catastrophic forces on an aircraft with the pilot not knowing until it’s too late to do anything about it.
Even very experienced pilots are susceptible to this without instruments to tell them what’s happening – with pilots in fog entering one of these spirals within 10-20 seconds of losing visual cues/instruments being turned off.
Flying by helicopter is also hard at the best of times, seriously compounding the issue.
When you’re walking around you’ve got a bunch of different systems in your body working to keep you upright and heading in the right direction, and without you even thinking about it. The two big ones are your eyes and something called the vestibular system, a couple of fluid filled loops in your ears that act like gyroscopes.
On a clear day you can rely on your eyes. When you can’t use your eyes, unless you have quite a bit of training, your vestibular system will try to take over for you.
But that system isn’t adapted to working when you’re in a vehicle, so it’s very easily tricked into giving you bad information. Like it will tell you you’re flying straight and level when you’re actually flying in a circle, and slowly descending into the ground (they call that one the graveyard spiral if you want to look it up).
And, because it’s built in, and you use it all day long without thinking about it, it’s *very* hard to ignore it, even when it’s lying to you, so you crash.
No one here has said it yet but flying a helicopter straight and level is incredibly difficult and requires constant minute adjustments to the stick and collective. Compare to a fixed wing aircraft where if you’re trimmed correctly, you can let go of the controls and the plane will fly pretty much straight and level indefinitely.
Plenty of people wash out of helicopter training because they can’t get the feel for it.
If you lose your visual reference, you quickly can start over correcting for what your inner ear is feeling which is unlikely to be 100% accurate. IFR helicopter flying is a thing, but it’s adding another huge mental load to the already high mental load of just keeping the thing in the air. Plenty of heli pilots don’t have IFR training because realistically you should only fly a helicopter in good weather.
Also, this is the reason for the floor windscreens to see out the bottom of the aircraft. You pretty much need a visual reference to get the thing of on the ground in one piece every time.
They don’t ‘drop out of the sky due to low visibility’ – they hit things they didn’t know were near because they lose track of their location and assume it’s somewhere else.
Aircraft are unique (along with perhaps submarines) in that they’re a vehicle which can travel in absolutely zero visibility and still be able to travel safely if they are making good use of their instrumentation and it is in good working order, their training is adequate, and errors are not made.
If any one of these elements fail, a crash can occur.
Imagine if I told you to drive your car to work in absolutely impenetrable fog at night – you can see absolutely nothing out the windows at all.
Your job is to navigate and drive safely using nothing but the compass on the sat nav and the odometer to work out your mileage.
It would be very difficult, if not utterly impossible, because the instruments aren’t accurate enough and your planning couldn’t be detailed enough to work out every road, corner and junction, nor could you predict other vehicles, pedestrians and objects on the road.
Well, aircraft *can* do this because the sky is, generally, very empty. As long as you know where you are and where other aircraft are, you have the potential to fly safely.
But this means you need impeccable, flawless planning, operation, technology and so on. When one or more of those elements fails, crashes can occur.
Bad weather and low visibility doesn’t make an aircraft crash, but it makes that crash much more likely.
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