Could SONAR detect air turbulence ?

[Widdekind]

In 1966, a BOAC aircraft flying over Mt. Fuji was beset by turbulence, broke apart, and crashed (DC What You Can't See -- In the Air (DVD)). Could some sort of SONAR system, facing forward from the cockpits of passenger planes, perceive pockets of turbulence ? Could such systems "Whale / Dolphin blast" forward-fired intense SONAR pulses, to break apart those pockets, before finally flying through them ??

[alpha2cen]

It's too slow compare to airplane speed. Are there any echo coming back? Isn't the SONAR sound waves?

[TonyMcC]

Aircraft flying into turbulence is a serious problem. There is ongoing research into detecting it using radar and, I believe most recently, optical systems. If interested some information about optical systems can be found http://www.ophir.com/turbulence_detection.html

I can't see sonar being useful because (as alpha2cen says) the speed of sound waves through air is too slow. In fact slower than some military aircraft!

Edited December 30, 2010 by TonyMcC

[CaptainPanic]

Sound just doesn't bounce off turbulence, as far as I know. It may change direction or diffuse altogether... but not deflect.

Air turbulence is just wind (but then with an additional vertical component). It's a chaotic stream of air. The problem is that between two streams of air going in different directions, there is a transition, which is not a clearly defined plane or surface... it's like a zone with even more turbulence, where one stream gradually becomes another. There's nothing for the SONAR sound to bounce off from.

[ewmon]

Some ground-based radar systems already detect microbursts, wind shear and other air turbulence. Does the history of navigation support the need (and the cost and maintenance) for aircraft-based systems?

[HerpetologyFangirl]

It would be interesting to do some experiments, fitting an aircraft with every technology available, including a device for detecting turbulence, and sending them into the Burmuda Triangle... Then again, some say the triangle's mysterious forces mess with technology and put it all out of wack. It would still be interesting though.

[TonyMcC]

Some ground-based radar systems already detect microbursts, wind shear and other air turbulence. Does the history of navigation support the need (and the cost and maintenance) for aircraft-based systems?

From what I read ground based radars are not very good at detecting clear air turbulence (CAT) at long range. With development this may improve. However if an aircraft can be given a system that reliably detects CAT at relatively short range it would be an additional safety device that would save lives.

When you consider the cost of buying and maintaining a Jumbo Jet the cost of one more safety device would (in my opinion) be negligible.

[CaptainPanic]

From what I read ground based radars are not very good at detecting clear air turbulence (CAT) at long range. With development this may improve. However if an aircraft can be given a system that reliably detects CAT at relatively short range it would be an additional safety device that would save lives.

When you consider the cost of buying and maintaining a Jumbo Jet the cost of one more safety device would (in my opinion) be negligible.

You have to do a risk assessment.

 

Risk = change of something happening * probability

 

In this case:

Probability = very very small... aircraft can withstand all but the most severe turbulence

Effect = 400 dead, 400 families in distress, multi-million euro damage

 

The effect certainly suggests that it's worth the money to invest in more safety equipment.

The probability however is already so small that maybe we'd better keep our money in our pocket.

 

I actually have no opinion about whether the money would be well-spent. I just wish to point out that you shouldn't look only at the Effect, but also at the probability.

[ewmon]

I'm thinking airports use ground-based units because that's where airplanes fly close to the ground and might crash (ie, unintended contact with terrain) due to air turbulence. The 1966 BOAC incident was actually air turbulence that caused the craft to disintegrate in midair (ie, tore it to pieces). How often do such disintegrations occur?

[TonyMcC]

I'm thinking airports use ground-based units because that's where airplanes fly close to the ground and might crash (ie, unintended contact with terrain) due to air turbulence. The 1966 BOAC incident was actually air turbulence that caused the craft to disintegrate in midair (ie, tore it to pieces). How often do such disintegrations occur?

Not very often, but occasionally when an aircraft hits turbulence and drops suddenly people get hurt, sometimes breaking bones.

If a reliable airborne detector of air turbulence is perfected I would be surprised if the Civil Aviation Authority (CAA) did not insist that passenger carrying aircraft be equipped with it.

On a lighter note :- A little old lady asked at the check in desk "Do your aircraft crash often?". She received the reply "No Madam, only once".