Quite easy. The science dealing with the prediction of upper atmosphere winds is part of Meteorology...

Even at altitudes of 60.000ft and at a considerable disatnce from the launch point? Did not one balloon end up over Costa Rica? Clearly Chinese meteorologists need to sharpen up.

And yet apparently they have been coming over the United States for years now...without NORAD or the USAF being aware of it.

Well, without NORAD and the USAF saying to the public they've been aware of it..

I see in reports this AM in parts of the MSM that it's now being claimed the balloon was actually tracked from launch..

https://www.theguardian.com/world/20...e-spy-balloons

You mean like the RAF did in 1960/61?
Vulcans managed to enter US airspace not once but twice!

Two balloons with equal buoyancy launched from the same spot at the same time will very rapidly diverge, regardless of being at very similar heights at any one time. This is due to the inherent randomness of what might be generalised as turbulence in pseudo horizontal directions. Not that the divergence would be massive but it would increase with time and travel.

I have done the experiment professionally with three balloons on several occasions.

This implies that, however good the upper wind is known and forecast, precise "targeting" of a track to achieve an aiming point is beyond science unless the balloon has some means of applying horizontal thrust, thus increasing weight and decreasing payload.

I agree, over that distance, without some form of propulsion, I think "beyond science" is understating it!

I suppose that a track (or rather the altitude profile for a desired track) couldn't be targeted in advance, but the point is that the systems would be adaptive based on current position and real-time wind measurements. As I understand it, the development of sensors for remote observation of wind speed and direction is a key part of the systems. I don't have any special expertise to say what the possible navigation accuracy might be, but people in the DoD (and private industry) who know the technology think that it is worth funding. That suggests that it might have some value.

Jet streams involve clear air turbulence, so I was told. How does it feel at zero true air speed?

CAT is not necessarily a feature of jet streams, and has a variety of causes from the surface upwards.
The best practical answer might come from a hot air ballooner or a glider pilot near the stall in wind sheer conditions.

Unpleasant at an informed guess.

I am white knuckle self loading freight, having lectured on "Met. hazards to aviation" for three years. Too much information as they say.

I don’t think you have CAT in the jetstream. More in the boundary layers.

Very complicated!

CAT "more likely" on top, bottom and sides of jet, and where jet changes direction sharply such as trough or even ridge.

Looking for CAT reported by one aircraft by another aircraft has been likened to finding one fish in a shoal in an ocean.

I was privileged to work for a pioneer in post-WW II study of CAT. I think modern airborne radar at the right wavelengths will be the long term solution for a given flight ............ forecasting is much better than it was but will never be a silver bullet. Modern aircrew will know more about the vagaries of CAT than a long-retired forecaster.

I firmly believe in keeping my seat belt and flies closed on a flight. A visit to the loo will bring on severe CAT without fail.

There is a sure fire way of finding CAT. Start serving drinks in the cabin. Never fails on the flights I have been on.

Yes, the seatbelt sign switch, also referred to as the turbulence switch.

US intel assessing possibility that Chinese spy balloon’s path over US was accidental

Who'd have thought it ?

Janus? :)

A diplomatic attempt to give everyone an "out" and return to status quo ante balloon?

Now that was funny! :ok:

Your informed guess is correct. :E

I have done a lot of glider-towing in lee-wave conditions at Cowley Alberta, which is Canada's premier wave-soaring location*. Last October, I had some of the most severe CAT I have ever experienced, such that I am debating wearing a parachute in future! We normally try to tow towards the lower, southern end of the Livingstone Range, which generates the wave, to try and avoid the rotor turbulence.

However, on two occasions, very experienced glider pilots had to release because they had lost control and on another flight, I watched my pen floating in front of me for several seconds!

A very experienced tow-pilot at my club used to say "The rotor is not rough, unless you get rolled inverted!"

* See Cowley Canada's Diamond mine. There is a panorama on this page which shows the wooded lower ridge we aim for in order to minimize turbulence.

I’m astonished to read that you don’t wear a parachute as a matter of course. I know two people personally that have used them in gliders (wing not correctly installed and a midair collision) plus read many accident reports where they were used

How does one know two people impersonally?

good point. I guess one could know of two people indirectly, but in my case I know them directly. One broke his neck.

I used to work with the first glider pilot in Australia to use a parachute. He'd flown bombers in WW II and aerial photography in (then) Dutch East New Guinea, and never had to use one, He was only wearing his because the rules of the competition required it. After that, he always wore one. He may have been the first one you mentioned.
As he was descending, he tried to remember all the things he'd been taught more than 20 years before. Just before he landed, he remembered to spit his false teeth out.

Here we go again…

Putting this potential balloon at 45k feet (avg of the reported height between FL400-500) and running NOAA's HYSPLIT model shows a very interesting future trajectory over the next 48 hours for an object being steered by the wind.

Right over Hawaii.


https://cimg0.ibsrv.net/gimg/pprune....896d201f53.png
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Aviation content:

Twitter

Wow...it's not often you see a U2 at low level. I bet the pilot was wondering why he couldn't see both coasts.

I like that the U2 pilot used his own plane's shadow for scale.

4G Inverted by any chance??? :oh: :} := :E

Slightly better version from the BBC News article:
https://cimg1.ibsrv.net/gimg/pprune....684df1c492.png
From https://www.bbc.com/news/world-us-canada-64735538

Edit: higher resolution version here on Twitter:

More here https://www.thedrive.com/the-war-zon...m_medium=email

Smooth

The RAF Vulcans being special in that regard was always a myth. A large number of the hundreds of SAC bombers (B-47s, B-52s, B-57s) also penetrated the NORAD air defences during those same Operation Sky Shield exercises of the early '60s, the first large-scale tests of NORAD/SAGE after it's initial deployment. The illusion that the Vulcans achieved something unique is owed to the fact that their success was leaked by someone to the British press shortly thereafter (in1963) who in turn happily crowed about it, while on the other side of the pond OPSEC and classified materials relating to the capabilities of the then-new North American air defence system were taken far more seriously, for obvious reasons. Thus, for the next 35 years the perception that the RAF Vulcans succeeded where others had failed persisted, grew in the re-telling, and became part of British aviation lore. Any magazine article, program, or discussion about the Vulcan was almost sure to mention this "amazing" fact.


Then, in 1997 the Sky Shield files were de-classified and that particular RAF Vulcan myth got popped like a Chinese spy balloon: The files showed that, in 1961, the initial NORAD/ADC system was very porous over such a large geographic area vs a large-scale, coordinated attack employing hundreds of bombers employing all manner of tactics and available ECM not because a few RAF Vulcans had succeeded but because the true scope of success by the SAC bombers as well. In fact, the majority of bombers flying SAC and RAF profiles/formations were successful (NORAD/ADC had better success picking-up/intercepting those assigned to fly Soviet profiles/formations). Obviously, it would be pretty stupid, even traitorous, to let your Cold War adversaries know the full extent of that weakness and fortunately it wasn't revealed at the time despite those publicly trumpeting the handful of RAF Vulcans. Once the full scope was revealed in 1997 however, instead of pride in the Vulcan affair there should instead be a dose of embarrassment for the leak plus for the decades of glorifying a success that was, in reality, not uncommon for all bomber types and crews during Sky Shield.


Of course, all of the above occurred when JFK was president. During the following 6 decades, NORAD has mostly likely managed an upgrade and tweak or two, so I doubt the balloon is like the Vulcans at all.

A bit of closure from the i. Seems it wasn't spying after all.

Remember the furore seven months ago when what was described as a Chinese spy balloon passed over the United States until it was finally shot down by US fighters on 4 February over the Atlantic, from which its wreckage was later dredged up by the US navy. The US-China confrontation escalated significantly as Republicans criticised the White House for failing to shoot it down earlier.

But last weekend, the retiring chairman of the Joint Chiefs of Staff, General Mark Milley, said that the alleged spy balloon was not, in point of fact, spying, having most probably been blown off course by the wind when approaching Hawaii.

In contrast to the previous uproar, American politicians and media scarcely reacted when Milley told CBS News last Sunday that the balloon was not spying. “The intelligence community, their assessment – and it’s a high-confidence assessment – [is] that there was no intelligence collection by that balloon,” he said.

What was the balloon doing over the US, having got there by way of Alaska and Canada? Milley had a prosaic explanation, saying that it had been heading towards Hawaii at 60,000 feet when it was diverted by the wind. “Those winds are very high,” he said. “The particular motor on that aircraft can’t go against those winds at that altitude.”

When the errant balloon was examined by American experts they discovered that its sensors had never been switched on. Milley still described it as a spy balloon, though he added that “we know with a high degree of certainty that it got no intelligence, and didn’t transmit any intelligence back to China”.

So it WAS a spy balloon, but simply switched off!

And lost

…but found itself over some interesting sites.

Given the altitude and the potential area of observation, could you draw a serpentine route over the US that didn't?

Has there been any previous suggestion that the balloon had a ‘motor’ to counter winds? Seems rather improbable to me.

Good question; to stand still or slow down substantially the "motor" needs to produce at least 100kt, sustainable ............. the fuel burn [portmanteau phrase] would be big and would itself demand a lot of lift.
Just possible but very unlikely.

Is Hawaii still a part of the USA? Is it ok to fly suspicious looking balloons over just Hawaii?