quote:

Originally posted by DrDan:

quote:

Originally posted by WaterburyBob:
So, not being a pilot, what causes a plane to go into a flat spin like that? Loss of power?

According to this, the center gravity of the aircraft shifts too far rearward. Perhaps a load in the cargo hold wasn't properly secured and shifted backwards?

That's one possible cause, but I believe other possibilities include asymmetrical thrust, symmetric wing stalling, inappropriate pilot input, a combination of high angle of attack, low airspeed, and uncoordinated flight....

quote:

Originally posted by kkina:

quote:

Originally posted by Milliron:
I rather think the missing right elevator had something to do with it, but what do I know?

Where do you see that?

Maybe not. On the initial video, it appeared be missing one of the rear stabilizers, but in the second video, it seems to be intact. It's a bit hard to see.

It looks like a flat spin, though the nose pitch does vary quite a bit. It could be a deeply stalled spin with some aggravation.

The T-tail design suffers from the possibility of blanking out the airflow over it. Especially with flaps down, but it is possible with flaps up. Once the aircraft stalls with the tail airflow disrupted it can be impossible to pitch down to recover from the stall.

Increasing the engine power could flatten out a spin. So where we see the aircraft pitched steeply nose down at first and then flattens out, that could be due to the pilots adding power trying to break the stall. Although each airplane will have its own spin characteristics which include how much the pitch oscillates.

Twin engine aircraft can be impossible to recover from a spin. The angular momentum can be too much for the rudder to overcome. And if the tail is washed out, it would be even worse. We never pushed a twin of any size, including turbo-prop airliners, anywhere near a full stall or spin. You never know if you will be able to recover.

One possible technique to recover from a flat spin is to invert the aircraft, then recover from the inverted spin. That's going to take some serious altitude and ability.

Airline pilots are trained these days to recover from a stall by pushing forward on the stick to zero G's, then add power (unless steeply nose down), level the wings with aileron, then recover from the resulting dive without getting into a deeper secondary stall or over stressing the aircraft.

That procedure assumes a stall, not a spin. Adding power could flatten the spin, and using ailerons could tighten the spin.

It will be interesting to learn how this event developed. Was it a stall recovery that proceeded to a secondary stall and spin? Was it a tail washed out? Another possibility would be if they picked up severe icing in a thunderstorm and stalled the tail.

^Thank you for the analysis. Here's the flight tracker data, does it tell you anything?

quote:

The flight that crashed near Vinhedo, Brazil, began losing altitude a minute and a half before crashing, flight tracking data from Flightradar24 shows.

The plane, which belonged to Voepass Linhas Aéreas, had been cruising at 17,000 feet until 1:21 p.m. local time (12:21 p.m. ET), when it dropped approximately 250 feet in 10 seconds.

It then climbed approximately 400 feet in about eight seconds.

Eight seconds later, it lost just under 2,000 feet. Then, in approximately one minute, it began rapidly descending — roughly 17,000 feet in just one minute.

The last data transmission from the plane was at 1:22 p.m. local time (12:22 p.m. ET).

CNN

quote:

Originally posted by Sig2340:
“The number of victims is still not clear.”

Try “Every one onboard.”

Plus potential victims on the ground.

That looks like a flat spin. There are multiple Twitter vids from different viewpoints and it's just remarkable to see that there is zero forward airspeed. It just corkscrews in.

quote:

Originally posted by kkina:
^Thank you for the analysis. Here's the flight tracker data, does it tell you anything?

quote:

The flight that crashed near Vinhedo, Brazil, began losing altitude a minute and a half before crashing, flight tracking data from Flightradar24 shows.

The plane, which belonged to Voepass Linhas Aéreas, had been cruising at 17,000 feet until 1:21 p.m. local time (12:21 p.m. ET), when it dropped approximately 250 feet in 10 seconds.

It then climbed approximately 400 feet in about eight seconds.

Eight seconds later, it lost just under 2,000 feet. Then, in approximately one minute, it began rapidly descending — roughly 17,000 feet in just one minute.

The last data transmission from the plane was at 1:22 p.m. local time (12:22 p.m. ET).

CNN

That seems like a possible thunderstorm penetration with resulting loss of control. Either a stall during severe turbulence inside the storm, or severe icing causing loss of control. Severe icing can cause the main wing to stall asymmetrically and/or the tail to stall. Severe icing can also disrupt the pitot/static sensors which then cause erroneous information on the flight instruments such as incorrect airspeed, altitude, and vertical speed.

Another possibility is just a plain old stall which progressed to total loss of control. We would need more information such as airspeed (or groundspeed as a proxy). If they just got way too slow for some reason, it could lead to a stall.

17,000 feet is not so high as to bring in Mach effects. Recovering from a stall at twice that altitude is really touchy, but at 17,000 it should be pretty easy assuming one has proper training. It suggests to me some additional factor rather than just distraction. A mechanical problem, or a cargo shifting problem, thunderstorm, icing, etc. They will need the black boxes to reconstruct the causes.

quote:

Originally posted by sgalczyn:

quote:

Originally posted by Sig2340:
“The number of victims is still not clear.”

Try “Every one onboard.”

Plus potential victims on the ground.

CNN reports "No one was killed in the residential area where the plane crashed, Valinhos City Communications Director Ana Cândida Briski told CNN."

CNN World

Four crewmembers, fifty-eight passengers.

https://www.msn.com/en-us/news...ca7ac0dfc07734&ei=10

quote:

Originally posted by WaterburyBob:

quote:

Originally posted by DrDan:

quote:

Originally posted by WaterburyBob:
So, not being a pilot, what causes a plane to go into a flat spin like that? Loss of power?

According to this, the center gravity of the aircraft shifts too far rearward. Perhaps a load in the cargo hold wasn't properly secured and shifted backwards?

Thanks for that

While rearward centers of gravity can lead to or contribute to entering a flat spin, that is not the only possible cause.

quote:

Originally posted by rat2306:
Four crewmembers, fifty-eight passengers.

https://www.msn.com/en-us/news...ca7ac0dfc07734&ei=10

Amended to 61.

CNN World

^^Thanks, kkina. Interesting smaller stories mention in the link that at least 10 more potential victims missed the flight by waiting at the wrong gate.

quote:

Once the aircraft stalls with the tail airflow disrupted it can be impossible to pitch down to recover from the stall.

Increasing the engine power could flatten out a spin. So where we see the aircraft pitched steeply nose down at first

I know nothing about airplanes other flying a flight simulator once. To someone like me with below novice level of knowledge, how does this happen? It seems to me that you would go full throttle and down to gain speed so that your flight surfaces had enough lift?

Having never been in a cockpit in my life, what am I missing?

Fly-Sig gave a good description. It’s a safe bet that the airplane was stalled and experienced yaw, either due to differential thrust of improper use of the rudder pedals.

Flat spins are a lot of fun in an appropriate airplane.* Any spin at all in a twin? No thanks, and absolutely not in a T-tail.

*In a Pitts, you can establish the spin, then add full aileron against the spin. This takes out the rolling component and makes almost if not completely yaw. This also raises the nose a little. Adding full power brings the nose right and significantly adds to the rotational energy. Whee! To recover, simple PARE: Power - OFF, Ailerons - NEUTRAL, Rudder - Against the Rotation**, Elevator - Break the Stall***.

**If you’re spinning to the right, use left rudder. If you’re spinning to the left, use right rudder. If you can’t tell which way you’re spinning, step on the heavy one.

***If you’re upright, you push forward to break the stall. If you’re inverted, you pull back to break the stall.

Transitioning from an upright flat spin to inverted would require passing through an accelerated spin which would greatly increase the rate of rotation and likely be quite disorienting. It would be a bold move. I don’t know how one would do it if the tail is blanked out.

I don’t know that it would work any better, and I have no intention of finding out, but I wonder if differential thrust against the yaw might do better in arresting the spin. Of course, in a deep stalled T-tailed airplane, you’d probably still be hosed. Only thing that comes to mind there is have everyone run to the front of the passenger cabin (and hope you can get them to spread back out if you do succeed in getting the nose down and breaking the stall).

All in all, an extremely tough spot to be in and much better avoided than trying to get out of it.

quote:

Originally posted by slosig:

Any spin at all in a twin? No thanks, and absolutely not in a T-tail.

My instructor certificate includes rating for multi-engine, but after one ham-handed client scared the crap out of me, I stopped instructing in twins other than Flight Reviews with the very few pilots I knew and trusted.

Can we back up to pilots doing pilot shit??

One question, does a high-tail rudder have inherently less yaw authority in a flat spin situation?

Flat Spin.....mist have been terrifying for those few seconds

Definitely looks like a classic icing condition.