Delta airlines plane crashes at Toronto airport

I'd thought the notice for the mid air turbulence incident was negligible , so using belt needs to become instinctive, albeit people were injured by the trolley's too in that incident.
(first time I'd used public transport for a while a couple of months back I had reflected on lack of instinct to use the belt in train and bus I used - incidents like the childrens coach that went off the road quickly go out of your mind)
 
Yes - it’s rotated about the vertical axis (yawing) so the direction travel stays on the runway heading even though the nose is pointed off left or right into the wind. About the moment of touchdown this is cancelled out to hopefully make it go straight down the tarmac:

...

Overcorrect on landing though and it can give the tyres something to complain about:

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Broadly speaking you are correct, however there are couple of things worth mentioning.

There are actually a few techniques for landing in a crosswind which can vary slightly according to aircraft type but most commonly as you've mentioned, as you come over the runway threshold with the aircraft nose pointing into the wind and thus, not aligned with the runway, you can then use the rudder (in or just before the flare) to rotate the aircraft nose to align with the runway (de-crab). This however, particularly on swept wing aircraft, causes the airflow over the upwind wind to increase, causing a subsequent increase in lift on that wing. Essentially you notice this as the downwind wing dropping and you need to quickly counter this with ailerons to keep the wings level throughout the flare and touchdown. This may (or may not) be a point that investigators look at.

Also, using the above technique to early can cause a sideways drift of the aircraft during the touchdown which can cause it's own problems.

In addition the runway condition also plays a role in how the landing is conducted. This is aircraft dependant and I'm not familiar with the CRJ however, if the runway is contaminated (or in this case slippery), you may elect to touch down without using the rudder to correct to nose into wind until the wheels are firmly on the ground. You basically rotate the aircraft in yaw on to the runway centreline as you de-rotate the aircraft nose back onto the runway. The B737 for example has castoring main wheels which allow you to do this up to the crosswind limit of the aircraft. (Although most companies don't like this as it gets expensive on the tyres)

The reason you may want to do this is it's easier to make a firmer landing which is something you want to do on a contaminated runway (make the wheels break through any contaminant and contact the runway surface), also using the above crosswind technique can cause the flare to become prolonged which you want to avoid on a slippery runway, where landing distance can be a factor.

There is a another technique which is to fly the latter part of the approach with crossed controls (sideslip) but I've never really figured that one out.

I've been sent a video from a friend, filmed from the flight deck of the aircraft at the holding point, waiting to cross or line up. (Subject aircraft travelling left to right). I can't link due to expletives, but I'm sure it'll soon be in the public domain sooner or later if not already.

When the aircraft was filmed through the captain's window, the aircraft appeared to have a slight nose up attitude. As the camera pans past the frame between the captain's and FO's window, the aircraft then appeared to have a nose down attitude, and as you suspect, a sudden full upward elevator deflection less than a second before impact.

E: The video also indicates there was a significant headwind, perhaps slightly crossed from the right, judging be the way the snow is being blown.

E2: the METAR at the time of the incident:

CYYZ 171900Z 27028G35KT 6SM R24L/3000VP6000FT/U BLSN BKN034 M09/M14 A2993 RMK CU6 SLP149

In the initial part of the video everything looked normal to me, and I couldn't really tell how things exactly went wrong at the last minute however I watched on my phone so may have missed some details. It does look like all three wheels touched down on the runway at the same time, which may indicate a hard landing.

I believe the landing was on runway 23 which gives a crosswind of 18Kts gusting to 23kts. It's difficult to say since I don't know the runway condition, or the aircraft or company limits but it could be close to the allowable limit.
 
Broadly speaking you are correct, however there are couple of things worth mentioning.

There are actually a few techniques for landing in a crosswind which can vary slightly according to aircraft type but most commonly as you've mentioned, as you come over the runway threshold with the aircraft nose pointing into the wind and thus, not aligned with the runway, you can then use the rudder (in or just before the flare) to rotate the aircraft nose to align with the runway (de-crab). This however, particularly on swept wing aircraft, causes the airflow over the upwind wind to increase, causing a subsequent increase in lift on that wing. Essentially you notice this as the downwind wing dropping and you need to quickly counter this with ailerons to keep the wings level throughout the flare and touchdown. This may (or may not) be a point that investigators look at.

Also, using the above technique to early can cause a sideways drift of the aircraft during the touchdown which can cause it's own problems.

In addition the runway condition also plays a role in how the landing is conducted. This is aircraft dependant and I'm not familiar with the CRJ however, if the runway is contaminated (or in this case slippery), you may elect to touch down without using the rudder to correct to nose into wind until the wheels are firmly on the ground. You basically rotate the aircraft in yaw on to the runway centreline as you de-rotate the aircraft nose back onto the runway. The B737 for example has castoring main wheels which allow you to do this up to the crosswind limit of the aircraft. (Although most companies don't like this as it gets expensive on the tyres)

The reason you may want to do this is it's easier to make a firmer landing which is something you want to do on a contaminated runway (make the wheels break through any contaminant and contact the runway surface), also using the above crosswind technique can cause the flare to become prolonged which you want to avoid on a slippery runway, where landing distance can be a factor.

There is a another technique which is to fly the latter part of the approach with crossed controls (sideslip) but I've never really figured that one out.



In the initial part of the video everything looked normal to me, and I couldn't really tell how things exactly went wrong at the last minute however I watched on my phone so may have missed some details. It does look like all three wheels touched down on the runway at the same time, which may indicate a hard landing.

I believe the landing was on runway 23 which gives a crosswind of 18Kts gusting to 23kts. It's difficult to say since I don't know the runway condition, or the aircraft or company limits but it could be close to the allowable limit.

FYI - I’m speaking from an engineering background and thus keeping it incredibly simple. I will happily defer to any actual pilot in these circumstances :D

But yes, please don’t scrape the brand new tyres sideways down the runway…
 
I flew out of Toronto on Thursday. The city had just been hit with it's 2nd snowstorm in a week, a 3rd one came in over the weekend after I left. The entire airport was absolute chaos, most flights were cancelled or heavily delayed and there seem to be a total lack of plan on how to deal with it and very little staff to manage the situation.

Thousands of people were milling about in the main arrival hall as you walked in and there was 1 single queue to get through security which snaked the entire length of the terminal. It took me more than 2 hours to get through security but a lady on my flight said she'd queued for 4 hours. I managed to track down a member of staff who told me that the airport manager had never seen anything like it although given what's happened there in the last few days, it probably now seems like a distant memory to them.
 
In the initial part of the video everything looked normal to me, and I couldn't really tell how things exactly went wrong at the last minute however I watched on my phone so may have missed some details. It does look like all three wheels touched down on the runway at the same time, which may indicate a hard landing.

I believe the landing was on runway 23 which gives a crosswind of 18Kts gusting to 23kts. It's difficult to say since I don't know the runway condition, or the aircraft or company limits but it could be close to the allowable limit.
From what I can see (full disclaimer: not a pilot at all) the landing wasn't wings level, it looks maybe 10 degrees canted on contact with the starboard wing being lower.

The resolution on the video isn't good enough to reach any firm conclusions. Would you agree that the two likely scenarios to explain the contact of the starboard wing at a shallow angle seem to be either 1) a hard landing and a lot of flex in the starboard wing, or 2) a main gear collapse?
 
From what I can see (full disclaimer: not a pilot at all) the landing wasn't wings level, it looks maybe 10 degrees canted on contact with the starboard wing being lower.

The resolution on the video isn't good enough to reach any firm conclusions. Would you agree that the two likely scenarios to explain the contact of the starboard wing at a shallow angle seem to be either 1) a hard landing and a lot of flex in the starboard wing, or 2) a main gear collapse?
Its difficult to say but it looks like at least one main gear collapsed, either through mishandling or mechanical failure and causing the wing to contact the ground, detach and flip the aircraft. But i would be wary of drawing too many conclusions based on the short video that seem to be available, although to be fair it also looks to me that the aircraft was banked significantly. And I must say I'd be surprised that a main gear failure could cause a wing to detach like that. I may be mistaken but I believe the wing root where it attaches to the fuselage is generally the strongest part of the aircraft.
 
Its difficult to say but it looks like at least one main gear collapsed, either through mishandling or mechanical failure and causing the wing to contact the ground, detach and flip the aircraft. But i would be wary of drawing too many conclusions based on the short video that seem to be available, although to be fair it also looks to me that the aircraft was banked significantly. And I must say I'd be surprised that a main gear failure could cause a wing to detach like that. I may be mistaken but I believe the wing root where it attaches to the fuselage is generally the strongest part of the aircraft.

Gears usually have a weak point to enable them to break away in a known fashion, much underwing engine pylons. Put enough force vertically through it and it could just push the gear through the wing instead. Is it enough to then cause the wing to snap off? Only physics knows, but there has to be a limit eventually.

At least the FDR will tell us the exact descent rate at impact, and the boffins can then work out why it failed.
 
Its difficult to say but it looks like at least one main gear collapsed, either through mishandling or mechanical failure and causing the wing to contact the ground, detach and flip the aircraft. But i would be wary of drawing too many conclusions based on the short video that seem to be available, although to be fair it also looks to me that the aircraft was banked significantly. And I must say I'd be surprised that a main gear failure could cause a wing to detach like that. I may be mistaken but I believe the wing root where it attaches to the fuselage is generally the strongest part of the aircraft.
Good points. I'd add that from what I know from the engineering side of incidents, the wing box itself is very tough, but the wing itself is less so. Where wings do break off on contact with the ground, it's often at the connection between wing and wing box.
 
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