Power sliding a regional jet (O'Hare)

kaiser

kaiser

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The pilot formerly known as Cool Beard Guy
Just saw this
https://abc7chicago.com/plane-slides-off-runway-at-ohare-airport-during-snowstorm/5689573/

As a newer pilot and generally interested in all things aviation, here are my questions:
1) Differential reverse thrust didn't help? or was it too late/slow of a reaction? Perhaps the wheelbase was too long to notice the slide before it was too late?
2) I don't see spoilers up (and this will engage the lively debate as to whether more surface pressure or less surface pressure is best) - but today's snow is on the dry side, so I'd imaging as much down force as you can get to get the tires onto the concrete.
 
1. Reversers are generally stowed by taxi speed so that you don’t suck up fod. Don’t know what the speed is for a 145.

2. Spoilers at taxi speed would be irrelevant.
I’m not familiar enough with the 145 to know if that video is showing the wing outboard of the spoiler or if they weren’t deployed at all.
 
He looked to be going a little fast for a slick runway when trying to make that taxiway. Probably what sent it sliding. Looked to be a lot of runway left, should have just rolled out further.
 
I love how all of the passengers say "There was no visibility", "We shouldn't have tried to land here!", " We tried once and couldn't make it. Why did we try again?". But as soon as they would have diverted somewhere else, you would have heard how disrupting it was to everyone's schedule and that the airline "owes" them for not landing in Chicago.
 
Sounds like this would have made for a squirrelly day for air traffic in Chicago.
 
jallen0 said:
I have to come up with better titles. I posted the same thing before yours under aviation mishaps. I'll work on my witty titles capability.

Mine does have an explanation attached to it however :p

https://www.pilotsofamerica.com/community/threads/plane-skids-on-snow-stops-using-their-wing.122561/
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haha I thought I checked there! I debated whether this was technically a mishap... and I ended up here. I’m pretty bad at titles as well - original title was “in a spin both feet in”, but wasn’t sure how many would get the reference.
 
kaiser said:
2) I don't see spoilers up (and this will engage the lively debate as to whether more surface pressure or less surface pressure is best) - but today's snow is on the dry side, so I'd imaging as much down force as you can get to get the tires onto the concrete.
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That is what I thought the first time I watched it, but upon looking again, the spoilers were deployed. On the ER145, only the onboard spoilers deploy on landing. They are indeed up in the beginning, but according to some 145 pilots, the spoilers auto-stow once it gets below a certain speed.
 
midwestpa24 said:
He looked to be going a little fast for a slick runway when trying to make that taxiway. Probably what sent it sliding. Looked to be a lot of runway left, should have just rolled out further.
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I’m not sure the turn was ever intentional. They had a pretty strong x-wind and I suspect it just started to weather vane.
 
The pilot was just being thoughtful by getting the wing low enough, it was easier for ground crews to check it for ice before the next flight.
 
Fearless Tower said:
I’m not sure the turn was ever intentional. They had a pretty strong x-wind and I suspect it just started to weather vane.
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I've seen that comment in other places now too. If that is the case, notice the aileron in the video...nearly level. A little crosswind technique would have come in handy.
 
I'll post the explanation I read from the other article linked above:

"I’m an airline pilot that flew out of Chicago during this storm. What happened here was you have a contaminated runway, snow and ice with braking action advisories in effect, plus a strong gusty crosswind. After touchdown, the mostly likely cause was as the plane slowed and the rudder loses effectiveness you rely more on nose wheelsteering, but since the runway is slippery and you have a strong crosswind blowing on the tail, the plane will start to weather vane. The wind pushes the tail to the right and the nose goes left with the end result you see here. Since they had limited nose wheel steering due to the snow and ice covered runway you can’t overcome the wind pushing the tail around. I don’t want to second guess this crews decision, but I would think very hard about landing on a contaminated runway with a gusty strong crosswind. However, there were planes that landed ahead of this one with minimal issues."
 
jallen0 said:
I'll post the explanation I read from the other article linked above:

"I’m an airline pilot that flew out of Chicago during this storm. What happened here was you have a contaminated runway, snow and ice with braking action advisories in effect, plus a strong gusty crosswind. After touchdown, the mostly likely cause was as the plane slowed and the rudder loses effectiveness you rely more on nose wheelsteering, but since the runway is slippery and you have a strong crosswind blowing on the tail, the plane will start to weather vane. The wind pushes the tail to the right and the nose goes left with the end result you see here. Since they had limited nose wheel steering due to the snow and ice covered runway you can’t overcome the wind pushing the tail around. I don’t want to second guess this crews decision, but I would think very hard about landing on a contaminated runway with a gusty strong crosswind. However, there were planes that landed ahead of this one with minimal issues."
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And with two engines, they could use different power settings on each side to compensate, it wasn't a PC12.
 
Shuswap BC said:
And with two engines, they could use different power settings on each side to compensate, it wasn't a PC12.
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Are you referring to reversers or using power to counteract the weather vaning or sliding?

If you’re referring to using differential thrust, you would never use that in a jet aircraft on a contaminated runway during a landing? Never.

The whole point is to quickly get it slow enough to stop the weather vaning and allow the nosewheel to gain control again. Differential thrust would cause accelerating the aircraft and making things much worse. Using the reversers much longer would be a better solution.
 
Shuswap BC said:
And with two engines, they could use different power settings on each side to compensate, it wasn't a PC12.
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With fuselage mounted engines differential reverse thrust isn’t nearly as effective as wing mounted engines. Also you would have to account for engine spool up time not to mention that things happen extremely fast.
 
Fracpilot said:
Are you referring to reversers or using power to counteract the weather vaning or sliding?

If you’re referring to using differential thrust, you would never use that in a jet aircraft on a contaminated runway during a landing? Never.

The whole point is to quickly get it slow enough to stop the weather vaning and allow the nosewheel to gain control again. Differential thrust would cause accelerating the aircraft and making things much worse. Using the reversers much longer would be a better solution.
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For taxiing in to the ramp.
When I owned my Baron, even just in that small twin, it was very effective when I would taxi on an icy runway/taxiway/ramp.
 
midwestpa24 said:
I've seen that comment in other places now too. If that is the case, notice the aileron in the video...nearly level. A little crosswind technique would have come in handy.
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Given the runway conditions, the aircraft's decaying speed on rollout, an apparently significant crosswind component, and considering the aileron effectiveness against the size of the vertical stabilizer and rudder in that crosswind, I believe the PIC could have pegged the ailerons against the stop and it wouldn't have made a bit of difference.

The aircraft was oriented perpendicular to its direction of travel when it left the runway.
 
Cold enough for ice on the runway but it looks like the gear punched right down into the muck off the side. Tough day.

I was thinking, “just firewall it and go somewhere else” but I was thinking “Maule”. Not appropriate here.


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Reverse thrust to control drift is not recommended on transport category aircraft. Excessive reverse thrust can in fact cause rudder blanking on many aircraft with tail mounted engines. Use of differential forward thrust is also not recommended and if the reversers are deployed would take way to long before you got the buckets stowed. The correct answer is probably that they needed a different runway or a divert.
 
Looking at the reports now they had a 60 degree crosswind at 18 gusting to 24 with poor to medium braking. The outcome was somewhat preordained. The correct option was a new runway or divert.
 
Jeff767 said:
Looking at the reports now they had a 60 degree crosswind at 18 gusting to 24 with poor to medium braking. The outcome was somewhat preordained. The correct option was a new runway or divert.
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I wonder if the embraer 145 has reduced crosswind limits based on braking action ... do you know? I flew the 175 embraer but it’s been over ten years ago now and I don’t remember.
 
I have to say, I feel for the guys up front. I don't think this was their fault, it was an accident, and j wonder what the repercussions are going to be for them. At the end of the day I'm just glad there were no injuries.
 
Jeff767 said:
Looking at the reports now they had a 60 degree crosswind at 18 gusting to 24 with poor to medium braking. The outcome was somewhat preordained. The correct option was a new runway or divert.
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Do we all agree that that level of crosswind is enough to make that outcome inevitable? Other planes were landing. If this is enough of a gusting cross wind to cause this, why wasn't the airport closed?
 
3393RP said:
Given the runway conditions, the aircraft's decaying speed on rollout, an apparently significant crosswind component, and considering the aileron effectiveness against the size of the vertical stabilizer and rudder in that crosswind, I believe the PIC could have pegged the ailerons against the stop and it wouldn't have made a bit of difference.

The aircraft was oriented perpendicular to its direction of travel when it left the runway.
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I'm curious, does aileron correction do that much against weather vaning? I understood that was all about rudder / nose wheel.
 
kaiser said:
I'm curious, does aileron correction do that much against weather vaning? I understood that was all about rudder / nose wheel.
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Depends a little on the airplane. In older tailwheel airplanes it does indeed help and can make all the difference.

In some corporate jets (like certain models of CE-500) you can’t apply differential aileron because the nose wheel steering is interconnected with the ailerons.

I can’t speak to the ER-145
 
PPC1052 said:
Do we all agree that that level of crosswind is enough to make that outcome inevitable? Other planes were landing. If this is enough of a gusting cross wind to cause this, why wasn't the airport closed?
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It’s not the airport authorities responsibility. They collect the data on conditions and report to us smart pilots. It’s up to us to make appropriate decisions.
 
Many years ago (32) I was landing at ACK (Nantucket, MA) during an ice event. I was typically the first person to land each morning. I landed on the lone runway which had a crosswind and no breaking action reports and started a sliding adventure. It turned out that while I could not steer the airplane using the little wheel in front, I could easily yaw the airplane using differential thrust. I yearned for the reverse thrust available on the Nomad but today was a Navajo day. I skated my way to the ramp, unloaded, knocked off the ice, went into ops to call FSS. The airport manager approached me for a breaking action report. I told him it was poor until I left then it was nil. After I left the airport closed. I'm pretty sure the airport has the authority to stop traffic when it wants to do so. I just think you need a disaster before ORD closes.
 
Tarheelpilot said:
It’s not the airport authorities responsibility. They collect the data on conditions and report to us smart pilots. It’s up to us to make appropriate decisions.
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Fair point. Is there anything in the ops specs that would have precluded landing?
 
kaiser said:
I'm curious, does aileron correction do that much against weather vaning? I understood that was all about rudder / nose wheel.
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No. What it would do is help keep the wing from lifting if there is a gust of wind.
 
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