Ya I’m assuming that’s their daily normal landing design but they aren’t supposed to break at that point. I’m more curious what they have to certify the gear to withstand before collapsing.
The ultimate load limit is 1.5x, i.e. 15fps, unless that has changed since this document (from 2000):
The group considered including a 12 fps sink rate design ultimate landing condition (safety
factor of 1.0) in addition to the existing landing conditions. The existing requirements specify a
limit condition of 10 feet per second upon which all loads are multiplied by a safety factor of 1.5 to
establish ultimate loads. The increase in energy for the 12 fps condition, combined with the
reduced safety factor, results in a similar but different condition requiring additional analysis, and
potentially resulting in more severe loads.
The group considered the 12 fps condition because, as discussed in the working group report
for the landing descent velocity task, recent survey data indicates that in-service sink rates could
potentially be higher than anticipated by the regulations. The 12 fps condition would cover the
higher sink rates, while allowing a reduction in safety factor. In addition, at least one special
condition applied to a center gear configuration called for a shock absorption test that simulated a
12 fps landing condition. Finally, the 12 fps second ultimate condition is required by the Russian
regulations.
The group decided against the 12 fps condition because the landing sink rate survey data is still
inconclusive, as described in that working group report. Furthermore, the condition would not
likely result in significantly different loads, but would require a large amount of additional
analysis.
Although I found this accident report where the gear of an MD-10 collapsed at 14.5fps:
fish4life wrote: ↑Thu Mar 20, 2025 3:32 pm
I’m also curious what the certification standard is for the aircraft’s gear.
From the report: "The MLG shock struts on this aircraft are designed to absorb the energy of a 720 fpm (12 fps) descent velocity at the maximum landing weight."
The FAA certification standard is 10fps.
When doing a search for the certification standard, I came across one other gear collapse accident:
It is a very similar type (CL-600-2B19 vs CL-600-2D24), it hit the runway at 20fps (compared to 18.3fps in this accident), and it was also at Toronto.
Ya I’m assuming that’s their daily normal landing design but they aren’t supposed to break at that point. I’m more curious what they have to certify the gear to withstand before collapsing.
The FAR's for certification states that the gear withstand 10 ft/sec and must not collapse at 12 Ft/sec....anything more than that is fair game. However this is when landing on both mains. When landing on one gear - it must not break up and spill fuel at 5 ft/sec. These are just a few of many factors that must be designed into the gear....note that there are also side load limits as well, and although it doenst sound like they were crabbed at all - landing with a bank angle is going to impart some sort of sideload to the gear and airframe. Landing at 1100 ft/min, on one gear, in a bank.......clearly these limits were exceeded by a large factor. I highly doubt that there is a design issue here
25.723 Shock absorption tests.
(a) The analytical representation of the landing gear dynamic characteristics that is used in determining the landing loads must be validated by energy absorption tests. A range of tests must be conducted to ensure that the analytical representation is valid for the design conditions specified in § 25.473.
(1) The configurations subjected to energy absorption tests at limit design conditions must include at least the design landing weight or the design takeoff weight, whichever produces the greater value of landing impact energy.
(2) The test attitude of the landing gear unit and the application of appropriate drag loads during the test must simulate the airplane landing conditions in a manner consistent with the development of rational or conservative limit loads.
25.473 Landing load conditions and assumptions.
(a) For the landing conditions specified in § 25.479 to § 25.485 the airplane is assumed to contact the ground—
(1) In the attitudes defined in § 25.479 and § 25.481;
(2) With a limit descent velocity of 10 fps at the design landing weight (the maximum weight for landing conditions at maximum descent velocity); and
(3) With a limit descent velocity of 6 fps at the design take-off weight (the maximum weight for landing conditions at a reduced descent velocity).
(4) The prescribed descent velocities may be modified if it is shown that the airplane has design features that make it impossible to develop these velocities.
(b) The landing gear may not fail in a test, demonstrating its reserve energy absorption capacity, simulating a descent velocity of 12 f.p.s. at design landing weight, assuming airplane lift not greater than airplane weight acting during the landing impact.
(c) In lieu of the tests prescribed in this section, changes in previously approved design weights and minor changes in design may be substantiated by analyses based on previous tests conducted on the same basic landing gear system that has similar energy absorption characteristics.
25.721 General.
(a) The landing gear system must be designed so that when it fails due to overloads during takeoff and landing, the failure mode is not likely to cause spillage of enough fuel to constitute a fire hazard. The overloads must be assumed to act in the upward and aft directions in combination with side loads acting inboard and outboard. In the absence of a more rational analysis, the side loads must be assumed to be up to 20 percent of the vertical load or 20 percent of the drag load, whichever is greater.
(b) The airplane must be designed to avoid any rupture leading to the spillage of enough fuel to constitute a fire hazard as a result of a wheels-up landing on a paved runway, under the following minor crash landing conditions:
(1) Impact at 5 feet-per-second vertical velocity, with the airplane under control, at Maximum Design Landing Weight—
(i) With the landing gear fully retracted; and
(ii) With any one or more landing gear legs not extended.
Dry Guy wrote: ↑Thu Mar 20, 2025 1:07 pm
So if the Captain wasn't a line pilot what was he? A babysitter to try and force through the diversity hires that couldn't meet standards?
It couldn’t have been training at that point. She was there a full year and had 400 hrs on type. No company would keep someone on line indoc that long DEI or not. Bad combination though. A sim instructor who hardly flies and a low experience new hire.
When they need meat in the seat. On a good day they can just...pass, and hope they'll pick up enough to improve for next time. Not always the case. Some people just shouldn't be flying
rookiepilot wrote: ↑Thu Mar 20, 2025 9:13 pm
The lawyers are gonna have a field day with this, as they should.
I hope the judge or whoever throws the book at Delta, assuming this information is the complete picture.
That’s how the system is disciplined, through financial pain, and then people who don’t even deserve a PPL are forcibly removed from having any responsibility for people’s lives.
I doubt this crew will be fired. The Capt will be downgraded and the FO will eventually end up at Delta (assuming they don't remove themselves from flying altogether... I certainly would).
Regarding "the system", it's Delta Airlines. At the end of the day this is just a bump in the road for them.
rookiepilot wrote: ↑Thu Mar 20, 2025 9:13 pm
The lawyers are gonna have a field day with this, as they should.
I hope the judge or whoever throws the book at Delta, assuming this information is the complete picture.
That’s how the system is disciplined, through financial pain, and then people who don’t even deserve a PPL are forcibly removed from having any responsibility for people’s lives.
I doubt this crew will be fired. The Capt will be downgraded and the FO will eventually end up at Delta (assuming they don't remove themselves from flying altogether... I certainly would).
Regarding "the system", it's Delta Airlines. At the end of the day this is just a bump in the road for them.
I know of 2 pilots who were involved in crashes at the 703/704 level and 2 who landed Dash 8s short of or past the runway at a 705 who are at the NHL of airlines.
rookiepilot wrote: ↑Thu Mar 20, 2025 9:13 pm
The lawyers are gonna have a field day with this, as they should.
I hope the judge or whoever throws the book at Delta, assuming this information is the complete picture.
That’s how the system is disciplined, through financial pain, and then people who don’t even deserve a PPL are forcibly removed from having any responsibility for people’s lives.
I doubt this crew will be fired. The Capt will be downgraded and the FO will eventually end up at Delta (assuming they don't remove themselves from flying altogether... I certainly would).
Regarding "the system", it's Delta Airlines. At the end of the day this is just a bump in the road for them.
Your statement honestly terrifies me.
I doubt the captain will even be downgraded. Remedial training is more likely based on how quickly it when to shit right at the end and his experience level. The same carrier had a wingtip strike in the CRJ900 almost exactly 1 month later. This looks like a training issue.
goingnowherefast wrote: ↑Fri Mar 21, 2025 11:10 am
Shit can go wrong really fast. Reading the narrative, they're talking about "3.6 seconds before touchdown".
Thats not a lot of time to see something go wrong, figure out what it is, figure out a course of action and implement it.
Does the capt take control? Does he call a deviation? Does he call go-around? Any combination of the options?
These aren't 172s, they are high performance airliners. They'll get one into trouble quickly.
It'll be interesting to see what influences the final report comes up with. Obviously they botched the landing, the question is "why?"
All fair comments, I don’t pretend I could ever land a jet, but it’s hard to see chopping power to idle at 200 feet even in a 172 in a gusty 30 knot condition with a long runway.
goingnowherefast wrote: ↑Fri Mar 21, 2025 11:10 am
Shit can go wrong really fast. Reading the narrative, they're talking about "3.6 seconds before touchdown".
Thats not a lot of time to see something go wrong, figure out what it is, figure out a course of action and implement it.
Does the capt take control? Does he call a deviation? Does he call go-around? Any combination of the options?
These aren't 172s, they are high performance airliners. They'll get one into trouble quickly.
It'll be interesting to see what influences the final report comes up with. Obviously they botched the landing, the question is "why?"
The problem didn’t start “3.6 seconds before touchdown”. It started at 150’ AGL when the thrust was reduced to idle.
A professional crew that has complete situational awareness anticipates challenges, discusses them, creates a plan of action, and modifies the plan if circumstances unfold differently than briefed and on a moments notice if that is what is required.
PM duties, CA responsibilities, callouts, stabilized approach criteria and crew actions are all SOP. We don’t brief SOP as we are assumed to be competent, qualified, and current and will fly to the SOP.
This is not about assigning blame. That is up to the TSB and NTSB. This is about every other professional aviator recognizing what transpired and acknowledging what they would have done differently to avoid this outcome. In this case we don’t have to wait for the final report to assimilate the known details of this accident in to our own library of experience.
goingnowherefast wrote: ↑Fri Mar 21, 2025 11:10 am
Shit can go wrong really fast. Reading the narrative, they're talking about "3.6 seconds before touchdown".
Thats not a lot of time to see something go wrong, figure out what it is, figure out a course of action and implement it.
Does the capt take control? Does he call a deviation? Does he call go-around? Any combination of the options?
These aren't 172s, they are high performance airliners. They'll get one into trouble quickly.
It'll be interesting to see what influences the final report comes up with. Obviously they botched the landing, the question is "why?"
All fair comments, I don’t pretend I could ever land a jet, but it’s hard to see chopping power to idle at 200 feet even in a 172 in a gusty 30 knot condition with a long runway.
Exactly. This is the scariest part. You're sitting there gliding in with gusty conditions how does your instinct not tell you to bring the power up. They felt the plane sinking and losing energy and sat there along for the ride. Some people just don't have "it" and should really question what they are doing in a transport category aircraft.
And then there's the blatant procedural failure of not initiating a go-around on the sink rate warning. 1100fpm at 50ft, when they got the warning, that gave them nearly 3 seconds before touchdown. That's more than enough time to call "unstable" and firewall the throttles.
3.6 seconds is not a lot of time to recognize things going wrong. Except for the fact you are in the landing phase and at your highest alertness. You should be anticipating deviations and ready to correct for them. It’s like going through a traffic light, each one could turn yellow and red, and you need to make a split second decision to stop or go. But you already made the decision when the light was green at what point you would decide to continue or stop at the light. Everyone with a drivers license is making this split second choice. So I don’t see this as 3.6 seconds is not lots of time to react, because you spend the previous 10 seconds anticipating and building an idea of how you would react to all the possible things that could cause you to go around. Just the same as a traffic light changing on you.
I just think it sounds like if we say this, we are making excuses. Meanwhile thousands of planes land in crosswinds every day. And some of those there may have been transfer of control, some of the approaches lead to go arounds etc. they were all managed to not flip over on the runway. In all of those cases split second decisions were made because pilots were anticipating and alert for any deviation they pre set as limits.
JustaCanadian wrote: ↑Sat Mar 22, 2025 3:44 am
3.6 seconds is not a lot of time to recognize things going wrong. Except for the fact you are in the landing phase and at your highest alertness. You should be anticipating deviations and ready to correct for them. It’s like going through a traffic light, each one could turn yellow and red, and you need to make a split second decision to stop or go. But you already made the decision when the light was green at what point you would decide to continue or stop at the light. Everyone with a drivers license is making this split second choice..
True sometimes. There will be times that I am approaching a light and am thinking that it may turn yellow and when should I continue even though it turns yellow. I will silently day “Go” to myself when that subjective decision is made. Other times, it is made easy with the crosswalk countdown timer(in areas where it normally has the light change to yellow when the countdown hits zero).
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Last edited by pelmet on Sat Mar 22, 2025 9:19 am, edited 1 time in total.
JustaCanadian wrote: ↑Sat Mar 22, 2025 3:44 am
3.6 seconds is not a lot of time to recognize things going wrong. Except for the fact you are in the landing phase and at your highest alertness. You should be anticipating deviations and ready to correct for them. It’s like going through a traffic light, each one could turn yellow and red, and you need to make a split second decision to stop or go. But you already made the decision when the light was green at what point you would decide to continue or stop at the light. Everyone with a drivers license is making this split second choice..
True sometimes. There will be times that I am approaching a light and am thinking that it may turn yellow and when should I continue even though it turns yellow. I will silent.y day “Go” to myself when that subjective decision is made. Other times, it is made easy with the crosswalk countdown timer(in areas where it normally has the light change to yellow when the countdown hits zero).
Just some interesting information about lights, I’ve been told and it seems to work, where the dashed line turns solid coming up to the lights is the decision line. If you are at the solid line and it turns yellow there is time to get through at the speed limit.
As for this event, if the FO went to idle at 150’ I would tell them to add thrust and follow that with a go around call if they didn’t add it back immediately, as Captain you need to be aware of what the FO is doing
BTD wrote: ↑Fri Mar 07, 2025 5:59 pm
Almost certainly the crew screwed up. Big time. That doesn’t make them evil or not worth of empathy. And nobody said more than the passengers.
I am not letting this go. You went after me (and not only you) for simply saying the pax deserve a lot more empathy than this crew.
Still your position BTD? They deserve empathy?
Isn’t it evil to commence a flight that knowingly has a high probability of an accident?
You say — they had no idea or intention. This is a professional crew. There are supposed to know.
Why isn’t chopping the power at 200 feet arguably wilful negligence? And it was pretty obvious what happened before the latest update came out.
You want to go after me? Answer the questions.
I think a bunch of you guys are mental for defending this crew.
Then put your wife / children/ grandchildren on their next flight. In a winter storm.
BTD wrote: ↑Fri Mar 07, 2025 5:59 pm
Almost certainly the crew screwed up. Big time. That doesn’t make them evil or not worth of empathy. And nobody said more than the passengers.
I am not letting this go. You went after me (and not only you) for simply saying the pax deserve a lot more empathy than this crew.
Still your position BTD? They deserve empathy?
Isn’t it evil to commence a flight that knowingly has a high probability of an accident?
You say — they had no idea or intention. This is a professional crew. There are supposed to know.
Why isn’t chopping the power at 200 feet arguably wilful negligence? And it was pretty obvious what happened before the latest update came out.
You want to go after me? Answer the questions.
I think a bunch of you guys are mental for defending this crew.
Then put your wife / children/ grandchildren on their next flight. In a winter storm.
Rookie, do you honestly think the crew set out knowing the potential outcome and to be PERFECTLY CLEAR, the winds were within the limits set by my company on the same aircraft for new hire FOs!
This was not an extremely challenging environment, it was one that required your attention and diligence which a professional crew should have, I can’t speak to why this Captain didn’t notice the thrust levers at idle but it is most certainly something that should have been noticed and corrected before it became a problem. The sink rate also should have been corrected but it was not, this speaks to a possible saturation, to which that speaks to the crew again.
There is no doubt in my mind the crew screwed up but to suggest they set out knowing this was the outcome is outright ignorant and irresponsible to even suggest!
BTD wrote: ↑Fri Mar 07, 2025 5:59 pm
Almost certainly the crew screwed up. Big time. That doesn’t make them evil or not worth of empathy. And nobody said more than the passengers.
I am not letting this go. You went after me (and not only you) for simply saying the pax deserve a lot more empathy than this crew.
Still your position BTD? They deserve empathy?
Isn’t it evil to commence a flight that knowingly has a high probability of an accident?
You say — they had no idea or intention. This is a professional crew. There are supposed to know.
Why isn’t chopping the power at 200 feet arguably wilful negligence? And it was pretty obvious what happened before the latest update came out.
You want to go after me? Answer the questions.
I think a bunch of you guys are mental for defending this crew.
Then put your wife / children/ grandchildren on their next flight. In a winter storm.
Rookie, do you honestly think the crew set out knowing the potential outcome and to be PERFECTLY CLEAR, the winds were within the limits set by my company on the same aircraft for new hire FOs!
This was not an extremely challenging environment, it was one that required your attention and diligence which a professional crew should have, I can’t speak to why this Captain didn’t notice the thrust levers at idle but it is most certainly something that should have been noticed and corrected before it became a problem. The sink rate also should have been corrected but it was not, this speaks to a possible saturation, to which that speaks to the crew again.
There is no doubt in my mind the crew screwed up but to suggest they set out knowing this was the outcome is outright ignorant and irresponsible to even suggest!
Was the experience, flying record, and training record of this crew up to the weather?
Its gonna be a fun argument in court.
The competence of this crew prior to this flight — they will be absolutely shredded to pieces by the lawyers.
Thats why you guys hate lawyers. They don’t blanket brutal f-ups in empathy.
I am not letting this go. You went after me (and not only you) for simply saying the pax deserve a lot more empathy than this crew.
Still your position BTD? They deserve empathy?
Isn’t it evil to commence a flight that knowingly has a high probability of an accident?
You say — they had no idea or intention. This is a professional crew. There are supposed to know.
Why isn’t chopping the power at 200 feet arguably wilful negligence? And it was pretty obvious what happened before the latest update came out.
You want to go after me? Answer the questions.
I think a bunch of you guys are mental for defending this crew.
Then put your wife / children/ grandchildren on their next flight. In a winter storm.
Rookie, do you honestly think the crew set out knowing the potential outcome and to be PERFECTLY CLEAR, the winds were within the limits set by my company on the same aircraft for new hire FOs!
This was not an extremely challenging environment, it was one that required your attention and diligence which a professional crew should have, I can’t speak to why this Captain didn’t notice the thrust levers at idle but it is most certainly something that should have been noticed and corrected before it became a problem. The sink rate also should have been corrected but it was not, this speaks to a possible saturation, to which that speaks to the crew again.
There is no doubt in my mind the crew screwed up but to suggest they set out knowing this was the outcome is outright ignorant and irresponsible to even suggest!
Was the experience, flying record, and training record of this crew up to the weather?
Its gonna be a fun argument in court.
The competence of this crew prior to this flight — they will be absolutely shredded to pieces by the lawyers.
Thats why you guys hate lawyers. They don’t blanket brutal f-ups in empathy.
None of us has seen the training record yet. Have seen some rumours about diversity hiring but seeing as the TSB is even more blatant about this sort of thing in their advertisements for work than this airline was in promoting it through on-line postings, I wouldn't expect an unbiased look into it. That is what happens when you enter this corrosive policy into aviation. Confidence is lost....in the company and in the investigation agency.
I calculate a station pressure for the start of every accident sequence involving similar types of HWC oscillation as described (ie tsb data given yesterday) and sure enough here at 153agl is 1008hPa again, as i have found over time is quite reliably the case in like narratives of the past. Still haven’t figured out quite how to begin to try and explain those numerous airspeed incidents so often incipient at that pressure.
pdw wrote: ↑Sat Mar 22, 2025 1:47 pm
I calculate a station pressure for the start of every accident sequence involving similar types of HWC oscillation as described (ie tsb data given yesterday) and sure enough here at 153agl is 1008hPa again, as i have found over time is quite reliably the case in like narratives of the past. Still haven’t figured out quite how to begin to try and explain those numerous airspeed incidents so often incipient at that pressure.
Aren't such pressures at those heights generally associated with low altitude funnel gunnels?
pdw wrote: ↑Sat Mar 22, 2025 1:47 pm
I calculate a station pressure for the start of every accident sequence involving similar types of HWC oscillation as described (ie tsb data given yesterday) and sure enough here at 153agl is 1008hPa again, as i have found over time is quite reliably the case in like narratives of the past. Still haven’t figured out quite how to begin to try and explain those numerous airspeed incidents so often incipient at that pressure.
The angle of the dangle is inversely proportional to the heat of the meat, provided that the maxis of the axis, and the gravity of the cavity, remain constant.
BTD wrote: ↑Fri Mar 07, 2025 5:59 pm
Almost certainly the crew screwed up. Big time. That doesn’t make them evil or not worth of empathy. And nobody said more than the passengers.
I am not letting this go. You went after me (and not only you) for simply saying the pax deserve a lot more empathy than this crew.
Still your position BTD? They deserve empathy?
Isn’t it evil to commence a flight that knowingly has a high probability of an accident?
You say — they had no idea or intention. This is a professional crew. There are supposed to know.
Why isn’t chopping the power at 200 feet arguably wilful negligence? And it was pretty obvious what happened before the latest update came out.
You want to go after me? Answer the questions.
I think a bunch of you guys are mental for defending this crew.
Then put your wife / children/ grandchildren on their next flight. In a winter storm.
You are such an asshole and you really do have main character syndrome. Yes I think this crew deserves some empathy. Reducing the thrust to idle at 150 ft is a bad decision, but I highly doubt it will be shown to be gross negligence. They no doubt did not intentionally crash the airplane.
I never said they should be coddled or given more empathy than the passengers. Nor did I say they should not be held accountable.
Now just in case you don’t know, here is the definition of empathy: “the ability to understand and share the feelings of another.” You seem to be confusing that with sympathy.
In your world I suppose they should be taken out back and shot?
So thanks for the straw man argument again. Even your quote of mine above is crystal clear, yet you somehow managed to (almost certainly intentionally) misunderstand it. Probably to make yourself centre of attention again.
Frankly I don’t give two shits what you think of me. I am simply engaging in this so that others can see our positions next to each other and come to their own conclusions.
55+ wrote: ↑Tue Feb 18, 2025 4:20 pm
I feel for the Capt and FO, no doubt emotionally scarred by this accident and will be for a lengthy time if not throughout the remaining aviation career. If there is such thing as consolation for them , nobody died on their watch.
Yet. 3 in critical condition at last report.
I feel for them, and other pax emotionally scarred by being violently turned upside down in an aircraft.
Whether I feel as much for the Cap and Fo will depend on the substance of the TSB’s report.
I highly doubt they set out that morning to crash an airplane. You can still have empathy for those who made errors that led to bad outcomes. Doesn’t absolve their responsibility. But I certainly feel for them, unless it turns out to be gross negligence.
BTD wrote: ↑Fri Mar 07, 2025 5:59 pm
Almost certainly the crew screwed up. Big time. That doesn’t make them evil or not worth of empathy. And nobody said more than the passengers.
I am not letting this go. You went after me (and not only you) for simply saying the pax deserve a lot more empathy than this crew.
Still your position BTD? They deserve empathy?
Isn’t it evil to commence a flight that knowingly has a high probability of an accident?
You say — they had no idea or intention. This is a professional crew. There are supposed to know.
Why isn’t chopping the power at 200 feet arguably wilful negligence? And it was pretty obvious what happened before the latest update came out.
You want to go after me? Answer the questions.
I think a bunch of you guys are mental for defending this crew.
Then put your wife / children/ grandchildren on their next flight. In a winter storm.
You are such an asshole and you really do have main character syndrome. Yes I think this crew deserves some empathy. Reducing the thrust to idle at 150 ft is a bad decision, but I highly doubt it will be shown to be gross negligence. They no doubt did not intentionally crash the airplane.
I never said they should be coddled or given more empathy than the passengers. Nor did I say they should not be held accountable.
Now just in case you don’t know, here is the definition of empathy: “the ability to understand and share the feelings of another.” You seem to be confusing that with sympathy.
In your world I suppose they should be taken out back and shot?
So thanks for the straw man argument again. Even your quote of mine above is crystal clear, yet you somehow managed to (almost certainly intentionally) misunderstand it. Probably to make yourself centre of attention again.
Frankly I don’t give two shits what you think of me. I am simply engaging in this so that others can see our positions next to each other and come to their own conclusions.
I feel for them, and other pax emotionally scarred by being violently turned upside down in an aircraft.
Whether I feel as much for the Cap and Fo will depend on the substance of the TSB’s report.
I highly doubt they set out that morning to crash an airplane. You can still have empathy for those who made errors that led to bad outcomes. Doesn’t absolve their responsibility. But I certainly feel for them, unless it turns out to be gross negligence.
Hang em’ high.
Just so it’s crystal clear.
Lawyers gonna make them wish they had never been born. I will be cheering.
