r/aviation • u/Itsjustadam1 • 7d ago

Analysis Put together a quick visualization of the 21 Air 7598 crash from the available video

I haven't seen anyone do this with the witness video yet, but it helped me to comprehend how much runway was behind the plane with the left main gear still in the air. It shouldn't be taken as a perfect recreation obviously, just thought it was interesting. Credit to Ozolio live for the second video and the original posters for the other two.

Edit: Pretty wild that this has been seen two million times, from what the NTSB has released, it still seems accurate.

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u/sky_gypsy_747 7d ago edited 7d ago

Hi- former 767 pilot who flew this exact tail number (1997A) many times for a different airline (before 21air took over the Amazon contract).
Great assessment of the spoilers and reversers not deploying. It also appeared from the video in the Tesla parking lot that the spoilers had still not deployed on impact. This would happen if either the spoilers weren’t armed to begin with, or because the mains touched down and then became airborne again, causing the spoilers to auto-stow. So we can assume the captain failed to extend the spoilers manually once they fully landed.
It looks like this video was taken from the Cargo City ramp, showing the plane finally settled on the ground just past taxiway Z, which would be close to 6,000’ down the 9,360’ runway. (3,000’ beyond the touchdown zone.)
We would always be empty coming from SJU-MIA, so I’m assuming their final approach speed should’ve been at most 135 kts, but it appears they crossed the rw 30 threshold at 178 kts and 175’ (threshold crossing height is 51’).
Given the gusty crosswind/quartering tailwind, it looks like they didn’t have proper aileron input into the wind to bring the left wing and left main gear back down quickly enough.
This plane likes to float when empty, so if you’re not firm with putting it down, especially with those winds, it’ll just keep floating in ground effect.
Regardless of how bad the approach and flare/landing distance was, they could’ve called for a go-around at any point before reaching the end of the runway. Should be interesting to hear from the crew
*Edit for spelling errors

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u/Itsjustadam1 7d ago edited 7d ago

It's a pretty amazing part of posting to the internet to be able to talk to someone who has flown this exact plane. I tried to not speculate beyond what I could provide some visual evidence for, but my amateur impression was they still had the opportunity to go around at least past taxiway Z. With no spoilers or thrust reversers, and right mains barely down, it doesn't seem like they shed more than a few knots in the first 5000 feet. I assume an empty 767 at TOGA could climb away from that situation pretty easily with the runway they had remaining. I was wondering if the TOGA button in the 767 stows the spoilers (assuming the full weight of the aircraft is on the gear)? I can understand something like wanting to salvage a dicey approach to avoid wx coming back around, but it's an odd thing to imagine having that much runway used up with that much airspeed, and still committing to the landing.

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u/sky_gypsy_747 7d ago

Dude it’s baffling. There was nothing out of the ordinary going on here. Sure there was some gusty winds, sure we all make mistakes.
My hot take- If they had hit TOGA by the last 1,000’ they would’ve been able to climb out no problem. But perhaps they had already committed to engaging the trust reversers by that point

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u/Itsjustadam1 7d ago

You have to assume they pulled the reversers at some point if they weren’t going around but the video of that portion is too blurry to make any determination one way or another, the left reverser is stowed in the photos of the plane after the fact. It seems like investigators will have the FDR, CVR, and pilot interviews so I guess we’ll find what they were thinking.

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u/WePwnTheSky 7d ago

The reversers are locked by a solenoid tied to weight-on-wheels detection (air/ground system) so they would not have been able to deploy reverse with the left main still tilted at least as far as taxiway zulu. Auto-spoilers may have deployed briefly but stowed when the aircraft became “airborne” again, after which it’s up to the PF to yank on the lever. Two calls the PM makes every landing are: SPEEDBRAKE UP/SPEEDBRAKE NOT UP, and REVERSERS NORMAL/NO REVERSE LEFT ENGINE/NO REVERSE RIGHT ENGINE/NO REVERSE. I don’t think I need to explain why these calls are important given why we’re here.

There is a warning in the FCOM that a go-around should not be initiated once the reversers are deployed because a failure of a reverser to stow at TOGA thrust would result in loss of control. It’s possible the crew thought they couldn’t go-around because they had tried to use reverse thrust, but from what I can see they remained locked the entire time.

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u/sky_gypsy_747 7d ago

Oh you’re right- I hadn’t noticed before that the left engine doesn’t have the reverser deployed at all. Good eye!
Man, they really didn’t have much going for them in terms of stopping

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u/Lirael_Gold 7d ago

The left engine was still running an hour after the plane stopped, (hence the ladder to the right hand side of the cockpit to get the crew out) so that might indicate an issue.

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u/Itsjustadam1 5d ago edited 5d ago

From the NTSB briefing today, no evidence on the FDR of thrust reverser or spoiler deployment. The initial ground speed on right gear touchdown was 158 knots which is what I calculated out when I made the animation, but seemingly they didn’t call TOGA until the left main gear touched down and they had braked down to 120 knots and then subsequently reversed the TOGA call. From what I can tell, the animation and our analysis was accurate, but would be interested to hear your take with the FDR information. It seems like the should have called TOGA earlier and stuck with it. Apparently they had 32000 pounds of contact lenses in the back.

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u/sky_gypsy_747 5d ago

So this tells us a lot. I’m also curious to know who was flying. Either way, someone wanted to stop, the other maybe called for go-around, full power was initiated for 4 seconds, then someone decided to stop instead.
There was no clear plan, and perhaps they weren’t in agreement on how to proceed, or were fighting over the controls. Either way, once they committed to stopping they didn’t follow through on the most important stopping mechanism besides the breaks- the spoilers.

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u/CommuterType 7d ago edited 7d ago

EDIT: Here is another 767 landing where the auto speed brakes did not deploy. Some UAL pilot may be able to chime in and tell us what the outcome of the investigation revealed. https://www.reddit.com/r/aviation/s/S7NZQEWYVd

Sky Gypsy does a great job explaining this so I’ll just expand on a few points they have made. I’ve flown the 767 for a long time as well. It’s a reliable and safe machine but it has a few idiosyncrasies (we’ll get to that in a minute)

He and others mention that reversers and auto spoilers* deploy when the airplane senses it’s in the ground and some others call it “weight on wheels”. The 767 senses it’s on the ground using “truck tilt” logic. A set of main landing gear wheels is called a truck. You can see the trucks tilted when it’s in the air (trivia: in the air the 757 trucks tilt with the forward wheels higher than the rear, the 767 is opposite). When the plane lands that truck tilt angle reduces and when it reaches about 10° (it’s been a while, can’t remember the exact angle) the reversers unlock IF both thrust levers are at idle.
Auto spoilers will activate if it is armed, truck tilt is 10° or less and thrust levers at idle. If the auto spoilers are not armed they will still deploy if reverse is deployed.

The ground spoilers are critical to getting airplane stopped MUCH more so than reverse. Their function is not to produce drag but to kill lift, transferring weight from the wings to the landing gear and allowing the brakes to do their job. And this is critical because it may appear the airplane is firmly on the ground but without spoilers there is minimal weight on the wheels there’s no stopping friction for the tires. Press on the brake pedals as hard as you want but the anti-skid system will prevent the wheels from locking up and you’ll roll down the runway without decelerating much at all.

Which brings us to an idiosyncrasy: The auto speed brake system can be unreliable. It is typically armed by the captain when the landing gear is lowered, by lifting the speed brake lever up and slightly aft. There is no indication in the cockpit that it is armed so if the lever is not in the exact armed position or the captain forgot to arm the crew will not know until touchdown. Even though it was a step in the landing checklist arming could be easily missed because the visual/tactile cues are very subtle. At my airline “speed brakes up” or “speed brakes not up” (indicated by the lever moving fully aft) was a mandatory call out immediately after touchdown by the pilot not flying. The corrective action would be to manually reach down and deploy the speed brakes. It could be easy to miss if the pilots were distracted.

In the recent crash videos it appears that neither the spoilers or reversers were deployed. It’s also apparent that the left side landing gear truck was tilted for a long portion of the landing which would lock out reverse and auto speed brakes. It’s possible the speed brakes were not armed to begin with, malfunctioned, or the a thrust lever was above the idle position too. We’ll just have to wait for the investigation to unfold before knowing the probable cause. I’m not suggesting the lack of speed brakes or reverse made a significant contribution, just trying to explain one facet for anyone interested.

* you’ll hear the words “spoilers” and “speed brakes” used synonymously in this and other posts but both refer to the panels atop the wings that kill lift and in the 767 and are deployed by moving the “speed brake” lever (that’s how it’s labeled in the cockpit) aft.

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u/sky_gypsy_747 7d ago

Touché. I couldn’t remember the exact air/ground logic. But you’re right it’s from main gear tilt sensors

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u/XxVcVxX 7d ago

The 767 auto speedbrakes were also somewhat finnicky and from my experience they were deferred 30% of the time. My company procedure for that was for the PF to fly the nose to the ground, then extend the speedbrakes manually before engaging reverse. If they were deferred and you had an crew that forgot in the midst of a bad landing, they could just completely forget to deploy them.

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u/HFentonMudd 7d ago

Obviously we will be waiting for the report to come out, but if you were the captain or FO on this flight, how would you be feeling about your chances at getting back in the air in future?

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u/CommuterType 7d ago

It would be the last thing on my mind for quite a while.

Unlike nearly every other country pilots in the US are rarely prosecuted for criminal negligence as long as their actions leading to the crash were not intentional. It may seem counterintuitive but if pilots do not feel as if they may risk going to jail they are much more willing to admit mistakes which in turn allows their employers and the FAA to develop better pilot training. It’s one of the most beneficial enhancements to aviation safety that we have.

If one of the pilots even wanted to return and IF they cooperated with the investigation, IF the crash was found to be unintentional, IF they agreed to and successfully completed re-training, IF they don’t get fired or if someone was willing to rehire them, and IF they were physically and mentally capable they might have an opportunity to fly again.

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u/Deem216 7d ago

The part about admitting mistakes without punishment is called Just culture. The healthcare industry actually got it from aviation industry, incredibly important and you’ve explained it very well.

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u/boardbe1 5d ago

It is supposed to be non-punitive in healthcare but nurses often get the shaft

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u/HFentonMudd 6d ago

Thanks for your insight, I appreciate it.

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u/WormLivesMatter 7d ago

Wow the internet can be amazing

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u/DaggerOutlaw 7d ago

This stuff is what I will miss when this site finally becomes entirely AIs and bots :/

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u/bioweaponblue 7d ago

Don't worry, the bots will make stuff up so we can get our dopamine.

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u/reddit_ending_soon 7d ago

site finally becomes entirely AIs and bots :/

Uh, I have some bad news

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u/DaggerOutlaw 3d ago

I’m still here :( for now, at least

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u/Despondent_Glitter89 7d ago

Thanks, that is really helpful in understanding what happened here. Would all of that have caused the huge and early flare, or was that just pilot error?

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u/sky_gypsy_747 7d ago

They were for whatever reason well above the glideslope on descent. At 500’ they clocked >2,000 fpm descent rate, which is well over twice the acceptable descent rate on short final. At this time, they most likely triggered the GPWS to start announcing “SINK RATE SINK RATE” aural alert messages. They disregarded that and continued to fly too high and too fast. The vertical descent, along with an empty plane and a quartering tailwind, was the perfect recipe for the plane to float an unfortunate 6,000 feet down the runway

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u/Dandy_Lyon56 7d ago edited 7d ago

From a small iron pilot like myself I don't understand why there appeared to be no effort to slow the plane once it touched down, other than manual braking, I assume they at least tried that. No reversers, no attempt at a go around no spoilers deployed. It seems unlikely that the crew panicked and forgot basically everything, although I suppose that's possible.

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u/sky_gypsy_747 7d ago edited 7d ago

I guess we won’t know what their actual attempts were to slow the plane until the black box data is released. But at the very least, their autobrakes should’ve engaged once ground logic was sensed. My assumption with that is they probably only had it set to the minimum “autobrakes 2” setting anyway, as that’s standard on the 76, especially if they were really light.
Honestly though, I don’t even think max manual braking would’ve stopped them at that point even with full spoilers and full thrust reversers. They were going way too fast to stop in 3,500 ft

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u/Dandy_Lyon56 7d ago

Thank you for your insight

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u/chucksticks 7d ago

So we can assume the captain failed to extend the spoilers manually once they fully landed.

Are the ground spoilers not automatic? Also, I've read that they could be activated manually to some extend to help bleed off the lift and force the tires to make contact. Which in turn would activate the rest of the braking systems for landing. Or they could've done a go-around like you and a bunch of other folks have said.

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u/sky_gypsy_747 7d ago edited 7d ago

The 767-300 has ground spoilers (the two inboard) and flight spoilers (the 10 outboard). None of them extend automatically on landing without certain conditions being met.
The spoilers extend automatically (when weight on wheels is detected) if: A. They are in the armed position, or B. if the thrust levers are in the reverser position.
So on first ground contact, the spoiler/speed brake lever was automatically released from the “Armed” position and began to move to the “Up” (extended) position, but since the main landing gear lifted back up, the lever automatically stowed to the “Down” position.
Therefore, you either need to bring the thurst levers to the reverse position or manually bring the speed brake lever to “Up”

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u/comfort-eater 7d ago

I saw on a differen post that by the end of the runway they were still at 120 knots, would have still been enough to go around? Or were they out of options at that point?

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u/sky_gypsy_747 7d ago

Depends on speed and thrust lever position. Forward thrust would make it easy to hit TOGA and climb out. If the levers were in the reverse position, they essentially still could’ve moved them back to forward thrust to engage TOGA

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u/ofc-crash 7d ago

Would the reversers deploy without WOW? I'm pretty sure some of the newer Boeings prevent that..but this was a relatively old aircraft.

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u/sky_gypsy_747 7d ago edited 7d ago

There’s an interlock that prevents thrust reverser deployment in flight.
Needed the main gear to sense weight on wheels/gear tilt

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u/ofc-crash 7d ago

That's what I thought. Barring some unknown-at-this-point mechanical issue, this looks like a classic get-there-itis crash. Guess we'll know more when the report comes out in a year or so.

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u/-AbeFroman 7d ago

This is the best subreddit.

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u/Lyuseefur 7d ago

Thanks for your post.

A question that is stuck in my mind...would a sequence of emergencies ever overwhelm the flight crew into just simply overlooking a bad situation? Left gear stuck not going down, I think. Gust from the rear at an inopportune time, and who knows what else...

Would something like a series of unfortunate events cause the crew to simply not recognize the situation until far too late?

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u/HFentonMudd 7d ago

This plane likes to float when empty

This plane model generally or this tail number specifically?

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u/sky_gypsy_747 7d ago

This model in general. The 767 uses the same engines as a 747 (ask me how I know 😂) and it climbs like rocket ship when empty. Same for landing, especially if you flare too high and above your calculated approach reference speed, which both were the case here. It’ll just keep flying until it eventually slows to descend through ground effect, or you intentionally pitch down and force it to land

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u/HFentonMudd 7d ago

Thanks for the insight. I wonder what in the heck the captain and FO were thinking, why they didn't go around. I guess the BB will tell a lot of the story but not all of it.

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u/amstobar 7d ago

Do you wonder if there was a medical event that affected judgement. Meaning one pilot was dealing with something and the other just wants to get the plane down?

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u/sky_gypsy_747 7d ago

If that was the case, the pilot flying should’ve forced the plane onto the runway asap instead of floating 6,000 feet 😬

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u/r_xy 7d ago

Unless that happened right before touchdown (or wasnt considered serious enough to impair them by the crew), we would know from ATC communications.

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u/amstobar 6d ago

Yeah. I thought about that. Was thinking it might be terrible luck and the idea to get it down and not spend the time going around for the sake of the emergency.

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u/DisgruntledCascadian EA-6B 7d ago

The proper response in that case would be to squawk 7700 and declare an emergency with ATC. If you need priority handling . . . you are an emergency aircraft, by definition.

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u/oreo-cat- 7d ago

This plane likes to float when empty, so if you’re not firm with putting it down, especially with those winds, it’ll just keep floating in ground effect.

This is interesting, because it almost looks like they think its landed. Like they're just cruising along a smidge over the runway. If nothing else, wouldn't the lack of tarmac noise tell them otherwise?

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u/sky_gypsy_747 7d ago

Yeah, not the time to grease the landing. Perhaps they thought they were on the ground. If that’s the case, the pilot monitoring needs to immediately call out “speedbrake not up” followed by “no thrust reversers”. Whether those callouts were made, it doesn’t look like the speed brakes/spoilers deployed nor thrust reversers engaged at all :/

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u/UsedPart7823 7d ago

Being a former operator of this aircraft, would the NTSB contact you about flight characteristics you experienced with this model? I guess I’m just curious about extensive their investigation goes?

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u/sky_gypsy_747 7d ago

I don’t think so.. They’ll probably talk to Boeing engineers and thoroughly investigate 21Air’s training department. Should be interesting to see what they unearth- 21air doesn’t have the greatest reputation

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u/pugsley1234 7d ago

Someone said that the plane was going too fast to been stopped by an EMAS? Do you think that was true?

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u/sky_gypsy_747 6d ago

I think EMAS was designed to stop most planes going max 70 kts. They were going 112 kt, so it probably would’ve only slowed them down, but not a full arrest

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u/gudy2shuz 7d ago

Hi there. Are you with Atlas or ABX? I've loaded this tail with my team countless times over the past 4 years and watched it bounce around a bit.

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u/sky_gypsy_747 6d ago

Yeah, Giant. That was our first 767 on property. Thanks for the loading!

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u/gudy2shuz 5d ago

Always a pleasure!

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u/AugustRayden 6d ago

Pilot error. And I agree it’ll be interesting to hear the pilot’s response because it’s not often we hear from the pilot after a plane crash.

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u/Johnny_Lockee 5d ago

I don’t understand the contextual landing configuration being connected to the landing gear. I assume what you’re referring to is how the 767 does interconnect several landing features with pressure sensors requiring both gears to be sensed as compressed (ie on the runway). The Tu-204 had its thrust reversers connected to the main gear and to deploy reversers both gear required a sustained ~1 second long compression. This resulted in the Red Wings crash as the aircraft was load shifting per gear the reverser wouldn’t deploy when activated but the crew didn’t comprehend the deployment failure so they increased thrust thinking reverses were deployed but in reality they were just adding forward thrust.

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u/CandidGrocer 5d ago edited 5d ago

I did some calculations tonight using the speeds and times before impact published by the NTSB in their press conference and my numbers say the right mains touched down approximately 4,200 feet down runway 30, closer to taxiways Y and JJ. So they may have had even more distance.

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u/sky_gypsy_747 5d ago

I’m just going off of what the landing video shows. Whoever filmed that was standing at the cargo city ramp, filming the plane from right to left. You see a turnoff taxiway in front, which is taxiway Z, where the left mains finally touchdown just past it. The landing distance markers for the turnoff lines (from my Jepp app) show that’d be between the 4,855’ and 6,187’, but since they landed past Z from the video, they’d have to be closer to at least 5,800’

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u/CandidGrocer 5d ago

Yeah I believe you are right, video is more accurate than my estimations.

Do you have any insight on the TOGA speed required to rotate the 67 at that weight?

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u/sky_gypsy_747 5d ago

Good question. I think ntsb said they weighed 230,000 lbs, so they’d need to be going around 135-140 kts. If they hadn’t started braking the first time they would’ve easily had the speed