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quiet1
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 5:04 am

quiet1 wrote:
Further to the discussion above about there being an evacuation slide or no slide, where is the *door*? Door 1L is an outward opening door, and the photos show just a gaping hole for the door opening.

I found a YouTube video that panned past the front of the plane, and I did this screen grab which looks like it's an inward opening door hinged at the rear?
Image
 
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paullam
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DHL 757 off runway at SJO

Fri Apr 08, 2022 5:24 am

Boeing757100 wrote:
Sad that a 757 just left our skies. :(

Anyway, sorry if it seems like a dumb question, but in video that an above user mentioned, I don't see thrust reversers deployed? The pilots claimed that they had failure in the left hydraulic system, which impaired the braking. But wouldn't they have been able to deploy thrust reversers? Even if they only deployed the right thrust reverser, could they have done it slowly and gradually so the asymmetric thrust isn't as much of a problem? Would they not have overran if they did that? Sorry if it seems dumb but I was just wondering.
https://twitter.com/xbmpro/status/15121 ... V7eORoTClw

Usually asymmetric thrust isn’t much of a problem but in combination with other issues it might have contributed to the right turn.
On this picture you’ll be able make out the right thrust reverser being deployed whereas the left one isn’t:

Image
 
SkyVoice
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:03 am

WOW, A GROUND LOOP! And, as always, "Any landing you can walk away from . . ."
 
B777LRF
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:58 am

quiet1 wrote:
Further to the discussion above about there being an evacuation slide or no slide, where is the *door*? Door 1L is an outward opening door, and the photos show just a gaping hole for the door opening.


Depends on the P2F conversion, but most conversions ditch the “normal” L1 door in favour of one similar to that of the 757PF, which is an inward opening door. Provides room for 15 full main-deck positions, rather than 14.5 of the 757SF and similar conversions.
 
bennett123
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 9:44 am

Why do they refer to 'two souls on board' rather than two people?.
 
hpff
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 10:10 am

bennett123 wrote:
Why do they refer to 'two souls on board' rather than two people?.


It's standard terminology for giving the number of people on board in an emergency. I have no idea where the practice came from
 
CWL757
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 10:13 am

bennett123 wrote:
Why do they refer to 'two souls on board' rather than two people?.

Because souls are "living bodies " on board. Its not unheard of for aircraft to carry deceaced bodies on board so, as morbid as it sounds, its a way for rescuers to know how many live people they need to account for if the crash had taken a turn for the worst.
That's how I interpret it anyway.
 
Winterapfel
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 10:32 am

CWL757 wrote:
bennett123 wrote:
Why do they refer to 'two souls on board' rather than two people?.

Because souls are "living bodies " on board. Its not unheard of for aircraft to carry deceaced bodies on board so, as morbid as it sounds, its a way for rescuers to know how many live people they need to account for if the crash had taken a turn for the worst.
That's how I interpret it anyway.


In addition, it ensures there is no confusion between passengers, crew, or infants/children on their parents lap
 
Fixinthe757
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Re: DHL 757 off runway at SJU

Fri Apr 08, 2022 10:32 am

PSU.DTW.SCE wrote:
Dumb question - but to cargo aircraft have escape slides on the L1 door, or to they just use a rope for the crew to evacuate?

Some do, some dont, and for those that have an R1 door, they do as well. I do know Fedex has them on both L1 and R1
Last edited by Fixinthe757 on Fri Apr 08, 2022 10:46 am, edited 1 time in total.
 
hitower3
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 10:35 am

bennett123 wrote:
Why do they refer to 'two souls on board' rather than two people?.


This seemingly bizarre terminology is used to avoid any confusion. "Passengers" would not account for flight and cabin crew, "people" would not account for lap children, as they are treated differently on the passenger manifest. Also "souls" explicitly refer to people who are alive - aircraft sometimes carry deceased people.

The usage of the term "souls" in the context of people on board of a ship can be traced back to the 1700s. Back then, the word "people" would have a strong connotation of being a member of a certain nation (like today, "the American People"). Also, humans belonging to a certain descendance or social group would not be considered as "people" in these ancient times, e.g. slave workers from African origin.

In short, the term "souls" is the most universal and unambiguous way to designate every living human being on board of a ship or an airplane.

Best regards,
Hendric
 
SEAorPWM
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 10:50 am

Jesus... the media is having a field day with this one and they're linking it with the MU crash, of course.

:banghead:
 
trnswrld
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 11:03 am

paullam wrote:
Usually asymmetric thrust isn’t much of a problem but in combination with other issues it might have contributed to the right turn.
On this picture you’ll be able make out the right thrust reverser being deployed whereas the left one isn’t:

Image


Interesting because to me that picture shows no sign of a thrust reverser activated, left or right side. I even watched the video that picture was snapped from and don’t see it either. I mean a thrust reverser activation on that side would make sense to the aircraft spinning, but I just don’t see the engine cowling opened up.
 
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flyPIT
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 11:25 am

quiet1 wrote:
Further to the discussion above about there being an evacuation slide or no slide, where is the *door*? Door 1L is an outward opening door, and the photos show just a gaping hole for the door opening.

It is an inward opening, plug type door.
 
ltbewr
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 11:56 am

One area that will be looked at in the investigation will be the condition and mx of the landing gear and related hydraulic systems. Perhaps it may be due to a odd metal failure, an error or incorrect mx procedure, perhaps the landing gear was stressed on a previous flight. Landing gear failures are rare but do happen on various model aircraft of major makers. For sure this ended relatively well with both crew safely evacuated and it appears while broke up, no fire happened.
 
Curiousflyer
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 12:15 pm

Is it a write-off?
 
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bobdarvey
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Re: DHL 757 off runway at SJU

Fri Apr 08, 2022 12:44 pm

JannEejit wrote:
I don't think that's going to be repaired somehow.


Your crystal ball looks awesome. Give me the brand.
 
SJOtoLIR
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 12:54 pm

I've read the source from the cabin desk in Spanish, which is my natural language.
They literally said: "somos dos almas... we're two souls..."
The crew is from Guatemala.
Check this caption from today's local media:

Image

Edited on April 08th, 2022.
 
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JannEejit
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Re: DHL 757 off runway at SJU

Fri Apr 08, 2022 12:55 pm

bobdarvey wrote:
JannEejit wrote:
I don't think that's going to be repaired somehow.


Your crystal ball looks awesome. Give me the brand.


Sure, It's a C-thru-PO Golden Ball XIV. If you buy one, they probably saw you coming. :lol:
 
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Boeing757100
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Re: DHL 757 off runway at SJU

Fri Apr 08, 2022 1:23 pm

bobdarvey wrote:
JannEejit wrote:
I don't think that's going to be repaired somehow.


Your crystal ball looks awesome. Give me the brand.


It's FLAIRPORT's snowglobe...

Anyways, I saw some people discussing thrust reversers, and I couldn't see it deployed on the right engine, as seen in this image. The image isn't all that clear on that side though, so I may be wrong, but the cowling doesn't seem opened up other than from damage sustained from the crash.
Image
 
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paullam
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 1:36 pm

Boeing757100 wrote:
bobdarvey wrote:
JannEejit wrote:
I don't think that's going to be repaired somehow.


Your crystal ball looks awesome. Give me the brand.


It's FLAIRPORT's snowglobe...

Anyways, I saw some people discussing thrust reversers, and I couldn't see it deployed on the right engine, as seen in this image. The image isn't all that clear on that side though, so I may be wrong, but the cowling doesn't seem opened up other than from damage sustained from the crash.
Image

The more I think about it and the more I look at the videos and pictures I doubt my earlier assumption of the thrust reverser being deployed. Seems you guys are right
 
Wacker1000
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 1:41 pm

Wonder if either of the pilots owns a Mustang? Looks like someone forgot that they weren't leaving a cars and coffee.
 
peterjohns
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 1:56 pm

Looking at the skid marks- there are three on each side- one thick one in the middle. That means the aircraft was skidding sidewards with fully locked brakes on both sides.
Then it went off into the ditch and slid halfway up again tilting the nosegear backwards. There was a hell of a lot of energy left when it cartwheeled around!
 
nkops
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 2:05 pm

LTEN11 wrote:
This is why the ground next to a runway should be level with the runway wherever it is practical. If there hadn't been the depression/ditch between the runway and the road, this aircraft would most likely still be intact.


I am pretty sure the a/c is well out of the Runway Safety Area.
 
bluefrog
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 2:11 pm

BlueberryWheats wrote:
It's incredible how many accidents/incidents are caught on camera these days. Even a 737 suddenly nose diving in the middle of China just happens to be caught on at least two cameras.

as we say "big brother is watching you "
 
A320B737NGCapt
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 2:36 pm

paullam wrote:
Boeing757100 wrote:
bobdarvey wrote:


Your crystal ball looks awesome. Give me the brand.


It's FLAIRPORT's snowglobe...

Anyways, I saw some people discussing thrust reversers, and I couldn't see it deployed on the right engine, as seen in this image. The image isn't all that clear on that side though, so I may be wrong, but the cowling doesn't seem opened up other than from damage sustained from the crash.
Image

The more I think about it and the more I look at the videos and pictures I doubt my earlier assumption of the thrust reverser being deployed. Seems you guys are right

An
You were correct the first time. Full reverse thrust is being used on the No2 engine “it can clearly be heard in the video” you can see the sleeve deployed as the aircraft comes into view behind the emergency vehicle.

Idle thrust is selected just after the aircraft passes the emergency vehicle from the angle of the camera. The spin occurred as they lost effectiveness of the rudder, and limited or none nose wheel steering.
 
Tan Flyr
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 2:58 pm

well, once all the investigations at the site are done, somehow transfer it to a hanger..finish the paperwork for the insurance.Then remove the usable/rotable parts (maybe the engines too??)
Then cut it up and send to the local salvage yard. Sad way for a great aircraft to end her career.
 
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Boeing757100
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 3:07 pm

A320B737NGCapt wrote:
paullam wrote:
Boeing757100 wrote:

It's FLAIRPORT's snowglobe...

Anyways, I saw some people discussing thrust reversers, and I couldn't see it deployed on the right engine, as seen in this image. The image isn't all that clear on that side though, so I may be wrong, but the cowling doesn't seem opened up other than from damage sustained from the crash.
Image

The more I think about it and the more I look at the videos and pictures I doubt my earlier assumption of the thrust reverser being deployed. Seems you guys are right

An
You were correct the first time. Full reverse thrust is being used on the No2 engine “it can clearly be heard in the video” you can see the sleeve deployed as the aircraft comes into view behind the emergency vehicle.

Idle thrust is selected just after the aircraft passes the emergency vehicle from the angle of the camera. The spin occurred as they lost effectiveness of the rudder, and limited or none nose wheel steering.


The spin could have also been caused by the brakes locking up, as someone might have said upthread? Though I don't know. I usually thought that rudder isn't used as much for ground steering, I thought they used a tiller and the nosewheel, no? Though the nosewheel steering was obviously affected by the hydraulic issue, so I think the brakes might have locked up causing the turn. (I may be wrong so please correct me if I am).
 
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Boeing757100
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 3:09 pm

Tan Flyr wrote:
remove the usable/rotable parts (maybe the engines too??).



I doubt the engines would really be "usable" after that overrun. Maybe they could salvage some small parts but I doubt it.
 
LCDFlight
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 3:11 pm

SEAorPWM wrote:
Jesus... the media is having a field day with this one and they're linking it with the MU crash, of course.

:banghead:


But if you question their opinions, you are an "ignorant conspiracy theorist."
 
A320B737NGCapt
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 3:22 pm

Boeing757100 wrote:
A320B737NGCapt wrote:
paullam wrote:
The more I think about it and the more I look at the videos and pictures I doubt my earlier assumption of the thrust reverser being deployed. Seems you guys are right

An
You were correct the first time. Full reverse thrust is being used on the No2 engine “it can clearly be heard in the video” you can see the sleeve deployed as the aircraft comes into view behind the emergency vehicle.

Idle thrust is selected just after the aircraft passes the emergency vehicle from the angle of the camera. The spin occurred as they lost effectiveness of the rudder, and limited or none nose wheel steering.


The spin could have also been caused by the brakes locking up, as someone might have said upthread? Though I don't know. I usually thought that rudder isn't used as much for ground steering, I thought they used a tiller and the nosewheel, no? Though the nosewheel steering was obviously affected by the hydraulic issue, so I think the brakes might have locked up causing the turn. (I may be wrong so please correct me if I am).


Effectiveness of an aircraft’s rudder increases with speed. Slower speeds require larger inputs to get the desired effect until the point where there is not enough airflow over the rudder to have any effect. Yes the tiller is used for manoeuvring a transport aircraft on the ground, taxing, line up.
At Takeoff rudder pedals are used to steer the aircraft, as speeds increases the movement of the nose wheel decreases, and that is taken over by the rudder as speed increases. The opposite happens during landing.

Loss of hydraulics and to heavy inputs from the Pilot on alternate braking, or on accumulator presser will cause brake to lock.

I hope that helps.
 
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ER757
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 3:48 pm

smokeybandit wrote:
Well, makes unloading the cargo easier with the new rear cargo door.

Guess we could call it a "banana split" now :smile:
Sad to see one of my a.net namesake planes trashed. Glad no one was hurt
 
Blockplus
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 3:48 pm

If I remember correctly, the 757 has anti skid on each wheel for normal brakes, wheel pairs for alternate brakes.
 
lhrnue
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 4:18 pm

We've been all there after a misjudged handbrake turn .
 
gzm
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 4:33 pm


It makes me sad every time I see this picture. But why do they build airports with such traps? It’s « manoeuvre field » after all, isn’t it? It should be all-flat. That’s criminal.
 
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Thunderboltdrgn
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 4:39 pm

gzm wrote:

It makes me sad every time I see this picture. But why do they build airports with such traps? It’s « manoeuvre field » after all, isn’t it? It should be all-flat. That’s criminal.


I don't know, but perhaps due to geological geographical reasons which makes such features are necessary.
 
trnswrld
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 5:16 pm

I’ve seen multiple times in this thread where people mention brakes “locking up”. Correct me if I’m wrong, but a wheel should never lock up on a commercial airliner correct? They have advanced anti-skid systems to prevent this. So here when we see all the smoke coming from the tires I assumed that’s when the thing started to slide.
This is a completely uneducated guess from someone who has no clue about this aircrafts systems. They probably had no nose wheel steering due to the hydraulic issue, and managed to do just fine after touchdown since they still had some rudder authority at speed. Then they activated reversers (only the right side activated), that pulled them to the right and they couldn’t do anything about it and off they go. Had they not touched the reversers would they have essentially been just fine?
As mentioned earlier I didn’t think I saw the right side reverser activated, but upon further watching of videos I think I do, and you certainly hear it. Infact it sounds like heavy reverse usage.
 
CosmicCruiser
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Re: DHL 757 off runway at SJU

Fri Apr 08, 2022 5:16 pm

Redwood839 wrote:
PSU.DTW.SCE wrote:
Dumb question - but to cargo aircraft have escape slides on the L1 door, or to they just use a rope for the crew to evacuate?


Don't know the answer to that, but they were actually taken off the aircraft by firefighters using ladders. Just saw a video a few minutes ago of them coming out.[/quote

Cargo planes have escape slides L1 R1.
 
IADCA
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 5:29 pm

gzm wrote:

It makes me sad every time I see this picture. But why do they build airports with such traps? It’s « manoeuvre field » after all, isn’t it? It should be all-flat. That’s criminal.


It rains a lot in Costa Rica. The water has to go somewhere. If you build a board-flat airport, it won't even run off the runways and taxiways. Not exactly ideal for braking action. And if you need to move a lot of water, you need a big pipe or ditch. This isn't brain surgery.

I suppose the bigger question would be why drains aren't covered. The answer to that would be a couple things, most obviously cost, but also that covered drains require more maintenance because the covers help them clog. You'd be spending billions of dollars the world for negligible benefit.
 
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Nomadd
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 5:31 pm

AngMoh wrote:
Nomadd wrote:
How would you expect it to go if brakes on one side locked? Would locked wheels or wheels with properly operating brakes have more traction?


Locked wheels have less traction, properly working brakes and rotating wheels have more traction. ABS in cars is based on this principle: it reduces brake pressure on a single wheel if that wheel is locking up (rotates less than other wheels).

Sometimes. ABS on cars is also to keep all wheels braking evenly. On some surfaces, locking all four wheels is the quickest way to stop, but most people are too timid in braking, so they lock some wheels before others. Old school training was to stomp as hard as you could for emergency braking to lock all wheels simultaneously.
 
B737MAX
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 5:47 pm

gzm wrote:

It makes me sad every time I see this picture. But why do they build airports with such traps? It’s « manoeuvre field » after all, isn’t it? It should be all-flat. That’s criminal.


Flat like Funchal?
 
Redd
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:09 pm

quiet1 wrote:
Further to the discussion above about there being an evacuation slide or no slide, where is the *door*? Door 1L is an outward opening door, and the photos show just a gaping hole for the door opening.


Image
 
SEAorPWM
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:16 pm

LCDFlight wrote:
SEAorPWM wrote:
Jesus... the media is having a field day with this one and they're linking it with the MU crash, of course.

:banghead:


But if you question their opinions, you are an "ignorant conspiracy theorist."


It's probably because it has the text "Boeing" in it, and the dimwits who write and consume this crap consider the 757 an "old" plane (despite thousands of NG's, CEO's, and 772's built at the turn of the century still flying).

At this point it shouldn't be front-page news or "trending" on Google with everything else going on. Pilots were fine... we just lost a machine that can be replaced with another early 2000's 752 p-f.
 
B737MAX
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:29 pm

mcdu wrote:
Boeing757100 wrote:
Sad that a 757 just left our skies. :(

Anyway, sorry if it seems like a dumb question, but in video that an above user mentioned, I don't see thrust reversers deployed? The pilots claimed that they had failure in the left hydraulic system, which impaired the braking. But wouldn't they have been able to deploy thrust reversers? Even if they only deployed the right thrust reverser, could they have done it slowly and gradually so the asymmetric thrust isn't as much of a problem? Would they not have overran if they did that? Sorry if it seems dumb but I was just wondering.
https://twitter.com/xbmpro/status/15121 ... V7eORoTClw


On the 757 is you lose the left Hydraulic system you have to land F20. Some spoiler panels are inoperative, left thrust reverser is inoperative, nosewheel steering is inoperative. Use of differential braking is allowed and at the airport elevation and max gross weight they would have needed around 5,500’ of available runway. It should not have wound up doing a ground loop. Perhaps they had additional failures that are not know at this time.



Are you 100% sure about that, mcdu…?

Left reverser INOP with the left HYD system INOP, really?
 
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Boeing757100
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:41 pm

SEAorPWM wrote:
LCDFlight wrote:
SEAorPWM wrote:
Jesus... the media is having a field day with this one and they're linking it with the MU crash, of course.

:banghead:


But if you question their opinions, you are an "ignorant conspiracy theorist."


It's probably because it has the text "Boeing" in it, and the dimwits who write and consume this crap consider the 757 an "old" plane (despite thousands of NG's, CEO's, and 772's built at the turn of the century still flying).

At this point it shouldn't be front-page news or "trending" on Google with everything else going on. Pilots were fine... we just lost a machine that can be replaced with another early 2000's 752 p-f.



Please... What next, that AF 77W that landed few days ago was also Boeing fault? :banghead:

India delta india oscar tango sierra :roll: :roll: :roll:

A320B737NGCapt wrote:
Boeing757100 wrote:
A320B737NGCapt wrote:
An
You were correct the first time. Full reverse thrust is being used on the No2 engine “it can clearly be heard in the video” you can see the sleeve deployed as the aircraft comes into view behind the emergency vehicle.

Idle thrust is selected just after the aircraft passes the emergency vehicle from the angle of the camera. The spin occurred as they lost effectiveness of the rudder, and limited or none nose wheel steering.


The spin could have also been caused by the brakes locking up, as someone might have said upthread? Though I don't know. I usually thought that rudder isn't used as much for ground steering, I thought they used a tiller and the nosewheel, no? Though the nosewheel steering was obviously affected by the hydraulic issue, so I think the brakes might have locked up causing the turn. (I may be wrong so please correct me if I am).


Effectiveness of an aircraft’s rudder increases with speed. Slower speeds require larger inputs to get the desired effect until the point where there is not enough airflow over the rudder to have any effect. Yes the tiller is used for maneuvering a transport aircraft on the ground, taxing, line up.
At Takeoff rudder pedals are used to steer the aircraft, as speeds increases the movement of the nose wheel decreases, and that is taken over by the rudder as speed increases. The opposite happens during landing.

Loss of hydraulics and to heavy inputs from the Pilot on alternate braking, or on accumulator presser will cause brake to lock.

I hope that helps.


Thanks for the information. Do autobrake settings play a part in this or not, like an excessive setting or something? It could explain possibly the locking but I have no idea on that.
 
WayexTDI
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Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:45 pm

trnswrld wrote:
I’ve seen multiple times in this thread where people mention brakes “locking up”. Correct me if I’m wrong, but a wheel should never lock up on a commercial airliner correct? They have advanced anti-skid systems to prevent this. So here when we see all the smoke coming from the tires I assumed that’s when the thing started to slide.
This is a completely uneducated guess from someone who has no clue about this aircrafts systems. They probably had no nose wheel steering due to the hydraulic issue, and managed to do just fine after touchdown since they still had some rudder authority at speed. Then they activated reversers (only the right side activated), that pulled them to the right and they couldn’t do anything about it and off they go. Had they not touched the reversers would they have essentially been just fine?
As mentioned earlier I didn’t think I saw the right side reverser activated, but upon further watching of videos I think I do, and you certainly hear it. Infact it sounds like heavy reverse usage.

Correct, brakes on an aircraft should never lock up. However, there are several situations where this can happen, and I am sure an hydraulic failure is one of them, since ABS activation uses a lot of hydraulic fluid/pressure and an hydraulic failure usually means you are running on accumulators.
 
WayexTDI
Posts: 3027
Joined: Fri Sep 21, 2018 4:38 pm

Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:47 pm

Nomadd wrote:
AngMoh wrote:
Nomadd wrote:
How would you expect it to go if brakes on one side locked? Would locked wheels or wheels with properly operating brakes have more traction?


Locked wheels have less traction, properly working brakes and rotating wheels have more traction. ABS in cars is based on this principle: it reduces brake pressure on a single wheel if that wheel is locking up (rotates less than other wheels).

Sometimes. ABS on cars is also to keep all wheels braking evenly. On some surfaces, locking all four wheels is the quickest way to stop, but most people are too timid in braking, so they lock some wheels before others. Old school training was to stomp as hard as you could for emergency braking to lock all wheels simultaneously.

ABS on cars is mainly to still be able to control the vehicle; it's been proven again and again that braking is longer with the ABS cycling than if it wasn't (especially if you're able to keep the wheels just right before locking up).
 
WayexTDI
Posts: 3027
Joined: Fri Sep 21, 2018 4:38 pm

Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:49 pm

Boeing757100 wrote:
SEAorPWM wrote:
LCDFlight wrote:

But if you question their opinions, you are an "ignorant conspiracy theorist."


It's probably because it has the text "Boeing" in it, and the dimwits who write and consume this crap consider the 757 an "old" plane (despite thousands of NG's, CEO's, and 772's built at the turn of the century still flying).

At this point it shouldn't be front-page news or "trending" on Google with everything else going on. Pilots were fine... we just lost a machine that can be replaced with another early 2000's 752 p-f.



Please... What next, that AF 77W that landed few days ago was also Boeing fault? :banghead:

India delta india oscar tango sierra :roll: :roll: :roll:

WOW. So, you know for a fact that the AF airplane was not at fault? I hope you contacted the BEA to let them know.
Just wait until the report is out, OK?
 
SJOtoLIR
Posts: 3316
Joined: Thu Jul 19, 2007 12:41 pm

Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 6:57 pm

The rainy season is just starting in Costa Rica by now.
We're experiencing heavy rain after 02.00pm, in average.
The runway was totally dry on the DHL accident. It occurred at 10.30am, local time.
SJO has a good management of the water coming from the rain, in my view.
It sustains aircraft operations exposed to the tropical rain.
For instance, MCO is surrounded for many water sources as shown in the picture.
However, we cannot say "the airport doesn't have a proper design and it's not safe for aircraft operations."

 
SEAorPWM
Posts: 257
Joined: Fri Jun 11, 2021 8:41 pm

Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 7:08 pm

Boeing757100 wrote:
SEAorPWM wrote:
LCDFlight wrote:

But if you question their opinions, you are an "ignorant conspiracy theorist."


It's probably because it has the text "Boeing" in it, and the dimwits who write and consume this crap consider the 757 an "old" plane (despite thousands of NG's, CEO's, and 772's built at the turn of the century still flying).

At this point it shouldn't be front-page news or "trending" on Google with everything else going on. Pilots were fine... we just lost a machine that can be replaced with another early 2000's 752 p-f.



Please... What next, that AF 77W that landed few days ago was also Boeing fault? :banghead:

India delta india oscar tango sierra :roll: :roll: :roll:

A320B737NGCapt wrote:
Boeing757100 wrote:

The spin could have also been caused by the brakes locking up, as someone might have said upthread? Though I don't know. I usually thought that rudder isn't used as much for ground steering, I thought they used a tiller and the nosewheel, no? Though the nosewheel steering was obviously affected by the hydraulic issue, so I think the brakes might have locked up causing the turn. (I may be wrong so please correct me if I am).


Effectiveness of an aircraft’s rudder increases with speed. Slower speeds require larger inputs to get the desired effect until the point where there is not enough airflow over the rudder to have any effect. Yes the tiller is used for maneuvering a transport aircraft on the ground, taxing, line up.
At Takeoff rudder pedals are used to steer the aircraft, as speeds increases the movement of the nose wheel decreases, and that is taken over by the rudder as speed increases. The opposite happens during landing.

Loss of hydraulics and to heavy inputs from the Pilot on alternate braking, or on accumulator presser will cause brake to lock.

I hope that helps.


Thanks for the information. Do autobrake settings play a part in this or not, like an excessive setting or something? It could explain possibly the locking but I have no idea on that.


They've already been dragging in the MU crash and AF incident. A certain rag which is not popular in Liverpool even referenced Trump Force One's emergency landing. :roll:
 
User avatar
Boeing757100
Posts: 1021
Joined: Wed May 06, 2020 10:09 pm

Re: DHL 757 off runway at SJO

Fri Apr 08, 2022 7:48 pm

WayexTDI wrote:
Boeing757100 wrote:
SEAorPWM wrote:

It's probably because it has the text "Boeing" in it, and the dimwits who write and consume this crap consider the 757 an "old" plane (despite thousands of NG's, CEO's, and 772's built at the turn of the century still flying).

At this point it shouldn't be front-page news or "trending" on Google with everything else going on. Pilots were fine... we just lost a machine that can be replaced with another early 2000's 752 p-f.



Please... What next, that AF 77W that landed few days ago was also Boeing fault? :banghead:

India delta india oscar tango sierra :roll: :roll: :roll:

WOW. So, you know for a fact that the AF airplane was not at fault? I hope you contacted the BEA to let them know.
Just wait until the report is out, OK?


Sorry, I worded it wrong. The AF 77W could be Boeing but we don't know yet. What I meant was that the media should stop pouncing everytime a Boeing plane runs into a small hiccup by connecting unrelated incidents/accidents. I saw another poster that said the media compared MU5737, the AF 77W, this DHL plane, and even the Trump emergency landing!
Anyways, let us not derail this thread, and discuss the topic at hand. My apologies.

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