[vreihen16]

Originally Posted by M-technik-3

737-800 crash today, appears gear up and flaps looked at maybe 40% at best. Did not declare an emergency as well. Not Good.

If you are talking about the South Korea crash, the talking heads on Sky News UK showed a video and had an "aviation expert" on this morning. It was obviously a gear-up landing from the video, and the plane was still moving *real* fast when it ran out of runway to slide on and crashed into a concrete barrier at the end of the runway.

The expert said that there was a hydraulic failure due to a possible bird strike, and the plane was allegedly doing a fly-by over the runway so people on the ground could confirm that the gear was down (which at least the nose gear was not in the video).....

[V1_ROT8]

Originally Posted by M-technik-3

737-800 crash today, appears gear up and flaps looked at maybe 40% at best. Did not declare an emergency as well. Not Good.

The tail as always survives, I imagine the two crew out the 181 total souls were in rear seating area.

Aircraft was hauling down that runway and appears to be flaps 5 at most, might even be flaps 1 or up. Hard to tell from the video. The accident investigation should be interesting. The 737 has a manual means to extend the gear (gravity “free-fall” and air load) and an alternate electrical means to extend the flaps to 15. Even a complete hydraulic failure shouldn’t prevent the aircraft from being configured for a somewhat “normal” landing configuration. As a 737 pilot I’d be very interested to know what kind of situation would preclude the use of either of those backup systems.

[flybigjet]

Originally Posted by M-technik-3

737-800 crash today, appears gear up and flaps looked at maybe 40% at best. Did not declare an emergency as well. Not Good.

The tail as always survives, I imagine the two crew out the 181 total souls were in rear seating area.

LOTS of questions here--

Why were the gear up, despite manual extension ability in the cockpit? You literally don't need hydraulics to drop the gear on a Guppy when using manual extension.

Hydraulic issue? If the gear were up (and why didn't they use manual extension?), that implies loss of System A (left) hydraulics.

It looks like the left thrust reverser didn't open, but the right did. That could imply that the System A hydraulics weren't working, but then the Standby System should drive the left reverser open. Or, it may simply be the cowl being forced open due to the landing. Unable to determine from the video.

It appears that no leading edge (inboard flaps and slats) or trailing edge devices were deployed/extended. The LE and TE devices are on System B (right) hydraulics. But, the LE devices can be driven by the Standby System and the TE devices can be driven down electrically in an emergency.

Why such a long touchdown? It looks to be about two-thirds down a 9800' runway.

Even if you lost A, B and Standby hydraulics systems *and* an engine, it's still a (marginally) landable configuration. It would definitely be unfun and would take *serious* checklist discipline (and I'm assuming that they had at least 45-60 minutes of fuel remaining at the end of the flight), but it could be done by a well-trained crew.

It'll be an interesting investigation, to say the least.

The two survivors were Flight Attendant's in the tail.

R.

[V1_ROT8]

Definitely no leading or trailing edge flaps in that pic. I suppose a botched low pass could be the culprit, as vrehein16’s post suggested. However, you would think that at least the nose gear doors would be open if they were trying to verify an attempted manual extension.

[Lady Jane]

What am I looking at here: thrust reversers operating or just the cowling coming apart?

[V1_ROT8]

That is where the thrust reverser sleeve normally opens. Without the FDR data I’d say it’s impossible to know if they were selected open or ripped open from scraping the ground.

[vreihen16]

Originally Posted by V1_ROT8

Definitely no leading or trailing edge flaps in that pic. I suppose a botched low pass could be the culprit, as vrehein16’s post suggested. However, you would think that at least the nose gear doors would be open if they were trying to verify an attempted manual extension.

What's the single-engine climb performance with the thrust reversers open on a dead engine?

Would a System A hydraulic failure prevent the thrust reversers from retracting on a live engine for a go-around? Could it climb out on one engine with that engine's reversers open either fully or partially?

I hate playing armchair pilot with zero hours of flight time and no log book, but my first thought upon seeing the Sky News video was that they were doing a low pass to confirm gear down, couldn't climb out, and made a last-second decision to belly flop onto the runway.....

[V1_ROT8]

It would be very awkward and difficult (by design) to go around with a thrust reverser open. In theory one could be open, but in order to advance the thrust levers normally for a go around the thrust reverser lever located on the thrust lever must be stowed. The autorestow circuit should also keep the sleeve closed if it open uncommanded or the lever position doesn’t match the sleeve position. To answer your other question, the airplane should be able to climb adequately with 1 reverser sleeve open and that engine at idle. If for some reason the sleeve was open and the engine well above idle, which is nearly impossible to occur unintentially, then I’d imagine the airplane would be pretty difficult to control and struggle to climb.

2 additional thoughts: no way to be sure but I highly doubt they tried to go around with one engine in reverse. I obviously don’t know every airline’s procedures, but the one’s I am familiar with prohibit a go around once reverse thrust is selected. I also have some doubt that they tried to manually extend the gear. If they had, the nose gear doors should be hanging open. Something strange definitely going on here.

[M-technik-3]

I am thinking this will be a crew error. This appears to be an tragedy that could be averted. The jet touched down what appears to be very far down the runway. I'm just arm-chairing it obviously but, I hope I'm wrong.

[flybigjet]

Originally Posted by V1_ROT8

It would be very awkward and difficult (by design) to go around with a thrust reverser open. In theory one could be open, but in order to advance the thrust levers normally for a go around the thrust reverser lever located on the thrust lever must be stowed. The autorestow circuit should also keep the sleeve closed if it open uncommanded or the lever position doesn’t match the sleeve position. To answer your other question, the airplane should be able to climb adequately with 1 reverser sleeve open and that engine at idle. If for some reason the sleeve was open and the engine well above idle, which is nearly impossible to occur unintentially, then I’d imagine the airplane would be pretty difficult to control and struggle to climb.

2 additional thoughts: no way to be sure but I highly doubt they tried to go around with one engine in reverse. I obviously don’t know every airline’s procedures, but the one’s I am familiar with prohibit a go around once reverse thrust is selected. I also have some doubt that they tried to manually extend the gear. If they had, the nose gear doors should be hanging open. Something strange definitely going on here.

Yes, a deploying thrust reverser will kill you dead. But, you're not going to stay straight and level if it happens.

Reference the C-5 crash at Ramstein AB, Germany in late 1990 for a case study. Long story short, the #1 TR popped open (due to a design flaw) on takeoff. The full reverse thrust from the #1 engine killed the lift on the left wing, they rolled inverted and that was that.

We tested the scenario in the simulator shortly after it happened- if you knew it was coming? it was survivable (barely). If it was sprung on a crew with no warning? 100% kill rate.

R.

[Llarry]

The world's first turboprop-powered aircraft, the Trent Meteor E227, first flew in September of 1945.

The Gloster Meteor was originally a turbojet aircraft and the Rolls-Royce RB.50 Trent was a one-off experimental engine of 750 hp that was fitted for tests but never powered any other type of aircraft. The Trent name lives on today as a large turbofan engine.

[Llarry]

The Allison V-1710 liquid-cooled V-12 was the American engine that powered a number of important WW2 fighters like the P-38 Lightning, P-39 Airacobra and A-36/P-51A Mustang. Late in the war it was fitted to the P-82 Twin Mustang.

The Rolls-Royce V-1690 Merlin liquid-cooled V-12 was the slightly smaller UK engine that powered the Spitfire, Hurricane, Mosquito and Lancaster among many others. The Merlin was also produced in the USA and powered most P-51s starting with the P-51B model.

Here are photos of the two competitors. Both were built in huge quantities. The Allison has sections cut away to enable viewing of the innards of the engine.

[3798j]

Add in the 1947 Popular Mechanics magazine...

[Lady Jane]

Really fast and late touching down. And why a concrete barrier instead of a soft overrun section?

[flybigjet]

This got me thinking (which is a good thing in aviation) about what I'd do in a similar scenario.....

Hypothetically (and I'm NOT implying that this is what happened with the Korean crash), let's say that you take a bird strike and lose an engine, do a go-around, and then loose the second engine while maneuvering around the airport.

Somehow in all of this, both hydraulic systems fail (we'll assume the Standby System works for the sake of argument).

You're now down two engines with no hydraulics and the gear and flaps are up-- i.e. basically a glider that glides about as well as a cast iron bath tub. However, unlike most modern airplanes, the 737 can still fly without hydraulics. The 737 has "manual reversion"-- i.e. the ailerons and elevators can (believe it or not) be manually controlled with cables, the stabilizer can be manually positioned with the trim wheel, and the rudder will work with the Standby hydraulics).

Try that, Airbus.

What would you do when you literally have only a handful of minutes to figure this all out? There's NO time to "refer to checklist", so you'd have to get very creative, very fast and rely on systems knowledge, basic piloting skills and think "outside of the box".

It's an interesting thought exercise. Here's what I came up with.

(Full disclosure: I tried this in a C-5 sim years ago-- although I was able to keep (barely) enough hydraulics to move some of the flight controls since in a C-5 with no hydraulics, you're simply dead. I was four-engines out, about 2000' and about 6 miles from the runway, iirc. I successfully dead-sticked it into the landing zone and stopped on the runway so that's the experience I'm basing this off of, modified for the Guppy).

I'm listing the steps in order but realistically, everything would sort of happen almost at the same time.

1. Immediately fire up the APU and get it on the electrical busses. With the engine-driven generators dead, you'd be down to battery power only-- having full electrics will only help and that's one less thing to worry about. APU start would take less than a minute.

2. Turn towards the longest piece of runway that you feel you can reasonably make. Speed is life, so I'd try to manage my energy as best I could, using runway threshold next to the overrun of the selected runway as my target (I know I'm going to be faster than hell with very little ability to stop, so I'm going to aim at "brick one" to compensate for that. And, if I have to land short, I've got the overrun). I'll try to keep about 210 knots initially and slowly trade altitude for airspeed. Stall the jet now and you're dead. Gear will give drag, but getting leading and/or trailing devices out will help with lift. A lot of this would have to be TLAR (that looks about right), eyeballing and using seat of the pants flying to manage energy state in relation to the selected touchdown target.

2. Direct the copilot to turn on both Standby Rudder switches-- this would arm the Standby Hydraulic system and give rudder, thrust reversers (not that they're any help with both engines out), and leading edge devices (flaps & slats). Unfortunately, there's no way to get flight or ground spoilers back.

3. Next, have the copilot drop the gear manually. Manual gear extension in a 737 is *literally* pulling three cables that are directly connected to the gear uplocks. You open a door in the floor (you can reach it from either pilot seat, but it's easier from copilot's seat), pull each cable individually, and the gear will drop via gravity and the overcenter's will lock mechanically-- no hydraulics or electrics required.

4. Next, have the copilot arm the Alternate Flaps switch and immediately toggle the drive switch down-- this would drive out the leading edge flaps and slats hydraulically and start giving lift with essentially no drag (i.e. Flaps 1)-- then you can then start slowing down to about 190 knots to compensate for the drag of the gear.

5. Finally, have the copilot start driving down the trailing edge flaps using the Alternate Flaps system-- it's electric, so it's slow- but at least lift devices are coming out-- every degree would help. You'd have a F15 speed immediately available on the landing page of the FMC, so no math needed. As a wag, for a 150,000 lb -800, F15 Reference is 159 knots.

6. Announce "Brace, Brace, Brace" to the cabin over the PA. That will trigger the Flight Attendants that Something Bad is going down and to do what they can to prepare the passengers.

7. Announce to Tower that we're a) an Emergency, b) we're landing NOW on Runway X and c) to roll Crash Fire Rescue--- even a minute or two or warning might save lives once we touch down.

8. From this point on, all the cards are on the table-- it would be down to pure pilotage and playing the descent rate and airspeed to try to hit the target zone-- the only real tools you'd have to help with this would be s-turns or sideslip/cross-control if you had to lose energy. I'd attempt to touch down about 150 knots (if I possibly could) as close to the arrival end of the runway as I could manage (although that's going to be energy dependent). The jet wouldn't have any flight or ground spoilers and no engine reversers-- stopping ability would depend entirely on wheel brakes using accumulator pressure.

As a last ditch effort, the only other thing I could think of would be to use differential braking and/or rudder steering (above 60 knots or so) to attempt to steer the jet away from that berm if I knew I was going off the end of the runway.

Anyhow, like I said-- it's an interesting thought/chair-fly exercise that made me go look up and refresh myself on how a few things work on the Guppy. More knowledge is always good, so it wasn't a complete waste of time.

YMMV.

R.

[vreihen16]

Originally Posted by Lady Jane

Really fast and late touching down. And why a concrete barrier instead of a soft overrun section?

If you look at Google Maps street view of the airport, the entire perimeter is surrounded by concrete walls topped with barbed wire with several elevated guard towers along those walls. My guess is that it is/was a military base at some time, or else they are trying to secure it from invasion because it is along the coast and they have a pesky neighbor to the north.

Beyond the runway in that direction is a bunch of beach resorts/hotels, and then a huge bay. Nothing that a plane with any ability whatsoever to climb would have not been able to clear. At the speed that the plane was moving when it impacted the concrete wall, it would probably have kept sliding into the neighborhood like it was on skis and killed even more people if there was no wall and with a gravel trap at the end of that runway.

I saw a later news report claiming that the plane was initially trying to land on that runway south-to-north into the wind, and for some reason wound up landing north-to-south. The tower said that the flight crew called "Mayday, mayday, mayday. Bird strike, bird strike" before the crash.

There was also a report this morning that the South Korean government issued orders for airlines to mechanically inspect all 737's but the news didn't say what they were looking for.....

[vreihen16]

Originally Posted by flybigjet

What would you do when you literally have only a handful of minutes to figure this all out? There's NO time to "refer to checklist", so you'd have to get very creative, very fast and rely on systems knowledge, basic piloting skills and think "outside of the box".

How about taking this hypothetical emergency timeline down to seconds instead of minutes? Bird strike on approach takes out one engine, go-around to the opposite direction, and then another bird takes out the remaining engine about 30 seconds before touchdown. Is 30 seconds with no checklist enough time to realize what happened, go fishing in the floor for the emergency gear drop cables, manually set whatever flaps can still move, and reduce speed enough with a tailwind to make a controlled gliding touchdown? Is a belly flop halfway down the runway at high speed trying to keep the wing tips out of the dirt and nose straight to avoid a cartwheel the only plausible option if they didn't have enough speed left to glide another 3/4 miles to splash it in the bay?

I'm looking at this from a motorsports safety steward perspective, and have read several accounts of the Gimli Glider 767 dropping into the race course by surprise.....

[ezaircon4jc]

Originally Posted by flybigjet

This got me thinking (which is a good thing in aviation) about what I'd do in a similar scenario.....

Hypothetically (and I'm NOT implying that this is what happened with the Korean crash), let's say that you take a bird strike and lose an engine, do a go-around, and then loose the second engine while maneuvering around the airport.

Somehow in all of this, both hydraulic systems fail (we'll assume the Standby System works for the sake of argument).

You're now down two engines with no hydraulics and the gear and flaps are up-- i.e. basically a glider that glides about as well as a cast iron bath tub. However, unlike most modern airplanes, the 737 can still fly without hydraulics. The 737 has "manual reversion"-- i.e. the ailerons and elevators can (believe it or not) be manually controlled with cables, the stabilizer can be manually positioned with the trim wheel, and the rudder will work with the Standby hydraulics).

Try that, Airbus.

What would you do when you literally have only a handful of minutes to figure this all out? There's NO time to "refer to checklist", so you'd have to get very creative, very fast and rely on systems knowledge, basic piloting skills and think "outside of the box".

It's an interesting thought exercise. Here's what I came up with.

(Full disclosure: I tried this in a C-5 sim years ago-- although I was able to keep (barely) enough hydraulics to move some of the flight controls since in a C-5 with no hydraulics, you're simply dead. I was four-engines out, about 2000' and about 6 miles from the runway, iirc. I successfully dead-sticked it into the landing zone and stopped on the runway so that's the experience I'm basing this off of, modified for the Guppy).

I'm listing the steps in order but realistically, everything would sort of happen almost at the same time.

1. Immediately fire up the APU and get it on the electrical busses. With the engine-driven generators dead, you'd be down to battery power only-- having full electrics will only help and that's one less thing to worry about. APU start would take less than a minute.

2. Turn towards the longest piece of runway that you feel you can reasonably make. Speed is life, so I'd try to manage my energy as best I could, using runway threshold next to the overrun of the selected runway as my target (I know I'm going to be faster than hell with very little ability to stop, so I'm going to aim at "brick one" to compensate for that. And, if I have to land short, I've got the overrun). I'll try to keep about 210 knots initially and slowly trade altitude for airspeed. Stall the jet now and you're dead. Gear will give drag, but getting leading and/or trailing devices out will help with lift. A lot of this would have to be TLAR (that looks about right), eyeballing and using seat of the pants flying to manage energy state in relation to the selected touchdown target.

2. Direct the copilot to turn on both Standby Rudder switches-- this would arm the Standby Hydraulic system and give rudder, thrust reversers (not that they're any help with both engines out), and leading edge devices (flaps & slats). Unfortunately, there's no way to get flight or ground spoilers back.

3. Next, have the copilot drop the gear manually. Manual gear extension in a 737 is *literally* pulling three cables that are directly connected to the gear uplocks. You open a door in the floor (you can reach it from either pilot seat, but it's easier from copilot's seat), pull each cable individually, and the gear will drop via gravity and the overcenter's will lock mechanically-- no hydraulics or electrics required.

4. Next, have the copilot arm the Alternate Flaps switch and immediately toggle the drive switch down-- this would drive out the leading edge flaps and slats hydraulically and start giving lift with essentially no drag (i.e. Flaps 1)-- then you can then start slowing down to about 190 knots to compensate for the drag of the gear.

5. Finally, have the copilot start driving down the trailing edge flaps using the Alternate Flaps system-- it's electric, so it's slow- but at least lift devices are coming out-- every degree would help. You'd have a F15 speed immediately available on the landing page of the FMC, so no math needed. As a wag, for a 150,000 lb -800, F15 Reference is 159 knots.

6. Announce "Brace, Brace, Brace" to the cabin over the PA. That will trigger the Flight Attendants that Something Bad is going down and to do what they can to prepare the passengers.

7. Announce to Tower that we're a) an Emergency, b) we're landing NOW on Runway X and c) to roll Crash Fire Rescue--- even a minute or two or warning might save lives once we touch down.

8. From this point on, all the cards are on the table-- it would be down to pure pilotage and playing the descent rate and airspeed to try to hit the target zone-- the only real tools you'd have to help with this would be s-turns or sideslip/cross-control if you had to lose energy. I'd attempt to touch down about 150 knots (if I possibly could) as close to the arrival end of the runway as I could manage (although that's going to be energy dependent). The jet wouldn't have any flight or ground spoilers and no engine reversers-- stopping ability would depend entirely on wheel brakes using accumulator pressure.

As a last ditch effort, the only other thing I could think of would be to use differential braking and/or rudder steering (above 60 knots or so) to attempt to steer the jet away from that berm if I knew I was going off the end of the runway.

Anyhow, like I said-- it's an interesting thought/chair-fly exercise that made me go look up and refresh myself on how a few things work on the Guppy. More knowledge is always good, so it wasn't a complete waste of time.

YMMV.

R.

Wouldn't you want to do #7 first? That allows us to get everyone out of your way and the equipment rolling. Waiting could cause other issues, unless you're many miles from the concrete. Takes time to get other traffic out of your way and you're pretty much a ballistic missile headed toward the airport. Just a thought having delt with many, many emergencies (almost including the ASA Super-80 that went down about 35 miles west of LAX).

[flybigjet]

Originally Posted by ezaircon4jc

Wouldn't you want to do #7 first? That allows us to get everyone out of your way and the equipment rolling. Waiting could cause other issues, unless you're many miles from the concrete. Takes time to get other traffic out of your way and you're pretty much a ballistic missile headed toward the airport. Just a thought having delt with many, many emergencies (almost including the ASA Super-80 that went down about 35 miles west of LAX).

Like I stated, everything would more or less happen at the same time, but yes, I'd try to pickle off a radio call when I had a (literal) spare second.

The rule is "Aviate, Navigate, Communicate"-- the guys on the ground can't really immediately do much for me from a "flying the no-engine jet that's very definitely going to hit the ground" standpoint. Getting other traffic out of the way is a consideration, but in this situation, you'd have so much happening at once, trying Not to Die wold be Priority One and I'd be willing to go with "Big Sky, Little Airplane". Besides-- you already would have declared an emergency at some point if you had gone around due to a bird strike and subsequent loss of an engine. I'd take a leap of faith that Tower was watching me attempt an opposite direction landing and that they'd get any arrival traffic to that runway out of my way.

I look at it as "Which alligator is nearest the boat?" And remember, you're stressed, trying to hold back terror and rely on your training, dealing with something that's NOT in any book, with warning horns, caution and warning lights and all sorts of other distractors showing up in almost random order-- and this is all over the deafening sound of no thrust.

I NEED to get the jet from wherever I am to the ground-- and I suddenly have one hell of a countdown timer going-- THAT's my immediate priority.

That means that I have a very, very finite bucket of energy (defined as altitude and airspeed) that a) I can't refill, b) has a whole bunch of holes in the bottom and c) is emptying at a variable and unknowable rate. Think of it as a physics equation with potential energy (altitude) and kinetic energy (airspeed)-- you can trade one for the other, but there are consequences and limitations for every trade you make. Make too many trades too soon and you die. You don't want to stall (giving up too much airspeed) and you are going to hit the ground within a very specific (but unknown) distance (based on altitude)-- if the runway threshold isn't in that distance, you die. You would *immediately* have to start managing your energy and manage the trades by putting down gear (hurts you) and extending flaps and slats (helps you). In a perfect world, you'd hit the runway at a controllable airspeed. Every. Single. Thing. You. Do. is going to cost you energy (including manipulating the flight controls using Manual Reversion)-- managing that is my absolute and sole priority to start, because if I don't? Nothing else matters.

I need to get the jet into a landable configuration-- which means gear, leading edge devices and flaps. That takes time and switch/control manipulation. If the Captain is using every trick he can think of to stay in the air, the Copilot is going to be very, very, very busy trying to start the APU, drop the gear, get the Standby Hydraulics online, get the leading edge devices moving, getting the trailing edge devices moving (on this last one, the switch is spring-loaded and over the captain's head-- the copilot is going to have to be reaching cross-cockpit and up to hold it in position while watching the flap gauge) as well as possibly rolling the stabilizer trim wheel at the captain's command. Additionally, you're going to have to decide on the fly when to put out trailing edge devices, based on how much energy you have-- and all of this is going to have to be by the seat of your pants.

Somewhere in there-- yes, you'd tell the Flight Attendants to "Brace Brace Brace" over the PA and tell tower that you need Crash Fire Rescue-- my list wasn't necessarily "in order" since you'd do those two when you had a literal second to spare and an extra hand to grab the PA or the mike switch.

TIME and ENERGY is your problem here-- work through those first.

If I had more *time* there are obviously other considerations-- reference checklists, talk to outside experts, possibly attempt an engine start, etc. But in this scenario, the clock is ticking and you have to prioritize what's going to kill you first and what might keep you alive.

R.

[Lady Jane]

Originally Posted by flybigjet

If I had more *time* there are obviously other considerations-- reference checklists, talk to outside experts, possibly attempt an engine start, etc.

R.

Or go on-line and ask advice from internet video game pilots. You're my hero.

[vreihen16]

Here's the Google Maps link for the south end of the airport:

https://www.google.com/maps/place/34°58'38.9"N+126°22'58.6"E/@34.97747,126.3822735,339m/data=!3m2!1e3!4b1!4m4!3m3!8m2!3d34.97747!4d126.382 946!5m1!1e1?authuser=1&entry=ttu&g_ep=EgoyMDI0MTIx MS4wIKXMDSoASAFQAw%3D%3D

If you look at the street view, you can see the tall concrete walls and guard towers around the perimeter.

From looking at the runway pavement, it appears from the different pavement colors that both ends were extended at some point which took away more of the runoff space.....

[Lady Jane]

Now for something different: The Lippisch P-Planes.

https://en.wikipedia.org/wiki/Lippisch_P.13a