Boeing 737 Cargo Plane Ditches off Honolulu

[berkeman]

Yikes, this was a lot harder ditch/landing than I initially thought from the first reports. I thought they came in for the ditch with landing lights on so the pilot could judge the touchdown, but apparently with both engines off they had no lights (the APU can't power the landing lights?). No wonder the injuries to the pilot and co-pilot were so severe. I hope they both survive, although the one in critical condition sounds dicey...

https://abc7news.com/2-pilots-alive-after-plane-crashes-near-hawaii/10853475/

One pilot, a 58-year-old man, was hospitalized in critical condition, according to the Honolulu Fire Department.

The second pilot, who is 50, suffered a head injury and multiple lacerations, and was hospitalized in serious condition, according to Honolulu EMS.

The U.S. Coast Guard arrived at the scene of the crash within minutes of the call to them, but roughly an hour after the crash, the agency said.

The Coast Guard said rescuers were dealing with 17 mph winds, and even with night vision goggles it was extremely dark. By the time they arrived, there was a large oil slick in the water and lots of debris around the crash site.

At that time, they saw one of the cargo plane's pilots on the tip of the downed air plane waving his hands, and the other pilot bobbing in the ocean on a cargo load.

The Coast Guard said the intention was to rescue the pilot floating on the cargo first, but within seconds the tail of the plane began to disappear so they deployed a rescue swimmer to help the pilot who had been on the tail."It is extraordinary that both of the pilots survived this, because it was the middle that night," said ABC News contributor and retired Marine Col. Steve Ganyard. "They were trying to ditch with no engines and no lights ... not [able] see the tops of the waves."

 

[russ_watters]

Yikes, this was a lot harder ditch/landing than I initially thought from the first reports. I thought they came in for the ditch with landing lights on so the pilot could judge the touchdown, but apparently with both engines off they had no lights (the APU can't power the landing lights?).

If memory serves from The Miracle on the Hudson, that wasn't on any of the relevant checklists, and Sully elected to do it on his own. Not sure if the checklists have changed...

But yeah, it's hard enough to land on a calm river in the daytime.

 

[anorlunda]

The U.S. Coast Guard arrived at the scene of the crash within minutes of the call to them, but roughly an hour after the crash, the agency said.

That's odd. The ABC news report said that the pilots asked for the Coast Guard before they ditched. Why the hour delay?

 

[berkeman]

Helicopters be slow...

 

[nsaspook]

https://www.hawaiinewsnow.com/2021/...ases-video-cargo-plane-crash-rescue-off-oahu/

WATCH: Coast Guard video shows dramatic rescue of pilots after cargo plane crash​

 

[DaveE]

Helicopters be slow...

Yes, and in aviation and SAR work, sometimes you are better off not rushing out too fast. SOPs are good. SAR rule #1: don't add your name to the list of victims.

I also think that old phrase "work smarter, not harder" may come into play. The pacific ocean is a big place. The goal isn't to search, it's to find and rescue.

None of us are in a position to know how fast these guys should have been.

 

[anorlunda]

The U.S. Coast Guard arrived at the scene of the crash within minutes of the call to them, but roughly an hour after the crash, the agency said.

I think this part of the reporting is just wrong. The VASA transcript of the radio traffic (below) shows that the CG was called even before the plane crashed. There was no hour delay before notifying the CG.

The cause of the engine failures is not obvious. It doesn't sound like bird strikes. Since the pilots elected to use a long checklist rather than an immediate return, it suggests that they expected the 2nd engine to continue working. They were wrong about that and they got caught by surprise too far away from the airport to glide back.

The results of the investigation will be interesting to read.

 

[nsaspook]

 

[Astronuc]

They probably could have made Kalaeloa, if they had requested or were informed earlier. But the runways at Kalaeloa seem shorter.

Boeing/airlines will have to think about how an aircraft functions with loss of two engines. All critical equipment that needs electrical power should receive power from the APU. Then again, I've seen cases where the APU has been out of service.

Aircraft N810TA, Boeing 737-275C(A), First flight July 23, 1975, almost 46 years old! Engines 2x PW JT8D-9A

 

[anorlunda]

They probably could have made Kalaeloa, if they had requested or were informed earlier. But the runways at Kalaeloa seem shorter.

Much better than Kelaeloa, they could have stayed within gliding range of their takeoff runway the whole time. They declared an emergency early, so the controllers would have kept everyone else away if requested. I think they trusted that the 2nd engine would not fail.

Deploying the APU creates more drag and thus reduces your gliding radius. Your strategy when gliding at low altitude is very different than when powered or when gliding at ample altitude.

 

[Astronuc]

I think they trusted that the 2nd engine would not fail.

The audio recording indicated that they were expecting to lose the second engine (it was running hot). The reports indicated both engines had failed before the crash. The aircraft was at 2000 ft, and not much elevation for distance.

 

[anorlunda]

The audio recording indicated that they were expecting to lose the second engine (it was running hot).

Yes, but look at their position when they reported that. They were too far away and too low to glide back by the time they reported trouble with the second engine. They could have stayed within a mile or two of the runway the whole time, but they chose not to.

 

[Astronuc]

Yes, but look at their position when they reported that. They were too far away and too low to glide back by the time they reported trouble with the second engine. They could have stayed within a mile or two of the runway the whole time, but they chose not to.

Ok, I understand you point now. I was thinking about where they turned. The pilot does mention delaying the turn back while they do their checklist.

 

[anorlunda]

All pilots are schooled on their three priorities which they must never forget. 1-Aviate, 2-navigate, 3-communicate. Use checklists doesn't appear as one of the priorities; perhaps it should be. There have been several crashes where the pilots focused on emergency procedure checklists to the exclusion of aviate/navigate/communicate.

Cockpit resource management dictates delegation of tasks. One should aviate/navigate/communicate while the 2nd pilot does other important things.

In December of 1972, Eastern Airlines Flight 401, ferociously collided with the Florida Everglades. The plane was an L-1011-1 Tristar jumbo jet, which marked the first crash of a widebody aircraft. Reports claimed that the entire crew was busy attending to a faulty light bulb, and they were completely oblivious to the fact they were rapidly falling in altitude.

 

[DaveE]

Deploying the APU creates more drag and thus reduces your gliding radius.

I think you're confusing this with a RAT. The APU is a small gas turbine generator that has essentially no additional drag. However, the pilot would have to turn it on.

 

[Vanadium 50]

I think they trusted that the 2nd engine would not fail.

Boeing/airlines will have to think about how an aircraft functions with loss of two engines

This is very, very rare. This has happened, as far as I can tell, five times with the 737. Two were double-flameouts in thunderstorms (one as the plane was about to touch down). One was running out of fuel. One was a famous double bird strike (US1549) and one was pilot error: one engine failed and the crew shut down the other one by mistake.

This is over 184 million flights. It's a 3 x 10^-8 problem. It's not surprising that the pilots worked the "what to do when you lose one engine" problem first. Put another way, the frequency of a double-engine loss per aircraft is once per 7000 years or so.

 

[DaveE]

Boeing/airlines will have to think about how an aircraft functions with loss of two engines.

They do put a lot of thought into this, that's one reason there's an APU. However, there is a limit to what you can do with an airplane with no engines. Also, remember that the 737-200 was designed in the mid-1960's.

 

[russ_watters]

All pilots are schooled on their three priorities which they must never forget. 1-Aviate, 2-navigate, 3-communicate. Use checklists doesn't appear as one of the priorities; perhaps it should be.

I’m about a month from my private pilot checkride. Some expansion/clarification: ABC is always overriding, but specific circumstances carry additional requirements, including checklists.

In a small/single engine plane engine failure, you have:

A - Airpeed for best glide ratio
B - [identify]Best place to land
C - Checkists; memory items first, more detailed ones as the situation permits.
D - Declare an emergency
E - Execute the landing

Obviously the specifics of the situation dictate the specific approach. I agree that at least it would be good to stay close to the airport.

https://studentpilotnews.com/2019/04/22/if-faced-with-an-engine-failure-remember-your-abcs/

Dual engine failures often have a common cause. It will be interesting to see what this one was.

 

[anorlunda]

C - Checkists; memory items first, more detailed ones as the situation permits.

Situation permitting is the key. One obvious situation not permitting is when you meet the ground before finishing reading the checklist.

I assume that the VASA transcript is real time.

• At 0:26 in the VASA transcript, Flight 810 was cleared for takeoff.
• At 0:36 in the VASA transcript, Flight 810 said, "We'll have to return."
• For more than a minute, it sounded like the controller did not hear 810's transmissions, and also confused 810 with the inbound flight 809.
• At 1:50 in the VASA transcript, the controller cleared 810 to return to the airport. Flight 810's reply was, "We are going to have to run some checklists, if we could get delay vectors..."
• At 3:17 in the VASA transcript, the pilot asked to return to the airport, and said that they no longer had the airport in sight.
• At 3:42 in the VASA transcript, Flight 810 said, "We might lose the other engine as well."

So they spent at least 87 seconds on the checklist, all the while heading out to sea away from the safe landing site at the airport, and eventually out of visual range of the airport. I am not trying to suggest that the pilots were in error. Only the NTSB can pronounce the final cause.

With only 10 seconds between takeoff clearance and the pilot's call to return, it sounds like the first engine failed during or immediately after takeoff.

 

[Vanadium 50]

Since the pilots elected to use a long checklist rather than an immediate return

It appears that the checklist was the one for landing a 737 on one engine. Things like turning on the APU. Also, if you listen to the ATC, this event really did not unfold in a whole lot of time.

 

[berkeman]

I'm guessing that turning on the APU will be moved up in the 1-engine checklist now when it is dark. Landing in the water or on land in the total dark versus with landing lights on seems very problematic.

 

[Vanadium 50]

I'm guessing that turning on the APU will be moved up in the 1-engine checklist now when it is dark

Maybe. Maybe not. One needs to keep in mind that 99.5% of the time losing one engine does not cause loss of the second, but does lead to a safe landing. You don't want to make changes to improve the 0.5% and in the process make the 99.5% worse.

 

[Vanadium 50]

It's really astonishing that if you lose an engine, your odds of survival are still ~99.8%. (99.5% you keep the other engine, and even if both are lost, the survival rate seems to be over 50%)

It's hard to imagine independently losing two engines.

I was looking up NTSB reports of double engine losses, and found one due to fuel contamination. UA310 LAX-DEN on 19 August 1983 lost power in both engines "the inability of the engines to accelerate after the manually induced surge was due to contaminated fuel nozzles [emphasis mine] which significantly reduced combustion chamber efficiencies & which resulted in a subidle stall."

The same plane experienced a double flameout 2-1/2 years later, apparently due to pilot error.

Jet engines will burn pretty much anything that can burn. I suspect that "fuel contamination" really means "fuel filter clogged by contaminants".

 

[anorlunda]

Out of fuel is another reason. It applies regardless of how many engines you have.

Of course all common mode multiple failures are not statistically independent events, so the usual way to compute probabilities doesn't apply. Nor are they reported as multiple engine failures.

High AOA can also stall all engines. Faulty maintenance can also be a common mode failures.Once in the UK, the right engine failed, but the pilot mistakenly shut down the left engine. Not a multiple engine failure.

IMO in this case in Hawaii, the probability of a common mode cause (like bird strikes) is high

 

[Vanadium 50]

Once in the UK, the right engine failed, but the pilot mistakenly shut down the left engine. Not a multiple engine failure.

I included that one.

IMO in this case in Hawaii, the probability of a common mode cause (like bird strikes) is high

I can't think of any large birds native to Oahu. There is the nene, of course, but not so many on Oahu. They're also more walkers than flyers. I won't say this is imposible, but not the first thing to come to mind.

 

[anorlunda]

https://www.travelandleisure.com/travel-tips/responsible-travel/hawaii-largest-protected-area

Debris on the runway is another possible common cause. We can probably think of several other common causes.

 

[Vanadium 50]

Look at all the targets!

Thing is, this isn't anywhere near Oahu. I'm not arguing that there were two independent failures - that's ridiculously improbable - just that a flock of birds is not high on my list of likely culprits. Debris is certainly one possibility. Engine damage of some sort on the inbound that worsened when the engines were powered down is a possibility. My favorite at the moment is fuel contamination of some sort. The Oracle of Google tells me there have been three incidents involving DEF contamination in jet fuel.

 

[berkeman]

I haven't been keeping up -- did they locate the plane on the bottom and have they recovered the data recording boxes?

 

[berkeman]

I did a quick Google search, and it looks like they are working on the recovery...

 

[Vanadium 50]

The water is quite deep - a few hundred feet. (I know...Pearl Harbor would be a swell place to put a Navy base) It may take some specialized gear.

 

[russ_watters]

Jet engines will burn pretty much anything that can burn. I suspect that "fuel contamination" really means "fuel filter clogged by contaminants".

Water is a common contaminant.

 

[anorlunda]

They said the second engine was overheating. Does anyone know what makes a jet engine overheat?

 

[Vanadium 50]

Oil starvation.

 

[gmax137]

Do the engines share a common fuel supply? or does each have its own tank(s)?

 

[anorlunda]

Do the engines share a common fuel supply? or does each have its own tank(s)?

Typically, each engine has its own tank. There is a valve that can be opened to transfer from one tank to the other, but that valve is normally closed.

But both tanks may have been filled from a common source.

In searching for a common cause, I would skip all possibilities that do not lead to engine overheating. But the term overheating is not precise. EGT, exhaust gas temperature is my first guess, but there can be other temperature sensors on the engines.

Below is some discussion from another site. It suggests that internal damage can cause high EGT. That would make high EGT a secondary effect, not the primary one.

https://www.airliners.net/forum/viewtopic.php?t=762413
high EGT is due to high fuel flow. As an engine gets older the fuel flow and EGT will increase as the compressors and turbines get worn and have to work harder to do the job. I have seen over 50degC different EGT between two engines on the same aircraft, due to age. So you need to boroscope the engine to check the complete gas path for damage, not only blades and NGVs, but also the inside of the combuster for damage.. Take out the burners and check they are clean, they easily get clogged with carbon.