Pilot Explains: Boeing 737 Japan Airlines "PLUNGES" Suddenly | Flight JL8696

Japanese airline JL8696

plunges after sudden descent. As you can

see, the news company sharing the viral

clips of this company uh or of the

footage of these oxygen masks down here.

You can see some more of that. Uh the

headlines are that the aircraft diverted

because it was plunging out of the sky.

And so a lot of people have been

wondering, hey, like how serious is this

actually? And as a jet pilot, I'd like

to give you my point of view. First,

let's start with some of the facts. Uh

first what we have is the flight tracker

data which shows us here uh we were uh

originally departing uh the Shanghai PVG

airport ended up making an emergency

landing at KIX that's the Osaka airport

in Japan. Uh this was the flight path

here. So we're mostly uh above water

here. And then of course when the

descent started, if we uh if we go to

our timeline here and play our timeline.

Oops, timeline doesn't want to come up.

There we go. Uh we can play our time

line here, we can see at about 10:55 or

so is when we started seeing a descent.

Uh now again, a lot of news companies

calling this a sudden rapid descent or a

plunge. And when we take a peek at what

we see here, we find that the airline

offered 15,000 Japanese yen or $93 in

compensation to people who were diverted

in this flight because of the emergency

landing. No reports of injuries.

Apparently, there were signals

indicating abnormal behavior in the

plane's pressurization system. And uh

the aircraft bound for Narita, Japan

from Shanghai made an emergency landing

at uh the Osaka airport. Uh no quote

physical discomfort. This is probably a

poor translation here from Global Times.

Has been reported amongst passengers or

crew. The aircraft made an emergency

landing uh and apparently operates by

the or was operated by the Japanese

Airlines

lowcost subsidiary Spring Japan.

Uh and the notice also stated that

passengers affected by the cancellation

may opt for a free rebooking. So

basically you have a situation where the

oxygen masks deploy and the aircraft

starts rapidly descending. Now, what's

remarkable is they say that around uh

6:53 p.m. local time, the flight

suffered a drop in cabin pressure. Now,

on one of the other articles, we hear

that there were flight indication

errors. Here, it says the aircraft

suffered a drop in cabin pressure. So,

it's unclear if this was a sensing error

or if this was some form of actual loss

of cabin pressure. But the plane was

forced to descend rapidly from 36,000 ft

to just under 10,500 ft in 10 minutes.

And so, as a pilot, I'd like to give you

a heads up on how scary this actually

is. It's not. That actually sounds like

a completely normal descent rate of

about 25,000 ft in 10 minutes, which is

about 2500 ft per minute. Super normal

descent rate. Uh, and so this to me does

not even sound like an emergency

descent. As a pilot, when when we fly an

aircraft and we have a rapid

decompression, which is most dangerous

above 40,000 ft. I'll explain that in

just a moment. Uh, typically we have

every aircraft obviously different, but

most emergency procedures are relatively

the same. Landing gear down. Once you're

below your landing gear speed, speed

speed breaks out and and you're really

pulling the throttle idle and you're

pitching the nose over and your goal is

to get down really rapidly in in an

actual decompression or cabin uh

altitude loss. The reason for that is

the oxygen is so thin at higher

altitudes that anything above 12,500 ft,

the air is really too thin for you to

breathe continuously with you staying

conscious. So, your blood oxygen is

really going to start falling pretty

rapidly once you're over 12,500 ft.

Usually for pilots, passengers, they say

14,000 because they're maybe less

critical and the little wooziness that

you might feel is less important as a

passenger. Uh, but when you're flying at

30 to 40,000 ft, the pilots usually only

have about 30 seconds in the event of a

rapid decompression to dawn their oxygen

masks to make sure that they don't go

unconscious. Now, where this becomes

really dangerous is actually in the 40

to 45,000 ft altitude. Now, what we can

see is this aircraft was actually flying

at right here at about 37,000 ft. It

looks like it started to climb towards

about 39,000 ft. However, then started

descending. So, as they were potentially

getting to their final cruise altitude

of potentially 40,000 ft, uh maybe there

was a sensing error or software error or

something, uh or or potentially there

was a sudden drop in cabin pressure

which would lead the uh um the oxygen

mass to fall in the cabin as well, which

is obviously a scary occurrence for

people to see that. But the plane

descended at a relatively

stable descent rate of about 2500 ft per

minute. In fact, you can see that the

descent rate is pretty consistent, which

is usually not what you would find in a

handflown panic sort of descent rate

where this descent rate would be a

little bit more erratic. This graph

would be less uh you know, the first

derivative here would be a little bit

more of a volatile graph uh of the

changes in your descent rate. So 2500

feet per minute to me sort of indicates

they probably had some form of a sensor

fail. Decided, you know what, let's make

a diversion. Let's put our oxygen masks

on. Let's follow our procedures for

decompression, but let's descend to a

safe altitude. Typically, your emergency

descent is going to drop you to your

MSA, your minimum safe altitude, or

10,000 ft. Some aircraft will actually

automatically take you to 15,000 ft. So,

for example, the Phenom 300E, the 21

model that I fly, it actually has what's

called an emergency descent feature

built into it to where if we're at

flying at 45,000 ft and we suffer a

rapid decompression, we might not

actually have enough time to to have

both pilots get their masks on

technically at 45,000 ft. pilots should

already have like at least one pilot

should have their mask on because of

this because you only get about seven

seconds to put your mask on at 45,000

feet before all of a sudden you're out

of oxygen which is pretty scary. So at

45,000 ft the rush to get your mask on

is you again you've got 5 to 8 seconds

of useful consciousness just because the

air literally gets pressed out of your

gut. You're like and like the air is

gone and if you don't get a mask on

rapidly you're screwed.

That's less of a problem at where

commercial airliners fly at about 35 to

40,000 feet. But this aircraft has the

emergency descent mode, EDM, where uh if

there's a rapid decompression, it'll

actually drop you uh uh it'll it'll

generally it turns you 90° and then sets

your descent to bring you down to 15,000

ft. Sets your altitude for 15,000 ft and

descends you. If you don't have autole

throttles though, you've got to set the

throttles otherwise it'll, you know,

have some pitch mode problems to

actually get you down. And it doesn't

put the gear down either for you, which

usually we put the gear down to to uh to

maximize how quickly we can descend

because it creates so much drag that it

actually slows us down, which is what

you want. If you want to emergency

descent, you just point down, throw the

gear down, speed breaks out. Once you're

at speeds able for the gear to be put

down, you generally descend about 250

knots, you know, on your indicated and

you can spiral down really fast

somewhere between 6 to 8,000 ft per

minute would be a usual emergency

descent. I've done it in this aircraft

before. Uh, and it's really

uncomfortable for passengers, but a 2500

ft per minute descent rate is not that

big of a deal. So to me, this was

probably an aircraft of that had some

kind of sensing issue or maybe there was

some sort of uh low pressurization fail.

Uh emergency mass probably deployed more

as a precaution. Uh the oxygen,

you know, if there was really a lack of

oxygen here, we would have seen a

substantially greater descent rate. And

so I actually don't see this as that big

of a deal. Usually we we do get

concerned about these, you know, rapid

decompressions because they can be very

dangerous and scary if you don't get

down quickly. But the fact that they got

down to 10,000 ft in a pretty casual

attitude indicates that this really

wasn't an emergency. It was more of uh a

an urgent precaution, I should say.

Obviously, they declared an emergency

and diverted. This is not unusual. This

is safe. They did a great job. They kept

everybody safe. good landing which is

best case scenario for any kind of

aviation situation but I would say of

the problems that can happen in aviation

your mass coming down and descending at

you know and your pilots's descending in

some form of manner yeah it means you're

going to a different airport yeah it's

going to seem really uncomfortable but a

controlled descent even on a honestly a

rapid spiral descent in a true

decompression

not something that pilots aren't

prepared for it is something pilots are

highly trained for. It typically is not

an issue unless your pilots go

unconscious or there's some kind of

catastrophic, you know, portion of the

plane missing like, I don't know, a

Boeing door blows off. Although that

occurred at a lower altitude where it

was also less of a problem and typically

parts of aircrafts don't rip off,

although there was one very famous case

where an aircraft uh disassembled

midair. Uh but that's extremely rare and

typically because of some form of major

uh maintenance or uh you know

maintenance oversight failure. Very very

rare for that to happen though. Anyway,

that's my take on this plunge uh of this

spring airlines plunge because that's

again those are the headlines people

were going with. That's what's being

talked about on social media. Terror on

Boeing plane as flight is forced to make

emergency landing. Spring Airlines

flight plunges 2600 feet. 2600 feet in

10 minutes is not a plunge. It's like

kind of like a normal descent rate,

honestly. So anyway, worth having a

little bit of extra perspective there.

Why not advertise these things that you

told us here? I feel like nobody else

knows about this. We'll we'll try a

little advertising and see how it goes.

Congratulations, man. You have done so

much. People love you. People look up to

you. Kevin Pra there, financial analyst

and YouTuber. Meet Kevin. Always great

to get your take.