737-8 max plane goes down (2018) - new not Max crash Indonesia

[denislawsbackheel]

I like EasyJet’s hands free service.
£7 gets priority at check in, no queuing, bag in the hold, line up with priority boarding, no bun fight with all the others trying to get the bags in the overhead lockers, just board at my convenience with my iPad and book in a small bag.

 

[Claytop]

Or have one fall out of the sky (from high altitude!) because one pilot had no idea what the other one was doing, and what he was doing was the exact opposite of what he should have been doing, but he was completely overwhelmed by dings, horns, lights, and displays...well, I’d say there are foibles on most aircraft that pilots learn to live with.

AF447? Pretty shocking that one.

 

[ChicagoBlue]

AF447? Pretty shocking that one.

Yup!

At least in the Boeing, you would see the other pilot holding the yoke full aft WHILE IN A STALL, and recognize the completely erroneous upset input!

PUSH
ROLL
THRUST
STABILIZE

NOWHERE in there does it say “pull back with everything you have because the aircraft is falling out of the sky!”

If an aircraft with 2 wings and a tail intact is falling out of the sky, pulling is not your friend, because the aircraft IS NOT FLYING!!

To get it back flying, you have to lower the nose, get airflow over the lift devices (wings) that ALLOWS the aircraft to fly. Once it’s flying again, even if it’s pointed straight at the ground, NOW you can recover by pulling a FLYING CONTROL SURFACE!

It’s Flying 101, and it’s required BEFORE you can solo ANY aircraft, but sometimes, with all the bells, lights and klaxons in a modern aircraft you don’t realize how simple the solution to the IMMEDIATE AND PRIMARY DANGER can be.

 

[west didsblue]

AF447? Pretty shocking that one.

Yep it’s rare that a 100% serviceable aircraft crashes into the sea when the crew have a full 5 minutes to work out that the only problem was that the copilot was pulling his stick fully back when he shouldn’t have been because he’d been confused by a misleading airspeed display caused by icing that had stopped being misleading within a minute or two, once the ice on the probe melted, but the copilot thought it was still wrong.

 

[ChicagoBlue]

Yep it’s rare that a 100% serviceable aircraft crashes into the sea when the crew have a full 5 minutes to work out that the only problem was that the copilot was pulling his stick fully back when he shouldn’t have been because he’d been confused by a misleading airspeed display caused by icing that had stopped being misleading within a minute or two, once the ice on the probe melted, but the copilot thought it was still wrong.

For me, he didn’t even need to know the pitot icing issue or the airspeed issue. It’s a primacy issue.

The aircraft isn’t flying...make it fly again. When you revert to that primacy, no matter the altitude or even attitude, the answer is lower the nose (even a 0.5G push is sufficient, you don’t have to lift people out of their seat!), DO NOT PULL UNTIL UNTIL THE WINGS ARE LEVEL AND YOU KNOW YOU'RE FLYING, as in positive control of flight surfaces...ailerons, elevator, rudder...and then recover with a combination (as needed!) of thrust and elevator/“pull.”

 

[west didsblue]

For me, he didn’t even need to know the pitot icing issue or the airspeed issue. It’s a primacy issue.

The aircraft isn’t flying...make it fly again. When you revert to that primacy, no matter the altitude or even attitude, the answer is lower the nose (even a 0.5G push is sufficient, you don’t have to lift people out of their seat!), DO NOT PULL UNTIL UNTIL THE WINGS ARE LEVEL AND YOU KNOW YOU'RE FLYING, as in positive control of flight surfaces...ailerons, elevator, rudder...and then recover with a combination (as needed!) of thrust and elevator/“pull.”

Yep, it was the most avoidable accident that I think I’ve ever heard about.

I had a particular interest in the cause at the time because I had design responsibility for the Air Data System on a new aircraft that used the same model of pitot static probes, so before the flight recorders were found there was a lot of concern about the safety of those probes, because the only available evidence was a few automated ACARS messages that related to the brief icing incident.

 

[Claytop]

Yup!

At least in the Boeing, you would see the other pilot holding the yoke full after WHILE IN A STALL, and recognize the completely erroneous upset input!

PUSH
ROLL
THRUST
STABILIZE

NOWHERE in there does it say “pull back with everything you have because the aircraft is falling out of the sky!”

If an aircraft with 2 wings and a tail intact is falling out of the sky, pulling is not your friend, because the aircraft IS NOT FLYING!!

To get it back flying, you have to lower the nose, get airflow over the lift devices (wings) that ALLOWS the aircraft to fly. Once it’s flying again, even if it’s pointed straight at the ground, NOW you can recover by pulling a FLYING CONTROL SURFACE!

It’s Flying 101, and it’s required BEFORE you can solo ANY aircraft, but sometimes, with all the bells, lights and klaxons in a modern aircraft you don’t realize how simple the solution to the IMMEDIATE AND PRIMARY DANGER can be.

Indeed, I’ve watched enough Air Crash Investigations to know in a stall to get the nose lowered and speed back and hope you’ve got the Altitude...

CVR from that flight makes for a very sobering read, Captain didn’t realise until it was too late and even then one of them still kept pulling up.

 

[ChicagoBlue]

Yep, it was the most avoidable accident that I think I’ve ever heard about.

I had a particular interest in the cause at the time because I had design responsibility for the Air Data System on a new aircraft that used the same model of pitot static probes, so before the flight recorders were found there was a lot of concern about the safety of those probes, because the only available evidence was a few automated ACARS messages that related to the brief icing incident.

Yes, the data burst prior to the accident was essential information and the Thales problems were known, but not resolved.

If the Captain had managed to get back to the cockpit 1 minute earlier, they may have survived, because he immediately recognized they were stuck in a stall. Alas...

 

[ChicagoBlue]

Indeed, I’ve watched enough Air Crash Investigations to know in a stall to get the nose lowered and speed back and hope you’ve got the Altitude...

CVR from that flight makes for a very sobering read, Captain didn’t realise until it was too late and even then one of them still kept pulling up.

Getting the nose down is to get airflow over the wing such that the relative wind reduces the angle of attack below the critical angle that creates an airflow separation. IT HAS NOTHING TO DO WITH SPEED...as the AF447 First Officer learned AGAIN immediately before he died!

An aircraft can fall out of the sky at ridiculous speeds in a full stall, purely because the air passing over the wing isn’t coming from the correct direction.

Regaining control of the aircraft requires getting the airflow over the big shit that sticks out of the fuselage. That requires getting the nose down, and gravity makes speed increase...but it’s a completely secondary action and often your enemy, NOT your friend, by the time you get that airflow over the control surfaces.

Seems counterintuitive, and killed all aboard AF447 because they hit the water going faster than any of those passengers had probably ever gone before, but they were still in a full stall while descending at 10,000 feet per minute (over 3 times any normal descent) at goodness knows how fast, AND ALL BECAUSE THE “RELATIVE WIND” HITTING THE AIRFOILS WAS AT TOO HIGH OF AN ANGLE (i.e. in excess of the airfoils critical angle of attack).

 

[Claytop]

Getting the nose down is to get airflow over the wing such that the relative wind reduces the angle of attack below the critical angle that creates an airflow separation. IT HAS NOTHING TO DO WITH SPEED...as the AF447 First Officer learned AGAIN immediately before he died!

An aircraft can fall out of the sky at ridiculous speeds in a full stall, purely because the air passing over the wing isn’t coming from the correct direction.

Regaining control of the aircraft requires getting the airflow over the big shit that sticks out of the fuselage. That requires getting the nose down, and gravity makes speed increase...but it’s a completely secondary action and often your enemy, NOT your friend, by the time you get that airflow over the control surfaces.

Seems counterintuitive, and killed all aboard AF447 because they hit the water going faster than any of those passengers had probably ever gone before, but they were still in a full stall while descending at 10,000 feet per minute (over 3 times any normal descent) at goodness knows how fast, AND ALL BECAUSE THE “RELATIVE WIND” HITTING THE AIRFOILS WAS AT TOO HIGH OF AN ANGLE (i.e. in excess of the airfoils critical angle of attack).

View attachment 9207

Thanks, that's why you're the Captain and I'm not! ;) Most laymans probably associate stalling with low speed. Would it be correct that the high angle of attack originally lowers the speed which then makes the aircraft enter the Stall? Think I read on the AF447 report that initially when he pulled back on the stick after AP disengage that speeds dropped from over 200 knots to about 50?

 

[west didsblue]

Thanks, that's why you're the Captain and I'm not! ;) Most laymans probably associate stalling with low speed. Would it be correct that the high angle of attack originally lowers the speed which then makes the aircraft enter the Stall? Think I read on the AF447 report that initially when he pulled back on the stick after AP disengage that speeds dropped to from over 200 knots to about 50?

I seem to recall from the report that forward speed was about the same as vertical speed, about 100 knots, so the aircraft was plummeting at about a 45 degree flight path angle. Although in the last minute just before the captain tried to recover it, it had slowed to 38 knots. In the very last few seconds the speed went right up while the captain tried to recover it but he had nowhere near enough altitude available. Absolutely tragic.

 

[flyer]

Getting the nose down is to get airflow over the wing such that the relative wind reduces the angle of attack below the critical angle that creates an airflow separation. IT HAS NOTHING TO DO WITH SPEED...as the AF447 First Officer learned AGAIN immediately before he died!

An aircraft can fall out of the sky at ridiculous speeds in a full stall, purely because the air passing over the wing isn’t coming from the correct direction.

Regaining control of the aircraft requires getting the airflow over the big shit that sticks out of the fuselage. That requires getting the nose down, and gravity makes speed increase...but it’s a completely secondary action and often your enemy, NOT your friend, by the time you get that airflow over the control surfaces.

Seems counterintuitive, and killed all aboard AF447 because they hit the water going faster than any of those passengers had probably ever gone before, but they were still in a full stall while descending at 10,000 feet per minute (over 3 times any normal descent) at goodness knows how fast, AND ALL BECAUSE THE “RELATIVE WIND” HITTING THE AIRFOILS WAS AT TOO HIGH OF AN ANGLE (i.e. in excess of the airfoils critical angle of attack).

View attachment 9207

Great explanation, very clear for everyone

 

[ChicagoBlue]

Thanks, that's why you're the Captain and I'm not! ;) Most laymans probably associate stalling with low speed. Would it be correct that the high angle of attack originally lowers the speed which then makes the aircraft enter the Stall? Think I read on the AF447 report that initially when he pulled back on the stick after AP disengage that speeds dropped from over 200 knots to about 50?

:-)
Yes and no.

Yes: When you pull back and don’t add thrust, speed decays.

No: “which then makes the aircraft enter the Stall?”

An aircraft stalls due to the AOA exceeding the critical angle of attack...because the lift needed to hold the aircraft aloft disappears (see the pic I posted).

Speed has NOTHING to do with the CAUSE, but can be a byproduct of the process. The AF447 aircraft was going very, very fast WHILE IN A FULL STALL, because one of the pilots raised the nose of the aircraft (which is actually pushing down the tail...which, in turn, is itself actually a movable wing!) by pulling the side stick controller aft and exceeding the aircrafts critical angle of attack.

Now, as the aircraft climbed well beyond its service ceiling (maximum flying altitude), there are TWO things that can cause a stall...exceeding critical angle of attack AND the aircraft being so high that the airfoil cannot create enough lift in the increasingly less dense high altitude atmosphere to hold the aircraft aloft.

This is why aircraft have a service ceiling...it cannot generate enough lift to overcome the mass (weight) of the aircraft EVEN BELOW THE CRITICAL ANGLE OF ATTACK!!

It’s called “coffin corner,” as the aircraft flight envelope gets smaller and smaller to the point that any decrease OR increase in speed WITH AN INCREASE IN ALTITUDE will cause a stall.

What’s confusing is sometimes stalls are identified as “high speed” or “low speed” stalls, but they’re both functions of other actions on the airfoil and aircraft!

Clear as mud, right? ;-)

Please take comfort in the fact that pilots still argue about these things, so you’re in good company!

 

[RadcliffeRick]

@ChicagoBlue many thanks for your posts on this and other plane discussions, they are really interesting and informative

 

[ChicagoBlue]

I seem to recall from the report that forward speed was about the same as vertical speed, about 100 knots, so the aircraft was plummeting at about a 45 degree flight path angle. Although in the last minute just before the captain tried to recover it, it had slowed to 38 knots. In the very last few seconds the speed went right up while the captain tried to recover it but he had nowhere near enough altitude available. Absolutely tragic.

38kts is, itself, a relative thing, as it’s based on airflow through the pitot, which is not getting steady airflow.

Accirdingly, I don’t think the “airspeed” at which the aircraft was moving could have been only 38kts, as we understand that term (except as it reached its highest altitude and gravity took over at its apex).

Now, if that’s a 4 satellite GPS speed, based on LATERAL MOVEMENT, that’s a different story, as it may have only been moving across the ground at 38kts, while falling out of the sky at terminal velocity!

:-)

 

[ChicagoBlue]

Great explanation, very clear for everyone

Thank you, because aviation is known for its jargon and confusing alphabet soup of acronyms and technical terminology.

 

[Indaparkside]

Thank you, because aviation is known for its jargon and confusing alphabet soup of acronyms and technical terminology.

You really are the man when it’s comes to explaining aviation on here, really enjoy reading your posts Top Man

 

[ChicagoBlue]

@ChicagoBlue many thanks for your posts on this and other plane discussions, they are really interesting and informative

Cheers, mate!

Sometimes it’s hard to try to explain technical stuff without coming off like “I’m a pilot, don’t I sound like a twat?!” so it’s appreciated.

 

[ChicagoBlue]

You really are the man when it’s comes to explaining aviation on here, really enjoy reading your posts Top Man

Very kind of you, thank you.

 

[Claytop]

:-)
Yes and no.

Yes: When you pull back and don’t add thrust, speed decays.

No: “which then makes the aircraft enter the Stall?”

An aircraft stalls due to the AOA exceeding the critical angle of attack...because the lift needed to hold the aircraft aloft disappears (see the pic I posted).

Speed has NOTHING to do with the CAUSE, but can be a byproduct of the process. The AF447 aircraft was going very, very fast WHILE IN A FULL STALL, because one of the pilots raised the nose of the aircraft (which is actually pushing down the tail...which, in turn, is itself actually a movable wing!) by pulling the side stick controller aft and exceeding the aircrafts critical angle of attack.

Now, as the aircraft climbed well beyond its service ceiling (maximum flying altitude), there are TWO things that can cause a stall...exceeding critical angle of attack AND the aircraft being so high that the airfoil cannot create enough lift in the increasingly less dense high altitude atmosphere to hold the aircraft aloft.

This is why aircraft have a service ceiling...it cannot generate enough lift to overcome the mass (weight) of the aircraft EVEN BELOW THE CRITICAL ANGLE OF ATTACK!!

It’s called “coffin corner,” as the aircraft flight envelope gets smaller and smaller to the point that any decrease OR increase in speed WITH AN INCREASE IN ALTITUDE will cause a stall.

What’s confusing is sometimes stalls are identified as “high speed” or “low speed” stalls, but they’re both functions of other actions on the airfoil and aircraft!

Clear as mud, right? ;-)

Please take comfort in the fact that pilots still argue about these things, so you’re in good company!

Thanks, again!

I often read pprune after any major accident or similar and it’s often pilots arguing amongst themselves in there too!