Boeing 777 plane crash-lands at San Francisco airport

F430murci · July 10, 2013

The auto throttles issue is an interesting one, and even the NTSB in yesterday's briefing couldn't sort that one out.. Yes they were found to be armed or engaged, but not clear if they were functioning or in what mode they had been set... The instructor pilot told them he "assumed" the auto throttles would have kept the aircraft's speed in line. I guess time will tell what happened with that.

But I keep coming back to the same issue... No matter what was or wasn't happening with the auto throttled, wasn't anyone in the cockpit actively monitoring their airspeed in the final minute of descent. And if they were, it's hard to find much indication that anyone did anything about the speed issue until the very end.

Playing devil's advocate, I can kind of get it if auto throttle disengaged, it is almost like taking for granted your brakes are going to work and don't. In heat of moment, you may not think to down shift and keeping pumping brake pedal. They eventually hit throttles. This stuff happens quickly and if it a system that goes out, it can be pretty disorienting. They still f'ed up either way, but I can get the delayed response if auto throttle failed or accidentally disengaged.

midas · July 10, 2013

A lame reason for not drug-testing Asiana pilots

http://www.latimes.com/news/opinion/opinion-la/la-ol-asiana-airlines-drug-test-20130709,0,40181.story

Edited July 10, 2013 by midas

F430murci · July 10, 2013

One of the pilots of Asiana Flight 214 that crashed in San Francisco shouted warnings that were ignored, according to South Korean media.

Sources in the country's transport ministry confirmed Bong Dong Won - who was in the cockpit jump seat - repeatedly yelled "sink rate" in the final minute before the crash, it was reported.

http://m.sky.com/skynews/article/1113782

First off, I don't think there was a glide slope issue even a minute away. It seems like they got out of sorts at the very end and the 500 foot mark keeps getting mentioned by NTSB. The NTSB has heard cockpit voice recorders by now and it seems as if they are saying none if the 3 pilots knew speed was falling off and the third pilot did not have a view of the runway from the jump seat.

The proper call here would have been speed up. Sink rate implies pull up, which he did and ended up at 106 knots.

jpinx · July 10, 2013

Hi jpinx,

your right that the cultural aspect may have played a part here. Its a very hierarchical society, particularly if one has had an illustrious career in the military which may or not have been the case here. The cockpit voice recorder makes for interesting listening I am sure.

I'm not sure how the "cultural" issue fits in in the relationship between the instructor pilot and the trainee pilot.

Just quickly doing this from my memory, the instructor pilot was the senior pilot overall in terms of tenure and hours flown, both overall and obviously in the 777. I think, from the NTSB briefing yesterday, it also indicated he was an ex military pilot, for whatever that's worth.

The trainee pilot was less tenured overall and relatively brand new on 777s. I don't recall the NTSB yesterday saying anything about him having a military background. He was a full captain flying Airbus jets previously for Asiana... But at least on the surface, there's nothing that would seem to put the instructor pilot in any kind of deferential role.

Except, and there's no way to know at this point how this factored in.... despite his pretty senior status, the SFO flight was his FIRST flight as an instructor pilot, from what the NTSB said....

I dunno if we'll ever know what the personal dynamics were that day in the cockpit. But I'd sure like to know.

Having worked with aircrew training in "cultures" where the social hierarchy is more important than qualifications, I can assure you that it has a huge bearing on the situation.

As was pointed out - the jump-seat pilot shouted about the height problem and he was much lower in rank/status, according to the reports. How long had he known of the problem and deferred his warning, thinking that the "seniors" would spot it and do something about it?

No matter if the auto-throttle was or wasn't working, there is a very basic requirement to staying airborne and that is airspeed. Someone/people had been playing in simulators too log and had forgotten how to actually *fly* an aircraft.

Edited July 10, 2013 by jpinx

F430murci · July 10, 2013

Hi jpinx,

your right that the cultural aspect may have played a part here. Its a very hierarchical society, particularly if one has had an illustrious career in the military which may or not have been the case here. The cockpit voice recorder makes for interesting listening I am sure.

I'm not sure how the "cultural" issue fits in in the relationship between the instructor pilot and the trainee pilot.

Just quickly doing this from my memory, the instructor pilot was the senior pilot overall in terms of tenure and hours flown, both overall and obviously in the 777. I think, from the NTSB briefing yesterday, it also indicated he was an ex military pilot, for whatever that's worth.

The trainee pilot was less tenured overall and relatively brand new on 777s. I don't recall the NTSB yesterday saying anything about him having a military background. He was a full captain flying Airbus jets previously for Asiana... But at least on the surface, there's nothing that would seem to put the instructor pilot in any kind of deferential role.

Except, and there's no way to know at this point how this factored in.... despite his pretty senior status, the SFO flight was his FIRST flight as an instructor pilot, from what the NTSB said....

I dunno if we'll ever know what the personal dynamics were that day in the cockpit. But I'd sure like to know.

Having worked with aircrew training in "cultures" where the social hierarchy is more important than qualifications, I can assure you that it has a huge bearing on the situation.
As was pointed out - the jump-seat pilot shouted about the height problem and he was much lower in rank/status, according to the reports. How long had he known of the problem and deferred his warning, thinking that the "seniors" would spot it and do something about it?

No matter if the auto-throttle was or wasn't working, there is a very basic requirement to staying airborne and that is airspeed. Someone/people had been playing in simulators too log and had forgotten how to actually *fly* an aircraft.

Just curious where you got info on the jump seat pilot's senority? Seems like he had more time monitoring trainee pilots than the pilot monitoring this flight.

Also, where are you getting they had a height problem for a long time and he just sat their silent. Seems like NTSB is saying they got out of sorts pretty much right at the end which makes sense if speed was bleeding off unknowingly. They have also only mentioned a voice saying need more speed at 7 second mark, stuck shaker at 5 or 6 second mark so no one was ignoring anything when first mention of speed occurred.

------

NTSB investigators completed preliminary interviews with those two pilots and the relief first officer, who was seated in a cockpit jump seat; they said he had flown into SFO as many as six times as a monitoring pilot and had experience on a 777 aircraft. But the jump seat pilot said he could not see the runway from his seat during the landing because the planes nose was pitched up.

http://sanfrancisco.cbslocal.com/2013/07/09/asiana-aircrafts-landing-gear-hit-seawall-first/

Edited July 10, 2013 by F430murci

TallGuyJohninBKK · July 10, 2013

One of the pilots of Asiana Flight 214 that crashed in San Francisco shouted warnings that were ignored, according to South Korean media.

Sources in the country's transport ministry confirmed Bong Dong Won - who was in the cockpit jump seat - repeatedly yelled "sink rate" in the final minute before the crash, it was reported.

http://m.sky.com/skynews/article/1113782

That's intriguing because there's been no mention of that kind of vocalizing by the NTSB in their briefings thus far, even though they've reviewed the cockpit voice recorder and also completed their interview with the reserve first officer who was sitting in the cockpit jump seat.

In her latest remarks Tuesday, NTSB chair Hersman summarized the instructor pilot's account of what happened. But made zero mention of anything from their interview with the reserve first officer other than that he couldn't see the PAPI landing lights, and only recited the bio information provided by the training pilot, not anything from any account he may have given them of what happened.

Edited July 10, 2013 by TallGuyJohninBKK

TallGuyJohninBKK · July 10, 2013

I went back tonight and re-reviewed Hersman's comments yesterday re the reserve first officer sitting in the cockpit jumpseat.

According to her summary, he had less overall experience than either the instructor pilot or the trainee pilot on the 777.

But he obviously had more flying time in the 777 than the trainee pilot, and had flown into SFO previously five or six times as a "pilot monitoring" -- not sure that's the same as being an instructor pilot. He also is an ex-military pilot, like the instructor pilot.

BTW, Hersman said the trainee pilot had been a simulator instructor and ground school instructor for other types of aircraft other than the 777, but NOT that he had been a flight instructor pilot in any type of aircraft.

Edited July 10, 2013 by TallGuyJohninBKK

jpinx · July 10, 2013

references as requested

http://www.pprune.org/rumours-news/518568-asiana-flight-crash-san-francisco-71.html#post7932987

http://www.pprune.org/rumours-news/518568-asiana-flight-crash-san-francisco-72.html#post7933113

http://www.pprune.org/rumours-news/518568-asiana-flight-crash-san-francisco-73.html#post7933193

Edited to add...

Obviously we are all speculating here and the full facts will come out in due course.

Meantime, amongst other things, the airlines will do well to be more aware of the relative qualifications, experience and status of the people they put together as a crew.

Edited July 10, 2013 by jpinx

MaxYakov · July 10, 2013

One of the pilots of Asiana Flight 214 that crashed in San Francisco shouted warnings that were ignored, according to South Korean media.

Sources in the country's transport ministry confirmed Bong Dong Won - who was in the cockpit jump seat - repeatedly yelled "sink rate" in the final minute before the crash, it was reported.

http://m.sky.com/skynews/article/1113782

That's intriguing because there's been no mention of that kind of vocalizing by the NTSB in their briefings thus far, even though they've reviewed the cockpit voice recorder and also completed their interview with the reserve first officer who was sitting in the cockpit jump seat.

In her latest remarks Tuesday, NTSB chair Hersman summarized the instructor pilot's account of what happened. But made zero mention of anything from their interview with the reserve first officer other than that he couldn't see the PAPI landing lights, and only recited the bio information provided by the training pilot, not anything from any account he may have given them of what happened.

You don't really think the NTSB is going to relate everything on the CVR at this point, do you? I'm wondering why the NTSB is saying anything at all. Do they have a twitter account yet? I expect next that an auto-thrust malfunction will be blamed for the low altitude/speed and that the pilots will be called heroes for saving the aircraft (or most of it, anyway) in the last seconds.

We have yet to hear from Obama on this. Maybe his comment would be something like: If I had an airplane, it would look like the ... uh ... the one used for Asiana Airlines Flight 214. Oh, wait! I already have an airplane ... uh ... sorry.

manarak · July 10, 2013

some of you think way too mutt

F430murci · July 10, 2013

references as requested

http://www.pprune.org/rumours-news/518568-asiana-flight-crash-san-francisco-71.html#post7932987

http://www.pprune.org/rumours-news/518568-asiana-flight-crash-san-francisco-72.html#post7933113

http://www.pprune.org/rumours-news/518568-asiana-flight-crash-san-francisco-73.html#post7933193

Edited to add...

Obviously we are all speculating here and the full facts will come out in due course.

Meantime, amongst other things, the airlines will do well to be more aware of the relative qualifications, experience and status of the people they put together as a crew.

These guys in the front seats had a lot of flight time. How much time do you think the pilots had on the 380 and 787 when they first rolled out?

Seniority not an issue, but media and people like to make issues out of stuff like this because its gets them riled up. They screwed up and the auto throttle makes sense. I said back on Saturday, no one would get that slow and fail to apply power absent mechanical, bird ingestion or believing auto throttle engaged. The last explanation would be the most reasonable explanation at to why they would think height first and speed last. Thinking it will come on any second is second or first nature.

khaosai · July 10, 2013

Hi,

F430murci, yeas the auto throttles do work below 500ft on this aircraft. We generally use the auto throttle from the start of take off when we press the take off switch until after touchdown and reverse thrust is selected which causes the auto throttle to disconnect.

The glare shield panel is where the mode control panel (MCP) is and which contains the auto throttle switches. There are two switches, one for the left throttle and one for the right throttle. When selected up they are armed and when selected down they are off.

In the armed mode the auto throttle will activate when vertical navigation (VNAV), flight level change (FLCH) or take off/ go around (TOGA) switch is pushed. It will also activate when the speed switch is pushed and the pitch mode is altitude (ALT), vertical speed (VS) or glide slope (G/S).

When selected off it disconnects the selected auto throttle, I.e. left or right or both and thus prevents the selected auto throttle activating. These switches are generally never selected off unless directed to do so, perhaps due to being unserviceable where the crew will follow the guidance in the minimum equipment list (MEL). Another reason for selecting them off is if a non normal checklist or memory item dictates so, I.e engine failure.

On the actual thrust levers you have auto throttle disconnect switches. Pushing this switch disconnects both auto throttles and as a result gives you an amber master caution light and aural sound. It also gives you a message on you engine indication crew alerting system (EICAS) which large upper screen located between both pilots. They are still in the armed position based on switch selection on the MCP.

Now the potential threats. If descending in FLCH the auto throttle (A/T) will be in HOLD mode until the altitude selected is reached when it would then change to speed (SPD). If you have selected zero in the altitude window then you can see the end result. It's very unlikely that a crew would do such a thing, but not impossible.

In HOLD mode the auto throttle servos are inhibited but the pilot can move them manually as required.

The auto throttle can support stall protection when armed but not activated, i.e having disconnected them using the switches on the thrust lever. If the speed gets close to stick shaker activation the the auto throttle engages and thrust will increase to maintain minimum manoeuvre speed which is indicated by the top of the amber band located on the primary flight display (PFD) speed indication.

Depending on the phase of flight vertical navigation speed (VNAV SPD) could be in IDLE or HOLD. With HOLD annunciated you do not get any stall protection. If FLCH is the pitch mode then you do not get stall protection. When below 100ft you do not get any stall protection.

The system logic allows the aircraft to be manually flown with the thrust levers engaged. So basically you can be looking out the window on a visual approach with no autopilot and the flight director guidance off. It may be in hold mode so you will have to set the required thrust. If the flight director is off the auto throttle will retard to idle at 25ft radio altitude (RA). So if substantially low over water the thrust lever would retard as you are getting radio altitude indications from the surface of the sea.

I am all for discussion, speculation information etc. The facts will soon become clear. Human factors played a huge part in this accident and will be discussed in recurrent training within airlines for decades to come.

Edited July 10, 2013 by khaosai

TallGuyJohninBKK · July 10, 2013

One of the pilots of Asiana Flight 214 that crashed in San Francisco shouted warnings that were ignored, according to South Korean media.

Sources in the country's transport ministry confirmed Bong Dong Won - who was in the cockpit jump seat - repeatedly yelled "sink rate" in the final minute before the crash, it was reported.

http://m.sky.com/skynews/article/1113782

As of right now, I'm not finding any article like being described on the website of the Korean newspaper cited, the Joongang Daily.

http://koreajoongangdaily.joins.com/search/search.aspx?sw=Asiana&x=0&y=0

But I am finding a reference I've not heard before that two THAIS were among the flight attendants on the flight.

According to the airline and media reports, Asiana cabin crews helped prevent further casualties. The company said that there were 12 flight attendants - 10 Korean and two Thai - on the flight and they worked to evacuate passengers until the last moment.
According to Asiana, seven out of the 12 flight attendants were knocked unconscious after the hard landing, but the five attendants who were mostly on the left side of the aircraft conducted a rescue drill, such as opening emergency exits, deploying the inflatable slides and guiding passengers to the emergency exits.

http://koreajoongangdaily.joins.com/news/article/article.aspx?aid=2974259

jpinx · July 10, 2013

Somewhere buried amongst the comments was one that queried the wisdom of doing a visual/manual approach after a long-haul flight, but apparently SFO had some technical issues which created that necessity.

Khaosai makes very valid technical points, but the fundamental question is why there was no-one monitoring airspeed during the approach. I maintain an open mind pending more facts being available, but a picture seems to be emerging.

F430murci · July 10, 2013

Khasoi:

Thanks. Yes. That sound like the MD11. Been since late 90s since I got to spend time in the Fed Ex's MD11 simulators.

You answered next question about disengaging on throttle levers for 777.

So, if he was coming in a little high at first, could he have reached for throttles and accidentally disengaged leaving the basically in idle without realizing it. But if he did that, why would NTSB say they were still engaged.

How involved would it have been to change auto throttle setting from 137 to say something like 125 or just above stick shaker? I ask because it seems as if auto throttle or speed was okay until very end.

What is stick shaker speed on 777?

F430murci · July 10, 2013

Somewhere buried amongst the comments was one that queried the wisdom of doing a visual/manual approach after a long-haul flight, but apparently SFO had some technical issues which created that necessity.

Khaosai makes very valid technical points, but the fundamental question is why there was no-one monitoring airspeed during the approach. I maintain an open mind pending more facts being available, but a picture seems to be emerging.

Because you don't with auto throttle. When I used to land MD11 simulators with auto throttle, I basically did nothing but keep the little dottie thingy between the cross hairs on final approach. Haha, 727 was an entirely different beast with heavy arse controls.

Point is, you probably don't think about speed because you never have to and being fly by wire you lose a lot of communication from the control surfaces.

How did AIR France end up in the drink just because of an air speed indicator problem. What happened during that flight was an incredible story. Automation greatly increases overall safety, but when it does fail it really can throw the cockpit for a loop.

TallGuyJohninBKK · July 10, 2013

Somewhere buried amongst the comments was one that queried the wisdom of doing a visual/manual approach after a long-haul flight, but apparently SFO had some technical issues which created that necessity.

The airport's Instrument Landing System (ILS) had been out of service since the beginning of June as part of some construction work, and incoming flights had been notified in advance of such.

TallGuyJohninBKK · July 10, 2013

Hi,

F430murci, yeas the auto throttles do work below 500ft on this aircraft. We generally use the auto throttle from the start of take off when we press the take off switch until after touchdown and reverse thrust is selected which causes the auto throttle to disconnect.

..................

Now the potential threats....

................

I am all for discussion, speculation information etc. The facts will soon become clear. Human factors played a huge part in this accident and will be discussed in recurrent training within airlines for decades to come.

Khaosai, I'm sure that was a very comprehensive and detailed explanation suitable for pilots....

But for the rest of us, what exactly are you trying to say?

It sounds from what you're posting, that the automatic throttles setting normally would be "armed" -- as it supposedly was -- during a landing in a 777. But after that, you presented so many different settings/flight mode options, I couldn't discern what the "normal" settings would be for a 777 plane in its final stages of descent on a visual flight rules landing.

Whatever settings the Asiana 777 actually had at the time, they obviously didn't prevent the plane for falling far below its designated airspeed just prior to landing.

Edited July 10, 2013 by TallGuyJohninBKK

khaosai · July 10, 2013

Hi,

Stick shaker speed will vary depending on the g loading. Bank angle and load factor will affect these. Remember you can stall an aircraft in any attitude and sometimes it's not immediately obvious.

Flap manoeuvre speeds are a function of aircraft weight, thus the heavier you are for landing the faster your approach and subsequent landing speed will be. On the primary flight display you have the flap up indication followed by the flap 1, 5, 15/20 and flap 30 which is generally used for landing. Flap 25 can also be used for landing but is not used that often.

Lets take a Boeing 777-200ER landing at a sea level airport at 200 tons using flaps 30. The velocity reference speed (VREF) will be 135 knots. That would then indicate to the crew how slowly they could fly with no flap selected and when they would have to select flaps to allow a speed reduction. The calculation is based on VREF30 plus 80 knots. So minimum clean speed would be 215 knots reducing by 20 knots per the next stage of flap selected, I.e select flaps 1 and reduce speed to 195 knots.

When flying at the appropriate speed for the flap setting you basically have full manoeuvre margin.

Also on the airspeed indication you have an amber band. The top of the amber band is minimum manoeuvre speed and is based on angle of attack and speed so is constantly changing during the flight. When you get approximately halfway into the amber band you will get an airspeed low caution.

At the bottom of the amber band you have a striped red and black brick type indication which is where you stop flying. The aircraft will be stalled if the speed is in this area.

The stick shaker indication to the crew will occur just before the speed reaches this area.

Hi TallGuyJohn, it does get a little technical so apologies for that.

This aircraft can be flown perfectly well with the auto throttle armed and engaged or armed and disengaged or even disarmed and therefore not engaged.

It comes down to awareness, proficiency, an understanding of the equipment you are operation/flying and never loose sight of the big picture. It's just another aircraft at the end of the day so the basics of pitch and power still apply.

Aim at the desired gear touchdown point, not the threshold but about 300 metres further down the runway which is indicated by they runway markings and generally are at the same point where the PAPI light indications are at. Some small corrections may be required until the selected point remains stationary in the pilots field of view and small changes necessary in thrust to control speed. These aircraft have the main wheels a considerable distance behind the pilot so you don't want to get low during the approach. You will aim to cross the runway threshold at 50 feet which will ensure the gear clearance and will also result in an accurate touch down.

Will be interested to see the final report.

Edited July 10, 2013 by khaosai

Chicog · July 10, 2013

One of the pilots of Asiana Flight 214 that crashed in San Francisco shouted warnings that were ignored, according to South Korean media.

Sources in the country's transport ministry confirmed Bong Dong Won - who was in the cockpit jump seat - repeatedly yelled "sink rate" in the final minute before the crash, it was reported.

http://m.sky.com/skynews/article/1113782

That's intriguing because there's been no mention of that kind of vocalizing by the NTSB in their briefings thus far, even though they've reviewed the cockpit voice recorder and also completed their interview with the reserve first officer who was sitting in the cockpit jump seat.

In her latest remarks Tuesday, NTSB chair Hersman summarized the instructor pilot's account of what happened. But made zero mention of anything from their interview with the reserve first officer other than that he couldn't see the PAPI landing lights, and only recited the bio information provided by the training pilot, not anything from any account he may have given them of what happened.

You don't really think the NTSB is going to relate everything on the CVR at this point, do you? I'm wondering why the NTSB is saying anything at all. Do they have a twitter account yet? I expect next that an auto-thrust malfunction will be blamed for the low altitude/speed and that the pilots will be called heroes for saving the aircraft (or most of it, anyway) in the last seconds.

We have yet to hear from Obama on this. Maybe his comment would be something like: If I had an airplane, it would look like the ... uh ... the one used for Asiana Airlines Flight 214. Oh, wait! I already have an airplane ... uh ... sorry.

Or perhaps Romney asking why we still don't have windows that open....

NeverSure · July 10, 2013

Hi,

Stick shaker speed will vary depending on the g loading. Bank angle and load factor will affect these. Remember you can stall an aircraft in any attitude and sometimes it's not immediately obvious.

Flap manoeuvre speeds are a function of aircraft weight, thus the heavier you are for landing the faster your approach and subsequent landing speed will be. On the primary flight display you have the flap up indication followed by the flap 1, 5, 15/20 and flap 30 which is generally used for landing. Flap 25 can also be used for landing but is not used that often.

Lets take a Boeing 777-200ER landing at a sea level airport at 200 tons using flaps 30. The velocity reference speed (VREF) will be 135 knots. That would then indicate to the crew how slowly they could fly with no flap selected and when they would have to select flaps to allow a speed reduction. The calculation is based on VREF30 plus 80 knots. So minimum clean speed would be 215 knots reducing by 20 knots per the next stage of flap selected, I.e select flaps 1 and reduce speed to 195 knots.

When flying at the appropriate speed for the flap setting you basically have full manoeuvre margin.

Also on the airspeed indication you have an amber band. The top of the amber band is minimum manoeuvre speed and is based on angle of attack and speed so is constantly changing during the flight. When you get approximately halfway into the amber band you will get an airspeed low caution.

At the bottom of the amber band you have a striped red and black brick type indication which is where you stop flying. The aircraft will be stalled if the speed is in this area.

The stick shaker indication to the crew will occur just before the speed reaches this area.

Hi TallGuyJohn, it does get a little technical so apologies for that.

This aircraft can be flown perfectly well with the auto throttle armed and engaged or armed and disengaged or even disarmed and therefore not engaged.

It comes down to awareness, proficiency, an understanding of the equipment you are operation/flying and never loose sight of the big picture. It's just another aircraft at the end of the day so the basics of pitch and power still apply.

Aim at the desired gear touchdown point, not the threshold but about 300 metres further down the runway which is indicated by they runway markings and generally are at the same point where the PAPI light indications are at. Some small corrections may be required until the selected point remains stationary in the pilots field of view and small changes necessary in thrust to control speed. These aircraft have the main wheels a considerable distance behind the pilot so you don't want to get low during the approach. You will aim to cross the runway threshold at 50 feet which will ensure the gear clearance and will also result in an accurate touch down.

Will be interested to see the final report.

I really appreciate and have "liked" your posts. Some of what you say is true of any fixed wing aircraft, and some is interesting as it relates to the 777, especially the throttles.

The bottom line continues to be however, that barring engine (power) malfunction, more than one guy should have been aware of the loss of speed and altitude soon enough to firewall the throttles and initiate a go-around. I've never been with a pilot including myself who wasn't fully watching the glide slope and airspeed on final.

Someone said that a plane will stall at any attitude. This is very true and it will also stall at any speed, although that wouldn't have come into play here. Only the "any attitude" could apply here.

Sorry to be redundant, but I just can't in my wildest imagination see how all of those pilots lost awareness of the angle of approach and airspeed, but maybe they did. Time will tell.

F430murci · July 10, 2013

Hi,

Stick shaker speed will vary depending on the g loading. Bank angle and load factor will affect these. Remember you can stall an aircraft in any attitude and sometimes it's not immediately obvious.

Flap manoeuvre speeds are a function of aircraft weight, thus the heavier you are for landing the faster your approach and subsequent landing speed will be. On the primary flight display you have the flap up indication followed by the flap 1, 5, 15/20 and flap 30 which is generally used for landing. Flap 25 can also be used for landing but is not used that often.

Lets take a Boeing 777-200ER landing at a sea level airport at 200 tons using flaps 30. The velocity reference speed (VREF) will be 135 knots. That would then indicate to the crew how slowly they could fly with no flap selected and when they would have to select flaps to allow a speed reduction. The calculation is based on VREF30 plus 80 knots. So minimum clean speed would be 215 knots reducing by 20 knots per the next stage of flap selected, I.e select flaps 1 and reduce speed to 195 knots.

When flying at the appropriate speed for the flap setting you basically have full manoeuvre margin.

Also on the airspeed indication you have an amber band. The top of the amber band is minimum manoeuvre speed and is based on angle of attack and speed so is constantly changing during the flight. When you get approximately halfway into the amber band you will get an airspeed low caution.

At the bottom of the amber band you have a striped red and black brick type indication which is where you stop flying. The aircraft will be stalled if the speed is in this area.

The stick shaker indication to the crew will occur just before the speed reaches this area.

Hi TallGuyJohn, it does get a little technical so apologies for that.

This aircraft can be flown perfectly well with the auto throttle armed and engaged or armed and disengaged or even disarmed and therefore not engaged.

It comes down to awareness, proficiency, an understanding of the equipment you are operation/flying and never loose sight of the big picture. It's just another aircraft at the end of the day so the basics of pitch and power still apply.

Aim at the desired gear touchdown point, not the threshold but about 300 metres further down the runway which is indicated by they runway markings and generally are at the same point where the PAPI light indications are at. Some small corrections may be required until the selected point remains stationary in the pilots field of view and small changes necessary in thrust to control speed. These aircraft have the main wheels a considerable distance behind the pilot so you don't want to get low during the approach. You will aim to cross the runway threshold at 50 feet which will ensure the gear clearance and will also result in an accurate touch down.

Will be interested to see the final report.

Good stuff for sure, but I was looking for the Thesaurus version and only for my curiosity. I kind of get the facts and calculations part, but I was just curious whether this 777 307 passengers and probably very little fuel would have a speed shaker at say 120 or would it have been more like 125. I was curious as to the probable speed at 7 second and at the 5 second mark where shaker occurs.

Pretty shitty scenario though dropping below glideslope because of lack of speed at that altitude. I guess some would panic and pull back due to proximity of the ground and then believing auto throttles are engaged (assuming they were not) this is what happens. But for auto throttles, these guys would certainly have been focused on speed and they would have been fine.

NeverSure · July 10, 2013

Hi,

Stick shaker speed will vary depending on the g loading. Bank angle and load factor will affect these. Remember you can stall an aircraft in any attitude and sometimes it's not immediately obvious.

Flap manoeuvre speeds are a function of aircraft weight, thus the heavier you are for landing the faster your approach and subsequent landing speed will be. On the primary flight display you have the flap up indication followed by the flap 1, 5, 15/20 and flap 30 which is generally used for landing. Flap 25 can also be used for landing but is not used that often.

Lets take a Boeing 777-200ER landing at a sea level airport at 200 tons using flaps 30. The velocity reference speed (VREF) will be 135 knots. That would then indicate to the crew how slowly they could fly with no flap selected and when they would have to select flaps to allow a speed reduction. The calculation is based on VREF30 plus 80 knots. So minimum clean speed would be 215 knots reducing by 20 knots per the next stage of flap selected, I.e select flaps 1 and reduce speed to 195 knots.

When flying at the appropriate speed for the flap setting you basically have full manoeuvre margin.

Also on the airspeed indication you have an amber band. The top of the amber band is minimum manoeuvre speed and is based on angle of attack and speed so is constantly changing during the flight. When you get approximately halfway into the amber band you will get an airspeed low caution.

At the bottom of the amber band you have a striped red and black brick type indication which is where you stop flying. The aircraft will be stalled if the speed is in this area.

The stick shaker indication to the crew will occur just before the speed reaches this area.

Hi TallGuyJohn, it does get a little technical so apologies for that.

This aircraft can be flown perfectly well with the auto throttle armed and engaged or armed and disengaged or even disarmed and therefore not engaged.

It comes down to awareness, proficiency, an understanding of the equipment you are operation/flying and never loose sight of the big picture. It's just another aircraft at the end of the day so the basics of pitch and power still apply.

Aim at the desired gear touchdown point, not the threshold but about 300 metres further down the runway which is indicated by they runway markings and generally are at the same point where the PAPI light indications are at. Some small corrections may be required until the selected point remains stationary in the pilots field of view and small changes necessary in thrust to control speed. These aircraft have the main wheels a considerable distance behind the pilot so you don't want to get low during the approach. You will aim to cross the runway threshold at 50 feet which will ensure the gear clearance and will also result in an accurate touch down.

Will be interested to see the final report.

Good stuff for sure, but I was looking for the Thesaurus version and only for my curiosity. I kind of get the facts and calculations part, but I was just curious whether this 777 307 passengers and probably very little fuel would have a speed shaker at say 120 or would it have been more like 125. I was curious as to the probable speed at 7 second and at the 5 second mark where shaker occurs.

Pretty shitty scenario though dropping below glideslope because of lack of speed at that altitude. I guess some would panic and pull back due to proximity of the ground and then believing auto throttles are engaged (assuming they were not) this is what happens. But for auto throttles, these guys would certainly have been focused on speed and they would have been fine.

By the time they are down to 5 or 7 seconds it's too late. It takes time for jet engines to spool up and develop power, and the kinetic energy of the dropping plane has to be overcome by gaining enough speed to develop lift from the wings.

A pilot develops what's called a kinesthetic sense. In layman's terms you could liken it to what allows you to ride a bicycle. You could call it a seat of the pants feel. After even just hundreds of hours of experience and in conditions with good visibility, he should feel the plane dropping. He should sense it getting mushy from too little lift. He should feel the plane approaching a stall by the sound of wind over the airframe, buffeting, losing control, beginning to drop...

If this was pure pilot error of allowing the plane to get too low and slow regardless of its equipment or the airport's equipment, it will be shocking to learn. It will be equally shocking that they didn't sense a problem by at least 500 feet when they still had time and room to put the nose down a little to gain speed and lift while fire walling the throttles to get the wings flying again and to do a full go around.

lomatopo · July 10, 2013

I'm in the U.S for a few days - flew on a 777 BKK-NRT and NRT-IAD - so there is a fair amount of coverage on TV here.

There was mention that some of the cockpit conversations were in Korean, and that those had to be translated.

The stick might have started shaking, indicating a stall, at ~ 115 knots.

Asiana Airlines has hired aviation law firm Condon & Forsyth LLP. I think Asiana has insurance coverage up to $2.5 B.

Asiana seems to be attempting to shift blame, with some public statements, from itself, its employees, et al., to the aircraft itself: engines and other systems.

F430murci · July 10, 2013

Hi,

Stick shaker speed will vary depending on the g loading. Bank angle and load factor will affect these. Remember you can stall an aircraft in any attitude and sometimes it's not immediately obvious.

Flap manoeuvre speeds are a function of aircraft weight, thus the heavier you are for landing the faster your approach and subsequent landing speed will be. On the primary flight display you have the flap up indication followed by the flap 1, 5, 15/20 and flap 30 which is generally used for landing. Flap 25 can also be used for landing but is not used that often.

Lets take a Boeing 777-200ER landing at a sea level airport at 200 tons using flaps 30. The velocity reference speed (VREF) will be 135 knots. That would then indicate to the crew how slowly they could fly with no flap selected and when they would have to select flaps to allow a speed reduction. The calculation is based on VREF30 plus 80 knots. So minimum clean speed would be 215 knots reducing by 20 knots per the next stage of flap selected, I.e select flaps 1 and reduce speed to 195 knots.

When flying at the appropriate speed for the flap setting you basically have full manoeuvre margin.

Also on the airspeed indication you have an amber band. The top of the amber band is minimum manoeuvre speed and is based on angle of attack and speed so is constantly changing during the flight. When you get approximately halfway into the amber band you will get an airspeed low caution.

At the bottom of the amber band you have a striped red and black brick type indication which is where you stop flying. The aircraft will be stalled if the speed is in this area.

The stick shaker indication to the crew will occur just before the speed reaches this area.

Hi TallGuyJohn, it does get a little technical so apologies for that.

This aircraft can be flown perfectly well with the auto throttle armed and engaged or armed and disengaged or even disarmed and therefore not engaged.

It comes down to awareness, proficiency, an understanding of the equipment you are operation/flying and never loose sight of the big picture. It's just another aircraft at the end of the day so the basics of pitch and power still apply.

Aim at the desired gear touchdown point, not the threshold but about 300 metres further down the runway which is indicated by they runway markings and generally are at the same point where the PAPI light indications are at. Some small corrections may be required until the selected point remains stationary in the pilots field of view and small changes necessary in thrust to control speed. These aircraft have the main wheels a considerable distance behind the pilot so you don't want to get low during the approach. You will aim to cross the runway threshold at 50 feet which will ensure the gear clearance and will also result in an accurate touch down.

Will be interested to see the final report.

Good stuff for sure, but I was looking for the Thesaurus version and only for my curiosity. I kind of get the facts and calculations part, but I was just curious whether this 777 307 passengers and probably very little fuel would have a speed shaker at say 120 or would it have been more like 125. I was curious as to the probable speed at 7 second and at the 5 second mark where shaker occurs.

Pretty shitty scenario though dropping below glideslope because of lack of speed at that altitude. I guess some would panic and pull back due to proximity of the ground and then believing auto throttles are engaged (assuming they were not) this is what happens. But for auto throttles, these guys would certainly have been focused on speed and they would have been fine.

By the time they are down to 5 or 7 seconds it's too late. It takes time for jet engines to spool up and develop power, and the kinetic energy of the dropping plane has to be overcome by gaining enough speed to develop lift from the wings.

A pilot develops what's called a kinesthetic sense. In layman's terms you could liken it to what allows you to ride a bicycle. You could call it a seat of the pants feel. After even just hundreds of hours of experience and in conditions with good visibility, he should feel the plane dropping. He should sense it getting mushy from too little lift. He should feel the plane approaching a stall by the sound of wind over the airframe, buffeting, losing control, beginning to drop...

If this was pure pilot error of allowing the plane to get too low and slow regardless of its equipment or the airport's equipment, it will be shocking to learn. It will be equally shocking that they didn't sense a problem by at least 500 feet when they still had time and room to put the nose down a little to gain speed and lift while fire walling the throttles to get the wings flying again and to do a full go around.

Exactly. This is what I have said all along. My question must be poorly articulated. I am curious about the stick shaker solely to understand how slow the plane was at the 5 to 7 second mark. If stick shaker was set at 115, they were f'ed a long time before the 500 foot mark. If shaker set to go off at 125 (probably a more reasonable number), then they got out of sorts pretty quickly, had little time to recover and rapidly lost the majority of speed between 5 seconds and impact from pulling back or flaring.

My brother and I have a little Duchess and I agree that you are very sensitive to speed and have a great awareness. Perhaps not so much with big fly by wire jumbos. I know there is a huge difference between flying a 727 simulator which is heavy, clumbsy and you do have a feel for everything and flying an MD11 simulator which feels very benign and disconnected. I have been told that the Redifusion full view, full motion Fed Ex simulators feel just like the real deal. If true, then I am not sure a slow bleed of 5 or 10 knots would be extremely noticeable.

When they start running scenarios off the black box, it will be interesting to see if he could have made it had he not pulled nose up and went full power at 7 or 5 second mark. I think he would have been fine if he had 125 at 5 second mark. Unfortunately, they apparently did not hit manual throttles until maybe 3 second mark based on PIC saying he noticed that auto throttles not engaged at 3 second mark.

khaosai · July 10, 2013

Hi,

I need to dig out some text books relating to performance A aircraft, but I think for the stall speed calculation it is as follows:

Reference speed for landing (VREF) is 1.3 or 1.23 times the stall speed.

When the landing weight is worked out based on the actual zero fuel weight added to the expected fuel on touchdown we get the VREF speed which is then entered into the flight management computer (FMC) via the control display unit. That then appears on the primary flight display speed tape located on the left hand side.

With auto throttle engaged we actually fly that speed plus an additional 5 knots, with the objective being to touch down at VREF. The actual landing distance is worked out based on that additional 5 knots of speed.

The B777 auto throttle logic during approach is designed to cope with gusty conditions and as a result is recommended during all phases of flight.

Engine spool up times will vary depending on the phase of flight. During approach with the flaps selected then the engines are at approach idle. The reaction time for the engine in the event of a go around will therefore be reduced. Based on experience my estimate is that the engine will reach full thrust after approx 4 to 5 seconds.

On approach the engines N1 parameter would be in the region of 55 to 60% when fully configured, i.e. gear down and flaps set at 30. The equivalent engine pressure ratio (EPR) would be 1.060 to 1.070. After landing you should cancel reverse thrust completely when the engines have reached idle which is approx 23% N1. From that you can see that full thrust would be achieved sooner on approach than lets say during take off.

Edited July 10, 2013 by khaosai

Mosha · July 11, 2013

Passengers were initially told to remain in their seats, and evacuation was not begun until 90 secs after the aircraft came to a halt.

Edited July 11, 2013 by Mosha

skippybangkok · July 11, 2013

On approach the engines N1 parameter would be in the region of 55 to 60% when fully configured, i.e. gear down and flaps set at 30

Yep, but because too high, they were descending fast on idle. Shud have pushed it up to this when hit glide path

skippybangkok · July 11, 2013

Now here is an interesting dynamic - the instructor has less total flying hours than the new 777 pilot. Sounds like a "pi" / "nong" type situation where "nong" is the instructor.

Maybe instructor did not dare to speak up ?

khaosai · July 11, 2013

Hi skippy,

Yeah interesting dynamics for sure. Lets see how they were communicating in the flight deck. Regarding the idle descent, may well be the case. All goes back to approach stabilisation, as power setting appropriate to the configuration is a parameter that needs to be considered.

Resilience needs to emphasized during crew training.

I always thought that hearing was the first sense to go until one of my peers recently highlighted that it is in fact touch that goes first then hearing.

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