Asiana Pilots Fault Equipment Malfunction in SFO Crash

[Autothrust Blue]

How is setting pattern altitude any safer than spinning it to zero?

...

Because it's the next usable altitude if you have to go-around vmc. Especially at smaller uncontrolled airports. Even if the tower gives you some thing different you don't have as far to go. Zero is never an altitude that'll be used. You might as well use all available tools. Which is what we do, set VFR pattern alt in vmc or missed approach alt in ifr conditions.

FLCH + 0 in the window gives you a suboptimal result...assuming, of course, you can't be bothered to fly the airplane.

 

[jtrain609]

How is setting pattern altitude any safer than spinning it to zero?

Because when you're climbing like a bat out of hell on the missed, you'll (hopefully) capture the missed approach altitude, or at least realize that maybe you should pull the power back a bit when you hear the 1,000 call while you're climbing at 4.000 FPM and think to yourself, "Oh crap, I'd better stop climbing here real fast or we'll out everybody on the ceiling in a second."

 

[Bumblebee]

OK cleared for the visual...fly the plane...oops go around, ok how high?...ok set that in the box oh crap passed that already...

actually even moreso because you are purposefully operating the aircraft and its systems, rather than just arbitrarily spinning a number in that means absolutely ZERO to the operation.

 

[typhoonpilot]

Is there no speed warning once you get into the bottom redline of the speed tape ? - And I'm assuming there's some sort of warning or caution range on the speed tape once you approach vSO..

I did not read the article and I am still not sure what mode the Asiana crew was in, but let's assume they were in Flight Level Change ( FLCH ) with field elevation set in the Mode Control Panel (MCP ).

On the B777 there are two ways to "disconnect" the autothrottles. The most common way is by pressing the autothrottle disconnect switches located inside the side of the autothrottle levers. This is usually done with one's thumb. That will result in an audible caution and illumination of the Master Caution light as well as an EICAS AUTOTHROTTLE DISC on the upper center display. Basically pretty hard to miss if they have been disconnected.

The second way to "disconnect" is to turn the A/T/ arm switches to off. One would only do this if directed to do so by a non-normal checklist. It is normally done in the event of an engine failure and only with confirmation from both pilots. So I can safely assume that the A/T arm switches were not turned off, or maybe not if they were really stupid.

So that leaves us in FLCH with field elevation set in the MCP. As the speed starts to decay lots of things happen. As the speed approaches the top of the amber band, basically the minimum maneuver speed ( 1.3G ), the Pitch Limit Indicator would appear if the flaps were not extended. We can assume they were extended for the approach so it should have already been in view. Next the trim function for speed is inhibited once reaching the top of the amber so the pressure required to hold the yoke would become much larger as speed decays further. In their case they got below the path so were not holding enough pressure to maintain a 3 degree path. As the speed drops further into the amber band ( about halfway ) there will be a Master Caution with EICAS AIRSPEED LOW and the speed box itself will turn amber. It is at this point that the autotrottle wake up feature would activate if not in FLCH or any other HOLD mode. Autothrottle wake up is a protective feature designed to avert just such an accident. It will automatically increase the thrust until the speed is at the top of the amber band or to the speed set in the MCP, whichever is higher.

It is normal procedure ( at least at intelligent airlines ) to turn off both flight directors and then turn the PM's back on as part of a visual approach or basic modes non-precision approach. It is stated to do this in the Boeing Flight Crew Training Manual. The reason for this is stated in the FCTM like this:

Turn both F/Ds OFF, then place the PM’s F/D ON. This eliminates unwanted commands for the PF and allows continued F/D guidance for the PM in the event of a go-around when pitch or roll mode is changed.

However, the more important reason is that it resets the autothrottles into a Speed mode. Turning just one flight director off will not do it, both of them have to be turned off. The turning the PM one back on part is for the reason quoted in the FCTM.

Hope that helps.



Typhoonpilot

 

[Screaming_Emu]

Zero is never an altitude that'll be used.

"Descend and maintain Gate B18"

 

[crazyjaydawg]

AFAIK, FedEx also sets MCP to zero.

That's because FedEx never goes around.

 

[N519AT]

We set field elevation rounded up to the nearest hundred (dirt) at glide alive in the Dash. Then at the 1000' to go chime, we set the missed approach altitude or if it's VMC, essentially whatever makes sense.

We don't have auto throttles or any of that jazz though.

 

[pullup]

Thanks Obama!!

 

[Tommay85]

AFAIK, FedEx also sets MCP to zero.

I sincerely don't see how it matters. A quick glance at the plate and you know where you need to go if you forgot. Personally, everything gets set to as low as I'm allowed to go for the current situation at the current employer. *bite

 

[///AMG]

Only a poor craftsman blames his tool. My .02

 

[Tommay85]

Only a poor craftsman blames his tool. My .02

Since flying airplanes is just as much blue collar as digging ditches or installing toilets, I certainly agree!

 

[dasleben]

I sincerely don't see how it matters. A quick glance at the plate and you know where you need to go if you forgot. Personally, everything gets set to as low as I'm allowed to go for the current situation at the current employer. *bite

The issue is when you're flying on the automation, the jet won't level itself at MDA if you're in V/S and get distracted (or FLCH, though that's used inside the FAF). It'll happily fly you into the ground.

In terms of the missed approach, VNAV or FLCH won't operate properly without having the MCP set higher. Sure, you can disconnect everything and fly it manually up to the altitude, but why work harder when you can work smarter?

 

[Tommay85]

The issue is when you're flying on the automation, the jet won't level itself at MDA if you're in V/S and get distracted (or FLCH, though that's used inside the FAF). It'll happily fly you into the ground.

In terms of the missed approach, VNAV or FLCH won't operate properly without having the MCP set higher. Sure, you can disconnect everything and fly it manually up to the altitude, but why work harder when you can work smarter?

Indeed, I guess I'm speaking more from my altitude select merely being something to reference. It has nothing to do with the autopilot. For better or for worse. Normally I would put the DH to the exact MDA/DH in the radar altimeter and the altitude to the nearest hundredth(upwards, since mine doesn't do hundredths or tenths ) in the altitude select. That's in what I currently have now though and I'm only going 130ish kias. Plenty of time to read things on the fly at those speeds in turbo-trash powered by a garret. Unless you have a headache, and can see the rum darkening the most flamboyant of cupware at your house, then mins and semantics don't exist!

Why work harder if you can work smarter? Did you used to be an awesome SPIFR guy(I know you were)? Irrelevant then!

 

[dasleben]

Indeed, I guess I'm speaking more from my altitude select merely being something to reference. It has nothing to do with the autopilot. For better or for worse. Normally I would put the DH to the exact MDA/DH in the radar altimeter and the altitude to the nearest hundredth(upwards, since mine doesn't do hundredths or tenths ) in the altitude select. That's in what I currently have now though and I'm only going 130ish kias. Plenty of time to read things on the fly at those speeds in turbo-trash powered by a garret. Unless you have a headache, and can see the rum darkening the most flamboyant of cupware at your house, then mins and semantics don't exist!

Why work harder if you can work smarter? Did you used to be an awesome SPIFR guy(I know you were)? Irrelevant then!

We're only doing 130-150 knots on the approach, too. We just like to be fancy.

 

[Pépé le Pilot]

I did not read the article and I am still not sure what mode the Asiana crew was in, but let's assume they were in Flight Level Change ( FLCH ) with field elevation set in the Mode Control Panel (MCP ).

On the B777 there are two ways to "disconnect" the autothrottles. The most common way is by pressing the autothrottle disconnect switches located inside the side of the autothrottle levers. This is usually done with one's thumb. That will result in an audible caution and illumination of the Master Caution light as well as an EICAS AUTOTHROTTLE DISC on the upper center display. Basically pretty hard to miss if they have been disconnected.

The second way to "disconnect" is to turn the A/T/ arm switches to off. One would only do this if directed to do so by a non-normal checklist. It is normally done in the event of an engine failure and only with confirmation from both pilots. So I can safely assume that the A/T arm switches were not turned off, or maybe not if they were really stupid.

So that leaves us in FLCH with field elevation set in the MCP. As the speed starts to decay lots of things happen. As the speed approaches the top of the amber band, basically the minimum maneuver speed ( 1.3G ), the Pitch Limit Indicator would appear if the flaps were not extended. We can assume they were extended for the approach so it should have already been in view. Next the trim function for speed is inhibited once reaching the top of the amber so the pressure required to hold the yoke would become much larger as speed decays further. In their case they got below the path so were not holding enough pressure to maintain a 3 degree path. As the speed drops further into the amber band ( about halfway ) there will be a Master Caution with EICAS AIRSPEED LOW and the speed box itself will turn amber. It is at this point that the autotrottle wake up feature would activate if not in FLCH or any other HOLD mode. Autothrottle wake up is a protective feature designed to avert just such an accident. It will automatically increase the thrust until the speed is at the top of the amber band or to the speed set in the MCP, whichever is higher.

It is normal procedure ( at least at intelligent airlines ) to turn off both flight directors and then turn the PM's back on as part of a visual approach or basic modes non-precision approach. It is stated to do this in the Boeing Flight Crew Training Manual. The reason for this is stated in the FCTM like this:



However, the more important reason is that it resets the autothrottles into a Speed mode. Turning just one flight director off will not do it, both of them have to be turned off. The turning the PM one back on part is for the reason quoted in the FCTM.

Hope that helps.



Typhoonpilot

Thanks for this clarification !

 

[Tommay85]

Eh, I'm sure I could fly this stupid Swearigen thing like a Cessna if I didn't mind the NTSing(half assed auto feather basically that just makes the airplane yaw back and forth really annoyingly). I do recognize that there's a difference when it comes to something properly heavy with engines that should be HUGE garrets, but aren't! A large airplane with Garrets... Holy HELL!!! WANT! The noise!

 

[Tommay85]

Eh, I'm sure I could fly this stupid Swearigen thing like a Cessna if I didn't mind the NTSing(half assed auto feather basically that just makes the airplane yaw back and forth really annoyingly). I do recognize that there's a difference when it comes to something properly heavy with engines that should be HUGE garrets, but aren't! A large airplane with Garrets... Holy HELL!!! WANT! The noise!

 

[///AMG]

Since flying airplanes is just as much blue collar as digging ditches or installing toilets, I certainly agree!

(cue Archer voice) duh

 

[Pépé le Pilot]

Let's not forget that the 3rd person in the cockpit was a 777 instructor...

 

[pete2800]

Only a poor craftsman blames his tool. My .02

That's what she said?