That's where some of the recent confusion in this thread comes from:

 

- A/THR has different modes: speed and thrust, depending on the vertical mode you choose

Thrust will change to keep your speed, anything else is a misinterpretation or a rubbish design

 

Nothing against you Oliver, I am just wondering what are we flying on ?

olli4740, on 09 Jul 2013 - 12:15 PM, said:

That's where some of the recent confusion in this thread comes from:- A/THR has different modes: speed and thrust, depending on the vertical mode you choose

There are indeed two modes but the thrust mode is never used in finals (confirmed by a 777 captain, FI and friend).

bendead, on 09 Jul 2013 - 12:11 PM, said:

Not really, it controls thrust, which will give you a different glide slope more than a speed increase on final

In the approach/landing phase, the variable the AT is controlling is speed (you set a speed set point and the AT will modulate thrust to maintain the desired speed).

 

Rgds,

Bruno

 

PS : (edit) the need to maintain the correct approach, then landing speeds seems obvious, especially in light of this accident. That's what the AT is doing when it is ON and operating correctly.

Thrust will change to keep your speed, anything else is a misinterpretation or a rubbish design

 

Nothing against you Oliver, I am just wondering what are we flying on ?

 

 

Be aware this is a B777 thread.  

 

As a different example, look at the attempted go-around: The corresponding A/T mode is (would be, Asiana probably applied thrust manually) a thrust mode and it's the pilot's duty to control pitch in order to achieve and maintain the desired speed on climb (something in the area of V2 or V2+xx).

 

Two different concepts (thrust for speed/pitch for speed). Both are legitimate and one is chosen depending on the situation at hand.

There are indeed two modes but the thrust mode is never used in finals (confirmed by a 777 captain, FI and friend).

In the approach/landing phase, the variable the AT is controlling is speed (you set a speed set point and the AT will modulate thrust to maintain the desired speed).

 

Rgds,

Bruno

 

PS : (edit) the need to maintain the correct approach, then landing speeds seems obvious, especially in light of this accident. That's what the AT is doing when it is ON and operating correctly.

 

 

It's the same in any aircraft: On landing you have a Vref/Vapp to take care of.

As a different example, look at the attempted go-around: The corresponding A/T mode is (would be, Asiana probably applied thrust manually) a thrust mode and it's the pilot's duty to control pitch in order to achieve and maintain the desired speed on climb (something in the area of V2 or V2+xx).

You're right : Considering how slow they were, one can expect the only proper response would have been : TOGA ! (forget the AT).

It's the same in any aircraft: On landing you have a Vref/Vapp to take care of.

Yes but I was answering your previous post. My point : In the landing configuration, AT is either in speed mode or OFF and it seemed to me that that's not what you were writing (unless there was a misunderstanding of course).

 

Rgds,

 

Bruno

(...)

Yes but I was answering your previous post. My point : In the landing configuration, AT is either in speed mode or OFF and it seemed to me that that's not what you were writing (unless there was a misunderstanding of course).

 

Rgds,

 

Bruno

 

 

Agreed on that A/T on landing.

 

The confusion I was referring to ... I don't feel like going through 20 pages again, but IIRC it wasn't restricted to landings. It appeared to me as a more general discussion on how to use the throttles.

This thread is a shining example of how great the AVSIM community is. There is more and better info here than on all of the news channels combined.

 

Thanks, all !

I feel privileged to eavesdrop on the conversation here between Ro, KevinAu and Rob here. Thank you for your insight into the procedures and information.

 

Speculation is human nature, something we should not avoid. What we have been hearing and seeing on CNN/Fox and co is not even speculation to some extent.

 

My respect to the cabin crew who managed to get 300+ people off a burning aircraft with almost no loss of life. My thoughts to the families of those injured or killed in this unnecessary and tragic event.

 

Although it very much looks like pilot error, we must wait and see what the investigation unturns and act accordingly.

 

A

Agreed.  Really appreciate the commentary and the ideas.  

 

Pretty sure that every hour of watching CNN cost you 3 IQ points.  Much more direct and accurate speculation here. 

 

 

Question from the peanut gallery:  What are flight rules for a long flight like this, 11 hours?  How do they handle the impact of sleep and fatigue?  

Agreed.  Really appreciate the commentary and the ideas.  

 

Pretty sure that every hour of watching CNN cost you 3 IQ points.  Much more direct and accurate speculation here. 

 

 

Question from the peanut gallery:  What are flight rules for a long flight like this, 11 hours?  How do they handle the impact of sleep and fatigue?

 

There are 4 pilots, a relief crew so that origional crew can rest. Then they switch back after.

This thread is a shining example of how great the AVSIM community is. There is more and better info here than on all of the news channels combined.

 

Thanks, all !

 

I agree, that is because all of us here love planes and study aviation so even those of us who are not pilots know a hell of a lot more than the average person. Plus I am sure the news networks have the experts dumb it down when they are speaking on the news channels so the average person can understand it.

 

When I was on my lunch break at work last night a few co workers started talking about this crash. One of them said the runways at KSFO are very short and when you land there it looks like your going to crash into the water and then went on to say they have to land very close to that rock ledge so they can stop in time.. Then also added that pilots can't see out the front of the plane when landing because it's angled up.

 

I kept my mouth shut, I did not feel like explaining how

 

1. the 28's are 11000 plus feet long

 

2. the concept of a displaced threshold

 

3. Pilots can see out the front quite well

 

BTW another guy in the conversation said the plane hit at 400 MPH!!!!!!!

 

BTW I don't want to brag because I think it was pretty obvious but I hit the cause dead on in my post prior to the NTSB initial info. I said that IF pilot error is the cause then the most likely scenario is the flight crew lost situational awareness and allowed airspeed to decay to the point of causing a unstable approach and if eyewitness reports of a late spool up is true that a recovery attempt was too late.

 

 

You heard it right here on avsim first 3 hours before the NTSB report.

 

 

LOL the news networks should hire me as a aviation expert. LOL LOL

 

 

OK just kidding there..   

I can give you ten tips for the stock exchange - up to five of them will prove to be correct for solely statistical reasons.

 

Call me a financial markets guru, please!  

1,000' IMC

500' VMC.

 

That was an exageration for effect, Hyperbole.

 

Indeed, I'd hope I was a pretty humble guy, and am well aware of how aircraft seem to suddenly turn against you the moment you declare that you've mastered them, the 321 has done that numerous times I should have learnt at this stage. No offence intended, I'd hope I didn't come across as arrogant.

 

Regards,

Ró.

 

I don't think you've come across as arrogant at all. Frankly I'm surprised at the suggestion from Kevin. Way over the top.

olli4740, on 09 Jul 2013 - 10:26 AM, said:

 

I can give you ten tips for the stock exchange - up to five of them will prove to be correct for solely statistical reasons.

 

Call me a financial markets guru, please!

i was just joking but regardless

 

i still got it right.

 

This was my thoughts about it at the time.

 

I read the eyewitness reports and while these reports are usually inaccurate all the ones from the ground and in the plane seemed to indicate the plane was very nose high at the very end of flight.

 

Then looking at the debris field you could see the tail hit well before anything else and the only cause I can think of for the deck angle to be that extreme was a stall or near stall condition.

 

I looked at the flightaware data that showed low airspeed and compared it to several flights prior, none of them indicated airspeed as low as the flight that crashed..

 

So at that point the one thing that is clear if that info is correct is this plane had the airspeed decay on short final.

 

So then what are the most likely causes of that?

 

Most likely cause if pilot error is that that flight crew lost situational awareness and then airspeed decayed causing the approach to become unstable.

 

My other possible cause I thought was likely was what happened to BA038

 

BTW this is not the first time a airliner has crashed because the pilot flying lost track of airspeed. go look at the colgan air NTSB video and watch the airspeed tape and throttle lever position prior to the stall. He advanced the condition levers but left the throttle near idle.

i was just joking but regardless 

 

i still got it right.

 

 

Are you implying I missed your three LOL's?

 

Just joking myself ...

Are you implying I missed your three LOL's?

 

Just joking myself ...

 

So no stock tips ?