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Lionair plane down in Bali.

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Lionair plane down in Bali.

Old 16th Apr 2013, 17:35
  #421 (permalink)  
 
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It was raining so hard, it appeared as if we were under water...

BTW, we use VS to complete VNAV approaches that do not have guidance to the runway.
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Old 16th Apr 2013, 17:37
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OKC,

I completely agree with all of your post. No offence taken. Its an interesting discussion.

Our pilots understand the limitations of IAN, in fact we were one of the first carriers to buy it and use it. Understanding its limitations allows us to use it as another reference point on an approach. Our book is very clear as to its place in the hierarchy of references for the visual part of a IAP. It is remarkably accurate, simple to use and also not an ILS, as you said. We have a different philosophy on their use.

The use of FDs and AT are sometimes idiosyncratic to companies. Understanding their role should not be. The use of the AT may in fact be especially relevant to this accident.

Cheers,

Last edited by JPJP; 16th Apr 2013 at 17:38. Reason: Syntax
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Old 16th Apr 2013, 18:19
  #423 (permalink)  
 
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JPJP: As I'm sure you are well aware (though for the enlightenment of others) here's what the Boeing Flight Crew Training Manual (FCTM) has to say about use of the AutoThrottle on the B737-800:

"Autothrottle Use: Autothrottle use is recommended during takeoff and climb in either automatic or manual flight. During all other phases of flight, autothrottle use is recommended only when the autopilot is engaged in CMD."

"Autothrottle ARM Mode: The autothrottle ARM mode is normally not recommended because its function can be confusing. The primary feature the autothrottle ARM mode provides is minimum speed protection in the event the airplane slows to minimum maneuver speed. Other features normally associated with the autothrottle, such as gust protection, are not provided."

"Category II Operations: The autothrottles should be disconnected when the autopilot is disengaged."

"Decision Altitude (DA(H)) or Minimum Descent Altitude (MDA(H)): Disconnect the autothrottle when disengaging the autopilot."

"Final Approach using V/S: Disconnect the autothrottle when disengaging the autopilot.

Furthermore, the Boeing FCTM also includes numerous references to the following statement: "Turn both F/Ds OFF, then place both F/Ds ON. This eliminates unwanted commands for both pilots and allows F/D guidance in the event of a go-around." E.g. see: Circling Approach OR Final Approach using V/S....

Accordingly, unless one is flying an Autoland (i.e. landing with both autopilots engaged), when you disconnect the autopilot, Boeing recommend that you should also disconnect the auto-throttle.... and for certain non-precison approach types (if and / or when below the MDA on those approaches) also turn off, then on, your Flight Directors and wherein as JPJP (correctly) states above:
"On an IAN approach the FDs will guide you down to 50 feet above the runway. However, it's not good practice to rely on them since you are below MDA. PAPI, VASI or visual reference are the approved guidance below MDA;.... a difference in actual airfield QNH/Temp and VNAV Baro, may cause a difference between VGSI and the GP indication."
the point being that you can't rely on it to be correct, hence why it's classified as 'non-precision' (unlike an ILS), and that therein the Flight Director guidance might be duff... so turn them off to avoid any ambiguity in the guidance one is following (but have them available - in Pop-up' mode / hidden out of view unless the TOGA button is pressed - in the event that one has to go-around) !

Boeing have / had also issued a Operational Bulletin / Amendment to Part B FCOM 1 (which presently and for the life of me I can't seem to locate... though I'll edit this post with the relevant link when I do find it) which explicitly prohibits the practice of using "Speed Off" / 'Arm' mode during an approach & landing (apparently due to the auto-throttle - when in 'Arm' mode - being able to cause a tail-strike during a go-around from a very low height, as it can seemingly apply TOGA power 'too aggressively', and that there's also the risk that the auto-throttle might choose that very moment to fail and therein not apply the TOGA power that one is expecting, whilst one errantly uses both hands to pitch the aircraft into a climb... go figure?! .. ).

Last edited by Old King Coal; 16th Apr 2013 at 19:22. Reason: terminological inexactitude
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Old 16th Apr 2013, 18:20
  #424 (permalink)  
 
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I am curious on the mechanics of the weather radar and wind shear alert system. Doesnt the windshear alert use the weather radar? I am aware that some models use a laser system for windshear, I am just not positive about the connection between the 2 systems.
If the settings for the weather radar had been to look up, with the windshear system auto engage at 2500 feet, does this automatically reposition the dish?
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Old 16th Apr 2013, 18:41
  #425 (permalink)  
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Originally Posted by babemagnet
Inside info tells me :
Go around due to heavy rain runway not inside.

Badly flown go around due to the fact the autothrottle was off. Only toga was pressed and no thrust was added.
(I take 'inside' to mean "in sight").

If true, that sounds more and more like One-Two-Go at Phuket and brings in the notion that the aircraft may have stalled, ("rain-roughened" airfoil?) - I see BOAC's thread on TechLog - good one

The remarks make the most sense of anything produced on the thread thus far, (in terms of actual/possible causes. I certainly agree with most observations regarding the corporate and safety culture at Lion Air).

The METARs do indicate local CBs but not TS. That there was heavy rain there is little doubt but I find the windshear theory puzzling as it takes more than the kind of downdraft just heavy rain brings to compromise the energy level and reserve thrust from what would be a fairly light B738, (guessing 55t or so).

I wouldn't be surprised if the pitch attitude was quite high at impact, (15 - 18deg or so).

PJ2

Last edited by PJ2; 16th Apr 2013 at 18:53.
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Old 16th Apr 2013, 19:24
  #426 (permalink)  
 
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Earlier, my speculation was to point out the possibility that there may be a way to at least qualify, and hopefully quantify, the rain observations (and occasional absence of same) from the published reports and witness statements.
The statements and reference documents here and on the "Aerofoils in heavy rain" thread suggest the possibility of other cheese holes, at least one of which needs to be robustly filled: -
- The temperature and pressure sensor performance, affecting data accuracy; leading to one or more of
- Aircraft flight control (margins) becoming degraded
- Engine control may become degraded margin reductions in auto-relight, idle setting, acceleration schedule(s) and handling bleed (water centrifuging)

0 n 1
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Old 16th Apr 2013, 20:10
  #427 (permalink)  
 
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OKC,

We don't use the Boeing FCOM. Boeing approves our manuals along with the FAA. You'll probably be horrified to know that we use the AT without the AP, and we also de - select the AT on occasion. We do turn off the FD during circling approaches for obvious reasons, then we turn them back on prior to selecting a lateral and vertical mode. We only circle with VMC (common here). As I said, Boeing approved our manuals.

I disagree with you on the use of the FD below minimums, specifically in IAN, it's a useful tool. One of many, as long as one isn't relying on it solely and understands its limitations. I also multiply DME times three

We rely on our pilots not to forget to push the Thrust levers forward during a go around and not to allow a TOGA tail strike. So far so good ...... Touch wood.

By the way; low speed protection is disabled below 27feet. The incidents with AT de-selected, during the flare, were caused by low speed prior to 27 feet.

Apologies for derailing the thread slightly. Although; if this was a botched Go-around, the AT being on might have saved the crew from the walk of shame. As would shoving the thrust levers forward

Last edited by JPJP; 16th Apr 2013 at 20:18.
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Old 16th Apr 2013, 20:22
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Originally Posted by PJ2
I wouldn't be surprised if the pitch attitude was quite high at impact, (15 - 18deg or so).
Yep.
That is probably how the back of the aircraft got broken, maybe the starboard HS too (with the aid of a bit of coral)
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Old 16th Apr 2013, 23:07
  #429 (permalink)  
 
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All the technical jargon between JPJP and OKC makes me want to go and lie down - trying to get all that right and coping with all the variable options whilst approaching minima ? Just proves that today's airline pilots are computer button pushers, not pilots.

I always found it much harder to accurately set up, and control, even the basic autoland facilities of the auto-pilots of yesteryear to accomplish a Cat III ILS - than just clicking the A/P and A/T out and just flying the bl**dy thing, which of course was forbidden, it has to be auto all the way to touchdown - but on a Non-precision approach such as this was ??

When in doubt look out of the window and fly the aeroplane.

We rely on our pilots not to forget to push the Thrust levers forward during a go around.......
What an indictment of modern airline procedures !

How many more LIONS will be led to the slaughter ?
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Old 16th Apr 2013, 23:34
  #430 (permalink)  
 
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ExSpeedbird,

Apologies for the discussion between OKC and myself. I respect his opinion and its an interesting subject. His airline adheres to the Boeing manual. My airline had our manuals approved by Boeing. Nevertheless, there's a difference in procedures.

You're right. It's become an even more complex business. You also summed up the essence of the solution - Fly the airplane.

Today's worst professional pilots are button pushers. The best are able to operate the aircraft from zero level of automation through to the highest. Equally important is knowing when, and how much automation is appropriate.

Interestingly: I find that new F.O.s, when cleared by ATC for a tight visual approach, feel automation pressure. They then revert to manual operation of the controls. This is reassuring in some ways. It indicates to me that they are more comfortable hand flying the aircraft. It also shows that in some circumstances the automation can become slightly overwhelming. Either due to circumstances or inexperience. These are pilots with many thousands of hours in Jets, but the specific type may be new to them.

Lion Air appears to have some very, very new pilots.

Last edited by JPJP; 16th Apr 2013 at 23:55.
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Old 16th Apr 2013, 23:37
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Lomapaseo, I agree with your statement because I posted what a resident said about two miles away that the weather was fine. The wall of water may have been post crash. The FDR will say where their thrust levers and attitude were at and airspeed but I have a good guess. Automation dependency had them pushing buttons when they should have been aviating with their hands like us old timers always did. Who cares what the buttons do just aviate. That is what we were trained for.
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Old 16th Apr 2013, 23:57
  #432 (permalink)  
 
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As a teenager - 60 years ago (!) - I remember my then girl friends RAF Wellington Bomber pilot Father telling me, as I joined the RAF myself - " When in doubt, lash out, everything forward for speed " Mixture,Pitch,Throttles, Carb. heat," etc etc (according to type ).

Can't see what's different about that theory today ?
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Old 17th Apr 2013, 00:15
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I posted what a resident said about two miles away that the weather was fine.
He actually said he lived 4 miles east of the 27 threshold, which would put him in the water. He then said he lived in Sanur which is actually northeast of the airport and further away than 4 miles. Add the 2 miles to rwy 09 and we are already well past 6 miles away. He then said he had lived there for 30 years only to say a bit later that he had lived there for 20 years.

He wouldnt be high on my list of reliable sources.
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Old 17th Apr 2013, 00:22
  #434 (permalink)  
 
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Excellent Discussion

@OKC. Thank you taking the time and trouble to explain the NG systems and JPJP for adding to an excellent discussion.

@PJ2. Based on my observations of the weather in Bali at the time of the accident, I have always thought that your conjecture may be correct.

Just to add, this flight came from Bandung so was landing from the West onto 09. This configuration generally avoids the stack over South Bali with separation maintained by speed and usually involves a very slow and gentle descent from just after Surabaya. So there should not have been any last minute panic.

As an inadequate analogy, the NG system reminds me somewhat of the iDrive system in my BMW. It's a miracle of modern technology which I never use once set. Too many options and too difficult to use. Would it not make sense for line SOP's to minimise the number of options used, especially for Landing then incorporate that into Landing checklists?

Last edited by philipat; 17th Apr 2013 at 04:45.
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Old 17th Apr 2013, 00:57
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Originally Posted by babemagnet
Inside info tells me :
Go around due to heavy rain runway not inside.

Badly flown go around due to the fact the autothrottle was off. Only toga was pressed and no thrust was added
Insider info :

F/O selects FLAPS 15 passing the MDA, without go-around command (that's explain the "drag down from the air" claimed by PIC).
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Old 17th Apr 2013, 01:24
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Cheese holes

Old King Coal, thanks for your contribution, especially the explanation of Integrated Approach Navigation.

The Bali VOR/DME approach for 09 (15 MAR 13) has a profile requiring 290ft per nm. (2.74 deg rather than 2.8 as quoted) This results in an arrival at the 2.0DME Missed Approach point at 500ft, still above the MDA of 470ft.


Could this upset the automatics (or a crew) when performing an IAN approach ?
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Old 17th Apr 2013, 01:27
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Sanur Metar

@philipat

Sanur is about 10 miles away from the point of the raining or not raining.

Witnesses were inside the plane, pax, 2 pilots and reported rain.

Rain is local and makes it difficult to forecast it, not only in Bali. U can also see a dark clound in the pictures made shortly after the crash.

It would be surprising, that only rain or maybe the more difficult handling of a B737 than a bmw cause the crash.
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Old 17th Apr 2013, 02:07
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I live in the Florida Keys so know how localized cells are but wait until the FDR results are out and see what really happened. Thrust lever position, speed, sink rate and attitude and we will know what happened. I have flown into a cell at MIA and gone around with a FAA check airman looking over my shoulder and it was a manual normal go around. No big deal. But we were just flying a B727 so couldn't push any buttons. Life was simple then.
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Old 17th Apr 2013, 02:14
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This all happened below MDA when we lost the runway.
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Old 17th Apr 2013, 02:14
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Weather @tmny

I don't know how many times I have to repeat this but I DID NOT say there was no RAIN. I acknowledged from the outset that "There was scattered low cloud and some localised rain showers" BUT NO TS. And I stand by that and only that. That is a fairly normal condition landing at DPS yet this is the first time that any aircraft has landed on the reef.

The presence of surfers, as noted by other posters also, would tend to confirm the lack of TS, when all good surfers retire to the bar.

I find it most interesting that Lion would have issued a statement to the effect that there was no rain and that visibility was good when they could have retained that possibility as a mitigating circumstance. If proven incorrect, as does seem to be the case, Counsel for the Passengers will latch right onto that.

Last edited by philipat; 17th Apr 2013 at 02:29.
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