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another autothrottle rollback

densoo

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Qantas 737 suffers altimeter fault similar to doomed THY aircraft var era_rc = { ERADomain: 'atwonline.firstlightera.com' };
April 13, 2009

Qantas and the Australian Transport Safety Bureau said they will consult with and assist Dutch crash investigators after a QF 737-800 last week suffered a radio altimeter malfunction similar to the one that is suspected of causing the loss of a Turkish Airlines -800 on approach to Amsterdam on Feb. 25.
Qantas Flight 1020, an -800 operating from Hobart to Sydney on April 7, experienced the radio altimeter fault on approach. According to a QF spokesperson, the -800 was "at approximately 100 ft. when the captain's radio altimeter indicated that the aircraft was at around 10 ft., about where the auto thrust activates full retard on the throttles."
As in the THY crash, the captain's altimeter was indicating a different set of data than the first officer's (ATWOnline, March 5). "Upon noticing the fault, the captain immediately disconnected from the auto thrust and manually flew the aircraft into Sydney," the spokesperson said. "It is Qantas flight operations policy for pilots to guard the thrust levers and fly with hands on the levers when the aircraft is on auto, which ensures that should a fault with the thrust levers occur, the pilots are immediately able to fly manually."
The carrier self-reported the incident to ATSB, which confirmed it will investigate due to the similarity of the fault to the assumed cause of the THY crash. The QF spokesman told ATWOnline that "there is no suggestion by the ATSB that Qantas or its pilots were at fault. This investigation is simply to assist European regulatory authorities."
A preliminary investigation by the Dutch Safety Board revealed that the only fault discovered on the aircraft was in the captain's radio altimeter, which suddenly changed from 1,950 ft. to read -8 ft. in altitude although the right-hand altimeter functioned correctly.

Do some carriers require autothrottle to 50' or even landing? I can see the FAA's response to this--autothrottle off at 1,000' unless flying a coupled approach and landing. That still won't prevent rollback though if the RA is wrong.
 
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Aerosurfer

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we never turned them off on the 170.
 

propilot

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We usually fly A/T all the way to touchdown in the MD11, but you're hands on from 10K to touchdown. Never forget who's flying the airplane.
 

EatinRamen

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I fly the 737 for my airline, and we are required to disconnect the a/p and a/t 50' below the DH on a CAT I ILS.

And yes, we are also required to be hands on below 10K... as everybody always should!
 

Mongolikecandy

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I fly the 737 for my airline, and we are required to disconnect the a/p and a/t 50' below the DH on a CAT I ILS.

And yes, we are also required to be hands on below 10K... as everybody always should!

And I never read in the cockpit!
 

luckytohaveajob

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On the B737, I have personally experienced an A/T roll back at cruise on a 737-300.

At FL350, with LNAV and VNAV engaged, the auto throttles brought the engines back to idle in cruise. I immediately disconnected and pushed the throttles up to cruise. The FMC also displayed reverse video and a changed commanded speed of 190 knots on the CRZ page from the normal .74 as well as the descent page which was a significant obervation for mx.

Upon landing, I wrote it up and spoke with maintenance. Mx expected to find a failed TAT sensor which is an A/T input that would cause such a roll back. It appears the failure mode of the A/T inputs cause the servos to command idle thrust on the B737 series.

I don't know what mx ended up signing off the next day.
 
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get2flyin

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I fly the 737 for my airline, and we are required to disconnect the a/p and a/t 50' below the DH on a CAT I ILS.

And yes, we are also required to be hands on below 10K... as everybody always should!

How about being hands on in the Airbus where the Autothrust system doesn't move the thrust levers?
 

Homer Jay

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Who the hell uses the autothrottles on a visual approach down to 50 feet? I know the article does not state the weather conditions but some of the responses indicate that people use them down to the bottom. 99% percent of the people I fly with, myself included, turn off the autothrottles at the same time the autopilot comes off. Doesn't anyone FLY anymore? Just curious....
 

kg911

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At our airline, anytime the autopilot is disconnected, the autothrottles are required to be disconnected as well. Our cat III hgs require autopilot/autothrottle disconnect at 500' afl. Cat III autoland is fully coupled through touchdown, at which point autopilot/autothrottle is disconnected manually.
 
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ron burgundy

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Who the hell uses the autothrottles on a visual approach down to 50 feet? I know the article does not state the weather conditions but some of the responses indicate that people use them down to the bottom. 99% percent of the people I fly with, myself included, turn off the autothrottles at the same time the autopilot comes off. Doesn't anyone FLY anymore? Just curious....


Airtran 717 pilots.
 

Mamma

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How about being hands on in the Airbus where the Autothrust system doesn't move the thrust levers?

Although this is a Boeing problem right now, I would think you would be paying attention to your speed. If the thrust levers initiated a decrease to idle at a less than ideal position, you could pull them back into a manual mode and fly it like a normal plane. If you are not ready with your hands at low altitude (should something like this happen in the Bus) then you will be a participant in Mr Toad's Wild Ride.
 

DrewBlows

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Although this is a Boeing problem right now, I would think you would be paying attention to your speed. If the thrust levers initiated a decrease to idle at a less than ideal position, you could pull them back into a manual mode and fly it like a normal plane. If you are not ready with your hands at low altitude (should something like this happen in the Bus) then you will be a participant in Mr Toad's Wild Ride.

So you are advocating keeping your hands on the thrust levers and joystick of an airplane that doesn't move them with the auto modes engaged? Really!??

I'm no expert, but my guess is the time time it takes to move ones hands from resting position (or whatever position they are in) to flying position is measured in tenths of seconds. Personally, I would rather have pilots think about what they are about to do for few seconds then to give a knee-jerk reaction.
 

Wesb737fo

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We usually fly A/T all the way to touchdown in the MD11, but you're hands on from 10K to touchdown. Never forget who's flying the airplane.

Bingo. I've got lots of time on 73NG's and have never seen that malfunction, however, there's always a first time, which is why my hands stay on during auto-lands.

Also, during visuals we are supposed to leave the A/T's on, but you can punch the speed button as technique to give you floor protection and still have the A/T's in case you need to go around.
 

ImbracableCrunk

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Also, during visuals we are supposed to leave the A/T's on, but you can punch the speed button as technique to give you floor protection and still have the A/T's in case you need to go around.

When do you kick them off?
 

starchkr

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I tend to become "connected" with the bus when the 1000' auto callout sounds. This lends to quicker response in case something happens. However, the bus will not go to idle on its own when in the flare like it appears the 73 will. We must manually retard the throttles or the bird will fly around the rest of the day screaming at us(retard, retard, retard) while at a manged speed set by the computer.

I know our training dept suggests we disconnect the a/p and a/t on a regular basis to get a feel for the bird, however, leaving them on is standard practice, especially the a/t to touchdown on all landings, and the a/p on all cat 2/3.
 

Ratherbsurfing

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And I never read in the cockpit!

I can't stand this kind of apathetic attitude. The crash in Amsterdam should never have happened. Take responsibility for the lives you're responsible for, shut up and concentrate below ten, and fly the jet. When and how did mediocrity become cool and virtuous?
 

DrewBlows

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I can't stand this kind of apathetic attitude. The crash in Amsterdam should never have happened. Take responsibility for the lives you're responsible for, shut up and concentrate below ten, and fly the jet. When and how did mediocrity become cool and virtuous?

Was the crash in Amsterdam caused by reading in the cockpit?
 
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