highflyer9790
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Reverse Thrust: How Often?

Sat Apr 01, 2006 2:50 am

A few years ago we landed in ATH on a BA 757 and no reverse thrust. since then, ive noticed on occasion reverse thrust isn't always used. could this be to Foreign object damage, hazards, certain requirements, or just choice of rolling to the last taki way therefore eliminating the need? is it due to engine wear?

comments appriciated!

ps- what is "idle" reverse?
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RichardPrice
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 2:56 am

These days, brakes are cheaper to maintain than engines, so the extra wear and tear thrust reversing puts on engines arent worth it.
 
Tristarsteve
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 3:55 am

Perhaps your aircraft had a U/S Reverser on your side.
Thrust reverse is normally deployed to Reverse Idle, but only powered up on a short runway.
 
SlamClick
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 3:59 am

As of my last duty day it was still policy here to use reverse thrust every landing where it was not prohibited.
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avioniker
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 4:25 am

The two companies I've been with that actually studied brakes vs reverse found a significant savings using reverse thrust over replacing brakes. (One was a very old "legacy" airline and one a newer company.)
Unless you base engine life and cycle count on power lever cycles the acceleration of the engine in reverse isn't any different than in normal operation aside from the translating sleeve or clamshell movements.
I'm personally not aware of any increased wear on the engine in reverse over normal thrust (BR-715 excepted of course).
These are just my own personal experience based views of course... Smile
One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533
 
ba299
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 6:12 am

At BA our policy are: Idle reverse except in case on runway contamination, autoland.
 
greasespot
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 8:18 am

Quoting HighFlyer9790 (Thread starter):
ive noticed on occasion reverse thrust isn't always used. could this be to Foreign object damage, hazards, certain requirements, or just choice of rolling to the last taki way therefore eliminating the need? is it due to engine wear?

 no 

Many airports in Europe severly restrict TR use under normal condtions.

A TR requires very low MTCE and it is much cheaper to use it than brakes....Especially at weights.

Since you do not count the time the TR is used it does not add wear and tear on it. After 6 years in an engine shop I have yet to see an engine that failed due to TR use.....In this day and age most engines come into a shop because a disk has reached it scrap life....
Sometimes all you can do is look them in the eye and ask " how much did your mom drink when she was pregnant with you?"
 
B747FE
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 9:34 am

Quoting Greasespot (Reply 6):
In this day and age most engines come into a shop because a disk has reached it scrap life....

Indeed.
But depend on the company policy/SOP. For us, 747 classic, steel brakes, short hops/quick turn-around, we are supposed tu use T/R as necesary and minimum brakes.

Regards,

B747FE.
"Flying is more than a sport and more than a job; flying is pure passion and desire, which fill a lifetime"
 
VC-10
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 10:21 am

If the a/c has carbon brakes it is more economical to refrain from using Rev Thrust.

Carbon brakes have a optimum operating temperature range. Using Rev Thrust delays the brakes reaching that temp range which increases brake wear & shortens their life. If the brake unit doesn't reach the manufacturers certified o/haul life when there is no defect, they will charge the airline more for the ensueing o/haul.
 
highflyer9790
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 10:51 am

Quoting B747FE (Reply 7):
In this day and age most engines come into a shop because a disk has reached it scrap life....

Now that we have established that, how powerful is reverse thrust? can plane land with no brakes at all? plus, to my knowledge, RT is actually just the re-direction of the air flow/exhaust....right?
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AmericanAirFan
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RE: Reverse Thrust: How Often?

Sat Apr 01, 2006 2:56 pm

Quoting HighFlyer9790 (Reply 9):
Now that we have established that, how powerful is reverse thrust? can plane land with no brakes at all? plus, to my knowledge, RT is actually just the re-direction of the air flow/exhaust....right?

I know WN doesn't use Autobrakes on landing but just use reverse thrust but they do apply manual braking once at a slower speed. So yes on a fairly lengthened runway you can stop without brakes but just reverse thrust and on the MD-80s they have the clamshells and are able to do a powerback.

I have another question. Though noone has beleive me you might here I was enroute AUS-ELP on a WN 737-300 and when we landed no airbrakes were used but reverse thrust was. then we flew ELP-LAX when I was about to get off the plane I asked the pilot why he hadnt deployed the spoilers at ELP and he had no idea that they didn't I have a picture with the runway bluring by and no airbrakes but full flaps and we had reverse thrust. So what kind of impact does not having the airbrakes have on landing in regular conditions? All I know is that they dump the lift and put the weight reassuringly onto the wheels rather than the wings. Can anybody explain?

Interesting topic and good question btw.

-AmericanAirFan
"American 1881 Cleared For Takeoff One Seven Left"
 
highflyer9790
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RE: Reverse Thrust: How Often?

Sun Apr 02, 2006 2:33 am

Quoting AmericanAirFan (Reply 10):
Interesting topic and good question btw.

Thanks a lot...you guys certainly have good answers too.  bigthumbsup 

Quoting AmericanAirFan (Reply 10):
So what kind of impact does not having the airbrakes have on landing in regular conditions? All I know is that they dump the lift and put the weight reassuringly onto the wheels rather than the wings. Can anybody explain?

yes, as far as i know the spoilers bisturb the airflow over the wing ensuring that the plane remains on the ground. it dumps lift. remember the jetblue emergency landing with the twisted nose gear at LAX? he didnt use spoilers because it enabled him to keep the nose wheel off the ground for a longer amount time. anyhow, spoilres are always set to auto, and they auto deploy on landing.

regards!
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Skyslave
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RE: Reverse Thrust: How Often?

Sun Apr 02, 2006 5:50 am

Quoting AmericanAirFan (Reply 10):
Now that we have established that, how powerful is reverse thrust? can plane land with no brakes at all? plus, to my knowledge, RT is actually just the re-direction of the air flow/exhaust....right?

My dad is a 747-400 captain. He was telling me that with the combonation of aerodynamic breaking (nose up attitude, ground spoilers etc..) and thrust reversers, he rarely has to use the breaks at all.
 
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HAWK21M
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 1:15 am

Brakes are rarely used,as compared with T/Rs.But then the Exceptions can be Regulatory based,SOP.
regds
MEL
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EssentialPowr
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 3:23 am

Quoting HAWK21M (Reply 13):
Brakes are rarely used,as compared with T/Rs.But then the Exceptions can be Regulatory based,SOP.
regds
MEL

??? I Don't agree w/ that at all.

1. Most US operators use autobrakes as part of the landing profile (Boeing or Airbus), which means brakes are applied as soon as the a/c knows it's on the ground and dissipate the majority of the kinetic energy.

2. With fuel costs where they are, brakes are cheaper than TRs.
 
KAUSpilot
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 4:36 am

Our company SOP is to deploy "the buckets" on every landing but only to spool up the engines if it's necessary to stop in a safe distance.

I could count on one hand the number of times I've spooled up the reversers in the past 6 months.

I've noticed that pilots on the 737's I ride on regularly are spooling up their reversers less and less as well. The fuel burn and engine wear and tear caused by using substantial reverse thrust power has been determined to be more expensive than the wear and tear caused by consistent break usage.
 
highpeaklad
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 4:57 am

I've just flown MAN-JFK and return on a BA 767 and no reverse seemed to be used on either landing. I couldn't see the engines so possibly idle reverse was engaged, would this give a noticable change in engine noise in the cabin?

Chris
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kaddyuk
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 5:17 am

As VC-10 said, carbon brakes are temperature sensitive... Unlike the steel brakes you find on old aircraft, the carbon brakes work better the hotter they are... Not only that, but it keeps noise down around the airport and makes local residents happy...

If you use reverse thrust AND braking, your brake unit might last 1500 cycles. If you just use brakes with no reverse thrust, well, i've seen units as high as 2400 cycles... the difference is MASSIVE!

and FYI, each landing takes about one thousandth of an inch off a brake unit...
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Starlionblue
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 6:42 am

Quoting Highpeaklad (Reply 16):
I've just flown MAN-JFK and return on a BA 767 and no reverse seemed to be used on either landing. I couldn't see the engines so possibly idle reverse was engaged, would this give a noticable change in engine noise in the cabin?

Idle reverse would likely not make much of a noticeable noise.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
AmericanAirFan
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 7:09 am

Quoting KAUSpilot (Reply 15):
Our company SOP is to deploy "the buckets" on every landing but only to spool up the engines if it's necessary to stop in a safe distance.

I could count on one hand the number of times I've spooled up the reversers in the past 6 months.

I've noticed that pilots on the 737's I ride on regularly are spooling up their reversers less and less as well. The fuel burn and engine wear and tear caused by using substantial reverse thrust power has been determined to be more expensive than the wear and tear caused by consistent break usage.

To add more to this discussion at AUS I always see the Delta Express and Continental Express and American Eagle don't use reverse thrust when landing on 17L and I can usually hear the brakes gripping the wheels very nicely. KAUSpilot I notice you are an ERJ pilot so can you explain on this at all I've only noticed that the ERJs dont even put R/T at idle thrust.
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Starlionblue
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 7:18 am

Quoting AmericanAirFan (Reply 19):
KAUSpilot I notice you are an ERJ pilot so can you explain on this at all I've only noticed that the ERJs dont even put R/T at idle thrust.

There's a simple explanation. Some ERJs don't have reverse thrust capability. It's a customer option.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
vikkyvik
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 9:45 am

Keep in mind also that thrust reverse is generally only used at higher speeds (generally above either 60 or 80 kts I think - I forget which). At lower speeds you risk the engine reingesting its own exhaust. So most of the braking power at lower speeds comes from the wheel brakes.

Also, autobrakes are designed so that each setting gives you a certain deceleration rate. So if you also use some thrust reverse, there will be less wheel brake pressure, and when you stow the reversers, the wheel brakes will pick up the slack.

Ground spoilers are used both as airbrakes, and also to dump the lift generated by the wing, thus putting more weight on the wheels and increasing wheel brake effectiveness.

At least, that's my understanding. Please correct me if I'm wrong.

~Vik
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KAUSpilot
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 10:59 am

Quoting AmericanAirFan (Reply 19):
KAUSpilot I notice you are an ERJ pilot so can you explain on this at all I've only noticed that the ERJs dont even put R/T at idle thrust.

Yep, some of eagles RJ's don't have the T.R's installed, and it was their policy for a long time not to use them at all. However, I believe a runway overrun incident at DSM back in late '04 caused them to revise this policy; I believe they now deploy the buckets on aircraft which are so equipped at the pilot's discretion.

All of Expressjet's aircraft are equipped with T.R's. It's always been their policy to deploy them, but not spool them up unless necessary.
 
Pihero
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RE: Reverse Thrust: How Often?

Mon Apr 03, 2006 8:25 pm

Quoting Skyslave (Reply 12):
My dad is a 747-400 captain. He was telling me that with the combonation of aerodynamic breaking (nose up attitude, ground spoilers etc..) and thrust reversers, he rarely has to use the breaks at all.

That technique is an absolute NO-NO these days.
Contrail designer
 
FDXmech
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 1:57 am

Quoting Kaddyuk (Reply 17):
If you use reverse thrust AND braking, your brake unit might last 1500 cycles. If you just use brakes with no reverse thrust, well, i've seen units as high as 2400 cycles... the difference is MASSIVE!

and FYI, each landing takes about one thousandth of an inch off a brake unit...

The cost of overhauling a carbon brake is also massive. FDX put out some info a few years ago saying a new carbon stack cost approx $40,000.
You're only as good as your last departure.
 
A/c train
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 2:12 am

Bend the bracket, put some swan necks on the wear pin, you'll get a few more landings out of it!
Has anyone seen the PPE requirements for changing a carbon brake unit! quite worrying.
 
highflyer9790
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 8:42 am

Quoting KAUSpilot (Reply 15):
Our company SOP is to deploy "the buckets" on every landing but only to spool up the engines if it's necessary to stop in a safe distance.

So, sometimes it may look like a RT landing, but you can manually reverse a controlled amount? (if that makes any sense)
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KAUSpilot
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 8:57 am

Quoting HighFlyer9790 (Reply 26):
So, sometimes it may look like a RT landing, but you can manually reverse a controlled amount? (if that makes any sense)

Exactly...there is a "detent" in each throttle (or thrust lever as we call it) column....to operate the engines in reverse, you have to pull upward on a pair of spring loaded switches just beneath the throttle grips with your middle finger and forefinger, then pull the thrust levers backward from the detent....the further back you pull, the more power the engine generates, and the greater the resultant stopping power.
 
highflyer9790
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 10:35 am

Quoting KAUSpilot (Reply 27):
Exactly...there is a "detent" in each throttle (or thrust lever as we call it) column....to operate the engines in reverse, you have to pull upward on a pair of spring loaded switches just beneath the throttle grips with your middle finger and forefinger, then pull the thrust levers backward from the detent....the further back you pull, the more power the engine generates, and the greater the resultant stopping power.

Ok thanks...I knew how they were activated and now it makes sense...
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highflyer9790
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 11:34 am

121
 
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Starlionblue
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 11:37 am

Quoting KAUSpilot (Reply 27):
Quoting HighFlyer9790 (Reply 26):
So, sometimes it may look like a RT landing, but you can manually reverse a controlled amount? (if that makes any sense)

Exactly...there is a "detent" in each throttle (or thrust lever as we call it) column....to operate the engines in reverse, you have to pull upward on a pair of spring loaded switches just beneath the throttle grips with your middle finger and forefinger, then pull the thrust levers backward from the detent....the further back you pull, the more power the engine generates, and the greater the resultant stopping power.

On FBW Airbi you just pull back beyond idle.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
vikkyvik
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 11:58 am

Quoting Starlionblue (Reply 30):
On FBW Airbi you just pull back beyond idle.

Correct me if I'm wrong, but I believe that on the Airbus there are also levers to engage the reversers, located forward of the thrust levers. I think you can see them in this photo:


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Click here for bigger photo!

Photo © Sam Lambert



~Vik
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
KAUSpilot
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 3:11 pm

Some of my Eagle friends would like me to correct myself about their TR policy:

Quote:
actually, all of our emb's have TR's....the policy is...IDLE reverse if
the runway is contaminated or any runway with usable length 7000ft or
shorter and of course max reverse is always available in an emergency or
during an abort
 
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LTU932
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 4:48 pm

Quoting Vikkyvik (Reply 31):
Correct me if I'm wrong, but I believe that on the Airbus there are also levers to engage the reversers, located forward of the thrust levers.

Not on the A32X it seems.

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Photo © Andrew Hunt - AirTeamImages
View Large View Medium
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Photo © John Farrington - FlightLineImages


However the A330, along with the A340 does have those extra levers for the T/Rs, while the A380 only has two of those extra levers, since only the inboards have T/Rs:

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Photo © Rui Sousa - Madeira Spotters
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Photo © Michael Fritz



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Photo © Tango3 - Team Ninervictor

 
Mir
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RE: Reverse Thrust: How Often?

Wed Apr 05, 2006 8:12 pm

Quoting HighFlyer9790 (Thread starter):
ps- what is "idle" reverse?

Idle reverse is pretty much what it sounds like - the reversers are deployed, and the engine is at idle power.

Quoting Vikkyvik (Reply 31):
Quoting Starlionblue (Reply 30):
On FBW Airbi you just pull back beyond idle.

Correct me if I'm wrong, but I believe that on the Airbus there are also levers to engage the reversers, located forward of the thrust levers. I think you can see them in this photo:

I believe that there are levers that you have to lift up to allow you to move the throttles back behind idle, but that they're only safety mechanisms.

-Mir
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highflyer9790
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RE: Reverse Thrust: How Often?

Thu Apr 06, 2006 12:04 am

The A320 has to release levers to allow the throttles to go back to RT position.


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Photo © Quinn Savit

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highflyer9790
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RE: Reverse Thrust: How Often?

Thu Apr 06, 2006 12:07 am

Here are two diagrams...the secong shows the A320 style throttles...






highlyer
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B757capt
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RE: Reverse Thrust: How Often?

Thu Apr 06, 2006 8:15 am

Quoting AmericanAirFan (Reply 10):

Well there is a little more to the WN story.

Orginally Southwest operated the 737-200,-300.
The SOP was written for the -200 which some had no autobrake feature. Some of their -300 also were not equiped with the autobreak feature either.

When the -500's, and -700's started to arrive WN MEL'd the autobreaks on every aircraft to keep the cockpit all as similar as possible. Furthermore WN would of had to put ALL of its pilots into a training class to teach them this.
A problem arose.
If they trained 300 pilots at once and UN-MEL'd the Autobreaks on 50 aircraft only those 300 pilots could of flown those 50 airplanes, and then if you need to swap pilots only pilots that went to that training class could fly your Autobrake aircraft. So Southwest to this day continues to have the AUTOBRAKE feature disabled.

Here is a -300 with the Autobrake installed.
http://www.airliners.net/open.file/1027074/M/

Here is a -700 with the Autobreak as well.

http://www.airliners.net/open.file/1004564/M/

The autoland switch is located below or next to the landing gear handle. (depending on the type aircraft.
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