Reverse Thrust...

[Guest Rahim Rani]

To: Airplane Driver...

 

From: Airplane Passanger...

 

One question still wondering in my head after a long talk with one of the AK Flight Eng. Is it true that every landing, pilot must use reverse thrust, no matter how you put the brake selection or even at slow approach?

 

The flight eng. said to me that, pilot shud use reverse thrust during landing...

 

I experience the situation twice, first time during my travel from Labuan to KL, second one during my flight from Labuan to KK...and both flight on MAS.

 

Appreciate if any real aviator could give me some explanation on this...

 

Thank you...

[Radzi 2]

Reverse thrust will help the plane to stop earlier. The downside is the loud noise and the extra fuel used. Therefore if the runway is long enough then reverse thrust may not be used.

[Michael Chai 0]

I can say everytime i on AK flight, they will be using thrust reversers when 32L & 32R in use. Bcaus they need to go to the terminal in tat period of time.

 

However, some cases such as MAS and other domestic flights do not use reverse thrust as their destination is at main terminal. Hehe.

 

Oh ya, radzi, by the way, y some reverse thrust doesn't hav noise ones?

 

Correct me if I'm wrong.

Edited August 2, 2008 by Michael Chai

[Radzi 2]

Oh ya, radzi, by the way, y some reverse thrust doesn't hav noise ones?

 

Must be idle reverse then.

 

[Muhd Hisyam 5]

 

 

What u mean....? can explain it...

Edited August 3, 2008 by Muhd Hisyam

[Andy 1]

well from what i understand Ak uses thrust reverser's all the time upon aircraft touch down is mainly to slow down the aircraft froward speed where during this period the brakes are not applied yet..but the ground spoilers and reverser's will deploy first helping the aircraft speed to be reduced to a certain value and then only the brakes would be operated. the reason why they are doing this is because they want to increase the brakes operation life..because if the brakes are used all the time at high speed when landing , this results the breaks rotor pads to wear off very fast and requires replacements at a shorter period,to save the cost and allow the breaks to be in service for a longer period ..the reverser and the ground spoilers are used to drop the aircarft speed after touch down until certain limits and then the breaks are applied

 

What u mean....? can explain it...

 

 

idle reverser's means the engine throttles are brought down to the lowest speed and the reverser's levers are raised until reverser deployed and throttles still remain in idle position and not pushed to the max

[Gavin Andrew David 6]

well from what i understand Ak uses thrust reverser's all the time upon aircraft touch down is mainly to slow down the aircraft froward speed where during this period the brakes are not applied yet..but the ground spoilers and reverser's will deploy first helping the aircraft speed to be reduced to a certain value and then only the brakes would be operated. the reason why they are doing this is because they want to increase the brakes operation life..because if the brakes are used all the time at high speed when landing , this results the breaks rotor pads to wear off very fast and requires replacements at a shorter period,to save the cost and allow the breaks to be in service for a longer period ..the reverser and the ground spoilers are used to drop the aircarft speed after touch down until certain limits and then the breaks are applied

 

Oh now this is interesting ! means , no need for Autobrakes eh ?

[Michael Chai 0]

However, y idle reverse thrust is more quiter compared to full reverse thrust? Basically can someone explain how reverse thrust functions? I thought every reverse thrust applied is noisy one since the cover of the engine is open?

[Khaled 2]

You can apply reverser using idle thrust or normal method where you apply more power to the reverser to get more braking action.

 

With the fuel price sky rocket high, sometimes it is better to use idle reverse(the no noise one) and let the brake do its job.

 

Brake wear has become secondary but of course there are a lot of factors to consider such as brake cooling, short runway etc...

 

On average using idle reverse can save approx 50kg of fuel on B734.

[BC Tam 2]

On average using idle reverse can save approx 50kg of fuel on B734.

Whoa, this is mind boggling (if I've got the facts as implied that is) !

You mean each time a 734 applies reverse thrust (the earth trembling, noisy one !) for the few seconds, extra 50kg of fuel is burnt off ?

You meant per cycle right ?

[Radzi 2]

Yup, 50 kg per cycle of full thrust reverser. Now if you slow down too much you'll need to open up the throttle again for the taxi, again using up fuel.

 

That is why it is important to know what you are doing, rather than "I follow what the book says" method.

[BC Tam 2]

Next naive question, how much RM for that 50kg fuel, approximately ?

 

Man, 50kg weight loss in those few seconds

If I can package that somehow for some weight loss programme, I'll be an instant millionaire many times over

[Sandeep G 1]

My understanding from when I was with AK is that Autobrakes are still a mandatory setting, and a gut feeling make's me feel that nothing has changed and such policy is pretty much standard with most airlines. Autobrake is primary means of slowing down, spoilers. reverse thrust are secondary. Brake wear is most accumulated from manual use of the brakes... hence probably why you see lots of AK 320's zooming around the taxiways of KLIA - riding the brakes to maintain speed is discouraged as brakes against power will definately lead to greater wear (no excuse for tazying fast). Best to use a low power/thrust setting after desired taxy speed is achieved (i.e. use higher power to get rolling, then when you are rolling, bring that power back)... again down to experience and as the good captain says, "important to know what you are doing". It's the same with GA aircraft and was drilled into us during training in Perth. Company policy here states idle reverse is to be used in all permitting circumstances - i.e. know what you are doing.

[Khaled 2]

Next naive question, how much RM for that 50kg fuel, approximately ?

 

Man, 50kg weight loss in those few seconds

If I can package that somehow for some weight loss programme, I'll be an instant millionaire many times over

 

Well, based on 1 us gal of jet fuel = 6.3 USD, by using idle reverse we can save up to RM340.

 

That means for 1 hour of flight, u need about RM16,500 to feed the engines!!

 

I won't bother much about the price, otherwise I'll be thinking twice everytime I need to push the thrust levers.

 

Safety, then saving.

[Chan CS 0]

Well, based on 1 us gal of jet fuel = 6.3 USD, by using idle reverse we can save up to RM340.

 

That means for 1 hour of flight, u need about RM16,500 to feed the engines!!

 

I won't bother much about the price, otherwise I'll be thinking twice everytime I need to push the thrust levers.

 

Safety, then saving.

 

Hey Khaled, do you roughly have idea that how is the fuel consumption pattern for B738? I believe it should be more efficient am I right? It would be interesting to see the comparison.

[Gavin Andrew David 6]

My understanding from when I was with AK is that Autobrakes are still a mandatory setting, and a gut feeling make's me feel that nothing has changed and such policy is pretty much standard with most airlines. Autobrake is primary means of slowing down, spoilers. reverse thrust are secondary. Brake wear is most accumulated from manual use of the brakes... hence probably why you see lots of AK 320's zooming around the taxiways of KLIA - riding the brakes to maintain speed is discouraged as brakes against power will definately lead to greater wear (no excuse for tazying fast). Best to use a low power/thrust setting after desired taxy speed is achieved (i.e. use higher power to get rolling, then when you are rolling, bring that power back)... again down to experience and as the good captain says, "important to know what you are doing". It's the same with GA aircraft and was drilled into us during training in Perth. Company policy here states idle reverse is to be used in all permitting circumstances - i.e. know what you are doing.

 

Agreed , most 320's , after getting sufficient thrust to roll along , there is no need to add more power to keep her rolling , returning it back to idle , will keep the bird rolling to about 10 - 15 knots ,

 

Unless u need to pull off corners like the BMW's that they sponsor , then , you definitely going to be riding the brakes , and soon after alot of that and a heavy weight landing , get a beautiful and sweet ECAM message , Telling you , that the brakes are hot , and ECAM telling you to turn on the BRK FAN and DELAY T.O.

[Sanjay Thaker 0]

" DONT RIDE THE BRAKES..IDLE POWER AND THEN BRAKE! " The very first thing my instructor told me during my very first flight in training..

[Aaron Goh 1]

" DONT RIDE THE BRAKES..IDLE POWER AND THEN BRAKE! " The very first thing my instructor told me during my very first flight in training..

 

In flight school, some single eng props, minimum is 800rpm.....can't go idle. actually usage of reversers does little to reduce landing distance, however with reversers it does help in reducing brakes workload.

[Andrew Lim 1]

I thought autobrakes are almost always used...

 

Reverse thrust act to relieve some pressure and reduce wear n tear on the wheels.

 

On the same autobrake setting, a landing without reverse thrust will cause the more pressure being applied to the wheelbrakes compare to one with reverse thrust.

 

If you dont plan to use reverse thrust, then you shouldnt use high autobrake settings either.

[Khaled 2]

Hey Khaled, do you roughly have idea that how is the fuel consumption pattern for B738? I believe it should be more efficient am I right? It would be interesting to see the comparison.

 

Sorry bro, no idea ....

 

Well, on airbus you got brake fan. On 737 you have to taxi properly. hehehe...BTW, all MAS planes got monitoring system. Everytime you do something funny,

it will be recorded and you can be called to the office.

 

 

[Radzi 2]

I thought autobrakes are almost always used...

 

Reverse thrust act to relieve some pressure and reduce wear n tear on the wheels.

 

On the same autobrake setting, a landing without reverse thrust will cause the more pressure being applied to the wheelbrakes compare to one with reverse thrust.

 

If you dont plan to use reverse thrust, then you shouldnt use high autobrake settings either.

 

Autobrake detects the deceleration rate. Therefore if you have a lot of reverse thrust then less braking will be applied, to achieve the same deceleration.