Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Costs of hard braking

Tech Log The very best in practical technical discussion on the web

Costs of hard braking

Old 25th Jul 2013, 14:51
  #1 (permalink)  
Thread Starter
 
Join Date: May 2013
Location: UK
Age: 51
Posts: 71
Costs of hard braking

I regularly fly into Malta, either with BA, Air Malta or Ryan Air.

It's noticeable that RA brake considerably harder than the other two airlines, to make the earlier exits and reduce taxiing time, and giving themselves an extra few minutes for the turnaround.

I assume this hard braking has a detrimental effect on the life of the brake pads and to a lesser degree disks and tyres, as it would on a car.

You'd have thought RA would want to save costs, by reducing wear and tear, and letting the plane have a gentler arrival. Even reverse thrust uses valuable fuel, so I's surprised they don't just use air brakes!

So do the advantages of a few minutes longer on the ground outweigh the increased maintenance?


Maybe I should send O'leary a suggestion
Interested Passenger is offline  
Old 25th Jul 2013, 15:02
  #2 (permalink)  
 
Join Date: Mar 2002
Location: Florida
Posts: 5,114
Brakes are cheaper than reverse thrust and cheaper than time.

One has to work in cost of maintenance for all parts of an aircraft affected by means of stopping as well time allocated.

Operators are pretty savvy about these cost balances, but of course crews and passengers have their say as well.
lomapaseo is offline  
Old 25th Jul 2013, 15:25
  #3 (permalink)  
 
Join Date: Jun 2013
Location: A warm pub
Posts: 1,163
I heard a rumour that as part of FRs most recent aircraft order, Boeing agreed to cover the cost of brake replacement on their fleet, that true?
Una Due Tfc is offline  
Old 25th Jul 2013, 15:51
  #4 (permalink)  
 
Join Date: Sep 2007
Location: Derby
Posts: 24
Hi, it also depends what type of brakes you have. Steel brakes wear quicker if you apply them hard. Carbon brakes only wear with each application so braking hard does not actually increase the rate of wear. In fact using auto brakes at a low setting along with reverse thrust can actually wear out carbon brakes quicker as the brakes modulate on and off.
double-oscar is offline  
Old 25th Jul 2013, 19:55
  #5 (permalink)  
 
Join Date: Sep 2012
Location: Warwickshire
Age: 32
Posts: 26
The pilot probably wants to make sure HE/SHE makes it in on time. Not worrying about the longer term effects of braking hard. Afterall, the pilots are probably not bothered about the airline's costs since the airline doesn't seem to value the pilots. In short, it's harder to record a pilot who is braking too hard than recording whether he arrived late or not...
nimsu1987 is offline  
Old 25th Jul 2013, 22:57
  #6 (permalink)  
 
Join Date: Nov 2010
Location: EU
Posts: 604
It's not a Ryanair thing, in fact whenever I fly with Monarch I get ready to be slammed against my seatbelt more than when I fly with Ryanair to the same airport.

If it was that much of a concern, I can assure you Ryanair would be straight onto their crews about it. Considering Ryanair is the very airline that would take pens from hotels where they would have conferences so they didn't have to buy pens for their office staff.
pudoc is online now  
Old 26th Jul 2013, 07:59
  #7 (permalink)  
 
Join Date: Jul 2002
Location: Ireland
Posts: 594
It also depends on the type of maintenance contract they have.

Many contracts are 'fixed price' where the agreement is to maintain X no. aircraft for X no. months for X.

In this case the cost of the extra brake pads is borne by the maintenance company rather than Ryanair.
Speed of Sound is offline  
Old 26th Jul 2013, 09:17
  #8 (permalink)  
 
Join Date: Feb 2009
Location: Austria
Posts: 674
Are there any hard numbers about how much time can actually be saved that way? Letting the aircraft run down the runway after touchdown, then slamming the brakes in order to come to a screeching halt just in time for the desired taxiway is sure to cause much discomfort for the passengers and unnecessary loads on the brakes and other structure.

Simply putting the aircraft down in the touchdown zone and then applying a constant deceleration to make the same exit by contrast is much more convenient for the passengers and I am convinced that this second method "costs" less than 5 seconds of turnaround time. Even with a minimum time turnaround of 30 minutes on my type, this can well be accepted as much more can be gained or lost by efficient ground handling.
Tu.114 is offline  
Old 26th Jul 2013, 09:45
  #9 (permalink)  
 
Join Date: Jan 2008
Location: Reading, UK
Posts: 10,642
Simply putting the aircraft down in the touchdown zone and then applying a constant deceleration to make the same exit
I don't think anyone is suggesting that RYR use a different braking technique simply to make the same exit that would have been available with a more gentle deceleration.

The OP said

It's noticeable that RA brake considerably harder than the other two airlines, to make the earlier exits and reduce taxiing time, and giving themselves an extra few minutes for the turnaround.
Depending on the airport layout, it's easy to envisage a scenario where, if you miss one exit you are faced with a lot of runway before the next available one, followed by a correspondingly longer taxi back to the gate. That's the trade-off that's being discussed.

It would be interesting to see how the economics stack up - I'd be willing to bet that some bean-counter has worked out that those extra few minutes (possibly enabling a late arrival to be turned round into an on-time departure) are worth however many cycles are lost from the brake TBO.

Without seeing the numbers, it's hard to argue with.
DaveReidUK is offline  
Old 26th Jul 2013, 10:47
  #10 (permalink)  
 
Join Date: Jan 2008
Location: lancs.UK
Age: 72
Posts: 1,196
Many contracts are 'fixed price' where the agreement is to maintain X no. aircraft for X no. months for X.

In this case the cost of the extra brake pads is borne by the maintenance company rather than Ryanair
@ SoS...So, you think the contractor has a free supply of brake parts???

A contract will based on "costs" plus margin.....If the margin is compromised due to costs being higher than planned,- a new or re-negotiated contract will reflect this (I suspect there would be a covering clause for excessive costs, anyway)
To consider that a Mx company exists to make donations to RYR is naive in the extreme.
RYR pays it's own costs.

I'd suggest that maybe those few extra minutes saved by "burning the brakes" are well and truly offset by enabling the next departure-slot to be met....AOG costs a fortune, flying aircraft is making revenue!
cockney steve is offline  
Old 26th Jul 2013, 12:13
  #11 (permalink)  
Thread Starter
 
Join Date: May 2013
Location: UK
Age: 51
Posts: 71
a bit of google map measuring, and if you don't take the exit half way down, then it's about 2 miles down to the end of the runway, loop and back to the terminal

2 miles of taxi time, and taxi fuel

https://maps.google.com/maps?ll=35.8...10378&t=h&z=13
Interested Passenger is offline  
Old 26th Jul 2013, 14:54
  #12 (permalink)  
Thread Starter
 
Join Date: May 2013
Location: UK
Age: 51
Posts: 71
measuring it on google maps the runway is about 3300m long

from the North, the first exit is about 800m, which would probably involve parking the plane in baggage reclaim

The next exit is 1700m from touchdown, which must be the one RA are using.

If you miss that, it's a further 1600m to the end of the runway, a tight turn, and of course a 1600m trundle back

so 2 miles extra taxiing time, and fuel.
Interested Passenger is offline  
Old 26th Jul 2013, 15:14
  #13 (permalink)  
 
Join Date: Aug 2011
Location: far too low
Posts: 231
And blocking the runway for any other traffic whilst you're trundling back
gorter is offline  
Old 26th Jul 2013, 16:33
  #14 (permalink)  
 
Join Date: Apr 2008
Location: Orlando
Posts: 1
And blocking the runway for any other traffic whilst you're trundling back
I can't imagine RA cares about that!
djk7 is offline  
Old 27th Jul 2013, 02:54
  #15 (permalink)  
 
Join Date: Jun 2000
Location: Australia
Posts: 3,865
There are excellent pilots and then there are the cowboy pilots. When it comes to braking after touchdown, then all things being equal, it is the cowboys that slam on the brakes and also taxi fast. It has always been thus regardless of the airline. of course the cowboys would never admit this of course.
Centaurus is offline  
Old 27th Jul 2013, 06:29
  #16 (permalink)  
Roo
 
Join Date: Nov 1998
Location: Sydney.NSW.Australia
Posts: 52
Centaurus, given you say there are only two types, I take it you are in the camp of excellent pilots then? You would never admit this of course
Roo is offline  
Old 27th Jul 2013, 07:39
  #17 (permalink)  
 
Join Date: Nov 2009
Location: flying by night
Posts: 504
sometimes PPRuNe makes me laugh
deptrai is offline  
Old 27th Jul 2013, 07:51
  #18 (permalink)  
Green Guard
Guest
 
Posts: n/a
Hi Roo
Are you telling us you are not in the same group as Centaurus ?
 
Old 27th Jul 2013, 10:50
  #19 (permalink)  
 
Join Date: Dec 2010
Location: Ireland
Posts: 1,166
Ryanair use steel brakes on there fleet.
Jack1985 is offline  
Old 27th Jul 2013, 10:55
  #20 (permalink)  
 
Join Date: Jun 2000
Location: Australia
Posts: 3,865
I take it you are in the camp of excellent pilots then?
Modesty forbids my reply
Centaurus is offline  

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.