Another Aircraft off the Runway at BRS?
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You are assuming that you're receiving information from journalists. The fact of the matter is that there aren't many journalists these days (except maybe by job title), just news readers, sensationalists and a few authors!
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Was this another "Paddington' waiting to happen? Crews expressed concern about a problem in good time to stop it happening. Had rail crew not done exactly the same thing about the signal at Paddington? Was BALPA aware of the concerns? Were numerous D.Op's in the loop about their crews' concerns? It sure sounds like lots of people knew something was wrong, and yet it still happend. I thought aviation, in particular, had learnt all about being proactive in matters like this. It will be a fascinating AAIB report and the insurance loss adjusters will be taking aim shortly afterwards.
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Hopefully the report will also comment on the way friction/braking action measurements are taken and reported in the United Kingdom and their correspondance to international practices and regulation. Quite a few of us who have made runway bitumen/asphalt or designed runway surfaces raised an eyebrow at some of the posts regarding alleged measurement practices. There's no point in having a system which does not yield reasonably consistent results (understanding that its a fairly basic test open to wide variability) and more importantly that pilots have confidence in.
Pinkman
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Friction - Friction number
Please be adviced that:
- a friction number is not a property of a surface. It is generated from a pair of surfaces in relative motion.
- a friction number must always be related to the measuring instrument used. (Friction measuring device, aircraft, etc)
- there is a lot of uncertainties related to the generated friction numbers.
- a friction number with multiple decimals (0.261) is not an "accurate" friction number.
- the term "accurate" can not be used together with a friction number as we do not have an universially agreed reference. The correct term is UNCERTAINTY
- the uncertainty involved when it comes to operation of aircrafts is in the order of 0.1 not 0.01.
- a friction number is not a property of a surface. It is generated from a pair of surfaces in relative motion.
- a friction number must always be related to the measuring instrument used. (Friction measuring device, aircraft, etc)
- there is a lot of uncertainties related to the generated friction numbers.
- a friction number with multiple decimals (0.261) is not an "accurate" friction number.
- the term "accurate" can not be used together with a friction number as we do not have an universially agreed reference. The correct term is UNCERTAINTY
- the uncertainty involved when it comes to operation of aircrafts is in the order of 0.1 not 0.01.
'but a passenger who is trying to get compensation from Easy on the basis that before they dispatched him to the frozen north, they knew they probably were not going to get him back.'
No airline can ever give this assurance if the weather is a significant factor in the argument. The major issue was relating to wet runway conditions. Therefore at the time Mr and Mrs bloggs departed, unless the airline knew that the runway was going to be wet at the time of their arrival X hours/days later, that claim wont stand up. Some airlines took a blanket descision once they new there was a period of extended wet weather likely to affect operations and safety, others obviously took a tactical on the day approach. Had there been a dry period, then the sliping and skidding issues would have been greatly reduced if not non existent.
Regarding brakeing assesment I wonder what the implications are for those airfields which use the 'center pedal' technique for their assesments? But thats probably a good question to ask in a technical forum and not in this thread.
No airline can ever give this assurance if the weather is a significant factor in the argument. The major issue was relating to wet runway conditions. Therefore at the time Mr and Mrs bloggs departed, unless the airline knew that the runway was going to be wet at the time of their arrival X hours/days later, that claim wont stand up. Some airlines took a blanket descision once they new there was a period of extended wet weather likely to affect operations and safety, others obviously took a tactical on the day approach. Had there been a dry period, then the sliping and skidding issues would have been greatly reduced if not non existent.
Regarding brakeing assesment I wonder what the implications are for those airfields which use the 'center pedal' technique for their assesments? But thats probably a good question to ask in a technical forum and not in this thread.
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How wet is wet....
Have been reading with interest entrys regarding tarmac friction measurement and aircraft braking perormance.
In a previous life I worked for many years on race tyre development, and reading from the pages of PPRuNe it appears the CAA have fallen into the trap (like some race tyre developers) of not recognising "degrees of wetness". A runway is regarded only as either "dry" or "wet".
For a race car the difference in lap times (ie tyre performance) between a damp circuit and a circuit with standing water, could be around 50%. But by definition both are "wet".
We found "degrees of wetness" very difficult to define for the purposes of tyre testing and invariably we resorted to a finger in the air type guestimation. Add to this that wetness of tarmac is inconsistent - at a given moment it either drying or getting wetter.
Given that aircraft tyres (by neccessity due to abuse) are not heavily treaded for water clearance and the fact that they are lightly loaded for a high proportion of the time they are used in anger (especially on the roller coaster ride like BRS 09/27 !) reduction of performance in "very wet" as apposed to "moderately wet" conditions is a factor the CAA bofins might want to consider.
In a previous life I worked for many years on race tyre development, and reading from the pages of PPRuNe it appears the CAA have fallen into the trap (like some race tyre developers) of not recognising "degrees of wetness". A runway is regarded only as either "dry" or "wet".
For a race car the difference in lap times (ie tyre performance) between a damp circuit and a circuit with standing water, could be around 50%. But by definition both are "wet".
We found "degrees of wetness" very difficult to define for the purposes of tyre testing and invariably we resorted to a finger in the air type guestimation. Add to this that wetness of tarmac is inconsistent - at a given moment it either drying or getting wetter.
Given that aircraft tyres (by neccessity due to abuse) are not heavily treaded for water clearance and the fact that they are lightly loaded for a high proportion of the time they are used in anger (especially on the roller coaster ride like BRS 09/27 !) reduction of performance in "very wet" as apposed to "moderately wet" conditions is a factor the CAA bofins might want to consider.
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How wet is wet
With respect to certification a runway is either:
Dry, wet or contaminated.
As part of the harmonization FAR/CS(JAR) process the term damp is no longer used and the surface is classified as wet.
In ICAO Annex 14 you will find:
"Water on a runway
2.9.4 Recommendation.— Whenever water is present on a runway, a description of the runway surface conditions on the centre half of the width of the runway, including the possible assessment of water depth, where applicable, should be made available using the following terms:
DAMP — the surface shows a change of colour due to moisture.
WET — the surface is soaked but there is no standing water.
WATER PATCHES — significant patches of standing water are visible.
FLOODED — extensive standing water is visible.
2.9.5 Information that a runway or portion thereof may be slippery when wet shall be made available."
One of the swedish oldtimers had this popular method to identify a wet surface. If you hesitate and do not want to sit down on the surface due to water - the surface is wet
Updating of ICAO documents within this field is on the agenda.
Dry, wet or contaminated.
As part of the harmonization FAR/CS(JAR) process the term damp is no longer used and the surface is classified as wet.
In ICAO Annex 14 you will find:
"Water on a runway
2.9.4 Recommendation.— Whenever water is present on a runway, a description of the runway surface conditions on the centre half of the width of the runway, including the possible assessment of water depth, where applicable, should be made available using the following terms:
DAMP — the surface shows a change of colour due to moisture.
WET — the surface is soaked but there is no standing water.
WATER PATCHES — significant patches of standing water are visible.
FLOODED — extensive standing water is visible.
2.9.5 Information that a runway or portion thereof may be slippery when wet shall be made available."
One of the swedish oldtimers had this popular method to identify a wet surface. If you hesitate and do not want to sit down on the surface due to water - the surface is wet
Updating of ICAO documents within this field is on the agenda.
Last edited by tribo; 11th Jan 2007 at 06:14.
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Aircraft tires vs. other tires application
Be careful to compare performance of aircraft tires with other tires.
Download the Goodyear Care and maintenance Manual and have a look at the figure at page 33, and you will understand why.
http://www.goodyearaviation.com/img/pdf/properties.pdf
Download the complete manual at: http://www.goodyearaviation.com/tirecare.html
Download the Goodyear Care and maintenance Manual and have a look at the figure at page 33, and you will understand why.
http://www.goodyearaviation.com/img/pdf/properties.pdf
Download the complete manual at: http://www.goodyearaviation.com/tirecare.html
Last edited by tribo; 10th Jan 2007 at 20:51.
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EXTREMELY windy, but more or less down the strip!
FCA SSH had to consider their perf' this morn, holding for a while to 're-think'. Close to MTOM, with wet wet wet, looked closely at braking efficiency etc. They went in the end anyway, and are now struggling to make it back for the r/way closure time........
FCA SSH had to consider their perf' this morn, holding for a while to 're-think'. Close to MTOM, with wet wet wet, looked closely at braking efficiency etc. They went in the end anyway, and are now struggling to make it back for the r/way closure time........
Last edited by WindSheer; 11th Jan 2007 at 14:20.
The events in this thread describe a James Reason ‘organisational’ accident. The many dormant issues and a few active failures which have been identified indicate a poor state of safety health in this segment of our aviation system – a systematic failure.
I hope that the relevant investigative authorities and even those not charged with formal investigation, undertake reviews that match the revolutionary report into the Dryden (Air Ontario) accident, by identifying and discussing the root contributors.
There are many issues yet to be understood and answered i.e.
Why after safety reports had been submitted about the runway, were no actions / communications forthcoming? Does this reflect a major weakness in the MOR system – an essential component of the CAA’s SMS?
Apparently there weaknesses in operational knowledge about reported braking action (friction level) and how this relates to landing performance; also about the inaccuracies of friction measurement and the hazards of landing on ‘slippery’ runways.
The hazard of new tarmac ‘sweating had been identified in a previous overrun accident – UK built aircraft, but overseas investigation / report. Even when the industry communicates, do we remember?
Complacency in applying landing performance and crosswind limits. Human error, human factors – ‘I know better’, ‘It won’t happen to me … because it worked before (I got away with it)’. Did similar patterns of thought contribute at management levels?
Why apparently, are particular aircraft types appearing more often than others in the overrun statistics?
Etc, etc.
This is not a call for a ‘blame’ seeking investigation, but something that provides the industry with more than the usual description of events and allocation of responsibility; we require substance that we might include in our personal, organisational, or regulatory accountability for safety.
A few contributions from whilst awaiting the report:
Managing the Threats and Errors during Approach and Landing..
Stopping on Slippery Runways. Boeing slippery runways.
Landing on Slippery Runways (Based on Boeing info).
AIC 14/2006 Landing performance of large transport aeroplanes. via http://www.ais.org.uk
AIC 15/2006 Risks and factors associated with operations on runways affected by snow, slush or water. via http://www.ais.org.uk
UK Air Pilot AD 1.1.1 section 15 Wheel Braking Action on Wet and contaminated Runways. via http://www.ais.org.uk
Runway Friction Accountability Risk Assessment.
CRFI.
Croswind limits.
Overruns on landing.
Getting to Grips with Aircraft Performance – Airbus publication via ‘wingfiles’
History of ICAO ice and snow tables.
Braking action.
Good, Fair, Poor, Nil.
Benefit-Cost Analysis of Procedures for Accounting for Runway Friction on Landing.
Overview of the Joint Winter Runway Friction Measurement Program, November 2004 (TP 13361).
Running Out of Runway: Analysis of 35 Years of Landing-overrun Accidents, Gerard van Es National Aerospace Laboratory (NLR), 58th annual lASS “Safety Is Everybody’s Business” Moscow, Russia November 2005.
From a positive aspect, this episode could be a ground breaking event for corporate (management) involvement in flight safety, an example of good safety culture (assuming action was taken as son as the information was available) and a basis of improving public understanding of flight safety.
I hope that the relevant investigative authorities and even those not charged with formal investigation, undertake reviews that match the revolutionary report into the Dryden (Air Ontario) accident, by identifying and discussing the root contributors.
There are many issues yet to be understood and answered i.e.
Why after safety reports had been submitted about the runway, were no actions / communications forthcoming? Does this reflect a major weakness in the MOR system – an essential component of the CAA’s SMS?
Apparently there weaknesses in operational knowledge about reported braking action (friction level) and how this relates to landing performance; also about the inaccuracies of friction measurement and the hazards of landing on ‘slippery’ runways.
The hazard of new tarmac ‘sweating had been identified in a previous overrun accident – UK built aircraft, but overseas investigation / report. Even when the industry communicates, do we remember?
Complacency in applying landing performance and crosswind limits. Human error, human factors – ‘I know better’, ‘It won’t happen to me … because it worked before (I got away with it)’. Did similar patterns of thought contribute at management levels?
Why apparently, are particular aircraft types appearing more often than others in the overrun statistics?
Etc, etc.
This is not a call for a ‘blame’ seeking investigation, but something that provides the industry with more than the usual description of events and allocation of responsibility; we require substance that we might include in our personal, organisational, or regulatory accountability for safety.
A few contributions from whilst awaiting the report:
Managing the Threats and Errors during Approach and Landing..
Stopping on Slippery Runways. Boeing slippery runways.
Landing on Slippery Runways (Based on Boeing info).
AIC 14/2006 Landing performance of large transport aeroplanes. via http://www.ais.org.uk
AIC 15/2006 Risks and factors associated with operations on runways affected by snow, slush or water. via http://www.ais.org.uk
UK Air Pilot AD 1.1.1 section 15 Wheel Braking Action on Wet and contaminated Runways. via http://www.ais.org.uk
Runway Friction Accountability Risk Assessment.
CRFI.
Croswind limits.
Overruns on landing.
Getting to Grips with Aircraft Performance – Airbus publication via ‘wingfiles’
History of ICAO ice and snow tables.
Braking action.
Good, Fair, Poor, Nil.
Benefit-Cost Analysis of Procedures for Accounting for Runway Friction on Landing.
Overview of the Joint Winter Runway Friction Measurement Program, November 2004 (TP 13361).
Running Out of Runway: Analysis of 35 Years of Landing-overrun Accidents, Gerard van Es National Aerospace Laboratory (NLR), 58th annual lASS “Safety Is Everybody’s Business” Moscow, Russia November 2005.
From a positive aspect, this episode could be a ground breaking event for corporate (management) involvement in flight safety, an example of good safety culture (assuming action was taken as son as the information was available) and a basis of improving public understanding of flight safety.
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Runway sorted as they are now in the process of laying the surface coat. Material will have to wait 72 hrs then be grooved.
Should be ok now pity the contractor cannot get his joints right though, still a bit bumpy at times
Should be ok now pity the contractor cannot get his joints right though, still a bit bumpy at times
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Any of you know anything about this?
Fresh concerns over the BRS runway... This is the top story on local BBC TV news
http://news.bbc.co.uk/1/hi/england/bristol/6379213.stm
Fresh concerns over the BRS runway... This is the top story on local BBC TV news
http://news.bbc.co.uk/1/hi/england/bristol/6379213.stm
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Ridiculous
What a shame that the Beeb has chosen to rate the high profile of its source (an MP) over the qualification of the source to make comment.
"I thought, why are they actually using this runway if they are admitting that on occasions it's not safe? Incredible."
No, your Right Honourable, business a usual.
"I thought, why are they actually using this runway if they are admitting that on occasions it's not safe? Incredible."
No, your Right Honourable, business a usual.
