Braking Action Table
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Joined: Aug 2005
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From: Europe
Braking Action Table
The birth of the ICAO Braking action table
Scandinavian perspective
Before 1950
Prior to 1950 the term Good, bad and indifferent, as practised in UK, were used for estimation of braking action with respect to aircraft operations. Triggered by the wish to concentrate as much as possible of the traffic in the Oslo area, DNL (SAS) wanted to transfer the continental traffic with DC-4 from Gardermoen airport to Fornebu airport. For winter operations a testing program was initiated and led by the airport manager at Fornebu, Ottar K. Kollerud. The outcome was a method using a GMC six by six,10 wheeler truck which was brought to a complete stop from a speed of 40 km/h. Stopping distance and stopping time was measured, and a retardation number (R m/sec2) generated. This was related to the stopping performance of the aircraft. The method got official Norwegian approval 18th January 1950.
1950 – 1960
Norway: The Kollerud method – also known as “Full stop method” were used at Fornebu airport throughout the 50’s. For the rest of the Norwegian airport the braking action was assessed.
Estimate - Retardation (R)
Good ≥ 2.7
Medium 2.2 – 2.6
Poor ≤ 2.1
In March 1954 Ottar Kollerud made a report describing the method. Report on the procedure for correction of Minimum Runway Length under Winter conditions at Oslo Airport, Fornebu. When ICAO published their first Circular with respect to operations on snow and ice, the Kollerud report was part of that Circular. (Circular 43-AN/38, Ice and Snow on Runways, 1955)
Denmark: The Kollerud method was also used at Kastrup airport, but from the winter 1957-58 the Tapleymeter were used.
Estimate - Measured friction
Good ≥ 0.35
Medium 0.26 – 0.34
Poor ≤ 0.25
Finland: Tapleymeter installed in 6.5 ton Sisu truck used at all airports from the winter 1959-60. Together with pilots following table were used.
Estimate - Measured friction
Good ≥ 0.45
Medium 0.30 – 0.44
Poor ≤ 0.29
Sweden: At Bromma airport four methods were tested. The Kollerud method, Taplymeter method in two different configurations, and the “skiddometer” method. At other airports the Tapleymeter were used.
Estimate - Measured friction
Good ≥ 0.35
Medium 0.25 – 0.35
Poor ≤ 0.25
According to regulations from 1958 the term medium could be divided into medium to good or medium to poor when close to the limits for good and poor respectively.
Harmonising
At a meeting in Stockholm 13th to 14th October 1959 the estimation of braking action were harmonised between Norway, Denmark, Finland and Sweden and one agreed upon using following table for Tapleymeter measurement at compacted snow and ice surfaces.
Estimate - Measured friction
Good ≥ 0.40
Medium to Good 0.36 – 0.39
Medium 0.30 – 0.35
Medium to Poor 0.26 – 0.29
Poor ≤ 0.25
ICAO
When ICAO (1967/68) established the SNOWTAM-format (Annex 15) this braking action table became a part of the SNOWTAM-format and thus became the world standard.
And now to my question:
Have a look into your manuals and tell me how many different braking action tables are in operational use today (46 years later)?
Scandinavian perspective
Before 1950
Prior to 1950 the term Good, bad and indifferent, as practised in UK, were used for estimation of braking action with respect to aircraft operations. Triggered by the wish to concentrate as much as possible of the traffic in the Oslo area, DNL (SAS) wanted to transfer the continental traffic with DC-4 from Gardermoen airport to Fornebu airport. For winter operations a testing program was initiated and led by the airport manager at Fornebu, Ottar K. Kollerud. The outcome was a method using a GMC six by six,10 wheeler truck which was brought to a complete stop from a speed of 40 km/h. Stopping distance and stopping time was measured, and a retardation number (R m/sec2) generated. This was related to the stopping performance of the aircraft. The method got official Norwegian approval 18th January 1950.
1950 – 1960
Norway: The Kollerud method – also known as “Full stop method” were used at Fornebu airport throughout the 50’s. For the rest of the Norwegian airport the braking action was assessed.
Estimate - Retardation (R)
Good ≥ 2.7
Medium 2.2 – 2.6
Poor ≤ 2.1
In March 1954 Ottar Kollerud made a report describing the method. Report on the procedure for correction of Minimum Runway Length under Winter conditions at Oslo Airport, Fornebu. When ICAO published their first Circular with respect to operations on snow and ice, the Kollerud report was part of that Circular. (Circular 43-AN/38, Ice and Snow on Runways, 1955)
Denmark: The Kollerud method was also used at Kastrup airport, but from the winter 1957-58 the Tapleymeter were used.
Estimate - Measured friction
Good ≥ 0.35
Medium 0.26 – 0.34
Poor ≤ 0.25
Finland: Tapleymeter installed in 6.5 ton Sisu truck used at all airports from the winter 1959-60. Together with pilots following table were used.
Estimate - Measured friction
Good ≥ 0.45
Medium 0.30 – 0.44
Poor ≤ 0.29
Sweden: At Bromma airport four methods were tested. The Kollerud method, Taplymeter method in two different configurations, and the “skiddometer” method. At other airports the Tapleymeter were used.
Estimate - Measured friction
Good ≥ 0.35
Medium 0.25 – 0.35
Poor ≤ 0.25
According to regulations from 1958 the term medium could be divided into medium to good or medium to poor when close to the limits for good and poor respectively.
Harmonising
At a meeting in Stockholm 13th to 14th October 1959 the estimation of braking action were harmonised between Norway, Denmark, Finland and Sweden and one agreed upon using following table for Tapleymeter measurement at compacted snow and ice surfaces.
Estimate - Measured friction
Good ≥ 0.40
Medium to Good 0.36 – 0.39
Medium 0.30 – 0.35
Medium to Poor 0.26 – 0.29
Poor ≤ 0.25
ICAO
When ICAO (1967/68) established the SNOWTAM-format (Annex 15) this braking action table became a part of the SNOWTAM-format and thus became the world standard.
And now to my question:
Have a look into your manuals and tell me how many different braking action tables are in operational use today (46 years later)?
Thread Starter
Joined: Aug 2005
Posts: 97
Likes: 0
From: Europe
Establishing the SNOWTAM-format
On 26 February 1963 IATA in a letter to ICAO expresses views resulting from recent winter experience in the European area with regard to the need for dissemination of information on runway conditions, due to the accumulation of snow, slush, ice and water.
In a subsequent letter, dated 20 March 1963, IATA provided detailed information about the proposals in the February letter.
As justification for this system, IATA advances its belief that recent experience during the severe 1962 - 1963 winter conditions in Europe has shown that this information on runway conditions is of operational importance equal to "other weather phenomena" determining the operational usability of aerodrome for "high speed turbine powered aircraft".
On 2 April 1963 the ICAO Air Navigation Commission considered the proposal from IATA. There were informal discussions with IATA and Airlines. The ICAO Secreteriat's understanding was that the total problem consisted of three related aspects:
[list=1][*]IATA was advocating that each State develop a comprehensive snow clearing plan i co-operation with the local operators, details of which should be included in tha AIP. [*]As soon as snow, slush or water affected the operational efficiency of an aerodrome, the State (as part of its snow plan) should issue an appropriate NOTAM warning.[*]The State should provide an adequate amendment service, updating the information given in the initial NOTAM[/list=1]
Informal meeting of European States concerned revealed that the areas particularly affected bythe winter 1962/63 slush problems were confined to those between the Atlantic, the Pyrenees, the Alps and Central Europe. While a few isolated cases irrregularities in airlines schedules were caused also in Spain and Italy, the primary difficulties centered around the North Sea and Central Europe.
AIP information from Sweden and Denmark together with an AIC No. 80/1962 from UK was distributed. And there was an First Informal Meeting in the ICAO Paris Office (16 - 23 September 1963) regarding the subject.
Then there was a Second Informal Meeting on Snow and Slush Problems in Europe (Paris, 27 April - 2 May 1964).
The review of the results of the measures proposed by the First Informal Meeting was facilitated by the availability of replies by States to a questionnaire circulated by the ICAO Secretariat prior to the Meeting. These replies and the comments by Delegates present showed that despite the short time available, States had made a considerable effort to follow the suggestions of the first Meeting.
At the Second Informal Meeting the content of the Snow Plan and the SNOWTAM-format was developed. The Snow Plan should be divided into two parts:
One part should be permanent and included in the AGA section of the AIP. This part should be applicable to at least all aerodromes within a State normally used for international traffic as destinations or alternate.
The other part should be issued seasonally as NOTAM Class II, well in advance of the beginning of the winter season, and preferably not later than the last AIRAC published before November.
In 1965 the ICAO Air Navigation Commission decided to make a trial application of a Study Group system for advancing specific projects on which the Secreteriat lacked adequate knowledge and/or capacity to complete them unaided. One of these projects was snow, slush, ice and water on aerodromes.
The Study Group on this project commenced work by correspondence towards the end of 1965. The group had an informal meeting in Montreal in November 1966 where members of the group were attending an informal IATA Meeting on Aircraft Stopping Capability. The Study Group agreed that their aim should be to produce a comprehensive paper for consideration by the 5th AN Conference. The Study Group met from 21 - 25 August 1967 and developed the paper which deals with following aspects of the subject:
[list=1][*]Runway surface texture and drainage characteristics.[*]Clearance and removal of contaminants from surfaces.[*]Measurement.[*]Notification of aerodrome movement area conditions.[/list=1]
The SNOWTAM-format developed by the Second Informal Meeting in 1964 are however close to the SNOWTAM-format as we know it today. You will find it in the ICAO Annex 15.
There has been two important changes for improving the precision level:
[list=1][*]Identification of type of friction measuring device.[*]Use of the term Unreliable when measuring/assessing the friction/braking action.[/list=1]
On 26 February 1963 IATA in a letter to ICAO expresses views resulting from recent winter experience in the European area with regard to the need for dissemination of information on runway conditions, due to the accumulation of snow, slush, ice and water.
In a subsequent letter, dated 20 March 1963, IATA provided detailed information about the proposals in the February letter.
As justification for this system, IATA advances its belief that recent experience during the severe 1962 - 1963 winter conditions in Europe has shown that this information on runway conditions is of operational importance equal to "other weather phenomena" determining the operational usability of aerodrome for "high speed turbine powered aircraft".
On 2 April 1963 the ICAO Air Navigation Commission considered the proposal from IATA. There were informal discussions with IATA and Airlines. The ICAO Secreteriat's understanding was that the total problem consisted of three related aspects:
[list=1][*]IATA was advocating that each State develop a comprehensive snow clearing plan i co-operation with the local operators, details of which should be included in tha AIP. [*]As soon as snow, slush or water affected the operational efficiency of an aerodrome, the State (as part of its snow plan) should issue an appropriate NOTAM warning.[*]The State should provide an adequate amendment service, updating the information given in the initial NOTAM[/list=1]
Informal meeting of European States concerned revealed that the areas particularly affected bythe winter 1962/63 slush problems were confined to those between the Atlantic, the Pyrenees, the Alps and Central Europe. While a few isolated cases irrregularities in airlines schedules were caused also in Spain and Italy, the primary difficulties centered around the North Sea and Central Europe.
AIP information from Sweden and Denmark together with an AIC No. 80/1962 from UK was distributed. And there was an First Informal Meeting in the ICAO Paris Office (16 - 23 September 1963) regarding the subject.
Then there was a Second Informal Meeting on Snow and Slush Problems in Europe (Paris, 27 April - 2 May 1964).
The review of the results of the measures proposed by the First Informal Meeting was facilitated by the availability of replies by States to a questionnaire circulated by the ICAO Secretariat prior to the Meeting. These replies and the comments by Delegates present showed that despite the short time available, States had made a considerable effort to follow the suggestions of the first Meeting.
At the Second Informal Meeting the content of the Snow Plan and the SNOWTAM-format was developed. The Snow Plan should be divided into two parts:
One part should be permanent and included in the AGA section of the AIP. This part should be applicable to at least all aerodromes within a State normally used for international traffic as destinations or alternate.
The other part should be issued seasonally as NOTAM Class II, well in advance of the beginning of the winter season, and preferably not later than the last AIRAC published before November.
In 1965 the ICAO Air Navigation Commission decided to make a trial application of a Study Group system for advancing specific projects on which the Secreteriat lacked adequate knowledge and/or capacity to complete them unaided. One of these projects was snow, slush, ice and water on aerodromes.
The Study Group on this project commenced work by correspondence towards the end of 1965. The group had an informal meeting in Montreal in November 1966 where members of the group were attending an informal IATA Meeting on Aircraft Stopping Capability. The Study Group agreed that their aim should be to produce a comprehensive paper for consideration by the 5th AN Conference. The Study Group met from 21 - 25 August 1967 and developed the paper which deals with following aspects of the subject:
[list=1][*]Runway surface texture and drainage characteristics.[*]Clearance and removal of contaminants from surfaces.[*]Measurement.[*]Notification of aerodrome movement area conditions.[/list=1]
The SNOWTAM-format developed by the Second Informal Meeting in 1964 are however close to the SNOWTAM-format as we know it today. You will find it in the ICAO Annex 15.
There has been two important changes for improving the precision level:
[list=1][*]Identification of type of friction measuring device.[*]Use of the term Unreliable when measuring/assessing the friction/braking action.[/list=1]
