How do you gauge depth of standing water
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How do you gauge depth of standing water
Any ideas how you gauge depth of standing water. I fly in countries where ATC have no idea what you are talking about when you ask for contam info.
Does anybody have a rough guide based on viz in rain what that equetes to as far as satanding water?
Does anybody have a rough guide based on viz in rain what that equetes to as far as satanding water?
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Should be reported on ATIS.
If you have a modern runway surface in good condition (crowned and grooved, good drainage) you really shouldn't ever see standing water, except maybe in the heaviest of downpours.
Which reminds me: The only time I've actually hydroplaned was at Chennai, India where the runway seems neither crowned nor grooved but quite "rutted out" and they were experiencing heavy rain due to a tropical depression that was moving through.
In that case, standing water was reported on the ATIS and given a depth in inches.
Probably better to get a report from a previously arrived airplane.
Which reminds me: The only time I've actually hydroplaned was at Chennai, India where the runway seems neither crowned nor grooved but quite "rutted out" and they were experiencing heavy rain due to a tropical depression that was moving through.
In that case, standing water was reported on the ATIS and given a depth in inches.
Probably better to get a report from a previously arrived airplane.
That is a very good question. A lot of ATC towers in Asia can't even understand when you ask "is the runway wet"?
If it's raining heavily and the runway is not grooved then be careful and if possible ask a preceding aircraft how his braking action was?
This happened in Tpe on rwy 24 ( which is not grooved ) and the ATIS was reporting "breaking action poor as reported by landing aircraft A330"
So I advised ATC that we required Rwy 23 which is grooved.
Qf have a policy of not landing on an un-grooved runway in heavy rain ( since their Bkk over run ) and it is quite possibly a good idea.
If it's raining heavily and the runway is not grooved then be careful and if possible ask a preceding aircraft how his braking action was?
This happened in Tpe on rwy 24 ( which is not grooved ) and the ATIS was reporting "breaking action poor as reported by landing aircraft A330"
So I advised ATC that we required Rwy 23 which is grooved.
Qf have a policy of not landing on an un-grooved runway in heavy rain ( since their Bkk over run ) and it is quite possibly a good idea.
Don't forget however that Pilot reports of breaking action are very subjective.
The only report that should be reliable is the one from the Airport Authority testing equipment.
In Cx we will not allow landing on a RWY that has a breaking action of "poor".
This does not apply if it's Pilot reported, only if it comes from an official measuring equipment report from the Tower.
Now do ATC in a lot of Asian counties have the correct Measuring equipment? Do they ever use it?
I've never seen it ( apart from Japan in Snow ) used in Mnl, Tpe, Kul, Sin, Cgk, Bkk, etc etc in heavy rain.
At the end of the day you are going to have to decide for yourselves based on local knowledge of the RWY surface at the place your landing.
Off the top of my head, RWY's that I know to be slippery when wet are:
BOM 09/27, TPE 06/24, MNL 06/24, PEN 04, CMB 04, BKK 14L.
Those RWY's are not grooved.
SIN, SEL, BKK, HKG, NRT etc all have nice grooved RWY's.
Refer to the Jepp chart for the correct details as my memory is not as good as it used to be!!
The only report that should be reliable is the one from the Airport Authority testing equipment.
In Cx we will not allow landing on a RWY that has a breaking action of "poor".
This does not apply if it's Pilot reported, only if it comes from an official measuring equipment report from the Tower.
Now do ATC in a lot of Asian counties have the correct Measuring equipment? Do they ever use it?
I've never seen it ( apart from Japan in Snow ) used in Mnl, Tpe, Kul, Sin, Cgk, Bkk, etc etc in heavy rain.
At the end of the day you are going to have to decide for yourselves based on local knowledge of the RWY surface at the place your landing.
Off the top of my head, RWY's that I know to be slippery when wet are:
BOM 09/27, TPE 06/24, MNL 06/24, PEN 04, CMB 04, BKK 14L.
Those RWY's are not grooved.
SIN, SEL, BKK, HKG, NRT etc all have nice grooved RWY's.
Refer to the Jepp chart for the correct details as my memory is not as good as it used to be!!
A practical way to judge the depth before dispatch is to see if the water splashes when a surface is stamped on; this test is preferably to undertaken by the First Officer or Engineer thus enabling the Captain to observe the result.
Easier still is to observe vehicles and see if they splash when moving. Another method is to see if the surface is a good reflector, if so then as above, the water depth is significant and probably enough to be considered ‘contaminated’ (3mm).
During landing it may be possible to judge a reflecting surface, particularly at night, but this is very much a last chance check or decision to go-around and reconsider.
If you can hear the rain on the windscreen during the approach then it is heavy; you will have to build experience to relate your aircraft type to the rainfall intensity.
All other advice as in previous posts.
Don’t assume that a grooved runway will be well drained; rubber, dust dirt, de-icing fluid, etc can block the grooves as can a strong crosswind dam the water on the runway with or without crowning.
Also ‘concrete block’ runways can dish in the centre or the edge sealant can dam water even in light rain.
Hydroplaning.
Running out of runway.
Safety aspects of aircraft performance on wet and contaminated runways.
Improving Braking Action Reports.
Approach and Landing.
Edit:- Links updated
Easier still is to observe vehicles and see if they splash when moving. Another method is to see if the surface is a good reflector, if so then as above, the water depth is significant and probably enough to be considered ‘contaminated’ (3mm).
During landing it may be possible to judge a reflecting surface, particularly at night, but this is very much a last chance check or decision to go-around and reconsider.
If you can hear the rain on the windscreen during the approach then it is heavy; you will have to build experience to relate your aircraft type to the rainfall intensity.
All other advice as in previous posts.
Don’t assume that a grooved runway will be well drained; rubber, dust dirt, de-icing fluid, etc can block the grooves as can a strong crosswind dam the water on the runway with or without crowning.
Also ‘concrete block’ runways can dish in the centre or the edge sealant can dam water even in light rain.
Hydroplaning.
Running out of runway.
Safety aspects of aircraft performance on wet and contaminated runways.
Improving Braking Action Reports.
Approach and Landing.
Edit:- Links updated
Last edited by PEI_3721; 8th Oct 2007 at 15:24.
PEI_3721 i got a 404 page not found error on both your Safety aspects of aircraft performance on wet and contaminated runways and your Approach and Landing. links
Please repost if possible.
Please repost if possible.
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Simple,a Pound coin.
Hi,
At Cardiff we carry different sized washers in the op`s vehicle,just drop it in and see what happens.But as said new runways have excellent drainage.
Have heard a pound coin(3mm) is a good subsitute.
PT.
At Cardiff we carry different sized washers in the op`s vehicle,just drop it in and see what happens.But as said new runways have excellent drainage.
Have heard a pound coin(3mm) is a good subsitute.
PT.
Last edited by pipertommy; 9th Oct 2007 at 07:08.
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Oicur12
Standing Water on Runway.
The Operator of the Airport is responsible, under ICAO standards,to measure the depth of snow or slush or water by means of a simple standard depth gauge. Readings are taken at approximately 300 metre intervals between 5 & 10 metres either side of centre line & clear of the effects of rutting. Depth information is given in millimetres for each third of the total runway, each being the mean of the reading obtained.
Additionally, when making these measurements observers carrying out the runway inspection will make an assessment of the nature of the surface covering, which will be described in the following categories:
(a) Dry snow (up to but not including 0.35 S.G)
(b) Wet snow (0.35 S.G.up to but not including 0.5 S.G.)
(c) Compacted snow (over 0.5 S.G.)
(d) Slush (0.5 S.G. to 0.8 S.G.)
(e) Standing water (1.0 S.G.)
Hope this helps
The Operator of the Airport is responsible, under ICAO standards,to measure the depth of snow or slush or water by means of a simple standard depth gauge. Readings are taken at approximately 300 metre intervals between 5 & 10 metres either side of centre line & clear of the effects of rutting. Depth information is given in millimetres for each third of the total runway, each being the mean of the reading obtained.
Additionally, when making these measurements observers carrying out the runway inspection will make an assessment of the nature of the surface covering, which will be described in the following categories:
(a) Dry snow (up to but not including 0.35 S.G)
(b) Wet snow (0.35 S.G.up to but not including 0.5 S.G.)
(c) Compacted snow (over 0.5 S.G.)
(d) Slush (0.5 S.G. to 0.8 S.G.)
(e) Standing water (1.0 S.G.)
Hope this helps
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The Operator of the Airport is responsible, under ICAO standards,to measure the depth of snow or slush or water by means of a simple standard depth gauge. Readings are taken at approximately 300 metre intervals between 5 & 10 metres either side of centre line & clear of the effects of rutting. Depth information is given in millimetres for each third of the total runway, each being the mean of the reading obtained.
Additionally, when making these measurements observers carrying out the runway inspection will make an assessment of the nature of the surface covering, which will be described in the following categories:
(a) Dry snow (up to but not including 0.35 S.G)
(b) Wet snow (0.35 S.G.up to but not including 0.5 S.G.)
(c) Compacted snow (over 0.5 S.G.)
(d) Slush (0.5 S.G. to 0.8 S.G.)
(e) Standing water (1.0 S.G.)
Additionally, when making these measurements observers carrying out the runway inspection will make an assessment of the nature of the surface covering, which will be described in the following categories:
(a) Dry snow (up to but not including 0.35 S.G)
(b) Wet snow (0.35 S.G.up to but not including 0.5 S.G.)
(c) Compacted snow (over 0.5 S.G.)
(d) Slush (0.5 S.G. to 0.8 S.G.)
(e) Standing water (1.0 S.G.)
The depth of solid ice (S. G. 0,91) may be difficult to measure and irrelevant to braking action, of course. But why is slush specified as 0,5 S. G. to 0,8 S. G? It should surely be 0,91 to 1,00 S. G?
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Oicur12
How do you gauge depth of standing water.
Reference your 2nd paragraph in original post, I am not sure of your request, has it anything to do with in-flight visibilty?
Reference your 2nd paragraph in original post, I am not sure of your request, has it anything to do with in-flight visibilty?
Weather radar may help during a rain storm, but don’t rely on it particularly when a storm has just passed and the runway is still draining.
Ref TP 14002E Wet Runway Friction: Literature and Information Review.
Page 10 table 2.1 Hydroplaning - correlates tyre tread / water depth with rainfall rates.
WXR colours indicate approximate rates – yellow up to 0.5 in/hr, red greater than 0.5 in/hr.
Thus with little tyre tread on a smooth runway you are at risk in yellow rainfall, elsewhere red rainfall.
Page 11, Figs 2.1, 2.2. suggest that water depth should not approach the 3 mm contaminated category, but I do not believe that this data takes into account puddles or only requiring 25% of the surface to be covered.
However Fig 2.7 on Page 15 does indicate the potential for flooding (0.1”) with yellow / red rainfall rates (0.5 in/hr). Note the text re factors and drainage.
Note page 34 re storms “The greatest decrease (friction) will probably occur at the start of the rainstorm if contaminants are present, as they are likely to produce a greasy surface.
Fig 3.11/12 Page 38 indicates that low friction levels can be experienced in ‘damp’ conditions on smooth concrete runways.
Note the summary on page 49 and the discussion on grooves, contaminants, and tyre pressure thereafter.
Hydroplaning aspects - page 59.
Summary Page 83.
Ref Colour standards for weather radar.
Ref TP 14002E Wet Runway Friction: Literature and Information Review.
Page 10 table 2.1 Hydroplaning - correlates tyre tread / water depth with rainfall rates.
WXR colours indicate approximate rates – yellow up to 0.5 in/hr, red greater than 0.5 in/hr.
Thus with little tyre tread on a smooth runway you are at risk in yellow rainfall, elsewhere red rainfall.
Page 11, Figs 2.1, 2.2. suggest that water depth should not approach the 3 mm contaminated category, but I do not believe that this data takes into account puddles or only requiring 25% of the surface to be covered.
However Fig 2.7 on Page 15 does indicate the potential for flooding (0.1”) with yellow / red rainfall rates (0.5 in/hr). Note the text re factors and drainage.
Note page 34 re storms “The greatest decrease (friction) will probably occur at the start of the rainstorm if contaminants are present, as they are likely to produce a greasy surface.
Fig 3.11/12 Page 38 indicates that low friction levels can be experienced in ‘damp’ conditions on smooth concrete runways.
Note the summary on page 49 and the discussion on grooves, contaminants, and tyre pressure thereafter.
Hydroplaning aspects - page 59.
Summary Page 83.
Ref Colour standards for weather radar.
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All interesting information. Thanks for the replys.
ACMS - TPE was a situation I had in mind when posting this question. I am becoming more conservative in my flying these days and would not land on a non grooved runway with rubber build up during heavy rain and strong crosswind. TPE atc are generally better than PRC but I have on occasion requested braking info from tower only to be ignored.
So it leaves you looking for alternative sources of info to apply an FCOM crosswind limit.
As for PRC, they generally wont even give you runway info at all, even when its snowing. All the decodes for MOTNE/Snowtam and quizzes in the sim amount to bubkis in the real world of china flying.
ACMS - TPE was a situation I had in mind when posting this question. I am becoming more conservative in my flying these days and would not land on a non grooved runway with rubber build up during heavy rain and strong crosswind. TPE atc are generally better than PRC but I have on occasion requested braking info from tower only to be ignored.
So it leaves you looking for alternative sources of info to apply an FCOM crosswind limit.
As for PRC, they generally wont even give you runway info at all, even when its snowing. All the decodes for MOTNE/Snowtam and quizzes in the sim amount to bubkis in the real world of china flying.
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I would be interested to know where a captain or company would draw the line and cancel the flight.
The example I can think of recently is TAF 35 knots crosswind and 800m in heavy rain. No braking action reports or windshear info available before departure. Its within viz and crosswind limits but would you land? If you wouldnt, why would you depart?
The example I can think of recently is TAF 35 knots crosswind and 800m in heavy rain. No braking action reports or windshear info available before departure. Its within viz and crosswind limits but would you land? If you wouldnt, why would you depart?
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The problem is that most countries/airports where they will report water/contaminate depth are invariably the ones which have well designed drainage and grooved runways ... It tends to be places where asking for a simple ATC request is diificult to communicate that tend to be the runways that are not properly drained or grooved ...
If your company is asking you to operate their machinery into such places one has to make a sensible judgement on the conditions, once the reversers are deployed on most types you negate the GA option and are only then finding out what the true BA is like having touched down ...
Commercial pressures are often the cause of overrun accidents, with not being able to 100% justify your actions in diverting in such cases with no 'hard facts' on the runway state to back up your decision.
(BTW: Chenia/Madrass mentioned above is undergoing runway grooving work over the next few months ... hopefuly Mumbai/Bombay will follow their lead in due course ...).
If your company is asking you to operate their machinery into such places one has to make a sensible judgement on the conditions, once the reversers are deployed on most types you negate the GA option and are only then finding out what the true BA is like having touched down ...
Commercial pressures are often the cause of overrun accidents, with not being able to 100% justify your actions in diverting in such cases with no 'hard facts' on the runway state to back up your decision.
(BTW: Chenia/Madrass mentioned above is undergoing runway grooving work over the next few months ... hopefuly Mumbai/Bombay will follow their lead in due course ...).
Re 35 knots crosswind and 800m in heavy rain”
Useful guidance is given in the Canadian AIM, AIR Para 1.6 (Aeronautical Information Manual – 12 Apr 07) where crosswinds are related to CRFI (Canadian Runway Friction Index).
Although CRFI is not widely used outside of Canada, table 4a surface conditions, and table 3 crosswind limits can be used for guidance.
From table 4a, heavy rain (where aquaplaning might be expected) relates to icy conditions which gives a CRFI in the range 0.15 – 0.3.
Entering these values into table 3 indicates that the maximum crosswind should be 15 kts.
Note that para 1.6.5 provides an example of aquaplaning in a 10kt crosswind resulting in drifting off a 200ft wide runway in 7secs !
Useful guidance is given in the Canadian AIM, AIR Para 1.6 (Aeronautical Information Manual – 12 Apr 07) where crosswinds are related to CRFI (Canadian Runway Friction Index).
Although CRFI is not widely used outside of Canada, table 4a surface conditions, and table 3 crosswind limits can be used for guidance.
From table 4a, heavy rain (where aquaplaning might be expected) relates to icy conditions which gives a CRFI in the range 0.15 – 0.3.
Entering these values into table 3 indicates that the maximum crosswind should be 15 kts.
Note that para 1.6.5 provides an example of aquaplaning in a 10kt crosswind resulting in drifting off a 200ft wide runway in 7secs !
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Reviving an old thread just to post an archived copy of the document alf5071h had above TP 14002E Wet Runway Friction: Literature and Information Review. That link is dead. The document is not longer available on the Transport Canada as a direct download link, only by email request.
However it was archived at the wayback machine: Wet Runway Friction: Literature and Information Review Prepared for Transportation Development Centre On behalf of Aerodrome Safety Branch Transport Canada August 2001
However it was archived at the wayback machine: Wet Runway Friction: Literature and Information Review Prepared for Transportation Development Centre On behalf of Aerodrome Safety Branch Transport Canada August 2001
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Interesting comment at Post #3 regarding QF policy of not landing on un-grooved runways in heavy rain (since their BKK overrun). The runway being contaminated may have been a minor contributory factor in that "Incident". From my reading of the report the major contributory factors were more related to a poorly executed approach (hot and high resulting in touch down well into the runway), lack of communication between the two pilots occupying LH & RH positions resulting in initiation of a go-around, an un-communicated abort of the go-around, one thrust lever left behind at about 1.50 EPR when other three moved to Reverse Idle etc etc. All compounded by a policy at that time to use only 25 Flap and Idle Reverse only. Many lessons learnt from this one.
