Heavy Rain on windshield and optical illusions
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Joined: Jun 2000
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From: Australia
Heavy Rain on windshield and optical illusions
Extract from The Boeing 737 Technical Guide by Chris Brady. Page 169. Quote: The rain repellent has been removed due to worries about the environmental effects of the "RainBoe" fluid which contains Freon 113 (a CFC). Furthermore, Freon 113 is poisonous and has been blamed in at least 12 deaths in industrial settings and the rain repellent canisters, which were stored behind the captain had been known to leak. In 1991, Boeing added D-limonine which has a strong smell of orange peel, into RainBoe so that leakage could be detected. There are no plans to replace the rain repellent with another liquid product even though there are safe alternatives.
On 25 May 1982, a 737-200 Adv (PP-SMY) was written off by a heavy landing in a rainstorm. Since early 1994 all Boeing aircraft have been built with Surface Seal coated glass from PPG Industries which has a hydrophobic coating. The coating does deteriorate with time depending on wiper use and windscreen cleaning methods etc but can be re-applied. Unquote.
I recall occasionally using RainBoe when landing in heavy rain in the South Pacific region where our operations involved landing at Pacific Atolls in a Boeing 737-200. A characteristic of some of these atolls was the presence of torrential rain from towering Cu hanging over the airports and where diversion to another atoll ran the risk of arriving in heavy un-forecast rain. In fact blinding rain was a more apt description. Crews operating in these regions were well aware of the difference in forward visibility between landing in light rain or drizzle (European experience) and that of landing in a heavy downpour common in the Pacific region where forward visibility was very limited and the danger of rain refraction causing a false horizon.
Talking recently to colleagues flying the Boeing 737 NG in Australia, they said the coated windscreen was virtually useless in heavy rain and not nearly as effective RainBoe rain repellent. Moreover, the coated windscreen became even less effective with time in service even though the coating could be re-applied. I know that some pilots in SE Asia were known to use small bottles of commercial rain repellent Rain-X used on car windscreens and apply this liquid to the outside of their aircraft windscreens prior to flight by the simple process of opening the side window and leaning out to rub the forward windows with Rain-X. They swear by its effectiveness in monsoonal rain.
Of course if it becomes imperative to land in blinding rain and even a coated windscreen is useless, then as a last resort the Boeing 737 FCTM advises: "If required , the windows may be opened in-flight, at or below holding speeds, after depressurising the aircraft. It is recommended that the aircraft be slowed since the noise levels increase at higher airspeed. Intentions should be briefed and ATC notified prior to opening the window as the noise level is high, even at slow speeds. Because of aircraft design, there is an area of relatively calm air over the open window. Forward visibility can be maintained by looking out of the open window using care to stay clear of the airstream".
I bet not many Boeing pilots are aware of that useful paragraph in the FCTM. In any case, because of simulator design, it's not the sort of thing you can practice. Yet it could be a life-saver if there is no other choice but to land.
Depending on local weather phenomena it is probable most pilots in their career rarely need to resort to using canister rain repellent even if it was installed. Who knows - perhaps the Global Warming debate of more extreme weather events (
) could persuade aircraft manufacturers to re-consider the cost effectiveness of going back to RainBoe or similar liquid, regardless of CFC perceived effect on the atmosphere.
The discussion should be about flight safety and the balance between the risks of attempting to land affected by optical illusion in blinding rain - and future atmospheric effects of CFC. The fact remains that coated windscreens are subject to wear leaving pilots with nothing to aid their forward vision in blinding rain. By the time the pilot realises his coated windscreen is not doing its job, it is too late.
Comments invited about your experience with coated windscreens compared to installed rain repellent.
On 25 May 1982, a 737-200 Adv (PP-SMY) was written off by a heavy landing in a rainstorm. Since early 1994 all Boeing aircraft have been built with Surface Seal coated glass from PPG Industries which has a hydrophobic coating. The coating does deteriorate with time depending on wiper use and windscreen cleaning methods etc but can be re-applied. Unquote.
I recall occasionally using RainBoe when landing in heavy rain in the South Pacific region where our operations involved landing at Pacific Atolls in a Boeing 737-200. A characteristic of some of these atolls was the presence of torrential rain from towering Cu hanging over the airports and where diversion to another atoll ran the risk of arriving in heavy un-forecast rain. In fact blinding rain was a more apt description. Crews operating in these regions were well aware of the difference in forward visibility between landing in light rain or drizzle (European experience) and that of landing in a heavy downpour common in the Pacific region where forward visibility was very limited and the danger of rain refraction causing a false horizon.
Talking recently to colleagues flying the Boeing 737 NG in Australia, they said the coated windscreen was virtually useless in heavy rain and not nearly as effective RainBoe rain repellent. Moreover, the coated windscreen became even less effective with time in service even though the coating could be re-applied. I know that some pilots in SE Asia were known to use small bottles of commercial rain repellent Rain-X used on car windscreens and apply this liquid to the outside of their aircraft windscreens prior to flight by the simple process of opening the side window and leaning out to rub the forward windows with Rain-X. They swear by its effectiveness in monsoonal rain.
Of course if it becomes imperative to land in blinding rain and even a coated windscreen is useless, then as a last resort the Boeing 737 FCTM advises: "If required , the windows may be opened in-flight, at or below holding speeds, after depressurising the aircraft. It is recommended that the aircraft be slowed since the noise levels increase at higher airspeed. Intentions should be briefed and ATC notified prior to opening the window as the noise level is high, even at slow speeds. Because of aircraft design, there is an area of relatively calm air over the open window. Forward visibility can be maintained by looking out of the open window using care to stay clear of the airstream".
I bet not many Boeing pilots are aware of that useful paragraph in the FCTM. In any case, because of simulator design, it's not the sort of thing you can practice. Yet it could be a life-saver if there is no other choice but to land.
Depending on local weather phenomena it is probable most pilots in their career rarely need to resort to using canister rain repellent even if it was installed. Who knows - perhaps the Global Warming debate of more extreme weather events (
) could persuade aircraft manufacturers to re-consider the cost effectiveness of going back to RainBoe or similar liquid, regardless of CFC perceived effect on the atmosphere. The discussion should be about flight safety and the balance between the risks of attempting to land affected by optical illusion in blinding rain - and future atmospheric effects of CFC. The fact remains that coated windscreens are subject to wear leaving pilots with nothing to aid their forward vision in blinding rain. By the time the pilot realises his coated windscreen is not doing its job, it is too late.
Comments invited about your experience with coated windscreens compared to installed rain repellent.
Last edited by Centaurus; 29th April 2014 at 06:42.
Joined: Apr 2013
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From: everywhere
Don't know about Boeings, but new Airbii come from Toulouse with a tank filled with rain repellant. Tried it once or twice in heavy (in European terms) rain and it seems to work.
Don't know the brand name of this stuff and once is used, the operator never refills it...
My only experience with tropical rains was in ATR. The windshields were supposedly covered with a hydrophobic coating (they did it every year prior to the start of monsoon season, so it was fresh). However, it didn't seem to make any difference. Landing in a good downpour, it felt like looking through a bottom of a bottle. Lots of water on the windshield and everything was distorted. After one or two landings like this, I just preferred to hold and wait till the rain was over...
Don't know the brand name of this stuff and once is used, the operator never refills it...
My only experience with tropical rains was in ATR. The windshields were supposedly covered with a hydrophobic coating (they did it every year prior to the start of monsoon season, so it was fresh). However, it didn't seem to make any difference. Landing in a good downpour, it felt like looking through a bottom of a bottle. Lots of water on the windshield and everything was distorted. After one or two landings like this, I just preferred to hold and wait till the rain was over...
Last edited by C_Star; 29th April 2014 at 06:54.
Joined: Sep 2003
Aviation Qualifications: ATPL
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From: away from home
As for the OP, having flown in such rains in Oceania, I would not want to open my side window. I´ll take my chances with poor visibility rather than drowning...
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Posts: n/a
if you have liquid rain repellent available
do not use it in any light rain !!
but if you once use it in "real" rain or showers
it is sooo much better then wipers
and you will never again wish to use windshield wipers
in those conditions
do not use it in any light rain !!
but if you once use it in "real" rain or showers
it is sooo much better then wipers
and you will never again wish to use windshield wipers
in those conditions
Last edited by Green Guard; 30th April 2014 at 14:09.
Joined: Jan 2014
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From: glendale
we had someone put rain x on douglas windshields about 20 years ago, the heating of the windshields seemed to cook it and ruin the windshields to the point of replacing the windshields SO YOU ALL BE CAREFUL OUT THERE
Joined: Jun 2009
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From: Australia
Ok I'll say it again.
Rain repellant is SERVICEABLE on our A330's.
They did deactivate it a number of years ago, explored other options but they re-activated it because nothing else worked.
Now what they actually put into the reservoir I don't know, but whatever the liquid is it seems to work.
Rain repellant is SERVICEABLE on our A330's.
They did deactivate it a number of years ago, explored other options but they re-activated it because nothing else worked.
Now what they actually put into the reservoir I don't know, but whatever the liquid is it seems to work.
Joined: Sep 2012
Posts: 202
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From: Nowhere near Shinbone Waterhole
...Rain repellent is replenished as a matter of course at our
mob. Wonder why the same isn't done with a lot of airlines.
Is it simply cost or some bloody tree-hugging element in it?
mob. Wonder why the same isn't done with a lot of airlines.
Is it simply cost or some bloody tree-hugging element in it?
Joined: May 2013
Posts: 121
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From: London
I used to fly with a captain in SE Asia who came to work with some car windshield rain repellant. It came as a box of tissues which he applied by just wiping the tissue on the outside. I used to decline any on my side. The difference between the two sides in rain was quite marked, he never needed to use the wiper!
Gawd only knows how compatible those chemicals are with Boeing windows!
Gawd only knows how compatible those chemicals are with Boeing windows!
Thread Starter
Joined: Jun 2000
Aviation Qualifications: ATP+Mil
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From: Australia
If it is squirted on through the installed rain repellent system, then under no conditions do you do it on a dry windscreen or light rain. If however, the rain is so heavy that you cannot see the runway properly through the windscreen then that is the time for one squirt only. The wipers should be on by then. It is effective immediately.
Boeing used to recommend one windscreen at a time. If squirted on a dry windscreen it leaves a coating. Our engineers discovered that shaking a bottle of Coca Cola and squirting that all over the windscreen successfully cleaned away the residue
Boeing used to recommend one windscreen at a time. If squirted on a dry windscreen it leaves a coating. Our engineers discovered that shaking a bottle of Coca Cola and squirting that all over the windscreen successfully cleaned away the residue
Joined: Nov 2004
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From: bkk
RAIN REPELLANT
While on the 320 in JAKARTA some years ago, my instructor paused to apply a coating of commercial (for your car) rain repellant on his window, he purchased at a local hardware store, just before we flew to Medan.Upon return, there was a heavy rain shower over the threshold of the only runway available at the time, reported visibility was 1500m.I was very very surprised at the difference between his view out the window compared to mine.He could see quite well, but on my side it was basically blind.I could only provide monitoring based on my instruments, visual support out the window was not available.An eye opener, excuse the pun,Peter.
