Centaurus
29th Apr 2014, 06:27
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 (:E) 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 (:E) 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.