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Cockpit Windscreens Getting Damaged By Winds?  
User currently offlineUSAFHummer From United States of America, joined May 2000, 10685 posts, RR: 53
Posted (7 years 6 months 1 week 1 day 4 hours ago) and read 2921 times:

http://www.9news.com/news/article.aspx?storyid=64966

I was at Denver yesterday flying on a CO flight DEN-IAH, and my flight had a lot of pax from a Skywest flight DEN-IAH that had been canceled on account of the story above...I was sitting next to two pax from the Skywest flight, and the story they told was that they were on the takeoff roll, very close to rotation speed, when the windscreens shattered and the takeoff was aborted...when they returned to the gate, the captain said they had been hit by a microburst and that was hat caused the shattering...(don't shoot the messenger, Im just reporting what was told to me!)

I checked with a friend who is a CRJ f/o about the plausibility of this explanation for a windscreen shatter and he argued that there was no way that a windscreen could be destroyed like that...are there any other alternative explanations?? WInds at Denver were pretty strong yesterday...I checked the METAR while I was at the airport and the wind reading was something like 33G40...but obviously it seems that windscreens should be able to withstand the wind...any ideas?

Thanks,
Greg


Chief A.net college football stadium self-pic guru
26 replies: All unread, showing first 25:
 
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 1, posted (7 years 6 months 1 week 1 day 3 hours ago) and read 2901 times:

A microburst can be full of rather large hail, so it is not implausible.

Cheers,
Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineA342 From Germany, joined Jul 2005, 4681 posts, RR: 3
Reply 2, posted (7 years 6 months 1 week 1 day 3 hours ago) and read 2894 times:

Maybe there was a crack in the windscreen already before it broke ?

Birdstrike ? (I know, the pilot should have seen it.)



Exceptions confirm the rule.
User currently offlineUSAFHummer From United States of America, joined May 2000, 10685 posts, RR: 53
Reply 3, posted (7 years 6 months 1 week 1 day 3 hours ago) and read 2877 times:

Quoting FredT (Reply 1):
A microburst can be full of rather large hail, so it is not implausible.

No hail yesterday in Denver, just light flurrying...

Quoting A342 (Reply 2):
Maybe there was a crack in the windscreen already before it broke ?

Birdstrike ? (I know, the pilot should have seen it.)

13 planes being struck by a bird in the same timeframe??? 13 planes with pre-cracked windscreens all going at the same time? Seems unlikely, oddswise...



Chief A.net college football stadium self-pic guru
User currently offlineFr8Mech From United States of America, joined Sep 2005, 5395 posts, RR: 14
Reply 4, posted (7 years 6 months 1 week 1 day 3 hours ago) and read 2877 times:

Rapid temperature changes have been known to crack windshields. Faulty controllers. Hail. Improper procedures (rare on newer aircraft).

But 8 winshields?

http://news.yahoo.com/s/ap/20070217/ap_on_re_us/winter_weather_86

I have no explanation.

We did have 2 windshields crack a couple of weeks ago, 1 night apart. It was pretty darned cold, but they both cracked at top of descent. A lot colder there, than at ground level.

FYI, some MELs allow an aircrfat to fly with a cracked windshield if certain conditions are met.



When seconds count...the police are minutes away.
User currently offlineJayDub From , joined Dec 1969, posts, RR:
Reply 5, posted (7 years 6 months 1 week 1 day 2 hours ago) and read 2856 times:

Possibly a combination of rapid temperature change and a rapid change in pressure?

Maybe New World Order living underneath DEN were testing some new weapons?

It's quite the mystery.


User currently offlineScooter01 From Norway, joined Nov 2006, 1201 posts, RR: 8
Reply 6, posted (7 years 6 months 1 week 22 hours ago) and read 2739 times:
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Quoting JayDub (Reply 5):
It's quite the mystery.



Quoting Fr8Mech (Reply 4):

Maybe the same gremlins that that cracks the dashboards in my cars?

2 in Toronto(BMW) and 1 in Oslo(Volvo)

Scooter



"We all have a girl and her name is nostalgia" - Hemingway
User currently offlineRalgha From United States of America, joined Nov 1999, 1614 posts, RR: 6
Reply 7, posted (7 years 6 months 1 week 21 hours ago) and read 2698 times:

Bullets can damage windows.


09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
User currently offlineAirfoilsguy From , joined Dec 1969, posts, RR:
Reply 8, posted (7 years 6 months 1 week 21 hours ago) and read 2656 times:

A comedian once said this about hurricanes but I think it applies here too. "It is not that the wind is blowing that is dangerous but what the wind is blowing. A reference to dirt stones and other assorted crap that the wind picks up.

User currently offlineJayDub From , joined Dec 1969, posts, RR:
Reply 9, posted (7 years 6 months 1 week 20 hours ago) and read 2597 times:

The more I hear about it...the more I keep hearing about large chunks of ice being blown off of the terminal buildings.

User currently offline1011 From United States of America, joined Feb 2001, 315 posts, RR: 0
Reply 10, posted (7 years 6 months 1 week 20 hours ago) and read 2553 times:

Did Denver have thunderstorms? It is kinda hard to have a microburst without a thunderstorm. Maybe it was a mountain wave?

User currently onlineGoldenshield From United States of America, joined Jan 2001, 6005 posts, RR: 14
Reply 11, posted (7 years 6 months 1 week 16 hours ago) and read 2357 times:

Quoting 1011 (Reply 10):
Did Denver have thunderstorms? It is kinda hard to have a microburst without a thunderstorm. Maybe it was a mountain wave?

Denver has them all of the time, storms or clear skies.



Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offlineUSAFHummer From United States of America, joined May 2000, 10685 posts, RR: 53
Reply 12, posted (7 years 6 months 1 week 15 hours ago) and read 2328 times:

Quoting 1011 (Reply 10):
Did Denver have thunderstorms? It is kinda hard to have a microburst without a thunderstorm. Maybe it was a mountain wave?



Quoting JayDub (Reply 9):
The more I hear about it...the more I keep hearing about large chunks of ice being blown off of the terminal buildings.

That seems to make a ton of sense...ice blown off roofs, hits cockpit while aircraft is still at gate...aircraft gets up to speed on the runway, windscreen fails on account of that...good thinking JayDub!



Chief A.net college football stadium self-pic guru
User currently offlineMemphis From United States of America, joined Mar 2006, 143 posts, RR: 0
Reply 13, posted (7 years 6 months 1 week 11 hours ago) and read 2202 times:

What about the massive windows lining the terminal? I bet they are not rated to withstand some of the forces that a windshield on a jet could take. Big grin Why weren't they busted?


nocturnal
User currently offlineDavid L From United Kingdom, joined May 1999, 9524 posts, RR: 42
Reply 14, posted (7 years 6 months 1 week 6 hours ago) and read 2145 times:

Quoting Memphis (Reply 13):
What about the massive windows lining the terminal? I bet they are not rated to withstand some of the forces that a windshield on a jet could take.

On the other hand, they tend not to be rattled along a runway at over 100 kts.  Smile


User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 15, posted (7 years 6 months 1 week 6 hours ago) and read 2135 times:
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DATABASE EDITOR



Stupid question, perhaps, but might the broken windshields have been caused by deicing? For example, if the fluid had been too hot, or sprayed in the wrong places? I know very little about deicing ops, so I'm really just thinking out loud...


2H4





Intentionally Left Blank
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 16, posted (7 years 6 months 1 week 6 hours ago) and read 2133 times:

Quoting 1011 (Reply 10):
Did Denver have thunderstorms? It is kinda hard to have a microburst without a thunderstorm. Maybe it was a mountain wave?

Naw, microbursts come out of CBs. CBs can be associated with thunderstorms. But there is nothing saying you can't have a microburst without a thunderstorm.

My bet is still on hail. Windshields are either cracked or they are not. If ice blown off a terminal roof could imperceptibly damage windshiels in such a way that they'd later break... and not on one occasion but on several... I'd go by train. The hail from a microburst can be VERY local. And very destructive, if it happens to go across a couple of parked aircraft. Even more destructive if an aircraft happens to fly through the hail storm.

High winds the cause? Not likely, unless the area was struck by winds in excess of 250 knots...

One factor is the fact that airliner windshields are more brittle when the aircraft is parked on the grund than in flight. The reason is the windshield heating.

Speculation, speculation and speculation is all we will be able to achieve without more facts.



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineFr8Mech From United States of America, joined Sep 2005, 5395 posts, RR: 14
Reply 17, posted (7 years 6 months 1 week 6 hours ago) and read 2131 times:

If it was flying debris, why are only the windshields affected? They are hardly the most vulnerable parts of the aircraft. In fact, I would say they are one of the most durable and capable of withstanding a hit.


When seconds count...the police are minutes away.
User currently offlineScooter01 From Norway, joined Nov 2006, 1201 posts, RR: 8
Reply 18, posted (7 years 6 months 1 week 4 hours ago) and read 2096 times:
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Quoting Scooter01 (Reply 6):
Maybe the same gremlins that that cracks the dashboards in my cars?



Quoting 2H4 (Reply 15):
Stupid question, perhaps, but might the broken windshields have been caused by deicing? For example, if the fluid had been too hot, or sprayed in the wrong places? I know very little about deicing ops, so I'm really just thinking out loud...

Well, they are both made from oil-based chemicals. Maybe some kind of chemical used in the cleaning/maintenance or deicing fluids works over longer time to change some of the properties in the finished product. I was told once by a car cleaning MASTER that use of "Armor-all" was the cause for the cracked dashboards, and the cracking happened during freezing temperatures all 3 times.

Scooter

[Edited 2007-02-18 16:49:17]


"We all have a girl and her name is nostalgia" - Hemingway
User currently offlineA342 From Germany, joined Jul 2005, 4681 posts, RR: 3
Reply 19, posted (7 years 6 months 1 week ago) and read 2031 times:

Quoting USAFHummer (Reply 3):
13 planes being struck by a bird in the same timeframe??? 13 planes with pre-cracked windscreens all going at the same time? Seems unlikely, oddswise...

Sorry, as I didn't read the link, I didn't know 13 aircraft were affected. Very strange indeed.



Exceptions confirm the rule.
User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 20, posted (7 years 6 months 6 days 17 hours ago) and read 1953 times:

Difficult to believe only Winds could have affected all those Aircraft Windshield.I believe The Wind was def carrying some Hail or similiar FOD.
regds
MEL



Think of the brighter side!
User currently offlineMemphis From United States of America, joined Mar 2006, 143 posts, RR: 0
Reply 21, posted (7 years 6 months 6 days 15 hours ago) and read 1930 times:

We were taught in never to spray de-ice fluid directly on the cock-pit windows. The intense heat added with the cold window could cause the window to crack. Instead, we were instructed to spray de-ice on the fusalage above the windows and let the hot fluid run down on top of the windows, wipers, etc in order to remove contamination.


nocturnal
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 22, posted (7 years 6 months 6 days 15 hours ago) and read 1926 times:
AIRLINERS.NET CREW
DATABASE EDITOR




Quoting Memphis (Reply 21):
We were taught in never to spray de-ice fluid directly on the cock-pit windows. The intense heat added with the cold window could cause the window to crack.

Well, that's what I was thinking. Perhaps the individual deicing the aircraft that day was new, forgetful, or uncaring.


2H4





Intentionally Left Blank
User currently offlineOuboy79 From United States of America, joined Nov 2001, 4581 posts, RR: 23
Reply 23, posted (7 years 6 months 5 days 17 hours ago) and read 1785 times:

Quoting FredT (Reply 16):
Naw, microbursts come out of CBs. CBs can be associated with thunderstorms. But there is nothing saying you can't have a microburst without a thunderstorm.

My bet is still on hail. Windshields are either cracked or they are not. If ice blown off a terminal roof could imperceptibly damage windshiels in such a way that they'd later break... and not on one occasion but on several... I'd go by train. The hail from a microburst can be VERY local. And very destructive, if it happens to go across a couple of parked aircraft. Even more destructive if an aircraft happens to fly through the hail storm.

Umm, I bet if you review the observations at the airport at the time you would note no weather close to what you are suggesting. Severe weather season isnt really here yet...though it will get a kicker here in the Southern Plains on Friday (woot woot). Anything that day would have been good ol sleet if there was any precip. Nothing reported in the US even approaching severe criteria that day.

Also any wind that day would not have been from any sort of convection.


User currently offlineUAL Bagsmasher From United States of America, joined Sep 1999, 2146 posts, RR: 10
Reply 24, posted (7 years 6 months 5 days 16 hours ago) and read 1769 times:

I've seen the landing light lens covers on our fleet crack on numerous occasions due to the hot glycol being applied to a cold soaked aircraft. Granted, the lens cover is nowhere near as beefy as a windscreen, but it's the same principle. For what it's worth, you can fly one leg with the damaged landing light lens cover removed to get to a MX base to have it replaced.

25 FredT : Now that is a good point.
26 Airgypsy : Years of maintenance control experience alerts me that this is a procedural problem. The outter Anti-ice pane is very thin and is usually very hot. It
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