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Would This Warrant An Emergency Descent?  
User currently offlineAvroArrow From Canada, joined Sep 2001, 1046 posts, RR: 0
Posted (11 years 1 month 1 week 21 hours ago) and read 4152 times:

Saw this new photo in the DB today.

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Photo © Robert Thomas

I know he says its only the outer pane, but to stay at FL450 as he mentions in his caption seems odd to me. Wouldn't you want to descend to a lower altitude (FL100?) to reduce the pressurization load on the windscreen in case the main layer of the windshield was damaged? Or maybe I'm just ignorant?

Give me a mile of road and I can take you a mile. Give me a mile of runway and I can show you the world.
10 replies: All unread, jump to last
User currently offlineContact_tower From Norway, joined Sep 2001, 536 posts, RR: 1
Reply 1, posted (11 years 1 month 1 week 20 hours ago) and read 4109 times:

If they where, let's say mid atlantic, FL100 would but a real dent in the range of the plane. Perhaps even make it impossible to make it to airport?

I've experienced controlling am 737 that got a cracked window, and they continued to destination, at filed cruiseing level.

User currently offlineCorey07850 From United States of America, joined Feb 2004, 2537 posts, RR: 4
Reply 2, posted (11 years 1 month 1 week 20 hours ago) and read 4099 times:

I think his comment meant the pane cracked at FL450, not that they are still at that altitude, but I could be wrong

User currently offline242 From United States of America, joined Oct 2000, 498 posts, RR: 0
Reply 3, posted (11 years 1 month 1 week 20 hours ago) and read 4092 times:

It's the outer layer. Not really a big deal-- but may require a ferry flight to get the aircraft to a maintenance station.

It's a windshield heat problem, and it happens more often than you think.

User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 9
Reply 4, posted (11 years 1 month 1 week 18 hours ago) and read 4006 times:

Depends, if it is only the outer layer, then the checklist may not require a descent. If I recall, speed is as much a limiting factor as pressure.

Proud OOTSK member
User currently offlineHAWK21M From India, joined Jan 2001, 31875 posts, RR: 54
Reply 5, posted (11 years 1 month 1 week 18 hours ago) and read 3994 times:

Not Sure what Alt he is when the Pic was taken.
But the Inner pane is capable of withstanding the pressure loads.

Think of the brighter side!
User currently offlineWing From Turkey, joined Oct 2000, 1601 posts, RR: 23
Reply 6, posted (11 years 1 month 1 week 18 hours ago) and read 3996 times:

What I understand from the caption that he says the window cracked at FL 450,he doesnt mention flying the rest of the flight at FL450.

I can not comment without seeing the QRH of the Gulfstream III on this incident,still I am sure they handled it according to the requirements and limitations of their aircraft

My A-321 QRH limits the max FL at 230 in a cracked window situation.

Don't mix the total cabin pressure loss with this situation since you still can control the pressurization on a crack windshield problem.An emergency descent to 10000 feet or highest alt on the route is required only when you cant control the cabin pressurisation anymore.

follow me on my facebook page" captain wing's journey log"
User currently offlineGreasespot From Canada, joined Apr 2004, 3104 posts, RR: 19
Reply 7, posted (11 years 1 month 1 week 15 hours ago) and read 3832 times:

No the maintenance manual pretty much says no restrictions unless the captains vision is obscured. It leaves it vague so different captains do different things. I have seen freighter come home from out station with windows like that after they cracked on descent to the station. Since there was no maintenance nd the pilots wanted to come home they flew home.

When you lose window heat i( usually what caused the cracking like that)t is a speed restriction due to less impat resistance as opposed to a pressuruzation problem.

The outer payne has nothing to do with pressurization. It is the heated layer for impact resistance.

You can continue to fly at altitude with out any problems.

At least that is the B727 and B737.


Sometimes all you can do is look them in the eye and ask " how much did your mom drink when she was pregnant with you?"
User currently offlineAmtrosie From United States of America, joined Jan 2005, 274 posts, RR: 0
Reply 8, posted (11 years 1 month 1 week 8 hours ago) and read 3618 times:

Per the emergency procedure for the GII: (virtually identical to III)
1. Reduce cabin pressure diff. to 6.0psi max.
2. Windshield heat switch-off.
3. Pull associated C/B's (it lists them, power and control)
4. Windshield heat switch-ON
5.Maintain current airspeed/mach or slower for remainder of flight.
BELOW 10,000 ft.
6. Airspeed max 235 KIAS
7. Max climb/descent 2000FPM
8. avoid all icing conditions.
It does caution the cockpit crew to do smoke goggles as a precaution.

User currently offlineAvroArrow From Canada, joined Sep 2001, 1046 posts, RR: 0
Reply 9, posted (11 years 1 month 1 week 7 hours ago) and read 3581 times:

Thanks for the input guys. I was unsure how much of an effect the crack on the outer layer would have. I guess the consensus is that it probably had minimal to no real effect. But it sure does look rather impressive.  Smile

Give me a mile of road and I can take you a mile. Give me a mile of runway and I can show you the world.
User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 4
Reply 10, posted (11 years 1 month 1 week 5 hours ago) and read 3546 times:

I have witnessed such a windshield failure once during a flight on a C-160 "Transall" (German Air Force). First there were some sparks visible on one part of the heated windshield area. The captain switched the heating off, the sparkes stopped. We could see a small area of delamination (one small bubble). Then he switched the window heating on again. The sparks were visible again and then there was a loud "bang". The windshield looked similar to the one one this picture of the Gulfstream. They reduced airspeed and flight level (no emergency descent) and we returned to our airbase.

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Photo © Stefan Welsch

This job sucks!!! I love this job!!!
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