AA off the end in Jackson Hole.......

[TUCKnTRUCK]

Re: Video

It's more than just that. There is literally NO ice forming on the aircraft AT ALL. The higher speeds and larger diameter of the surfaces make a huge difference. The aircraft capability is a separate matter. For example, there were many pilots at TWA who had not turned on airframe anti-ice on the 727 during their ENTIRE CAREER! It just does not form much on the bigger jets, and the 727 used to get a lot more than we do in the larger airplanes.

Thats pretty much what I was saying... what might be severe to me in the Dash, prob. wouldn't phase a 777. Speed, design, protection systems, excess thrust/lift available all matter, but usually pertain to the type. I will say once your systems capabilities are exceeded, it is amazing how fast it gets really bad.

 

[seagull]

Re: Video

Thats pretty much what I was saying... what might be severe to me in the Dash, prob. wouldn't phase a 777. Speed, design, protection systems, excess thrust/lift available all matter, but usually pertain to the type. I will say once your systems capabilities are exceeded, it is amazing how fast it gets really bad.

Your post makes it appear that you missed my point. Even absent the speed, protection systems, etc., just the sheer diameter of the surfaces makes it such that ice does not form.

Also note, and this is important, there has NEVER been a crash of a large swept wing transport, equipped with LED's, due to ice encountered in flight, OR not getting de-iced prior to takeoff. Ever. Don't bother with Palm 90, it would not have flown with that power setting no matter how clean the wings might be, and it does not meet either of the above criteria.

 

[seagull]

Re: Video

I've always wondered about speed too. Let's say I'm cruising along in the "transonic" speed regime, what effect is that going to have on the formation of ice on the aircraft? Is aerodynamic heating an actual factor at that point (I wouldn't think so), or does the airflow simply sublime any ice that forms on the wings pretty much instantly? Just a thought.

About 15 degrees of ram rise/100 kts, as I recall. It is possible for supersonic aircraft to raise the temp to the point that it melts so DOES form ice!

 

[PeanuckleCRJ]

Re: Video

I've always wondered about speed too. Let's say I'm cruising along in the "transonic" speed regime, what effect is that going to have on the formation of ice on the aircraft? Is aerodynamic heating an actual factor at that point (I wouldn't think so), or does the airflow simply sublime any ice that forms on the wings pretty much instantly? Just a thought.

The 757/767 was originally designed without a wing A/I system. Why? They just don't pick it up....

Not once did I ever see anything more than a light ice accumulation on the airframe.... the 737 is similar. The CRJ, on the other hand, picked it up like a bad habit.

I think part of it is aircraft size and air displacement as well as it just being a good design.

The brakes on the 757 are a freaking monster, and combined with a low approach speed you can stop QUICK in that thing. "Stick" it on the runway and you'll lose 15 knots or so just from the energy being transferred to the runway.

 

[coa787]

Re: Video

The super-cooled liquid water drop collection efficiency of a collecting surface depends on the drop size, the airspeed of the collecting surface, and the geometry of the collecting surface.

For example, a thick airfoil moving through an area of small water drops at a slow airspeed will have a lower collection efficiency. The slower you go, the less drops you fly though over a given period of time, therefore, less of them will impact the airfoil (assuming a constant angle of attack). The smaller the drops are, the less inertia they have, which makes them less likely to be able to penetrate the airflow around the airfoil, so they will just flow up and over the airfoil instead of impacting it. The thicker the airfoil, the more curvature it has, thus, it creates more negative static pressure (the "suction," lowered pressure due to increased airflow over the airfoil) and enough to pull the water drops over the airfoil and keep them in the airflow.

As seagull wrote, the thickness of the airliner airfoils is so much that, apparently, most of the water drops that they're flying through, because the drops are not large enough, just don't have enough inertia to overcome the negative static pressure being produced and, instead, remain in the airflow as it goes over the airfoil.

I've always wondered about speed too. Let's say I'm cruising along in the "transonic" speed regime, what effect is that going to have on the formation of ice on the aircraft? Is aerodynamic heating an actual factor at that point (I wouldn't think so), or does the airflow simply sublime any ice that forms on the wings pretty much instantly? Just a thought.

About 15 degrees of ram rise/100 kts, as I recall. It is possible for supersonic aircraft to raise the temp to the point that it melts so DOES form ice!

The temperature rises due to adiabatic compression. Using the total air temperature equation, at a true airspeed of 100 knots, for instance, a surface may experience a temperature rise of about 1 °C, while at 500 knots, that rise may be as much as 33 °C (relative to the ambient air temperature). The probability of ice accretion, in this situation, depends on what the ambient air temperature is.

 

[A300Capt]

Re: Video

The 757/767 was originally designed without a wing A/I system. Why? They just don't pick it up....

Not once did I ever see anything more than a light ice accumulation on the airframe.... the 737 is similar. The CRJ, on the other hand, picked it up like a bad habit.

I remember a flight in KMSP on the B757 one winter when folks were screaming about ice and many were holding due to the weather. We noticed rime ice all around the edges of the entire windshield begin to accumulate at a rapid pace and a hefty amount on the wiper bolt. After landing we noticed that everything that stuck out in the slipstream including the tail feathers and unheated part of the wing had a couple inches of Rime ice. The radome was completely covered. It was the worst accumulation I had seen since flying swept wing jets and even one of the worst I had seen in my flying career even while flying for the commuters in the NE US.

We rarely ever touched the wing anti-ice on the B727 or B76/76. That night, thankfully, we did and I'm glad we did. The A300-600 is a different beast. We are required to turn on the wing anti-ice along with the eng anti-ice, and leave it on anytime we're in icing conditions. We are also required to add an extra 5 kts to our maneuvering and landing speeds if the wing anti-ice has been used or on.

 

[seagull]

Re: Video

I remember a flight in KMSP on the B757 one winter when folks were screaming about ice and many were holding due to the weather. We noticed rime ice all around the edges of the entire windshield begin to accumulate at a rapid pace and a hefty amount on the wiper bolt. After landing we noticed that everything that stuck out in the slipstream including the tail feathers and unheated part of the wing had a couple inches of Rime ice. The radome was completely covered. It was the worst accumulation I had seen since flying swept wing jets and even one of the worst I had seen in my flying career even while flying for the commuters in the NE US.

We rarely ever touched the wing anti-ice on the B727 or B76/76. That night, thankfully, we did and I'm glad we did. The A300-600 is a different beast. We are required to turn on the wing anti-ice along with the eng anti-ice, and leave it on anytime we're in icing conditions. We are also required to add an extra 5 kts to our maneuvering and landing speeds if the wing anti-ice has been used or on.

I saw quite a bit on a 727 once also, but it is rare. Still, does not change the fact that people were flying around with LOTS of ice and not even bothering to get de-iced prior to takeoff ("it will blow off" was what they said) back in the 60s and 70s and there were NO accidents. The straighter winged aircraft, particularly without LED's are much more at risk, unfortunately, all the rules are built around them without any deference to the differences between those and the larger, swept wing transports.

 

[Polar742]

Re: Video

Since you Purple and Brown pilots are following the thread: Did you guys get your holdover time cut 50% on aircraft with LEDs too? We just got a bulletin, and I thought all that stuff is FAA-driven, however I thought I'd cross check with ya'll.

 

[A300Capt]

Re: Video

Since you Purple and Brown pilots are following the thread: Did you guys get your holdover time cut 50% on aircraft with LEDs too? We just got a bulletin, and I thought all that stuff is FAA-driven, however I thought I'd cross check with ya'll.

Haven't heard a peep about that....Yet! I'll let you know if we do.

 

[A300Capt]

Re: Video

I saw quite a bit on a 727 once also, but it is rare. Still, does not change the fact that people were flying around with LOTS of ice and not even bothering to get de-iced prior to takeoff ("it will blow off" was what they said) back in the 60s and 70s and there were NO accidents. The straighter winged aircraft, particularly without LED's are much more at risk, unfortunately, all the rules are built around them without any deference to the differences between those and the larger, swept wing transports.

I agree most of this is overkill for the swept wing LED equipped jets. Procedures are mostly generated and based upon the lower, slower straight wing aircraft and then eventually adopted by the swept wing crowd.

 

[Autothrust Blue]

Re: Video

I saw quite a bit on a 727 once also, but it is rare. Still, does not change the fact that people were flying around with LOTS of ice and not even bothering to get de-iced prior to takeoff ("it will blow off" was what they said) back in the 60s and 70s and there were NO accidents. The straighter winged aircraft, particularly without LED's are much more at risk, unfortunately, all the rules are built around them without any deference to the differences between those and the larger, swept wing transports.

Commonly overheard following "It'll blow off": "whump, whump, whump" goes #2!

 

[seagull]

Re: Video

Commonly overheard following "It'll blow off": "whump, whump, whump" goes #2!

True. All the anti-ice, including where they installed it on the 727, was really FOD protection for the engines. No aerodynamic concerns, just FOD.

 

[seagull]

Re: Video

Since you Purple and Brown pilots are following the thread: Did you guys get your holdover time cut 50% on aircraft with LEDs too? We just got a bulletin, and I thought all that stuff is FAA-driven, however I thought I'd cross check with ya'll.

There was something recently involving composites, but I checked today and there was nothing in particular. There was a small change that came out recently, but that was about a wash, more relief in some areas, less in others, but not a significant change. I do know that the initial FAA guidance contained errors which we caught, and notified FAA about, but not sure what all those issues were. I could find out.

 

[HeyEng]

Re: Video

So back to the original mishap...do any of the 121 guys discuss/practice (during initial or recurrent training) the possibility of going around while on the ground (I guess more of a touch and go?). I know they were screaming down the runway and with time compression issues/trying to figure out what's wrong/short runway etc. so there wasn't any real time to "discuss" this, but is it EVER discussed? I guess I am accustomed to doing T/G's in a big 'ole plane on usually long runways, but there is often a bunch of time to make a go/no go decision on the ground. I would think the 757 is overpowered enough that even with spool up time, they could have pushed the throttles up and "gone around". Just curious...

 

[dasleben]

Re: Video

So back to the original mishap...do any of the 121 guys discuss/practice (during initial or recurrent training) the possibility of going around while on the ground (I guess more of a touch and go?). I know they were screaming down the runway and with time compression issues/trying to figure out what's wrong/short runway etc. so there wasn't any real time to "discuss" this, but is it EVER discussed? I guess I am accustomed to doing T/G's in a big 'ole plane on usually long runways, but there is often a bunch of time to make a go/no go decision on the ground. I would think the 757 is overpowered enough that even with spool up time, they could have pushed the throttles up and "gone around". Just curious...

Well, personally, I'd rather take the low-speed overrun over buttoning everything up and trying for the touch and go! That's just me though.

Just to add: We did a few touch and goes in the sim, but it was planned in advance. The 757/767 training manual is explicit that once reverse is initiated, you're staying on the ground. With the translating sleeve moving somewhat in that video, it's evident that it'd already been selected. Stowing the reverse at the last second and trying to get off the ground on that runway doesn't sound like a good idea.

 

[Screaming_Emu]

Re: Video

"Stick" it on the runway and you'll lose 15 knots or so just from the energy being transferred to the runway.

So THAT'S why I always seem to stop quicker than everybody else

 

[HeyEng]

Re: Video

Well, personally, I'd rather take the low-speed overrun over buttoning everything up and trying for the touch and go! That's just me though.

Just to add: We did a few touch and goes in the sim, but it was planned in advance. The 757/767 training manual is explicit that once reverse is initiated, you're staying on the ground. With the translating sleeve moving somewhat in that video, it's evident that it'd already been selected. Stowing the reverse at the last second and trying to get off the ground on that runway doesn't sound like a good idea.

OK...makes sense. I know that it could be REAL tricky for a crew that isn't trained and/or proficient in the task. I could see how you wouldn't want to push up the throttles when the TR(s) could be deployed...that would be a BAD deal.

 

[TUCKnTRUCK]

Re: Video

I wonder what the spool time from reverse deployment on a 757/767 would be... I figure if you were at max reverse the engine should be pretty decently spooled already. If not, attempting a T&G might make the next 30 seconds some of the longest in your life.

Seagull, I'm quite aware that the planform of the surface determins how it will pick up ice, A barron in the soup may be in a bad situation, while you pass right though and get nothing. Severe really is something that is pretty much aircraft specefic...

It bugs me, because I get new FO's every once in a while, who will make a comment about the guy reporting Ice, and normally they have never seen ice in anything other than a Q or such... so they don't know what it's like to pack it on in a light piston thats really just barely able to pass CFIKI

In the Q we get screwed because we have big ole rubber boots... and Ice loves to stick to them. We quite commonly have more ice on the boot protected areas than we do on the clean metal sections of the wing. oh well Maybe is Bombardier had bothered to get the winshields certified above 248kts below 10k.. we wouldnt have as many issues

 

[Roger, Roger]

Re: Video

In the Q we get screwed because we have big ole rubber boots... and Ice loves to stick to them. We quite commonly have more ice on the boot protected areas than we do on the clean metal sections of the wing. oh well Maybe is Bombardier had bothered to get the winshields certified above 248kts below 10k.. we wouldnt have as many issues

It still boggles my mind that something the size of the Q couldn't dig up the bleed air to have hot wings.

 

[TUCKnTRUCK]

Re: Video

common type. (bs if you ask me.. the 400 is nothing like a 200, display, instument or operationally)

We have plenty of bleed air, we already have 1 always on bleed source. Engines are derated by nearly 2000hp, and we are allowed bleeds on depts.. so I am pretty sure the Q "could" do it.