Frost Downs a Mooney

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pdw
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Re: Frost Downs a Mooney

Post by pdw »

CpnCrunch wrote: Tue Nov 16, 2021 10:06 am Nosewheel shimmy can be quite violent when it happens.
Takes the right kind of bump to get one of those going. The NOTAM about “radio-controlled aircraft” is included, yet doesn’t go as far as to imply anything.
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CpnCrunch
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Re: Frost Downs a Mooney

Post by CpnCrunch »

pdw wrote: Wed Nov 17, 2021 1:57 pm Takes the right kind of bump to get one of those going. The NOTAM about “radio-controlled aircraft” is included, yet doesn’t go as far as to imply anything.
No bump is required for shimmy. Just some combination of high speed, forward pressure on yoke, oleo slightly flat, etc. There are various other things that will cause it too.
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pdw
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Re: Frost Downs a Mooney

Post by pdw »

AirFrame wrote: Tue Nov 16, 2021 7:58 am Carb ice could have caused a shudder. It's also the right time of year for that.
Well, it does look like most planes are hangared at that site. The “-3C” is 92rh Nov1 9am at “Ioliver3” (wundermap). By 9:30am 90rh and 1/2degree above.
If right then tkof …fuel injection intake-air rushes through wide open throttle-body butterfly, thaws any possible small “ice/frost” adhered/impacted to intake walls above the freezing mark with earlier “-3C” startup/taxi. Will that make it “shudder” as engine injests sudden release of ice all-at-once nearing nose up rotation with prop-tips at highest speed ?

Carburetor Ice / “carb ice” would be similar as ‘interior intake impact ice’ possible in non-carbureted piston a/c, but then only near freezing-point with high moisture.
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pelmet
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Re: Frost Downs a Mooney

Post by pelmet »

For the frost on the runway theorists…..

https://weatherworksinc.com/news/pavement-frost

“For pavement frost to occur, a radiative process as described above can create it, but it's typically hard to get pavements to cool rapidly enough to form frost (due to the heat stored in them from the day). It's also hard to get a cold air mass to contain enough moisture to allow this to occur (as cold air masses are typically drier). In other words, pavement frost is quite rare. However, here's how we can cheat the system, so to speak. Suppose there's just been an arctic outbreak for several days, with highs in the 20s and lows in the single digits. Pavements will start cooling to those sub-freezing temperatures. Now, with pavements well below freezing (let's say 20 degrees), we introduce a sudden spike or "advection" of dewpoints, in other words, pushing in air that contains more moisture. Dewpoints rise quickly from 5 degrees to 25 degrees...suddenly, pavements are colder than the dewpoint...and much like a cold bottle of soda, water will condense on the surface, which freezes as air and dewpoint temperatures are still below freezing. Voila, pavement frost and slippery travel is created with no precipitation falling from clouds.”

There likely wasn’t any frost on the runway.
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CpnCrunch
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Re: Frost Downs a Mooney

Post by CpnCrunch »

pelmet wrote: Sat Nov 20, 2021 6:30 am For the frost on the runway theorists…..

https://weatherworksinc.com/news/pavement-frost

“For pavement frost to occur, a radiative process as described above can create it, but it's typically hard to get pavements to cool rapidly enough to form frost (due to the heat stored in them from the day). It's also hard to get a cold air mass to contain enough moisture to allow this to occur (as cold air masses are typically drier). In other words, pavement frost is quite rare. However, here's how we can cheat the system, so to speak. Suppose there's just been an arctic outbreak for several days, with highs in the 20s and lows in the single digits. Pavements will start cooling to those sub-freezing temperatures. Now, with pavements well below freezing (let's say 20 degrees), we introduce a sudden spike or "advection" of dewpoints, in other words, pushing in air that contains more moisture. Dewpoints rise quickly from 5 degrees to 25 degrees...suddenly, pavements are colder than the dewpoint...and much like a cold bottle of soda, water will condense on the surface, which freezes as air and dewpoint temperatures are still below freezing. Voila, pavement frost and slippery travel is created with no precipitation falling from clouds.”

There likely wasn’t any frost on the runway.
Should be easy to check. What was the date? Various other factors can cause slippery pavement such as ice fog, melting snow, etc.
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pdw
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Re: Frost Downs a Mooney

Post by pdw »

Dropped below freezing there on Halloween morning (Ioliver4). Long time below freezing again all Halloween night until that next morning, was first time down to -3C this fall.

“Soda bottle” idea applies here; the runway at very least had SOME condensation moisture making it more “slippery” where the cold aviation-rubber grips so much less already than sudden brakes with warm tires on dry pavement.

It’s a tough call to be able to affirm whether or not it reached the frozen state. The phase change of zero degree liquid moisture into ice first loses fifty-or-so degrees worth of heat (at that same temperature) before frozen into zero degree ice. Runway care personel maybe would be able to judge heat loss of a runway much better as they are watching the changes year round.
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photofly
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Re: Frost Downs a Mooney

Post by photofly »

pdw wrote: Sun Nov 21, 2021 9:59 am . The phase change of zero degree liquid moisture into ice first loses fifty-or-so degrees worth of heat (at that same temperature) before frozen into zero degree ice.
78 degrees C, actually: latent heat of fusion of water is 334 J/g, thermal capacity is 4.3j/K/g, 334/4.3 = 77.7.
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DId you hear the one about the jurisprudence fetishist? He got off on a technicality.
CpnCrunch
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Re: Frost Downs a Mooney

Post by CpnCrunch »

pelmet wrote: Sat Nov 20, 2021 6:30 am For the frost on the runway theorists…..

https://weatherworksinc.com/news/pavement-frost

“For pavement frost to occur, a radiative process as described above can create it, but it's typically hard to get pavements to cool rapidly enough to form frost (due to the heat stored in them from the day). It's also hard to get a cold air mass to contain enough moisture to allow this to occur (as cold air masses are typically drier). In other words, pavement frost is quite rare. However, here's how we can cheat the system, so to speak. Suppose there's just been an arctic outbreak for several days, with highs in the 20s and lows in the single digits. Pavements will start cooling to those sub-freezing temperatures. Now, with pavements well below freezing (let's say 20 degrees), we introduce a sudden spike or "advection" of dewpoints, in other words, pushing in air that contains more moisture. Dewpoints rise quickly from 5 degrees to 25 degrees...suddenly, pavements are colder than the dewpoint...and much like a cold bottle of soda, water will condense on the surface, which freezes as air and dewpoint temperatures are still below freezing. Voila, pavement frost and slippery travel is created with no precipitation falling from clouds.”

There likely wasn’t any frost on the runway.
I'm not sure how accurate that is in general. Here on the BC coast we've had pavement frost the last few mornings. Temp around +6C day, -1C night, so the ground isn't frozen, but there is a light frost on asphalt in the morning. It isn't really sufficient to cause any noticeable traction issues though. And Oliver is quite far inland so presumably less moisture as well. You really need to have water on the ground from previous rainfall or melted snow, and that didn't seem to be the case here.

I wonder if it was an intersection takeoff.
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pdw
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Re: Frost Downs a Mooney

Post by pdw »

An intersection TKOF is a viable option, it’s even more likely if just a pilot no pax; and with mention of that NOTAM, can’t rule out radio controlled” a/c activity.
ground isn’t frozen but there is a light frost on ashphalt in the morning
Could be heavier frost on the coast (fully frozen, void of any “77.7” heat) settling out of even colder air above, perhaps further (‘sensibly’) cooled below freezing so now impacts a hefty subzero chill onto pavement nearing zero already from nighttime “ -1C”. During that ‘extra’ surface cooling your frost layer itself is already warming back a bit toward liquid side of phase change again (good “traction” happens even in shedding some of the “77.7” cold). The pavement remains hovering at zero (temp of precip’s semi-solid state) as its frost begins to lose adhesiveness accepting that heat.

Oliver situation colder/drier, “92rh” maybe slippery enough for a rejected TKOF if temps escalating above freezing (suddenly warming up) right after pavement exposed to “-3C” and sun’s absence for so long.
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SpyPilot
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Re: Frost Downs a Mooney

Post by SpyPilot »

No doubt the majority of readers of this thread are as well versed in the scientific thermodynamic property's, not to mention the timeline of the regional atmospheric and meteorological influences on the runway's asphalt surface, as well as their cumulative effects imposed upon the aircraft during the takeoff roll.

However, for the rest of us, could you dumb it down just a little?

Thanks
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pelmet
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Re: Frost Downs a Mooney

Post by pelmet »

SpyPilot wrote: Thu Nov 25, 2021 12:00 am
However, for the rest of us, could you dumb it down just a little?

Thanks
Remove frost from the wings before taking off.
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Re: Frost Downs a Mooney

Post by SpyPilot »

Thanks, but still a little too PDW for me.

I'll go with: wing no frost for TKOF.
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Re: Frost Downs a Mooney

Post by rookiepilot »

Dumbed down?

I don’t do intersection takeoffs unless such takeoff gives me 4000 feet or greater at or near sea level. (Ie, CYXU it’s common to takeoff from the middle of 15/33)

Out west with a high DA, never. Full length.

But you do you.
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photofly
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Re: Frost Downs a Mooney

Post by photofly »

the "accident-off": an AvCanada event where pilots use accident reports as the basis for out-butching each other by proclaiming their dedication to flight safety. Everyone's invited!

(On the positive side, this thread got to the second page and nobody mentioned COVID yet.)
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DId you hear the one about the jurisprudence fetishist? He got off on a technicality.
pdw
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Re: Frost Downs a Mooney

Post by pdw »

What pilot doesn’t consider themselves good at flying. If one speaks up upon reading about another’s event is the way we’ve got left to engage. Pilots can learn a lot (hone skills) from each other. Without write ups/discussion too much lesson material (learning from the mistakes of others) might get swept under the rug …ie will never see the the light of day.

(The “dedication” there IMO would be more about the striving ,,. good better best )
I don’t do intersection takeoffs unless that takeoff gives me 4000 feet or greater at or near sea level.
I remember backtracking becoming dominant, where at our 321’ elev the 2400’ remaining on rwy24 (at intersection) was so commonly used for many years. One reasoning was (an instructor speaking) “the more takeoffs you do the greater the chance of one day needing that extra”.
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In the opening post there was a parked car with only dew on it and the plane nearby with solid frost all over it. We talked about various substrates. ( metal surfaces and the pavement).

I wondered if that car was driven earlier so it had a warmer interior . (But it is sometimes still confounding what freezes sooner and what lingers longer yet unfrozen).

The alum metal wings radiate heat (chill to the core fastest) esp as they are surrounded 360 degrees by the cold morning air (top and bottom), unlike the vehicle where only dew on its steel/metal roof (if not from the early light) might also have extra heat units from underneath.
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karmutzen
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Re: Frost Downs a Mooney

Post by karmutzen »

Maybe frost downed another Mooney (/s), though whether the runway was frosty or not is academic if you touch down 1000' down a 1500' runway in a Mooney. I wouldn't even try it in a Citabria.

Training, PDM, knowing your airplane, and most importantly feeling your airplane. Instead of the rote dogmatic absolutes expounded on this forum.

https://www.nanaimobulletin.com/news/sm ... jured/amp/
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pelmet
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Re: Frost Downs a Mooney

Post by pelmet »

Unless you are truly on top of your game, Taking a Mooney into an airport like Duncan ain’t the brightest.

Best on a different thread. There is a Long Landing thread. I’ll post the TSB report there.
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pdw
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Re: Frost Downs a Mooney

Post by pdw »

Sharp enough though, to assert staying down when it goes wrong (and cut losses early) … both instances.
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pelmet
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Re: Frost Downs a Mooney

Post by pelmet »

karmutzen wrote: Wed Dec 08, 2021 4:47 pm Maybe frost downed another Mooney (/s), though whether the runway was frosty or not is academic if you touch down 1000' down a 1500' runway in a Mooney. I wouldn't even try it in a Citabria.

Training, PDM, knowing your airplane, and most importantly feeling your airplane. Instead of the rote dogmatic absolutes expounded on this forum.

https://www.nanaimobulletin.com/news/sm ... jured/amp/
Looks like frost on the runway was a factor. Frost may not be much of a performance issue for takeoff but for landing, different story. Then there is the usual landed long on a short runway in an aircraft type that is a bit questionable to be going in there anyway unless you really know what you are doing, something that was obviously was not the case here.


C-GDQE, a privately registered Mooney M20C, was on a recreational flight from Boundary Bay
(CZBB), BC to Duncan (CAM3), BC with the pilot and two passengers on board. The pilot
conducted an initial approach to Runway 13, executed a go around, and set up for a second
approach. After the second approach, the aircraft touched down with the pilot finding the braking to
be poor. Runway 13 has a 70 foot displaced threshold, a 0.5% downhill slope, and was reported to
have frost present on the morning of the accident. Skid marks were observed starting about 800
feet beyond the threshold of the 1494 foot runway. As the aircraft was not slowing as expected, the
pilot applied full power in an attempt to conduct a go-around. The aircraft ran off the end of the
runway. It bounced off of a small berm and came to rest, on its belly, in a gravel pit. All occupants
were able to extricate themselves and suffered various degrees of injuries. The airplane was
substantially damaged.

The RCMP and EMS services attended the scene and the pilot and passengers were taken to
hospital.



I seem to remember a serious C172 crash here a few years ago where another go-around was attempted after a botched landing. Would have been nice if this pilot had read the thread on it. Pilots touching down long at Duncan with tailwinds and frost on the runway. Bottom line, poor judgement.

viewtopic.php?p=1029545#p1029545
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