PA-34 RTO @ YPK-What happened

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GyvAir
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Re: PA-34 RTO @ YPK-What happened

Post by GyvAir »

If only you directed all this mental energy towards something useful!
pdw wrote: Sun Feb 04, 2018 12:31 pm That table near the bottom of page one with METARS imported by GyvAir was useful (as those inputs often are yet rarely acknowledged ), with the 3pm METAR being in there. Not so when searching WX Hist of CWMM (same source / off-airport station). The 3pm is closest to this incident occurrance (said rotation issue/ Cadors) approx 2km due west of CWMM at 2:45pm Nov 23/2017, yet not exactly sure how long before 3:00 the 3pm Metar is prepared for issue.

800Meters north of CWMM is IBritish217 / Pitt Meadows Cascade Douglas weather station and another 850 meters north of that one is IPITTMEA3 (Somerset Ave) with IPittMea7 (Somerset Estates) just a few hundred metars west of that .. all just north of 26 and verifying an East component nearest to incident timing.

On the south side / SW of 26 is a wide portion of the Fraser river (likely at max capacity with the extremely cold water from mountain runoff from previous days storms /news), and a more moderate southwesterly flow upriver at the surface would mean infuencing a cooler headwind prevailing there at times over the hour, as backed directionwise by the airport's version of the metars (page one).

It's possible:
With drier air advection moving above (which cools down faster adiabatically), that can strongly draw a recently heating / moist / lower air (about an hour or two of daytime heating opportunity there) into the stronger TCU-like updrafts just starting (shown to exist around the area just then) capable of seriously drawing hot air off every piece of heating airport ashphalt as well as so many flat roofs of major buildings EAST of 26 (275T) threshold.

So yeah ..it's possible under these particular "nice" conditions a visible sock is also assurring the vigorous V200 ..220 or 240 direction ie like in earlier metar(s), and the 120 or 130 / easterly direction of 5-10kts gets to be prevailing somewhere midrunway, so that significant subraction off airspeed is possible (10-20kt difference). Not to forget what rising groundspeed would then be at the point of RTO, or without a flap setting, only to reject just while re-entering the original sock-component while already bouncy.
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rookiepilot
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Re: PA-34 RTO @ YPK-What happened

Post by rookiepilot »

I admit....like a moth being drawn to a flame.....one reads these threads.
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PilotDAR
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Re: PA-34 RTO @ YPK-What happened

Post by PilotDAR »

only to reject just while re-entering the original sock-component while already bouncy.
:?: I've been flying for forty years, including lots at Pitt Meadows, and I have never heard of a "sock component". Imagine all this flying, while not understanding this - and I still don't. Should I worry?

FWIW, the runways at Pitt Meadows are not bouncy, they're quite nice.
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Schooner69A
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Re: PA-34 RTO @ YPK-What happened

Post by Schooner69A »

PilotDAR: flying for forty years and you've never heard of the "Sock Component"? You best take a trip here to Vernon...


We have a rule of thumb here:

If the angular horizontal difference between the wind socks is greater than ninety degrees, the angular vertical difference (droop) between the wind socks is less than five degrees, and the LEWIS indicates a 35 foot wind in excess of 20 miles per hour, we stay in the flying club and drink coffee. Come out some time and we'll show you how it works...


Now, if you've got time, check out the following and learn how "Left to its own devices, a parachute will always turn into wind".

Or so some people think.

We're not the only group, you see...




http://www.dropzone.com/cgi-bin/forum/g ... =ASC;mh=25
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PilotDAR
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Re: PA-34 RTO @ YPK-What happened

Post by PilotDAR »

So the "sock component" is the difference between two wind socks at the same airport? Fare enough, I've certainly seen this before, I just flew accordingly. The indication of the windsock in the direction I was going, having much more influence on my aircraft handling, than the indication of the sock from whence I was leaving. I have great faith that the controllers at Pitt Meadows would be warning pilots of any detectable variation of the wind worthy of concern. I've never flown out of Vernon, only driven through, but I understand that the topography of Vernon airport environs is quite different to that of Pitt Meadows.
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CpnCrunch
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Re: PA-34 RTO @ YPK-What happened

Post by CpnCrunch »

Here's a suggestion: let's all just not bother replying to the insane theories, and only post here if there is any useful information or intelligent speculation to share.
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Schooner69A
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Re: PA-34 RTO @ YPK-What happened

Post by Schooner69A »

PilotDAR:

Yes, you have to come to Vernon. Coffee is on at the club house every morning at 1000 hours. We even have beer in the fridge for those who are really thirsty... (;>0)

PS About the windsock thing: you do know that my tongue was firmly planted in my cheek, right?

J
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Re: PA-34 RTO @ YPK-What happened

Post by PilotDAR »

Schooner, I suspected tongue in cheek, though I don't assume that I know enough about a particular airport or flying environment to discard what could be valuable knowledge being passed along. I have flown into mountain runways, where the windsocks were pointed in considerably different directions. I assume that these possible conditions would be why the airport manager decided that it would be wise to put one at each end of the runway, rather than the common one at the center of the airport. So I pay attention, such odd winds could require an application of my skill in airspeed management, and aircraft control. Similarly, when arriving and departing lakes with nearby rising terrain, and no windsock, great attention is wise on a windy day.

But, in my opinion, none of the foregoing would have been a factor in a runway over run accident at Pitt Meadows. I would not want newer pilots to think that they could should attempt to attribute their accident to "winds" in such a circumstance. I'm certain that I'm not alone in this opinion. When investigating any accident/incident, the investigator must assure that they have considered the broad set of possibilities, which as HiFli and others have said, often comes back to a pilot doing their best, but it not being good enough, and then they don't recall the detail well afterward.
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pdw
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Re: PA-34 RTO @ YPK-What happened

Post by pdw »

"Component" is interpreted from a "sock", or from wave direction when float flying. Here at departure a sock would have been close to similar as IBRITISH217, only 1300m ENE/downwind of 26 threshold and 900m North of CWMM wx-station which is 1200m ESE of 26 threshold. At 2:42pm, which would be the approx departure time down rwy 26/275T, "217" shows SW 10.9kph-sustained there (coincidently at exactly the warmest temp of the day of that station, 13.9C). Then there are the two stations 800m north; IPITTMEA3 and IBCPITTM3 (2km NE of the actual incident on the runway) that have the record of easterly component at the time of this take-off roll.

The nosewheel would be light on the oleos if not elevated during the timing of this RTO decision in the middle of expected rotation. So the power maybe is chopped here while still at liftoff speed/AOA, and that would be higher groundspeed (which might prolong rollout airspeed too .. esp if farther along veers back to S/SSW/SW while braking).

From "10.9kph SW" in early roll (IBRITISH217/2:42pm) to an opposite direction "component" mid roll (ie: 4.8kph ESE at IBCPITTM3/2:48pm) is potentially already 10mph decay at this V1; so would that much decay suffice to trigger such RTO if unsuspecting (airspeed disruption) on the "nice" day ? How does a 747 like in the video fare if power were cut in RTO while nose high (as seen early in that footage) ?
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Re: PA-34 RTO @ YPK-What happened

Post by Aviatard »

pdw wrote: Mon Feb 05, 2018 9:49 pm "Component" is interpreted from a "sock", or from wave direction when float flying. Here at departure a sock would have been close to similar as IBRITISH217
You do realize that those Weather Underground stations you're using data from are amateur home stations, installed by their owners, and likely without regard to placement. They're not reliable for wind direction and speed, or temperature measurements. Anyone can buy a $100 home weather station, stick it anywhere and start uploading data.

That particular station, IBRITISH217 has reported temperature of -40C and pressure of 4872 Hpa. Unlikely to be accurate for Pitt Meadows.
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Re: PA-34 RTO @ YPK-What happened

Post by pdw »

Yes, that's often the case; only that station's data (Pitt Meadows 'Casa de Douglas' weather station or IBRITISH217) seems nearly at peak accuracy Nov 23/2017, esp for that stretch of daytime surrounding 2:45pm (thoroughly cross referenced it). Some good ones seem to cycle/reset occasionally, where they kick out some weird interval totally out of character (and yes, a lot of them are not good). And esp as mentioned before when they are tucked among trees or buildings .. is where a search for "component" can get underestimated. I'd suspect that's possibly the case at IPITTMEA3 and IBCPITTM3 northeast of this V1 (ie: if weaker easterly readings too), besides the fact those station's interval times may not have captured the exact timing of peak strength either.

At 2:42pm IBRITISH217 is 13.9C at 20 meters of elevation there (station registered as being 11 meters higher than the nearby airport) and 1005.6hPa. Enter those 3 numbers (temp, elev, and pressure) into a Sea Level Pressure calculator and it should read out MSL ... 1007.99 hPa, which is basically the same as CWMM 900meters to the South (looks like IMO this "217" station is situated up higher too .. maybe a rooftop ?).

In this case that closest one to CWMM ("217") contains extra intervals between the 2&3pm hourly data GyvAir put on page one, which is the same as the airport's CWMM except for where it's history misses that closest/3pm METAR .. the one 10-15 min after this 2:45pm incident description.

Notice even on many of the very poor stations the changes in pressure still register very accurately even though you might not want to trust the readings themselves, and temperature as well, even though might be off by a degree or more. And most still useful here for verifying the lowest daily relative humidity trending in that hour / area.

EDIT/PilotDar
For proof we need actual math to calculate component / change affecting the accelerating laminar surfaces that are building up their required relativewind for the lift to be/become airborne on 'fixed runway heading' at the point of this expected rotation ("wouldn't lift"/CADORS). If truly the type of lift-off hesitation it seemed to suggest there, then going solely by one single light METAR 15min late over there among buildings at CWMM (a mile or two away) by itself could not be sufficient evidence to exclude component-variation as partly a factor. Yes, lots of other potential factors/contributors are already listed in this thread, some pretty good ones; and as someone posted previously, anything obvious would already be included in the CADORS.
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Last edited by pdw on Wed Feb 07, 2018 2:21 pm, edited 1 time in total.
Hockaloogie
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Re: PA-34 RTO @ YPK-What happened

Post by Hockaloogie »

PilotDAR wrote: Mon Feb 05, 2018 7:08 am attribute their accident to "winds"
"Winds" are responsible for all aviation accidents. Surely you know that. You've been around long enough. :rolleyes:
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Re: PA-34 RTO @ YPK-What happened

Post by C.W.E. »

So getting back to sanity, does anyone have any idea on why that airplane got wrecked?
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short bus
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Re: PA-34 RTO @ YPK-What happened

Post by short bus »

Please...... Just stop
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Re: PA-34 RTO @ YPK-What happened

Post by rookiepilot »

C.W.E. wrote: Tue Feb 06, 2018 2:27 pm So getting back to sanity, does anyone have any idea on why that airplane got wrecked?
No. Apparently its impolite to even ask.
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pdw
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Re: PA-34 RTO @ YPK-What happened

Post by pdw »

Stopping is OK, no problem.

edit FYI Rookiepilot, your first page post was right on topic ...
Let's assume you're correct, PDW, for fun. I've taken off with V .. 15-20kt moving from slight headwind to tailwind and back again ...

I needed some preparation to engage in that discussion, by first researching a surface analysis of the pressure-pattern (storm system) involved.
And then this from page one:
10kts should not be an issue in any light aircraft.
Again, for only that much decay normally yes; except that in this reference the refusal to rotate comes totally as surprise / out of the blue (only looks like the perfect/stable day) where nothing remotely unusual could be expected.

Certainly, when AWARE of strong or gusty you'd ALWAYS be poised/prepared to compensate (you're on the ball). Yet not the same here, when simply not anticipating anything like a peculiar shear-hesitation at that most vulnerable V1 moment ... especially just after having-established / been-shown weak component prevailing via preflight wx-check or windsock on taxi (a "nice day" all around).

The unexplained delay for liftoff by surprise, might briefly unnerve a beginner multi to RTO in a snap decision.
_____________________________________________
EDIT: If the control locks weren't left in. Wow, that's incredible

(weather clears up real nice ...and off we go)
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Last edited by pdw on Thu Feb 08, 2018 6:42 pm, edited 10 times in total.
C.W.E.
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Re: PA-34 RTO @ YPK-What happened

Post by C.W.E. »

No. Apparently its impolite to even ask.
Yes there are some in this industry who seem to think that way.

To me it makes no sense to not discuss what happened and try and remember not to make the same mistakes.

It is unlikely it was a mechanical failure because they would have gone public with that information by now I would think.

So I guess we should be birds in this industry, ostriches and just bury our heads in the sand and see and know nothing.

Note:

I am aware that they do not actually bury their heads in the sand and it is only a saying.

I learned that when I got my degree in reading. :mrgreen:
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Re: PA-34 RTO @ YPK-What happened

Post by BGH »

Control lock was still in.

Daryl
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Re: PA-34 RTO @ YPK-What happened

Post by C.W.E. »

Incredible!!!

I can't imagine starting a take off without doing a controls free check.
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Re: PA-34 RTO @ YPK-What happened

Post by CpnCrunch »

BGH wrote: Thu Feb 08, 2018 6:23 pm Control lock was still in.

Daryl
Impossible. Every flight school has "controls free and correct" at least twice on their checklists.

Apart from that, it would imply that nobody noticed the control lock, the student didn't bother moving the controls while taxiing, and the instructor didn't do any of the above either.
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