MRU Hits Fence

[LousyFisherman]

I fly into Sundre lots. There is no excuse. Either you reject the takeoff and/or you use the other runway!

The fence is a standard 3 strand barb-wire, quite aways off the runway. How anyone can CHOOSE to be low enough to hit it is beyond my understanding.

No variable tailwinds, no DA miscalculations, poor PDM is the only excuse..

IMHO
LF

[trey kule]

Attempting to climb away more slowly than Vx is going to result in disappointment.

We used to have a question on our pre employment screening exam that asked Why? (Worded a bit differently).
About 3/4 of CPL licensed pilots did not understand the relationship between Vx and the back side of the curve.
Yet for clearing obstacles, the understanding is critical..

As to benefits to a student from a crash. Really? Cant people learn without having to wreck a plane of have a death defying experience?

[pdw]

As to benefits to a student from a crash. Really? Can't people learn without having to wreck a plane or have a death defying experience?

No one is ahead on learning there when the survivors ... who could become, and help others to be, better informed on their own misfortune/experience, just wish to put it behind them to avoid any more embarassment; thus no more input forthcoming from what would be a vital source. The learning benefits from the accident event can get lost just like the one that doesn't make the news, the close call whose coverage never sees the light of day.

(Edited for grammar)

[GyvAir]

I took trey kule's post to be referring to first hand learning.

It should be sufficient to have it explained that touching the hot stove is a bad idea. There should be no need to go over and place one's own hand on the hot stove to learn that it's a bad idea.

[pdw]

POH says 9kts headwind needs 10% less rwy, whereas 2kts tail requires 10% more. The switch progresses un-noticed to negative component among numerous off airport approaches; yet who knew that even 2kts tail can be that big, nevermind 5, and a 2 won't show that well on a sock either let alone for discerning correct direction from every proximity.

A previous post had mentioned down drafts, and another mentioned practicing aborting grassy short field take-offs; maybe also teaching what "down drafts" is and how to watch for that ? During grass stripping lessons it is easier to lose track of time focusing on time consuming procedures always competing with attention on the lone windsock post as it marks the changes.

The "3 strand" is cleared except for a lone 8ft wooden "toprail" not visible from right seat, which it "hits with the left gear". Low airspeed is too low after impact with the lumber ("slowed") and lands / stops in "200ft"; sounds like 6-8" wooden posts supporting the lumber "top rail" absorbed a fair bit of forward energy.

[pdw]

... and be sure you're not going to get any downdrafts

Is it even possible expecting "downdrafts" here in the Sundre take-off situation, or is this word on loan from it's use for actual down-drafts like found in mountain flying / microbursts / thunderstorms ? Sure, the aircraft drafts-down or sinks/can't climb when picking up a strengthening gust in light downwind taking off upslope here ... maybe, ie a sudden low airspeed and resulting sink-rate; yet when still in ground effect, even downwash from a wing doesn't draft downward in this type of situation. Just asking for interest's sake.

[CpnCrunch]

Is it even possible expecting "downdrafts" here in the Sundre take-off situation, or is this word on loan from it's use for actual down-drafts like found in mountain flying / microbursts / thunderstorms ?

I meant either sink due to the wind flowing over terrain (e.g. landing runway 29 at Three Hills you pretty much always sink on short final, due to the wind flowing downhill), or windshear due to gusty turbulence. It doesn't look like either of those factors apply to this accident, however. I was just talking in general about whether it's a good idea to fly in ground effect.

Interesting comment about the tailwind. I guess you should automatically factor in a 2 knot tailwind if the windsock is limp, i.e. 2000ft in this case. I don't think it's reasonable to assume they took off with a 5-6 knot tailwind (unless you have some info that we don't have).

[pdw]

double posting

[pdw]

I don't think it's reasonable to assume they took off with a 5-6 knot tailwind (unless you have some info that we don't have).

CYBW departure is WEST (on the hour reading at 4pm from West at 4kts) at which time the grass strip 20min north also just favours WEST (NNW5kts/cwav 4pm), which student and PIC/instructor would check for 4pm in preflight / 3pm NW 4kts cwav); the accident is at ~4:40pm. In that hour 5-6kts at Sundre/cwav; by 5pm 7kts NE (rwy hdg 237deg).

Wide open fields offers unobstructed EAST flow, so departure might end up in more easterly strength in the next 30 seconds of takeoff-roll ... seeing it goes to a greater elevation (a little bit stronger tailwind with height) and further west, if only a light increase at that location/time. The increasing strength in the negative component is really more in the change in direction to coming from nearly RB 180 (in that case the windsock not so much started from "limp" ... more like moving gradually to that direction away from a "breakeven")

[CpnCrunch]

CYBW departure is WEST (on the hour reading at 4pm West) at which time the grass strip 20min north also just favours WEST (NNW5kts/cwav 4pm), which student and PIC/instructor would check for 4pm in preflight / 3pm NW 4kts); the accident is at ~4:40pm. In that hour 5-6kts at Sundre; by 5pm 7kts NE (rwy hdg 237deg).

Ok, I didn't realise there was actually a weather station at the airport. It's saying the wind varied from 50 to 70 degrees true @ 7kt, which gives a tailwind of 6-7kts.

So they would have required a 2300-2400ft ground roll, meaning the plane performed *precisely* as expected.

[pdw]

It's a bit more complicated than hindsight 20/20, the belated windcheck from history.

After flyover (break-even windsock after 4pm) rwy24 choice has the windsock on right at poor proximity for accurate sock-angle to see neg-change during forced approaches/ landing and the shortfield takeoff that did damage to the fence. An 'early tailquartering while getting stronger' lifts the sock that also moves downwind; on flypast might still look similar esp more-strength / more-negative-angle even less obvious if faded or blends-in to background.

Steady component-change clockwise N to NNE / 348T to 034T (rwy 255T) is "NE"/34-56T by 5pm. In a few circuits 15-20min "2kts" up / 360, 10 .. 20T .... and the TODA gets shorter yet by 20-30T @ 7kts.

349T/N is ~ 90 xwind "5kts" ... slowly turning with time. Left seat has good view on this angle only when abeam right wingtip in passing, where sight can be blocked by right seat occupant or wing. A right-seat instructor divides attention toward left.

[pdw]

It's saying the wind varied from 50 to 70 degrees true @ 7kt, which gives a tailwind of 6-7kts.

So they would have required a 2300-2400ft ground roll, meaning the plane performed *precisely* as expected.

Where's it "saying" that for 4:30 pm ... are we looking at the same info ?

[CpnCrunch]

Where's it "saying" that for 4:30 pm ... are we looking at the same info ?

http://climate.weather.gc.ca/climate_da ... ame=sundre

There's no data for 4:30pm. It's 50 degrees true at 4pm and 70 degrees true at 5pm, both at 13km/h.

[pdw]

The above version CWAV info is shifted 1 hour ahead for some reason.
Correct Wunderground History CWAV:
3pm NW 9.3
4pm N 11.1
5pm NE 13

Interpolation (4:00pm is N from 349T to 11T ):

4:30pm direction is halfway between N and NE = NNE

Is that OK ?

EDIT:
That's a no then, .. ok I'll watch for Z time closer in the future. So used the "N 11.1" during pre-flight planning at/after 2200Z/3pm before departing for practise area with "NE 13", where W 4kts prevailing YBW.

[CpnCrunch]

The above version CWAV info is shifted 1 hour ahead for some reason.
Correct Wunderground History CWAV:
3pm NW 9.3
4pm N 11.1
5pm NE 13

Interpolation (4:00pm is N from 349T to 11T ):

4:30pm direction is halfway between N and NE = NNE

Is that OK ?

The wunderground data you need to look at 5pm and 6pm, as it is in MDT. It matches the Env Canada data, i.e. 50-70 degrees true (using the more accurate figures from Env Canada).