MRU Hits Fence

[DanWEC]

A pretty bad mistake mistake without a doubt, that raises some serious eyebrows, BUT:
So much of pilot training is about ingraining how to utilize knowledge and judgement in order to avoid mistakes at all costs- since the consequences are so grave.
Thing is though, you learn from mistakes. So it's a tough question to ask- is he still a shitty pilot because he ignored training and let it happen or is he and his student much better by virtue of it?

I'm not specifically trying to defend the pilot, I'm just pontificating in general regarding aviation where it's tough to learn from a mistake because you might not walk away, so your skill lies in adhering to preventative safety and training at all costs.
I haven't done anything like that in an airplane and I do my best every flight to prevent it- but every shifter kart and dirtbike I've put into the wall way back when, and every broken bone I sit and stare at for weeks on the couch after, I've learned volumes from.

[co-joe]

I'll take ripping the gear off on a 3' fence over a low level stall spin any day of the week. Not that either are desirable, but maybe once they realised they were low and slow and not gonna make it they made a bad call. Who knows. Stall horn going, buffet, nose high, lots of drag.

Students do messed up stuff sometimes. God how many times did someone reach for the throttle, I assume to add power cause we're about to stall 10' in the air and wow they just pulled it to idle....eeeEEEEEEE!!! BANG!

[pdw]

I am unsympathetic to an instructor who chooses to land a 172 in a grass runway, and then cannot get it back out safely.

Doesn't say land, just that they took off SW direction beside the paved runway 24 for that lesson. Big difference here because the changing windsock (earlier is just a light right crosswind) is also then not re-observed from the same proximity or angle as a normal taxi routine to the active, and importantly some time is also passing between that last look at it and any time-consuming pre-take off discussion that ensues. Yes, going in and out of an actual grass strip you would best observe accurate windsock direction from above before the quick turnaround; my bet is the small perfect tailwind picking up is simply missed, rather than the idea of discounting it as significant. Once barrelling toward that fence the eyes are on the kts and only option is to position AOA for best chance at a fence-clearing rotation. As a student and instructor have worked all the numbers .. no reason to suspect it won't clear.

[PilotDAR]

Doesn't say land, just that they took off SW direction beside the paved runway 24 for that lesson.

a flight instructor and a student had been conducting ‘forced approaches’ when they struck a fence,”....“What was reported to us was that the aircraft departed from the grass runway 24 at Sundre and didn’t appear to perform as expected, and got to the end of the runway and one of the landing gear caught the top rail of a fence.

I read that the instructor chose to land during forced approach training, and then departed. I presume that they did this by choice, which would fall to the instructor, as the higher authority on board.

As a student and instructor will have worked all the numbers, there would be no reason to supect it won't clear.

Yup, let's give them credit for working all the numbers out, which we must presume resulted in the conclusion that they had favourable conditions, or the decision should have been to not attempt that takeoff then. So yes, assuming favourable numbers, the plane should have cleared the fence - if flown with proper technique.

Big difference here because the changing windsock (earlier is just a light right crosswind) is also then not re-observed from the same proximity or angle as a normal taxi routine to the active, and importantly some time is also passing between that last look at it and any time-consuming pre-take off discussion that ensues.

I don't buy it. We agree that they worked out the numbers, which means they would have been satisfied that they had correct wind information - or the numbers would have been incomplete. A variable wind on a "normal" weather day (no nearby thunderstorms or tornadoes) will not vary between start of taxi and takeoff so much that it will turn a well flown takeoff into a fence strike. If a variable wind turned a worked out numbers takeoff into a fence strike, either pilot skill, or judgement about a suitable margin for safe operations, was lacking.

[pdw]

Fair enough; lacking it is, as flying 101 is all about the take-off direction too. Regardless of how readable a windsock is from one's vantage point, PIC is responsible. Observing WX history there ... shows a steady change, and not "variable" ( is when less-than 5). The "2kts for 10%" is such a huge gamechanger, so if that older POH doesn't contain tailwind numbers, helps understand how it's possible the short-field numbers could be lacking despite good intentions.

[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).