TBM Gear collapse on take off

[justwork]

I can't bring myself to read your posts anymore, pdw.

[pilotsmack89]

I can't bring myself to read your posts anymore, pdw.

I spent all morning in the FTGU, CARs, and AIM looking for "airframe speed" and "Contam-weather". It's almost like they aren't a thing...

Thanks for summing this one up Gyv

[pdw]

Well not so fast. I fixed the other one, previous page. But "Airframe speed" .. where rotation groundspeed immediately reduces by turning to the crab angle thru ground effect and at the same time by any amount that the straightline groundspeed lessens in turning up into the climb angle (just when groundspeed needs to be doing the opposite). An actual speed thru the air (but not true airspeed), to aid in highlighting losses the 'increasing aspect' of a tailquartering component can add in this case, for the poor-deicers/overloaders not convinced.

Is that better GyvAir ? Otherwise I have to take Cliff Jumper up on his offer (but only if the Doc has a pilots license ).

[justwork]

Well not so fast. I fixed the other one, previous page. But "Airframe speed" .. where rotation groundspeed immediately reduces by turning to the crab angle thru ground effect and at the same time by any amount that the straightline groundspeed lessens in turning up into the climb angle (just when groundspeed needs to be doing the opposite). An actual speed thru the air (but not true airspeed), to aid in highlighting losses the 'increasing aspect' of a tailquartering component can add in this case, for the poor-deicers/overloaders not convinced.

Is that better GyvAir ? Otherwise I have to take Cliff Jumper up on his offer (but only if the Doc has a pilots license ).

I don't know where to begin. I don't even want to, but it's like a plane crash, I can't look away.

where rotation groundspeed immediately reduces by turning to the crab angle thru ground effect

Your ground speed doesn't matter, you are in the air. Airspeed is all that matters. KIAS.

at the same time by any amount that the straightline groundspeed lessens in turning up into the climb angle

Again, you are in the air. The plane doesn't care what your ground speed is. KIAS FTW. I also don't understand how one would "turn up". Do you mean pitch up? Are you a pilot? When a pilot takes off he/she is rotating the aircraft, not "turning up". Basically he/she rotates the airplane to maintain a target airspeed, and unless there is the presence of low level wind shear, the airspeed will increase. That being said there are some factors that may reduce aircraft performance, wind shear, weight, temp, engine failure etc, but if you're pitching for a target airspeed the plane will achieve it as long as it is being operated within it's design envelope. Especially something like a TBM.

just when groundspeed needs to be doing the opposite

Your ground speed doesn't need to be doing anything, you're in the air. This is why a plane has a airspeed indicator and not a ground speed indicator, because your ground speed doesn't matter. Your speed across the ground will not keep you in the air.

An actual speed thru the air (but not true airspeed), to aid in highlighting losses the 'increasing aspect' of a tailquartering component can add in this case, for the poor-deicers/overloaders not convinced.

I honestly have absolutely no idea what the sentence is referring to. Why are you referring to true airspeed during take off? Who is the poor-deicer? Are the overloaders and poor deicers the ground crew? What are they not convinced of? Is a tail quartering component a quartering tailwind?

You seem to not understand that the plane doesn't care at all about ground speed. I'll use a very broad brush to paint this scenario. You rotate the plane at a set Vr, Vr is KIAS. It leaves the earth, you still target a KIAS. The tailwind is 10kts, your Vr is say 70KIAS. When you rotate the plane the ground speed will be approximately 80Kts. You get to 100' and are now targeting a climb speed, what ever that is based on the plane you fly. Lets say it's 100KIAS, the tailwind is now 20kts, and your ground speed approximately 120kts but you're still climbing at 100KIAS. The plane gives zero care what it's ground speed is, like I said earlier this is why you we have an ASI and not ground speed indicator.

Now if there is the presence of low level wind shear. This can cause reduced performance. The key here PDW is to understand that wind shear is not present in this accident. Generally speaking, as you climb wind velocity will increase due to reduced friction with the surface of the earth. It will also change directions. This is not wind shear, this is normal every day stuff.

[justwork]

This clip sums everything up nice and simple.

https://youtu.be/wKjxFJfcrcA

[pdw]

Thank you for having the courage to continue ...

You seem to not understand how the plane does not care at all about groundspeed.

Even though it "does not care" generally speaking when in normal flight, .. on an extra-accelerating takeoff like this one (a tailwind increasing/forming substantially at the precise time of this take-off roll) still has its 'matching groundspeed' (MG) for its IAS required to have established strong-enough rotation airspeed for countering all the questionable extra lift-loss. In this case MG, a lot higher than normal for the reason given, involves maintaining that extra speed out of ground-effect aligned to appropriate steepness of a stablized 'climb angle'. Lets say the "tailwind" (report finding) forced 90kts GS for 80kts IAS at this rotation, then followed with-in 5sec by 10kts neg-shear existing above the deck that needed MG-acceleration to 100GS in 5sec to "150ft". So the actual speed of the airframe aligning along this initial 5sec climb-angle would have to be 91 or 92kts actual speed to maintain that 90GS for the 80IAS right after the pitchup steepened to climb pitchaxis, and then very quickly at/up-to 102-103kts for holding-onto (after increasing to) a 90-IAS in process of absorbing a 10kt neg-shear.

* that extra speed:
A groundspeed number is only very accurate for an "Airframe" holding to a pitch-axis that is straight and level. Here we're discussing an accident that initiates immediately into rotation, so potentially enters it too steeply also. I was suggesting there is the possibility this AC (while questionably ground-iced) didn't quite get at the ideal actualspeed needed there either (what its lift-equation needed there) in order to 'establish' itself well into stable flight and proceed onward at a maintainable climb angle .... in light of that extra tailwind-shear in progress in addition to the questionable ice.

In figuring how to explain this point-of-view, needed to put it in terms of an actual speed (sort of like a customized groundspeed for/along that new upward pitchaxis) along that early climb flightpath pitched-into at Vr, now knowing it's having to be even greater than that barely achieved minimum MG achieved at Vr just a second before the rotation point is chosen/executed.

This was a 'blow off the precip' departure that went wrong because the laminar surfaces still had some solid precip left on them. I've seen this done and 'gets away with it', that's why I pushed the issue about the tailwind shear ... present when one of those (one of these take-off strategies) didn't work. For me it was more about showing that in this case once again there was the negative shear there at an accident with the questionable ice (but a good case for the contamination side of things) and making the point that on occasion cannot even predict it. The very reason why "clean concept" bails you out every time; the reducing components (the one's that cause a slowing) are not always predictable and sometimes hard to find in wx history. It's the reason why re-emphasizing not to take the chance with a blow-off run in the way this report shows it happened, and making sure to revitalize that in discussion (which this thread has permitted).

The key here PDW is that Windshear is not present in this accident.

None is mentioned in this report; and also also cannot tell from the KBLI weather indicator.

EDIT: No invention. A fair bit of innovating is necessary to describe it though. A trough coming up against the coast, the very cold "bubble" in northeast BC. It is affecting the lowlands around the coastal waters of Bellingham area, as the warm winter LO offshore forces againt central BC mountains.

[justwork]

You're inventing terms and facts while ignoring basic flight principles.

Mr. PDW, what you’ve just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response were you even close to anything that could be considered a rational thought. Everyone in this room is now dumber for having listened to it. I award you no points, and may God have mercy on your soul

.

[pdw]

This is not windshear, this is normal everyday stuff.

This is not everyday weather here either, so ground contamination makes it not normal. KBLI wx alone is unfortunately not useful for indicating any developed/developing/lingering negative shear from its records at ground in this particular weather signature. Rwy16 is through uneven topography / low areas so may be intowind initially or appearing so on an indicator/sock where taxiing at the remotest/low end of this field in a snowy/marginal vis. There's enough wundermap evidence / potential for effects of surrounding terrain / uneven topography for some unpredictable LL opposite air currents closer to the surface. Shows the N/NE surface air thinly underpins below opposing/warmer SE component (upwind side of trough / inversion) for a short period, moving onto +5C-watersurfaces/sealevel and increasing in strength for a short period including moments of the accident sequence.

We do not lose sight of the fact that there was an accident here on account of an error that was made which resulted in an aircraft departing without satisfactory de-icing. It is contaminated laminar surfaces that prevents from proceeding thru successful takeoff. Considering the other (shear-like) influence to this outcome isn't to disagree with the finding, but improve prevention strategy. The intent was to let speed "clean" it with the slipstream, where it would have/have-not been "sloughing off" enough before reaching the target airspeed and maintaining the speed-range of stable flight in climb; IAS dallys a bit in rising up, and freezing windchill on -0.6C is freezing/ no melt. Identifying that correctly is a better message to reduce ground ice infraction by illustrating in no uncertain terms that only "clean concept" is secure. Having the pilot's own pirep/admission and reading the report's conclusion, the discussion becomes closed to any other contribution. It's likely an honest oversight if the shear aspect is overlooked here, or considered negligeable on account of evidence being diffcult to see.

The typical ascent at rotation initiates after Vr with expected climb performance of an increasing headwind component with height, which might get a little too habitual for it's little extra kick of performance expected in ordinary "everyday stuff"; most of the time it's positive but also no worries if a little +/- , and even the case often when a "clean concept" breach might have occurred. Except, when positive relativewind expectation abruptly doesn't happen, instead drops off on the way to "150ft", it disadvantages airspeed/lift recovery on account of reduced "margin against stall"(PF). How many times does that misexpectation of positive result in overestimation of climbangle only to have-to concede pitch-reduction soon after ?

As a factor, a lighter decay gets big when joining up with icecatch losses of any sort, least forgiving being ground-ice/contamination taken into flight; insignificant only until factoring into an iced/raised stallspeed, where much more likely to be caught slow with it.