No bounce landing

[corethatthermal]

It looks like a stall, way too slow and nose attitude, only my opinion.

Would 2 experienced pilots be sooo ignorant as to stall the plane throughout the final approach ? There was no concerted pitch up to produce a quality stall in the sequence!
Possible scenario ( and I think DAR is right on ! ) Pilots were aghast at the props not feathering and the extra drag compelled them to approach at a very minimum speed above stall, to get to the runway, leaving them with little choice but to basically "drive her on" !

[digits_]

I don’t agree. The aircraft pitch was pretty much level, which, combined with a reasonable flight path angle, gives a moderate (not high) angle of attack.

Thats a total load of crap ! You are ignorantly looking at the A/C attitude relative to the runway plane ! The AOA is the approach path angle RELATIVE to the aircraft WIKI

the angle between the chord of an airfoil and the direction of the surrounding undisturbed flow of gas or liquid.

Or to paraphrase:

"You're wrong because you are right!"

Your underlined quote literally says he is comparing the level attitude with a reasonable flight path angle.

You can argue if the flight path angle was reasonable, or that the aircraft pitch was level, it was a crappy video anyway, but I do not think the definition of angle of attack is a point of disagreement...

[corethatthermal]

The FPA and AOA are relevant due to its "low energy state" high drag, steep approach and no thrust/overwing airflow to compensate !

[corethatthermal]

Not so digits ,

I don’t agree. The aircraft pitch was pretty much level, which, combined with a reasonable flight path angle, gives a moderate (not high) angle of attack.

The aircraft pitch was level, yes, with the runway !......

reasonable flight path angle

NO, the nose should have been much lower, generating a much higher airspeed BECAUSE it would take the airspeed to trade off for pitch change in the flare and g-load and drag to accomplish a safe landing !
I spoke about the backside in previous posts and got a load of shaming ! You kids cannot even understand the front side of the power curve!!

[corethatthermal]

Probably only DAR has done tests WRT windmilling props and its effect on this site, but can YOU imagine the loss of lift over the affected area(s) COMPARED to an increased airflow velocity and lift due to the positive prop slipstream effect ?

[PilotDAR]

NO, the nose should have been much lower, generating a much higher airspeed BECAUSE it would take the airspeed to trade off for pitch change in the flare and g-load and drag to accomplish a safe landing !

Exactly! It gives me the shivers to see planes flown in very low energy, for exactly the reason seen in that video. If you must, you must, but you have to know that an engine failure, and worse the drag of windmilling prop(s) shortly after are going to be a terrible surprise. 'Same thing for needless steep climbouts. If it quits, it will, at best, end up like that landing.

Pilots should practice power off landings more, and the realities of gliding would be better understood. But, practice with your hand on the throttle of running engine(s), in case you need a burst of power to prevent exactly what this pilot seemingly could not prevent.

For anyone fortunate to be able to fly/ride in a Cessna Caravan, when circumstances are ideal, and there are no passengers to alarm, set the plane in a nice glide way up high, get it all trimmed out on speed, leave the engine at idle, and gently feather the prop. It's like a magnificent push from behind, as the drag reduces. The PT-6 does not mind idling a feathered prop in flight. You'll really get a sense of how much drag a windmilling prop creates!

I'm amazed that the occupants exited without injured backs!

[corethatthermal]

DAR, you have called me out when I have erred and you have responded when what was printed was evident to be truth ! I have never had the opportunity to thank a person of integrity as you ! Thanks ! and please keep up the good work of educating both the beginners and reminding the experienced of all that is aviation !

[CFR]

DAR, you have called me out when I have erred and you have responded when what was printed was evident to be truth ! I have never had the opportunity to thank a person of integrity as you ! Thanks ! and please keep up the good work of educating both the beginners and reminding the experienced of all that is aviation !

When following posts here I regularly wait with anticipation for WDDT (What Does DAR Think) to happen!

[photofly]

I did some analysis of the video, and it looks like the aircraft was pretty much stalled on final approach.

I extracted five frames at -2 seconds, -1.5 seconds, -1 second, -0.5 seconds and at impact, and rotated and superimposed them to match the horizons:

overlay.jpg (233.29 KiB) Viewed 751 times

Then I was able to create a composite of the aircraft position, and make measurements of the apparent flight path angle. To allow for foreshortening I compared the vertical and horizontal sizes of the aircraft, which I believe is a Piper Seneca.

composite.jpg (105.79 KiB) Viewed 751 times

The angle of the video is shot from about 38 degrees off the nose of the aircraft (changing as the aircraft moves, but only a little.)

I estimate the actual flight path angle to be close to 19°, which is pretty darn steep.

Two seconds before impact the aircraft appears to be about 7m from the ground, giving a rate of descent of about 600fpm. If actually descending at 19° to the horizontal the forward velocity would be 20.3m/s and the airspeed 21.5m/s, or only about 42 knots.

All three gear legs appear to be down:

gear down.jpg (51.91 KiB) Viewed 751 times

[digits_]

I spoke about the backside in previous posts and got a load of shaming ! You kids cannot even understand the front side of the power curve!!

How about you understand what is posted?

The aircraft pitch was pretty much level, which, combined with a reasonable flight path angle, gives a moderate (not high) angle of attack.

If your pitch is 0, and your flight path angle is reasonable, let's say between 3-6degrees, it is highly unlikely you are stalled. An average wing stalls around 14-16 degrees. In the above described situation, you are nowhere near that.

If you don't agree with the premises (which I didn't), then attack that. Don't act as if you are the only one who has ever heard about an AoA just because you can't understand what was written. Nobody is disagreeing with the definition of AoA.

[Squaretail]

Two seconds before impact the aircraft appears to be about 7m from the ground, giving a rate of descent of about 600fpm.

From playing around with the Seneca and the Cherokee six, with power off, yet engine still generating power as opposed to a windmilling prop, holding the stick full back put the airplane into a mush attitude where exactly the same descent results and profile. The hershey bar wing really only does a hard nose drop stall if you force it to. I had wondered if this resulted in a survivable crash profile, for the most unskilled of pilots to just get it back on the ground and have a good chance of living. Looks like these guys put that theory to use.

[PilotDAR]

That is excellent Photofly! You've quantified a maneuver which looked bad, as being bad by numbers we recognize.

A concept to remember is that from a stable descent (which this was), it's necessary to add energy to the flight, to arrest the descent (accelerate up from the descending flight path). To have energy to add, you have to have it either as thrust available (not in this case apparently), or a reserve of airspeed, which you may spend to flare. This pilot created a very steep descent path, so much more energy would have been required to flare. And... add to that, that as one pulls to accelerate up from the steep descent path, you might be actually pulling a small amount of G. When you pull G, your stall speed increases, so if you were just about to stall, now you just did, and accelerating up is no longer possible. This video shows that happening.

I opine that it's possible during this event, the pilot probably did pull to flare at the last moment (who of us wouldn't!), and nothing happened, it just kept going down.

Transport Canada once asked me to demonstrate compliance with engine failures from 50 feet in a modified Grand Caravan at gross weight, at a specified speed slower than the 87 knots Cessna states for climb speed after becoming airborne. That was the most un nerving testing I've ever done. I'd get to the point of flaring, and there was nothing left when I pulled. I did not slam the plane on, but I admit to adding a whole bunch of power to cushion the touchdown each time. TC and I agreed with the test outcome, and a fair compromise was made for the approval, but right then and there, I learned why we should carry a reserve of speed anywhere near the surface. This video, and Photofly's super analysis show us why too!

I regularly wait with anticipation for WDDT (What Does DAR Think) to happen!

Thanks for the vote of confidence, and I still have lots to learn too! I just know the things I have learned so far, and try to pass them along in the interest of safety. Recently, when I hear of accidents, I ask myself what I could have contributed back to our industry which might have prevented that event. So, I'll speak up.....

[rigpiggy]

I stand corrected wrt the nosegear(all you video wizzes out there) however look at the damage to the props afterward. Now I'm not an acccident investigater, but it looks like there was no power to the prop( blades bent in middle, no rotational damage) does someone who does this for a livving want to chime in

[digits_]

I did some analysis of the video, and it looks like the aircraft was pretty much stalled on final approach.

I extracted five frames at -2 seconds, -1.5 seconds, -1 second, -0.5 seconds and at impact, and rotated and superimposed them to match the horizons:
overlay.jpg
Then I was able to create a composite of the aircraft position, and make measurements of the apparent flight path angle. To allow for foreshortening I compared the vertical and horizontal sizes of the aircraft, which I believe is a Piper Seneca.

composite.jpg

The angle of the video is shot from about 38 degrees off the nose of the aircraft (changing as the aircraft moves, but only a little.)

I estimate the actual flight path angle to be close to 19°, which is pretty darn steep.

Two seconds before impact the aircraft appears to be about 7m from the ground, giving a rate of descent of about 600fpm. If actually descending at 19° to the horizontal the forward velocity would be 20.3m/s and the airspeed 21.5m/s, or only about 42 knots.

All three gear legs appear to be down:
gear down.jpg

Ok. This is super cool. CSI much

The average vertical speed seems to be 700 fpm. Is that enough to break a landing gear though?
Maybe pilotDAR can chime in here. What is the minimum vertical speed a landing gear needs to be able to withstand upon touchdown for certification?

If memory serves (and it might not) from previous sim sessions, I believe gear damage on transport category jets was not an issue under 700 fpm touchdown. Granted, big planes, but if anything, smaller planes have much less inertia, so they should be more resilient. Makes me wonder if anything else was wrong that the gear literally flew off on this hard touchdown.

[Ki-ll]

I did some analysis of the video, and it looks like the aircraft was pretty much stalled on final approach.

I extracted five frames at -2 seconds, -1.5 seconds, -1 second, -0.5 seconds and at impact, and rotated and superimposed them to match the horizons:
overlay.jpg
Then I was able to create a composite of the aircraft position, and make measurements of the apparent flight path angle. To allow for foreshortening I compared the vertical and horizontal sizes of the aircraft, which I believe is a Piper Seneca.

composite.jpg

The angle of the video is shot from about 38 degrees off the nose of the aircraft (changing as the aircraft moves, but only a little.)

I estimate the actual flight path angle to be close to 19°, which is pretty darn steep.

Two seconds before impact the aircraft appears to be about 7m from the ground, giving a rate of descent of about 600fpm. If actually descending at 19° to the horizontal the forward velocity would be 20.3m/s and the airspeed 21.5m/s, or only about 42 knots.

All three gear legs appear to be down:
gear down.jpg

Ok. This is super cool. CSI much

The average vertical speed seems to be 700 fpm. Is that enough to break a landing gear though?
Maybe pilotDAR can chime in here. What is the minimum vertical speed a landing gear needs to be able to withstand upon touchdown for certification?

If memory serves (and it might not) from previous sim sessions, I believe gear damage on transport category jets was not an issue under 700 fpm touchdown. Granted, big planes, but if anything, smaller planes have much less inertia, so they should be more resilient. Makes me wonder if anything else was wrong that the gear literally flew off on this hard touchdown.

700fpm is about 3.5 m/s. How long did it take for the vertical speed to reach 0 here? 0.1 of a second would make it 3.6G touchdown. I don’t know if gear breaks at that point but that’s some serious load on the structure.

[the-minister31]

And keep in mind that they did not land on the asphalt...

[photofly]

They did have an gear problem, allegedly. So maybe 600-700fpm with an unlocked gear is enough to rip it off, but it might not if it had been locked down.

[PilotDAR]

Maybe pilotDAR can chime in here. What is the minimum vertical speed a landing gear needs to be able to withstand upon touchdown for certification?

Off to family Christmas...

In the mean time, here's the standard:

Sec. 23.473

Ground load conditions and assumptions.

(a) The ground load requirements of this subpart must be complied with at the design maximum weight except that Secs. 23.479, 23.481, and 23.483 may be complied with at a design landing weight (the highest weight for landing conditions at the maximum descent velocity) allowed under paragraphs (b) and (c) of this section.
(b) The design landing weight may be as low as--
(1) 95 percent of the maximum weight if the minimum fuel capacity is enough for at least one-half hour of operation at maximum continuous power plus a capacity equal to a fuel weight which is the difference between the design maximum weight and the design landing weight; or
(2) The design maximum weight less the weight of 25 percent of the total fuel capacity.
(c) The design landing weight of a multiengine airplane may be less than that allowed under paragraph (b) of this section if--
[(1) The airplane meets the one-engine-inoperative climb requirements of Sec. 23.67(b)(1) or (c); and]
(2) Compliance is shown with the fuel jettisoning system requirements of Sec. 23.1001.
(d) The selected limit vertical inertia load factor at the center of gravity of the airplane for the ground load conditions prescribed in this subpart may not be less than that which would be obtained when landing with a descent velocity (V), in feet per second, equal to 4.4 (W/S) except that this velocity need not be more than 10 feet per second and may not be less than seven feet per second.
(e) Wing lift not exceeding two-thirds of the weight of the airplane may be assumed to exist throughout the landing impact and to act through the center of gravity. The ground reaction load factor may be equal to the inertia load factor minus the ratio of the above assumed wing lift to the airplane weight.
[(f) If energy absorption tests are made to determine the limit load factor corresponding to the required limit descent velocities, these tests must be made under Sec. 23.723(a).]
(g) No inertia load factor used for design purposes may be less than 2.67, nor may the limit ground reaction load factor be less than 2.0 at design maximum weight, unless these lower values will not be exceeded in taxiing at speeds up to takeoff speed over terrain as rough as that expected in service.

[corethatthermal]

a mush attitude

When we say that, i believe we are implying that there is no stall BREAK or sudden loss of lift, but rather a gradual reduction of lift with lowering airspeed. Perhaps someone can come up with a proper definition of a stall or exactly at what point in the lift curve does this A/C qualify as being in the stall ?

[AuxBatOn]

a mush attitude

When we say that, i believe we are implying that there is no stall BREAK or sudden loss of lift, but rather a gradual reduction of lift with lowering airspeed. Perhaps someone can come up with a proper definition of a stall or exactly at what point in the lift curve does this A/C qualify as being in the stall ?

In flight test, the definition must be well defined as to remove subjectivity. Common definitions include full aft controls, uncommanded wing drop or uncommanded nose pitch.