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Posted

Do JS have a specific procedure for PNF to call out pitch attitude during takeoff? If they have, what happened? The PF was way too fast on the stick pullback?

 

If they haven't got a specific pitch attitude procedure, then it sure looks like they need one.

 

Not a lot of pitch angle to play with there on the 320, I would've thought tailstrike avoidance would have been hammered into them during training.

 

http://www.smartcockpit.com/docs/Avoiding_Tailstrikes_by_Airbus.pdf

 

 

Posted

Tailstrikes happen if you just pull back and don't watch what you are doing on the A/H. At rotate you go on instruments as you are heading for 18 degrees of pitch up after lift off. The rate you rotate at is critical to accelerating to the right lift off speed. Could the trim have been set a bit rearwards? A wind gust can momentarily reduce airspeed. While the book says a "continuous rotation", if it ends up happening a bit too fast a delay at safe attitude till it does lift off is required to prevent a tail strike. Where the horizontal stabiliser is lower (non "T" tail) the cushion of air between the tailplane and the runway surface usually acts to make it more rare. I don't think there is a skid as such on that aeroplane. Nev

 

 

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Posted

OK, hindsight is always 20 20 vision, but .... Surely a sacrificial tailskid would be in order here - something strong enough to protect the a/c, absorb some of the impact to prevent further damage and be not critical for flight. It could even have a tie-down hole in it, sort of doubling as a plimsol line as well as somewhere to hang the miscreant pilot (in effigy of course) (unless you fly for North Korea).

 

Sorry guys, overdosed on stupid pills today

 

David

 

 

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Posted
OK, hindsight is always 20 20 vision, but .... Surely a sacrificial tailskid would be in order here - something strong enough to protect the a/c, absorb some of the impact to prevent further damage and be not critical for flight. It could even have a tie-down hole in it, sort of doubling as a plimsol line as well as somewhere to hang the miscreant pilot (in effigy of course) (unless you fly for North Korea).Sorry guys, overdosed on stupid pills today

David

In excess of 78 tons rotating into the ground at more than 150kph horizontal and 10kph vertical is a hell of a lot of energy to absorb by a sacrificial abrading pad ... and it would require a fair old structure inside to carry and dissipate the loads into what is essentially a very light structure.

Probably still better to focus on pilot ops to avoid tail strike than add structure.

 

 

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Posted

Focusing on pilot skills is important, for sure, although unfortunately pilots are human (some of them). "B767-300 is equipped with a tail skid" (ATSB Report), not that it would do much protection, more telltale evidence. The APU drain probably protected some of the bodywork. A 'full-noise' tailstrike could really do some damage, I suspect most of the tailstrikes are fairly gentle, so a sacrificial pillar could help. Not a pad - not enough absorption of impact. Compare the old chrome bumper with the plastic versions, much kinder on idiot pedestrians. Of course, hanging extra junk underneath then reduces your maximum takeoff angle, so more strikes ...

 

David

 

 

Posted
In excess of 78 tons rotating into the ground at more than 150kph horizontal and 10kph vertical is a hell of a lot of energy to absorb by a sacrificial abrading pad ... and it would require a fair old structure inside to carry and dissipate the loads into what is essentially a very light structure.Probably still better to focus on pilot ops to avoid tail strike than add structure.

such a device exists and is in use during testing, I guess though not so practical for everyday flights

 

https://www.youtube.com/watch?v=EXYPcEVSjjo

 

 

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Posted
such a device exists and is in use during testing, I guess though not so practical for everyday flightshttps://www.youtube.com/watch?v=EXYPcEVSjjo

Yep. Used on the TEST aircraft. And that one has extra structures to have the skid attached for testing.

Can be done if you intend doing tests. But better options exist on a real life airframe.

 

 

Posted
Tail strike is no big deal if it is repaired correctlyJAL 123's repair wasn't done right

Quite true, Alf. The impressive lesson from the JAL disaster is that the Boeing investigator had the test data to accurately predict how many cycles the repair -a single row of rivets instead of the recommended double row-

would last.

 

 

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Posted

The B747pressure bulkhead repair isn't that relevant to the issue. The forward speed of the aircraft has nothing to do with the loads needing to be absorbed. You have to have a collapsible structure that absorbs energy over a reasonable distance and support structure around it. In the case of the "non "T" tail it's a lot harder to force the tailplane near to the ground because of the ground effect on the whole tailplane.

 

Flaps , underslung engines, can also strike the ground if you are beyond the WELL KNOWN angles for each type, that you should stay within. Planes don't wildly oscillate in pitch, even in turbulence. Prevention is better than cure in this instance. "Normal" controls configuration might have given the "trainer" more chance to block the trainee before the appropriate angle was exceeded. Maybe the reduced thrust take off effect wasn't the same as the simulated flying. If you are at max weights it all happens a bit more slowly. Nev

 

 

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Posted

Fwd speed is a serious consideration due to the high rate of abrasive removal of material that will happen when it contacts the concrete/Tarmac runway surface.

 

Yes the structural local load is more related to the vertical speed due to rotation but don't forget that the local loads are very high given it's probably got the best part of 1/3rd of take off load pushing it down even if only briefly.

 

 

Posted

Genuinely surprised this happened. I get that the cadet was training to be a first officer and that this was their first real world flight be come on. I agree with one of the other comments surely the climb angle is absolutely hammered into them in the class room and the simulator. To smack the tail on the ground on take off I think means you are not, as someone else said, monitoring your instruments with the nose up you can't see the horizon so surely you must use the a.h. Anyway we have 20/20 vision I am just saying I am really surprised.

 

 

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