
When the plane takes off, why doesn’t the tail hit the runway? - skellertor
http://www.thegigamax.com/2017/10/10/plane-takes-off-doesnt-tail-hit-runway/
======
kuhn
Interesting write up. I was just watching a video yesterday which had a pretty
good example of the testing aircraft manufacturers do for this scenario. It’s
called a velocity minimum unstick test. Some impressive flying.

[https://youtu.be/BWwUTJM3jbA](https://youtu.be/BWwUTJM3jbA)

~~~
zodPod
"They put the plane into a stall to make sure it can recover" CAN YOU IMAGINE?
lol Could you imagine being the guy who wakes up in the morning and is like
"Today I get to put a plane into stall to make sure it can recover" _shivers_

~~~
sjburt
This is a normal part of pilot training. I think it's less common in large
aircraft but for small planes it's not uncommon.

~~~
nsxwolf
It really doesn’t feel like anything special is happening either, and recovery
is quick and easy. It’s a non-event at altitude.

Spin training though, no thanks!

~~~
ubernostrum
Well, the nice thing about most planes is that they don't _want_ to stall, and
most of the time the correct action to recover is "stop doing things and let
the plane recover". It's when you _keep_ messing with it that you make things
worse and get toward unrecoverability.

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throwawayjava
The tailskid (physical tailstrike protection [1]) was removed from the
777-300ER in favor of software-based mitigation [2,3].

[1]
[http://www.boeing.com/news/frontiers/archive/2004/december/i...](http://www.boeing.com/news/frontiers/archive/2004/december/i_tt.html)

[2]
[http://www.airliners.net/forum/viewtopic.php?t=775483](http://www.airliners.net/forum/viewtopic.php?t=775483)

[3] [http://aviationweek.com/advanced-machines-aerospace-
manufact...](http://aviationweek.com/advanced-machines-aerospace-
manufacturing/boeing-rolls-out-777-upgrade-plan)

~~~
neurotech1
If there is a suspected tailstrike in an airliner, the tailskid might reduce
the damage but it still requires an emergency return and engineering
inspection for damage.

Most severe tailstrikes occur on landing, and the tailskid isn't going to help
reduce damage.

------
liorn
The cockpit recording from Japan Airlines Flight 123 (which crashed due to
improper repairs of tail strike damage 7 years earlier) is chilling.
[https://www.youtube.com/watch?v=Xfh9-ogUgSQ](https://www.youtube.com/watch?v=Xfh9-ogUgSQ)

~~~
wyldfire
Wow, that was a scary recording.

From the wikipedia article [1]:

> Casualties of the crash included all 15 crew members and 505 of the 509
> passengers

> ...

> deadliest single-aircraft accident in history, the deadliest aviation
> accident in Japan, the second-deadliest Boeing 747 accident and the second-
> deadliest aviation accident after the 1977 Tenerife airport disaster.

> ...

> During the investigation, Boeing calculated that this incorrect installation
> would fail after approximately 10,000 pressurization cycles; the aircraft
> accomplished 12,318 successful flights from the time that the faulty repair
> was made to when the crash happened.

> ...

> In the aftermath of the incident, Hiroo Tominaga, a JAL maintenance manager,
> killed himself to atone for the incident, while Susumu Tajima, an engineer
> who had inspected and cleared the aircraft as flight-worthy, committed
> suicide due to difficulties at work.

[1]
[https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123](https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123)

~~~
kbenson
> > In the aftermath of the incident, Hiroo Tominaga, a JAL maintenance
> manager, killed himself to atone for the incident, while Susumu Tajima, an
> engineer who had inspected and cleared the aircraft as flight-worthy,
> committed suicide due to difficulties at work.

That sucks. If ever there were two people that knew first-hand how important
it was to get right and would have worked to make sure that accident, and
likely others as well could never happen on their shift, those were them.
Suicide as atonement is a stupid, counter-productive cultural norm (and
hopefully it's much less of a norm in any modern society where it exists).

~~~
wallace_f
Interestingly, at the end of WWII, when Tojo was captured by the Americans, he
shot himself in the abdomen--creating referencss fo seppuku--and apologized
that "I am taking so long to die."

Not long after, he was tried for war cimes and executed by hanging.

I'm sure he would have rather have died from the gunshot.

Whether right in some cases and wrong in others, I think it's difficult to say
cultural norms are simply and plainly wrong.

~~~
kbenson
I'm not sure comparing a case where the person has a high likelihood of dying
anyway is necessarily appropriate based on what I was referring to. I don't
fault the skydiver that failed to pack their parachute correctly and causes it
to fail for committing suicide before hitting the ground, I do fault a system
that would cause the person responsible for re-checking the parachutes to
commit suicide because of the death.

I also didn't say the cultural norm was _wrong_ , just that it was stupid and
counter-productive. I meant stupid as an enhancement to counter-productive,
and I meant counter-productive in relation to actually advancing a society to
the point where the problem that caused the suicide in the first place is less
common.

------
Animats
Tail-draggers died out for larger aircraft partly because the slanted cabin
when on the ground was inconvenient. The DC-3 was the last successful tail-
dragger airliner.

Wolfgang Langewiesche, in his 1944 classic, "Stick and Rudder", writes that
the tail-dragger arrangement is a poor landing gear, but a good takeoff gear
for underpowered aircraft. It gives the effect of flaps on takeoff for planes
that don't have flaps. Tail-draggers are prone to nose-plant accidents and
ground loops.[1]

Worst landing gear ever - the U-2. Two inline wheel sets.[2] That's the result
of extreme weight reduction.

[1]
[https://www.youtube.com/watch?v=q5trygRQaV0](https://www.youtube.com/watch?v=q5trygRQaV0)
[2]
[https://www.youtube.com/watch?v=-ELjCkG4Gl0](https://www.youtube.com/watch?v=-ELjCkG4Gl0)

------
devnonymous
Why aren't people reading the article? Yes, as engineers we tends to
rationally think and come up with seemingly plausible explanations but like 3
comments out of the current 8 seemingly didn't even bother validating their
theory or verifying whether the article offered an explanation! News for
hackers indeed!

~~~
brian-armstrong
Yes, this is a frustrating trend. It would be nice to see ~2-week long posting
bans handed out for this sort of behavior

~~~
hk__2
Note that insinuating people haven’t read the article is itself against HN’s
guidelines [1].

[1]:
[https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html)

~~~
twic
This always reminds me of the rule that in parliament, MPs cannot accuse each
other of lying [1]. People do it, we all know they do it, and it's a genuine
problem that they do it - but we're not allowed to talk about it!

[1]
[https://www.theguardian.com/notesandqueries/query/0,5753,-22...](https://www.theguardian.com/notesandqueries/query/0,5753,-2245,00.html)

~~~
kbenson
The solution there is the same as here. Point out how people are wrong, and if
egregiously so, make it obvious that is the case. Replying "The article
mentions this exact case and explains it" Is sufficient.

------
jokoon
I remember seeing somewhere that some planes were fitted with some wooden ball
on the tail so it can touch the ground.

~~~
chrisseaton
I think Concorde had a wheel on the tail.

~~~
dingaling
And the Soviet Il-62. It was actually smarter than the more elegant British
VC-10 as it permitted the centres of pressure ( wing position ) and gravity to
be optimised for cruising rather than remaining in its main gear whilst in the
ground.

------
forgotmysn
i feel like it doesn't take a whole page to explain that planes are moving
forward faster than they are gaining lift when taking off.

~~~
larkeith
Or that the tail doesn't hit the runway because it's angled upwards.

~~~
KGIII
I guess you can make it hit the runway, if you want. I watched a doc with them
testing planes and they, quite literally, put some lumber on the tail to
protect it from damaging the metal when they hit the runway with the tail. As
in, they were intentionally trying to hit the runway with the tail.

~~~
mikeash
Yes, the actual answer to the question is "because the pilots are trained not
to hit the tail, since it's expensive and makes the passengers nervous."

It's a decent little article but it seems to not quite be on the same topic as
the headline suggests.

~~~
KGIII
Yeah, someone has added a video of this and it's currently at the top. I don't
think I'd like to try that.

~~~
mikeash
I know of at least one major crash caused by a tail strike, although the
problem took years to manifest after a bad repair job:
[https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123](https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123)

(Worth noting that this airplane's tail strike happened on landing, not
takeoff, but it's bad either way.)

Definitely best to avoid them if you can....

~~~
eternalban
"Explosive decompression":
[https://youtu.be/awMHJ_ZZF5Y](https://youtu.be/awMHJ_ZZF5Y)

------
jotjotzzz
Omg, scary stuff. How can we check the planes we are boarding have never had
this airstrike repair? Sounds crazy.

~~~
mulmen
You can't and without specialized experience you probably wouldn't know what
to look for anyway. This is why we have regulatory structures in place to
ensure airworthiness.

------
GrumpyNl
The tail wont hit the ground because the engineers designed the tail in a way
so it wont hit the ground.

~~~
mulmen
It is very easy to cause a tail strike. The article provides multiple examples
of how this can and does happen.

