
Is this plane landing or departing? - bluedino
http://aviation.stackexchange.com/questions/34586/is-this-plane-landing-or-departing
======
ozgung
There is motion blur on the traffic cone suggesting that camera was moving
right and slightly down. There is no blur on the plane itself since the camera
was locked to the plane's motion. So I deduce a landing photo.

~~~
neom
I 100% agree, and used this method. :P

------
Yetanfou
Landing, there is hardly any disturbed air behind the engines. While modern
engines don't produce all that much smoke they do produce lots of heat when
running at full power, leaving a tell-tale trail of visibly disturbed air and
exhaust gases behind them. No such trail is visible here so the engines are at
a low power setting (idle or close to it).

~~~
dx034
In addition to that, the engines of the Air Force One aren't really modern.
The disturbed air should be even more visible there.

------
macinjosh
The approach I would have taken is to check the EXIF data in the photo to see
what time it was taken. You could then look at historical records or news
records to see about when the President left or landed at that airport on that
day. If the time is closer to when he left its a take off, if it is before it
is a landing.

~~~
enkid
These planes can fly without the president, so you're not guaranteed an answer
this way.

~~~
tgb
I was thinking this too, but was guessing that there are databases of all
flights in the US - I know there are those flight tracker websites out there
and someone is probably recording that data.

~~~
tantalor
Yep, flightaware advertises flight history "dating back to 1998".

Example:
[https://flightaware.com/live/flight/DLH458/history](https://flightaware.com/live/flight/DLH458/history)

------
laen
A consideration not listed on the OP is that Air Force pilots are required to
conduct partial-flap landings on a continuing basis to maintain qualification.
This could explain why the flaps do not appear to be in landing configuration.
Normally, this training is conducted in the simulator, but if the president is
not onboard and and the aircraft is inbound for maintenance at Boeing Field
this would be plausible.

Partial flap landing distance is dependent on the aircraft, but 4,000+ feet as
the position suggests would be very reasonable. The pilot could have also
intentionally landed long to expedite taxi to parking.

All that said I still have no idea if the aircraft is arriving or departing.

~~~
Fiahil
See the comments for the answer:
[http://aviation.stackexchange.com/a/34609](http://aviation.stackexchange.com/a/34609)

> So...abelensky found the series of photo this was taken from, see for
> yourself:
> [https://drive.google.com/file/d/0BxQOwrukppp5WTlfaEFLTVNzTnc...](https://drive.google.com/file/d/0BxQOwrukppp5WTlfaEFLTVNzTnc/view)
> ...it's clearly landing.

------
gus_massa
Just for comparison, look at the standard "landing" sign in an airport
[https://www.google.com/search?q=airplane+landing+sign&tbm=is...](https://www.google.com/search?q=airplane+landing+sign&tbm=isch)
I always chuckle

~~~
bnegreve
Oh cool, now we know why it looks so stupid: it's because it's almost
impossible to distinguish takeoff from landing if you don't exaggerate the
angle.

~~~
atomwaffel
Exactly, that's why I think this is a great pictogram: it makes it clear what
it's supposed to represent, even though it has nothing to do with what a
healthy landing looks like. A pictogram's job is to fit most people's
conceptual model of what it represents while being simple and distinguishable,
not to be an accurate representation of whatever it stands for.

This pictogram is simple (just a few shapes), it's easy to distinguish (e.g.
from the pictogram for "departure"), and it fits most people's conceptual
model of a landing (plane comes down from sky to earth).

------
jMyles
I'm impressed that this question is so difficult. I presumed that, for an
aviation expert, a quick glance at _any_ photo of a similarly situated
aircraft was enough to make a determination.

TIL.

------
YZF
my first impression was landing but I can't quite explain why. I used to be an
air traffic controller so I have some amount of "machine learning" in this
area though not a lot from this angle or this kind of aircraft.

The angle didn't quite look right for a takeoff though after looking at a few
takeoff videos of similar airplanes it seems they mostly try for steeper
takeoffs but there's a lot of variability. There are conflicting requirements,
you want to get as much altitude as possible as fast as possible so you have
more options if there's any problem but you also want to gain speed and your
initial angle might be limited by stall speed or other factors (
[http://www.boeing.com/commercial/aeromagazine/aero_12/attack...](http://www.boeing.com/commercial/aeromagazine/aero_12/attack_story.html)
).

Even if I had 50% of being right it's always nice to be able to explain to
oneself how good you are and when you get it wrong you can blame something
else ;)

~~~
andrewflnr
For a human, it's just called "learning". :)

~~~
pbhjpbhj
I assumed the parent meant something slightly different from just learning -
something along the lines of: observation of instances of planes taking off
and landing but without conscious consideration of the features that differ
between the two sets of "training data". Not really learning _per se_ as that
would require some form of study of the planes and their differences??

~~~
somestag
I'd say the most appropriate term here is _intuition_ (which I'd say is
definitely regular ol' learning, but that's a matter of definitions and
semantics).

------
sikan
"If you wanted to take a picture of a plane taking off, I'm sure you would
have done it while it stil had some of its wheels on the ground. But if you
wanted to take a picture of a plane landing, you would probably do it while it
was still in the air."

The plane is in the air, so I say it is landing.

------
dnautics
Can we train a convnet to recognize departure vs landing and then analyze some
of the layers to see what is being activated?

~~~
joshvm
Although this may have been posted in jest, it would probably work quite well
or at least be an interesting experiment.

There's a large corpus of images in both categories, and it's a binary
classifier which keeps things simple. There are numerous image cues that
people have identified such as the flap angle relative to the wings, absence
of smoke from the tyres, absence of heat haze from the jet wash, wheel-spin
and so on. Depending on angle you could also get the landing markers on the
runway. It seems reasonable that a convnet would identify these features.

My only concern is that features like heat haze and wheel-spin might require
very high resolution inputs to the net. Also it's quite hard to search
explicitly for "planes taking off" as you get images from aircraft about to
take off, aircraft taxiing, etc. Finally it's quite hard to find publicly
available images, e.g. most photos on Aviation.net are copyrighted.

~~~
dnautics
nope! not in jest at all. i think the only possibly difficult thing would be
finding the solution classification.

------
everyone
amazing! How did such a discussion inducing question survive on modern stack
overflow? I guess the question-closing-mavens do not stalk the aviation
section as they do the programming/IT ones.

~~~
castis
My guess would be that the aviation SE doesn't see variants of the same
questions posted every day.

------
tim333
The angle of attack looks very low for an aircraft taking off with it's wheels
maybe 30' above the ground. If you look at this takeoff video they tend to
rotate more than that.
[https://www.youtube.com/watch?v=5ptrsx-A3H0&feature=youtu.be...](https://www.youtube.com/watch?v=5ptrsx-A3H0&feature=youtu.be&t=1m38s)

------
mrestko
This is a perfect example of nerd sniping.
([https://xkcd.com/356/](https://xkcd.com/356/))

------
peace011
As it relates to human nature, my non-scientific guess is that most people
want to witness the president arrive, so I bet the OP took the photo when the
plane was landing ;)

------
gambiting
It's interesting that a lot of answers say that it should be possible to
figure out if it's landing or taking off by figuring out the direction of the
landing strip. Do most airports have only one-way runways? I know my local
airport, in Krakow, Poland, can operate either way, depending on the wind on
that particular day. I've both landed and taken off in both directions, many
times.

~~~
coredog64
It's not so much the direction as it is the location of the aircraft along the
runway. Boeing Field (KBFI) has a number of recognizable landmarks along the
runway (as seen in the discussion), so some of the theories advanced had to do
with whether or not the aircraft could be in a given phase at the recorded
location.

~~~
FabHK
Furthermore, both landing and departing aircraft will move in the same
direction (into the wind).

------
a3n
Just to make this about me: I used to work across the street from the Museum
of Flight, shown in the aerial view of the field in question.

------
sandworm101
Landing. It"s not nose up enough for takeoff. This is a partial-flaps landing
at a relatively higher speed than is normal. If this was a takeoff the nose
would be higher. Shalow landings are optional, you can abort, but nobody does
shallow takeoffs. You want altitude asap (within reason) because there is no
abort once rubber leaves runway.

------
madads
I immediately thought landing because the entire plane doesn't look like it
has nice "straight" angles aligning with the runway. But I guess it is hard to
tell from the angle of the photo itself.

On take off, the back wheels would've been nicely aligned with the runway.

Oh well, I deduced right?.

------
clueless123
I don't see any spin blur on the wheels.. if the wheels are not rotating , it
would be a landing.

------
tomohawk
I can just hear the Dread Pirate Roberts say "Truly, you have a dizzying
intellect."

~~~
taneq
"I'm just getting started!"

------
Splines
OP has the picture and the file should have the date-time stamp of the flight.
Couldn't they look up visits by Air Force One or travel by the president
around that point in time? It may not give an answer 100%, but it should help.

~~~
enkid
Do we know the president was on it? These planes fly without the president for
maintenance, photo ops, etc.

------
logingone
Do those big planes take off with flaps? I didn't know that, so went with
landing.

~~~
sokoloff
Yes, flaps are routinely partially deployed for normal takeoffs. On the 747,
there are leading edge flaps in addition to the "normal" trailing edge flaps.

~~~
FabHK
On the leading edge, they're called "slats" [1]. Most passenger jets have
them, and they're rather important for take-off: The first fatal 747 crash, a
Lufthansa machine departing Nairobi, came down because the slats were not
deployed [2].

[1] [https://en.wikipedia.org/wiki/Leading-
edge_slats](https://en.wikipedia.org/wiki/Leading-edge_slats)

[2]
[https://en.wikipedia.org/wiki/Lufthansa_Flight_540](https://en.wikipedia.org/wiki/Lufthansa_Flight_540)

~~~
sokoloff
You're correct on most airliners, but not the 747 (on which the VC-25 is
based).

A 747 has Kreuger flaps [1] between fuselage and inner engines and 'variable
camber leading edge flaps' on the rest of the wing.

[0] - [https://en.wikipedia.org/wiki/High-
lift_device](https://en.wikipedia.org/wiki/High-lift_device) [1] -
[https://en.wikipedia.org/wiki/Krueger_flap](https://en.wikipedia.org/wiki/Krueger_flap)

~~~
FabHK
Awesome, thanks. Nice illustration as to the differences in the Wikipedia
article. The LH crash Wikipedia article seems inaccurate, then.

Edit: put a note in the Wikipedia article.

------
Logishort
I'd suggest to try and teach a neural net to decide upon airplane pictures
whether they're landing or taking off. That way the stackexchange debate could
be settled (with a chance to be wrong here, haha xD )

------
tvalentius
the flaps is in down-ward angle ,so i believe the plane is taking off

[https://en.wikipedia.org/wiki/Flap_(aeronautics)](https://en.wikipedia.org/wiki/Flap_\(aeronautics\))

------
branda22
By the position of the flaps its most likely departing the airport.

------
mbloom1915
why does this matter?

------
libeclipse
The self-censorship in this thread is insane. I've noticed at least two
(valid) comments now that have been deleted due to downvotes.

------
patcheudor
That cat is both dead and alive.

------
ccrush
Clearly a departure. Went wheels up right after rotate. No way they'd be that
low with the gear position the way it is without a failure. No landing markers
in sight. This is either a take off or a disaster.

~~~
robotmlg
Asker found the full set of photos confirming that it's a landing:
[https://drive.google.com/file/d/0BxQOwrukppp5WTlfaEFLTVNzTnc...](https://drive.google.com/file/d/0BxQOwrukppp5WTlfaEFLTVNzTnc/view)

~~~
niels_olson
Theory vs experiment. More data always wins.

------
stuckagain
In which the internet pretends to know things.

Isn't it a false choice? Why can't the answer be "both"? Explain in detail.

~~~
pavel_lishin
> _Isn 't it a false choice? Why can't the answer be "both"?_

How does a plane both take off and land at the same time?

~~~
innocenat
Unrelated to the picture, but touch-and-go probably qualify as "both",
although not _exactly_ same time either.

~~~
condescendence
I'm very surprised this maneuver wasn't assessed in any of the answers. It
actually does look like they're practicing a touch and go maneuver. The tires
aren't producing any smoke and the flaps are positioned at a T20 so its both a
landing and takeoff configuration. This is also a very late position for a 747
to be landing on an airstrip of this size. All evidence, for me at least,
suggests a touch and go.

The fact that its airforce one aswell and they'd likely be practicing
different techniques and training pilots.

Taking the lack of air distortion from the behind the engines, it could be
because the photo is extremely grained/blurry to begin with and the flaps
foiling the air to the ground rather than directly behind the engine.

My only other guess is they were practicing late landings.

