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Qb001
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 9:14 am

We know some inflight entertainment systems offer a tail view of the flight, through a camera. This is the case on the A380. Look at the video that I linked below (jump at the 37 minute mark). Wasn't that a very short landing or is it just some sort of distortion due to some camera effect?
www.youtube.com/watch?v=idVKahL_cDU
Never let the facts get in the way of a good theory.
 
flipdewaf
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 9:32 am

There is a time delay for the video played on the seat back screen. The video being played when you hear the gear touch down is from several seconds before.

Fred
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travelavnut
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 9:36 am

Not an expert here, but that looks mighty early!
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zeke
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 9:44 am

Quoting Qb001 (Thread starter):

This has been discussed before. My understanding there is a small delay in the video feed into the AV system, looking at the footage, they so not seem to be short. Looking at the spoilers, they only seem to come up after the PAPI.

I would expect the main wheels for an A380 to touch down before say a B1900 as the height from the receiver aerial to the main wheels is greater. The ILS receiver is in the nose, the landing geometry is based upon that receiver aerial following the glide-path, not the main wheels.
“Don't be a show-off. Never be too proud to turn back. There are old pilots and bold pilots, but no old, bold pilots.” E. Hamilton Lee, 1949
 
Qb001
Topic Author
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 9:51 am

Quoting zeke (Reply 3):
I would expect the main wheels for an A380 to touch down before say a B1900 as the height from the receiver aerial to the main wheels is greater. The ILS receiver is in the nose, the landing geometry is based upon that receiver aerial following the glide-path, not the main wheels.

Well, consider this other video, where the A380 lands past the white blocks (jump to 24 min 30 sec approx.)
www.youtube.com/watch?v=lnRKxkWAevA
Never let the facts get in the way of a good theory.
 
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zeke
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 1:14 pm

Quoting Qb001 (Reply 4):

The FAA use their own runway markings, they are not the same as the ICAO ones. What you see painted on the runway in DXB is not the same as JFK, they are at different distances.
“Don't be a show-off. Never be too proud to turn back. There are old pilots and bold pilots, but no old, bold pilots.” E. Hamilton Lee, 1949
 
Passedv1
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 7:15 pm

Quoting Qb001 (Thread starter):
We know some inflight entertainment systems offer a tail view of the flight, through a camera. This is the case on the A380. Look at the video that I linked below (jump at the 37 minute mark). Wasn't that a very short landing or is it just some sort of distortion due to some camera effect?
www.youtube.com/watch?v=idVKahL_cDU

On the shorter side of a normal landing...A little bit of a flare would have been a little nicer for the pax.

Quoting Qb001 (Reply 4):
Well, consider this other video, where the A380 lands past the white blocks (jump to 24 min 30 sec approx.)
www.youtube.com/watch?v=lnRKxkWAevA

On the longer side of a normal landing...Probably didn't want to float quite so much.

Both were well within "safe" parameters.

Quoting zeke (Reply 5):
The FAA use their own runway markings, they are not the same as the ICAO ones. What you see painted on the runway in DXB is not the same as JFK, they are at different distances.

They are different measurements but that is irrelevant as the function is the same. They are not LANDING POINTS they are AIMING points. This is the point on the runway that generally speaking the G/S and the PAPI/VASI are guiding you to. It is 1,000' down the runway in the US and 400 meters (1400'ish) down the runway elsewhere. Their functions are the same though.

The touchdown zone is considered the first 3,000' of the runway. A touchdown anywhere in this first 3,000' is generally considered acceptable.
 
Cactus105
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 7:37 pm

The second video shows the delay still. The Spoilers come up on the video a few seconds after the touchdown is heard. With regard to the first video, he probably touched down within the first 500-1000 feet of the runway which is pretty short, but the delay makes it seem worse.
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zeke
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 9:32 pm

Quoting PassedV1 (Reply 6):
It is 1,000' down the runway in the US and 400 meters (1400'ish) down the runway elsewhere.

Which equates to what numbers in threshold crossing heights on a 3 deg slope ? Keep in mind the pilots eye height is 30' higher than the wheels on the A380.....

How do pilots of large compensate for this ?

Quoting PassedV1 (Reply 6):
The touchdown zone is considered the first 3,000' of the runway.

Not according to the FAA or ICAO.

Quoting PassedV1 (Reply 6):
The touchdown zone is considered the first 3,000' of the runway. A touchdown anywhere in this first 3,000' is generally considered acceptable.

Not where I work.
“Don't be a show-off. Never be too proud to turn back. There are old pilots and bold pilots, but no old, bold pilots.” E. Hamilton Lee, 1949
 
jetskipper
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 9:42 pm

(DOD, NATO) 1. For fixed wing aircraft--The first 3,000 feet or 1,000 meters of runway beginning at the threshold. 2. For rotary wings and vectored thrust aircraft--That portion of the helicopter landing area or runway used for landing.


Read more: http://www.answers.com/topic/touchdown-zone#ixzz2OUnzX6dV

For US carries landing is required within the touchdown zone, anything outside the touchdown zone would be considered unacceptable.
 
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zeke
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 9:58 pm

Quoting jetskipper (Reply 9):
(DOD, NATO)

"US Defense Department Military Dictionary: touchdown zone"

What relevance does that have with civil operations ???????????

Quoting jetskipper (Reply 9):
For US carries landing is required within the touchdown zone, anything outside the touchdown zone would be considered unacceptable.

Not exactly true either, there is a touchdown zone marked on the runway (which is not the first 3000'). That does not mean for all US carriers (which operate aircraft from very very small to large jet transports) it would be unacceptable. The various Fedex feeder carriers operating C208s would be an example here.
“Don't be a show-off. Never be too proud to turn back. There are old pilots and bold pilots, but no old, bold pilots.” E. Hamilton Lee, 1949
 
jetskipper
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 10:21 pm

From the FAA PIlot/Controller Glossary:

TOUCHDOWN ZONE- The first 3,000 feet of the runway beginning at the threshold. The area is used for determination of Touchdown Zone Elevation in the development of straight‐in landing minimums for instrument approaches.

From FAR 91.175 (c):

(c) Operation below DA/ DH or MDA. Except as provided in paragraph (l) of this section, where a DA/DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, below the authorized MDA or continue an approach below the authorized DA/DH unless—

(1) The aircraft is continuously in a position from which a descent to a landing on the intended runway can be made at a normal rate of descent using normal maneuvers, and for operations conducted under part 121 or part 135 unless that descent rate will allow touchdown to occur within the touchdown zone of the runway of intended landing;

Translation: it doesn't matter if you are flying a Caravan or a Boeing for an airline, if you are filed under Instrument Flight Rules in the US under part 121 or 135 (which the FedEx Caravans would be), to continue below minimums under visual condition you must be in a position to land within the touchdown zone.

Please start citing references.
 
jetskipper
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 10:54 pm

No one ever said, nor do my citations state 3000' from the end of the runway. It states the touchdown zone is 3000' from the runway threshold, an threshold doesn't necessarily start at the beginning of the runway in the case of a displaced threshold.

Again from the Pilot/Controller Glossary:

DISPLACED THRESHOLD- A threshold that is located at a point on the runway other than the designated beginning of the runway.

Quoting zeke (Reply 10):
 
rfields5421
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Short Landing (way Before Threshold)?

Sun Mar 24, 2013 11:01 pm

Quoting zeke (Reply 8):
How do pilots of large compensate for this ?

Understanding the change in viewpoint is one part of transition training for pilots.

By the time they get to fly A380 or B747 type jets, they have a few thousand of hours and like over a thousand landings. It isn't that much of a big deal, and only takes a few times landing to get it perfect.

From after they complete their first pilots license, pilots are training to fly larger, faster, higher cockpit aircraft. They've done that transition several times before.

A somewhat similar issue is when a big metal pilot moves to flying biz jets, or even finally gets a personal GA plane. And wants to flare the aircraft 30 feet above the runway.
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vikkyvik
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RE: Short Landing (way Before Threshold)?

Mon Mar 25, 2013 4:59 am

Quoting zeke (Reply 8):
Which equates to what numbers in threshold crossing heights on a 3 deg slope ? Keep in mind the pilots eye height is 30' higher than the wheels on the A380.....

For an aiming point at 1000 feet, it equates to a 52-foot threshold crossing height. For an aiming point at 1400 feet, it equates to 69 feet. Now, in the US, the glideslope antennas and/or PAPI are typically close to 1000 feet down the runway. I don't know whether the antennas/PAPI are displaced further at other airports, or if the aiming point is simply different to account for the flare.

Actually, since I was bored, I just looked at a bunch of European airports on Google Earth. Interesting result - the PAPI tends to be located at or around the aiming point (1300 feet or thereabouts), while the glideslope antenna is still located in the vicinity of 1000 feet. My search was by no means exhaustive - I looked at LHR, CDG, BRU, and AMS. Just thought that was interesting.

Also perhaps worth noting that the ILS glideslope and the PAPI glideslope are not always coincident.

Quoting PassedV1 (Reply 6):
400 meters (1400'ish)

FYI, 400 meters is just over 1300 feet.
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KELPkid
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RE: Short Landing (way Before Threshold)?

Mon Mar 25, 2013 5:49 am

Quoting vikkyvik (Reply 14):
Also perhaps worth noting that the ILS glideslope and the PAPI glideslope are not always coincident.

As FAA approach plates and the TERPS constantly remind us...(at least here in the USA)  Sometimes standing NOTAMs, too...
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Mir
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RE: Short Landing (way Before Threshold)?

Mon Mar 25, 2013 1:56 pm

Quoting KELPkid (Reply 15):
Quoting vikkyvik (Reply 14):
Also perhaps worth noting that the ILS glideslope and the PAPI glideslope are not always coincident.

As FAA approach plates and the TERPS constantly remind us...(at least here in the USA)

Seems like they're more often not coincident in my experience.

-Mir
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citationjet
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RE: Short Landing (way Before Threshold)?

Mon Mar 25, 2013 4:15 pm

What about a long takeoff, after the threshold, and using the overrun?

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