Core77

What Gains 50,000 Pounds in 15 Minutes?

By Rain Noe - December 2, 2013

in Cars

[image via JBT AeroTech]

[image via JBT AeroTech]

Your correspondent managed to travel via subway this Thanksgiving, avoiding the car-clogged roads, the train-jammed tracks and most importantly, the airplane-choked skies. But this past weekend, I departed for Autodesk University on the other side of the country, meaning there's a plane ride in my immediate future.

On the jet bridge, I'll be looking out for that little wheeled thing in the photograph above, which I've not noticed (so much for being an observant industrial designer) on the numerous flights I've taken in my lifetime, probably because during the boarding process I'm more concerned with if there's any overhead bin space left. Slate, however, has been kind enough to point the object out and explain its function. Can any of you guess what it is, and what it does?While Slate used an Airbus A380 for their example, I'll be flying out on a Boeing 737-800, so I dug up some stats to do a little math. First off, that little wheel is attached to a sensor that judges the actual level of the plane relative to the jet bridge, which changes as the plane goes from laden to unladen, and vice versa.

Why? Because unladen, the 737-800 can weigh 80,000 to 90,000 pounds, depending on the configuration. The capacity maxes out around 210 people (or 210 "souls," if we crash; for some reason, whenever an air or sea vessel goes down, they always say "X number of souls were lost on [vessel] #213 out of New York." But I digress). Let's say we Americans have an average weight of 180 pounds—ha, ha, ha!—and that we've all maxed out our 40-pound carry-on allowance. Throw in the pilot, co-pilot and crew, and that means that once we've all packed our fat asses and gear onto that baby, we're looking at a plane that's had nearly 50,000 pounds added to it during the fifteen minutes it takes to board. And that's not counting whatever amount of fuel they're pumping into the thing, and the weight of the delicious, nutritious meals being loaded into the galley, and our checked luggage going into the belly.

During that time, the jet bridge needs to stay level with the entrance of the plane, and that's what the wheel is for; as the wheel travels, detecting if the plane has sunk (or raised, during de-planing), motors kick in and automatically raise or lower the jet bridge to match, so that we don't have a bunch of travelers tripping all over themselves and figuring out how much they can sue the airline for.

The little wheel and its attendant system, by the way, have a clever name: It's called "autolevel."

o

Favorite This
Q
8

Comment

Comments

Mr Focus

10 years ago

Z

Z

Reply

Auto-level has ruined the music industry.
!Report as spam
mikebdesign

11 years ago

Z

Z

Reply

I learned what that wheel does when I was traveling with someone and they reached over and rolled it up the fuselage slightly. The entire jet bridge started moving. Moral: don't touch the autolevel.
!Report as spam
ahmed

11 years ago

Z

Z

Reply

Thats an auto wheel.. when the aircraft is being loaded this synchronize the hight of the jet bridge not to damage the aircraft door by hitting the jet bridge floor
!Report as spam
22blades

11 years ago

Z

Z

Reply

It is an Autoleveler. Take an empty airplane and start loading it 10,000 pounds at a time, the struts will compress. If the Jetway doesn't follow it, the stationary Jetway will rip the door off the plane. It happens every once in a while. It can cause up to major structural damage. Veeerrryyy expen$ive. If you're on the jetway and you hear a constant beeping, it means it's out of tolerance and needs manual adjustment...BEFORE it rips the door off. You will then be delayed...majorly.
!Report as spam
brian

11 years ago

Z

Z

Reply

Supposedly, the in-house industry term for airline passengers is "self-loading cargo." Kind of explains a lot about the airlines, actually.
!Report as spam
scott

11 years ago

Z

Z

Reply

I would like to throw in, and I don't know if this is a hard and fast FAA rule or simply an old rule of thumb, but when calculating weight and balance for aircraft, the given weight for pilot and passengers used is 195lb each.

!Report as spam
Ryan

11 years ago

Z

Z

Reply

I have always noticed the auto adjusting when on the jet bridge but always thought the wheel was just used as an spring loaded alignment tool to prevent the operator from putting to much pressure on the plane skin. The wheel with the ability to roll up multiple shapes of plane skins.

Thanks for sharing.

Does it use the metal arm the wheel is attached to for measuring angle or the spin of the wheel?
!Report as spam
Rob Wilkey

11 years ago

Z

Z

Reply

Always wondered. Now I know.

I used to think that they had some mechanism for locking the hydraulics, on the airplane wheels, but this makes way more sense.
!Report as spam