Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
convair880mfan
Topic Author
Posts: 163
Joined: Fri Jun 25, 2021 12:33 am

Sinking feeling when leveling off on B757

Sat Jul 24, 2021 4:17 am

Back in the day when I used to fly on the Boeing 757 I often noticed a kind of sinking feeling in my stomach when the plane leveled off after takeoff.

I also experienced something similar on the Boeing 737-500 and Boeing 707-100. At liftoff I would get a sinking feeling and feel a little light headed and then again when those aircraft leveled off after takeoff.

Don't know much about aviation physiology. Perhaps someone could explain it to me. Thanks in advance.
 
User avatar
Starlionblue
Posts: 20759
Joined: Fri Feb 27, 2004 9:54 pm

Re: Sinking feeling when leveling off on B757

Sat Jul 24, 2021 4:56 am

It's physics. ;)

As the aircraft levels off at an altitude, it transitions from climbing to level. This means a slight decrease in G force acting on your body. The pitch change increases the effect.

An analogue would be going over the top of a hill with a pointy crest in a car.
 
Zeke2517
Posts: 64
Joined: Wed Jan 09, 2013 4:29 pm

Re: Sinking feeling when leveling off on B757

Sat Jul 24, 2021 5:45 am

Acceleration, man.
 
User avatar
Aaron747
Posts: 15676
Joined: Thu Aug 07, 2003 2:07 am

Re: Sinking feeling when leveling off on B757

Sat Jul 24, 2021 5:50 am

convair880mfan wrote:
Back in the day when I used to fly on the Boeing 757 I often noticed a kind of sinking feeling in my stomach when the plane leveled off after takeoff.

I also experienced something similar on the Boeing 737-500 and Boeing 707-100. At liftoff I would get a sinking feeling and feel a little light headed and then again when those aircraft leveled off after takeoff.

Don't know much about aviation physiology. Perhaps someone could explain it to me. Thanks in advance.


You would feel it most in the front or rear cabins and least over the wings where the center of gravity is.
 
Max Q
Posts: 9051
Joined: Wed May 09, 2001 12:40 pm

Re: Sinking feeling when leveling off on B757

Mon Jul 26, 2021 3:13 am

It’s also pilot technique, if you don’t anticipate your level off adequately you may have to apply more down elevator to avoid overshooting your assigned altitude and more abruptly than what is comfortable producing negative G


If you do anticipate the level off properly you’ll have a nice smooth level off without that uncomfortable sensation
 
Genista
Posts: 4
Joined: Mon Jul 26, 2021 5:47 am

Re: Sinking feeling when leveling off on B757

Mon Jul 26, 2021 7:13 am

OP is talking about the "level off" (in reality just a reduction of pitch) right after take off I think.

During that one you can get an almost "zero-G" feeling for a second or two. Especially if flying NADP2 take off procedure as seen on the chart below.

Image

In a nutshell, right after liftoff the pilot aim for the skies to make aircraft climb very fast, like a rocket (15-20deg of pitch).

Then you reach the acceleration altitude, usually between 800 and 1500ft (you reach that one quickly, a handful of seconds after liftoff). At this point, you reduce your pitch (to something like 10deg) so tha, instead of climbing like a rocket, you start gaining horizontal speed allowing you to put the aircraft in more efficient climbing configuration.

And it is when you get this feeling.

It is more a question of airline policy and departure airport/runway/SID than of airframe.
 
RR757
Posts: 18
Joined: Fri Mar 13, 2009 11:16 pm

Re: Sinking feeling when leveling off on B757

Mon Jul 26, 2021 9:47 am

The early autopilots were quite assertive. During Flight level changes it was noticeable. Sinking feel climbing, especially after take off. Descending - weightless feeling. I remember the MD-80 was like a rollercoaster feeling as it started decent - Grab your armrests!
 
BowlingShoeDC9
Posts: 66
Joined: Fri Jun 26, 2020 5:18 am

Re: Sinking feeling when leveling off on B757

Mon Jul 26, 2021 12:49 pm

Aaron747 wrote:
convair880mfan wrote:
Back in the day when I used to fly on the Boeing 757 I often noticed a kind of sinking feeling in my stomach when the plane leveled off after takeoff.

I also experienced something similar on the Boeing 737-500 and Boeing 707-100. At liftoff I would get a sinking feeling and feel a little light headed and then again when those aircraft leveled off after takeoff.

Don't know much about aviation physiology. Perhaps someone could explain it to me. Thanks in advance.


You would feel it most in the front or rear cabins and least over the wings where the center of gravity is.


I’m pretty sure you would feel it least in the rear. When the plane is pitch up and starts to level off, the rotational acceleration will push the rear passengers more into the seat, partially counteracting the negative vertical acceleration of the plane as a whole. Wing seats, or more specifically seats above the CG, would only have the negative vertical acceleration due to change in vertical speed with little to no influence of the rotation of the plane. First class would have both accelerations working in the same direction. I’m more familiar with vehicle dynamics than flight dynamics so I could be missing something though.
 
User avatar
rjsampson
Posts: 498
Joined: Sat Jul 31, 2010 12:00 am

Re: Sinking feeling when leveling off on B757

Mon Jul 26, 2021 9:40 pm

As you specifically referenced the 757, those aircraft can climb like a homesick angel, compared to virtually any other jetliner on which you'll fly. I suspect this exacerbates the effects mentioned above, thus making the sinking feeling more pronounced..
 
Max Q
Posts: 9051
Joined: Wed May 09, 2001 12:40 pm

Re: Sinking feeling when leveling off on B757

Mon Jul 26, 2021 10:57 pm

Still, correct pilot technique with good anticipation should minimize this sensation no matter the level of performance, whether it’s a reduction in pitch at power reduction after take off or a level off

There is a way to do it smoothly
 
graceintheair
Posts: 55
Joined: Sun Jun 27, 2021 4:11 am

Re: Sinking feeling when leveling off on B757

Sun Aug 01, 2021 3:56 am

RR757 wrote:
The early autopilots were quite assertive. During Flight level changes it was noticeable. Sinking feel climbing, especially after take off. Descending - weightless feeling. I remember the MD-80 was like a rollercoaster feeling as it started decent - Grab your armrests!


And when thrust was decreased it almost felt like you were hitting a wall. It was pretty noticeable. It's been a long time since I was on a 717. I can't remember if it behaved the same.
 
Max Q
Posts: 9051
Joined: Wed May 09, 2001 12:40 pm

Re: Sinking feeling when leveling off on B757

Sun Aug 01, 2021 7:34 am

The MD80 autothrottles were crude and could be really rough with their inputs

You soon learned to restrain them, if you didn’t passengers would definitely notice !

Who is online

Users browsing this forum: convair880mfan, DH106 and 18 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos