A question to Pilots and Airport Personnel

I'm not into aircraft or weapons, but I have a curiosity about passenger jets. I work by the Orange county airport (John Wayne), and there is a lnoise reduction law that requires pilots to reduce their jet's power for a couple of minutes after take off to reduce noise. I watch several take offs a day, and see planes taking off at different angles. Some as much as 45 degrees (or so it looks), and some at as little as 15 degrees. Is there a standard takeoff angle? And, given the law here, is it required that take offs be steeper to be able to cut power as required?

Just curious and I want to learn.....

Originally posted by sexymon
I'm not into aircraft or weapons, but I have a curiosity about passenger jets. I work by the Orange county airport (John Wayne), and there is a lnoise reduction law that requires pilots to reduce their jet's power for a couple of minutes after take off to reduce noise. I watch several take offs a day, and see planes taking off at different angles. Some as much as 45 degrees (or so it looks), and some at as little as 15 degrees. Is there a standard takeoff angle? And, given the law here, is it required that take offs be steeper to be able to cut power as required?

Just curious and I want to learn.....

There are noise abatement procedeures at most large airports that involve both reducing power right after takeoff and climbing at steep angles to get the aircraft higher over certain areas to reduce the noise. Some morons thought that it would be great to build next to an airport and then they have the nerve to complain about noise.

I agree with you JIM. And to your question about the angles when they take off. I have a simple answear. Sometimes the planes lift in different angles, but usually it is jsut your eyes that think that they are doing so. When a plane travels a longer distance, it can sometimes look like the planewould rise in 80 degrees angle. This has to do with the globe spinning...





I'am with you on this JIM, poeples should stop complaining...

Certain planes have what's known as a higher thrust to weight ratio, so they can climb at a steeper angle, for noise abatement rules. Basically what this means is that they have more thrust from their engines, and a lower weight. Planes like the Boeing 777 have 125,000 pounds of thrust from their two engines, so they can climb faster, whereas older planes have less thrust, and more weight, so they have to climb out at a shallower angle, and use other noise abatement procedures.

Originally posted by Figher Master FIN
I agree with you JIM. And to your question about the angles when they take off. I have a simple answear. Sometimes the planes lift in different angles, but usually it is jsut your eyes that think that they are doing so. When a plane travels a longer distance, it can sometimes look like the planewould rise in 80 degrees angle. This has to do with the globe spinning...

It's not an illusion. Some of them really are climbing at steeper angles than others. The MD-11 that FedEx flies is capable of running out of room, before hitting the max gross weight for take off, so it has plenty of power to spare on take off, so it can climb steeper to get above noise abatement altitudes. The 747-400 climbs at about 15-20 degrees or so, older 747s at 10-12 or so.

Originally posted by sexymon
Is there a standard takeoff angle? And, given the law here, is it required that take offs be steeper to be able to cut power as required?

Just curious and I want to learn.....

No, but there is a minimum take-off angle to clear the screen height.

I don't think the take-offs have to be steeper to enable cutback procedures, but to be honest I'm not completely sure on that, it would be sensible to assume cutback can only happen above a certain altitude, I guess the climb angle needed would be dependant on the distance from the airport runway to the population centre.

Originally posted by Zaphod58

It's not an illusion. Some of them really are climbing at steeper angles than others. The MD-11 that FedEx flies is capable of running out of room, before hitting the max gross weight for take off, so it has plenty of power to spare on take off, so it can climb steeper to get above noise abatement altitudes. The 747-400 climbs at about 15-20 degrees or so, older 747s at 10-12 or so.

In some cases you are right, but there are some "illusions" too... Isn't this an illusion in your opinion...??

CLICK HERE


[edit on 11-1-2006 by Figher Master FIN]

No such thing as a standard takeoff angle.


What you're seeing is pitch attitude which controls the speed of the aircraft.

Aircraft have a lot of different speeds for different things.
They're called V speeds and looking at a check list for a Cessna 150C shows nine different V speeds and another called Best Glide.

Best Glide meaning longest distance for least altitude loss.
Drag enters into it so you can't go too slow or too fast to attain the longest distance.
Flying, even simple airplanes like the C-150 requires more precision than non-pilots realize.
Best glide for the C-150 is 54 mph.
Faster or slower means a loss in glide distance.


On takeoff, simple aircraft like the C-150 have two speeds.

One called Vx for best angle of climb speed - used to get over an obstruction like tall trees etc.

The other is Vy for best rate of climb speed.

The C-150's sea level Vx is 51 mph.
Vy at sea level is 71 mph.
Higher altitudes require higher speeds. (Shown in the pilots handbook, but an example is Vx = 58 mph at 10,000'.)

Looking at it another way,

Vx is most altitude gained for shortest distance.
Vy is most altitude gained in the shortest time.

Pilots use pitch attitude to control airspeed.
Done so because the engine is wide open during climbout.
You can alter airspeed by pulling the throttle back, but it's seldom done.
Pitch attitude is how you control the plane's speed on climbout.

Small airplanes like the C-150 use the airspeed indicator to control pitch attitude.
Nose up will slow the plane down.
Nose down will speed the plane up.

Big aircraft like the 747's et al use a pitch attitude indicator on climbout and other times, but more than likely the pilots are taking note of the airspeed indicator when they visually sweep the instrument panel.

When the big aircraft depart an airport they have the thrust available to have an overly steep pitch attitude which gains altitude rapidly, but at the same time the airspeed is bleeding off and when airspeed gets to a certain point the pilot will nose the aircraft over to about level or in a very mild climb and retard the throttles for noise abatement.
It goes without saying the pilot is very conscious about maintaining airspeed considerably above stall level.

Low altitude stalls are very dangerous in any aircraft and stalling a big plane at the low altitudes where they roll over to level flight and throttle back usually spells doom for the airplane and all aboard.

Stalls are generally known as the point at which the wing no longer flies.

Stalls happen when most wings get close to a 16 degree angle above the oncoming air - in other words at a high angle of attack - and the attached air becomes turbulent, detaches and lift is lost.

(The V speeds etc. quoted for the C-150 are in MPH due to the airspeed indicator is marked in MPH. Later Cessna trainers like the C152 have their airspeed indicators marked in knots and the check list reflects that.)

(Edited for spelling.)

[edit on 11-1-2006 by Desert Dawg]

[edit on 11-1-2006 by Desert Dawg]

somebody needs to give desert dawg an applause. aside from a flight instructor (which he very well may be), that's the best explanation i have seen. in fact, it's better than the one i was composing in my head as i read through the posts.

[edit on 11-1-2006 by snafu7700]

thatnk you all, I have learned a lot here! Especially Desert Dawg.......a crash (wrong word!) course in flight dynamics.