XXXX10
Topic Author
Posts: 702
Joined: Mon Jan 03, 2000 7:10 am

Airspeed Fluctuations

Sun Dec 22, 2002 3:39 am

Can anyone help,

Does airspeed change when the head/tail winds change or is it just groundspeed that changes.

Could an aircraft find itself flying too fast or slow because of changes in wind speed?

many thanks
 
flyf15
Posts: 6633
Joined: Tue May 18, 1999 11:10 am

RE: Airspeed Fluctuations

Sun Dec 22, 2002 6:19 am

Very simple explaination is that it depends on how the change occurs. If an airplane is in a 20kt headwind which very quickly goes over to a 20kt tailwind, the airplane's airspeed will drop by 40kts while its ground speed will stay roughly the same. This is generally called windshear and can be very deadly. Now say the same change in wind speed happens, but very gradually over time. The airplane will maintain the same airspeed yet it will gain 40kts in ground speed.

Airplanes fly in relation to the air. They don't really care what the ground is doing while flying. Think of it as being in a stationary chunk of air with the ground having a speed (opposite in direction of the wind speed...its all about vantage point). That might help, or maybe really really confuse you.  Big thumbs up

On a side note, I'm friends with a private pilot who doesn't grasp the concept that air can have speeds, he thinks the airspeed indicator shows ground speed. *sigh*
 
fritzi
Posts: 2598
Joined: Sat Jun 30, 2001 2:34 am

RE: Airspeed Fluctuations

Sun Dec 22, 2002 6:36 am

On a side note, I'm friends with a private pilot who doesn't grasp the concept that air can have speeds, he thinks the airspeed indicator shows ground speed.

Who did your friend bribe to get his licence?

 
flyf15
Posts: 6633
Joined: Tue May 18, 1999 11:10 am

RE: Airspeed Fluctuations

Sun Dec 22, 2002 6:45 am

Fritzi, good question. It took him 3 tries to pass his checkride. His dad is a Continental pilot who I suppose has connections. You'd think having an airline pilot for a father would help, but he's not a very good pilot, actually an almost scary one.
 
JETPILOT
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

RE: Airspeed Fluctuations

Thu Jan 02, 2003 8:12 pm

Could an aircraft find itself flying too fast or slow because of changes in wind speed?

Windshear can be an extremely serious situation having catastrophic results.

To cite an example of the top of my head is the Delta L1011 that crashed across the highway at DFW after flying into a shear caused by a thunderstorm. The shear createded a situation where the planes airspeed had been low enough not to be able to further support flight and the L1011 simply fell out of the sky.

JET




 
AAR90
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: Airspeed Fluctuations

Fri Jan 03, 2003 12:57 am

>Could an aircraft find itself flying too fast or slow because of changes in wind speed?

In a word.... YES!

>Windshear can be an extremely serious situation having catastrophic results.
>
>To cite an example of the top of my head is the Delta L1011 that crashed across the
>highway at DFW after flying into a shear caused by a thunderstorm. The shear createded
>a situation where the planes airspeed had been low enough not to be able to further
>support flight and the L1011 simply fell out of the sky.

Not quite accurate. The plane had plenty of flying capability left, but the pilots were not trained in the proper technique to utilize that capability nor in recognizing when to utilize that technique. This was the "final straw" that forced FAA to _require_ windshear simulator training at Part-121 airlines. I've flown that exact scenario more than a dozen times in simulators and escaped every time (average at AA has been ~65% success rate). Probably because I got so d*** scared each time that I squeezed every ounce of performance the plane could provide. Probably burned up a couple of engines along the way as well.  Innocent
*NO CARRIER* -- A Naval Aviator's worst nightmare!

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