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Bruce
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Joined: Tue May 18, 1999 2:46 am

Question About Approaches

Wed Mar 08, 2000 3:17 am

Ok, when you turn on final you're lining up with the ILS (unless you're doing a visual) and that guides you straight in. But when I've watched planes land, sometimes they will kind of "zig-zag" on final. They'll go to the left of the runway, then execute another turn back, go a little to the right, then turn again. I saw it a couple months ago at HSV - an Atlas 747 heavy was approaching. Must have been at least 10 miles out. But it kept turning till maybe 4 or 5 miles then lined up straight with the runway. There was no other traffic. Why do they do that?

I've only seen it from the ground. I don't ever recall it happening when I was on a plane - all the approaches seem like they line up and go straight in for 7 - 10 miles.
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
 
mirage
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RE: Question About Approaches

Wed Mar 08, 2000 3:43 am

I'm not a pilot but a friend of mine who is, once told me that what you saw is called "to bake". It can be done to reduce speed or reduce altitude or to line up the plane as the pilot wants.

Luis, Faro, Portugal
 
Buff
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RE: Question About Approaches

Wed Mar 08, 2000 4:46 am

Additionally, even though you might not have seen traffic, perhaps there were airplanes taking off and extra time was needed by the Tower Controller. Or maybe it was a brand new pilot!

Best Regards,

Buff

PS Welcome back Luis!
 
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RE: Question About Approaches

Wed Mar 08, 2000 4:49 am

I think what you might have seen was called "side slipping" in which pilots correct for wind by keeping to the right (or left) of the runway every now and again and then let the wind blow them onto the centerline, using the rudder when about 300 ft above the ground

Tom
 
twa747100
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RE: Question About Approaches

Wed Mar 08, 2000 5:02 am

Maybe he was following a bird?   
 
Guest

RE: Question About Approaches

Wed Mar 08, 2000 5:05 am

This "S" turing is a technique used to increase spacing behind other aircraft or to increase total distance flown in order to lose additional altitude or airspeed if high or fast. Most of the time pilots will ask for "S" turns, but sometimes ATC will ask the pilot to do it so he/she can squeeze out another departure before you land.

Bill
 
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Bruce
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Joined: Tue May 18, 1999 2:46 am

The S Turn

Wed Mar 08, 2000 5:28 am

That might explain some of the turns at busier airports like MIA but the Atlas 747 I watched was approaching 18L at HSV and there was no departing traffic and no other arrivals on 18L or 18R.

Maybe he was correcting for wind....as someone mentioned
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
 
Ralgha
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Joined: Tue Nov 09, 1999 6:20 pm

RE: BY285A

Wed Mar 08, 2000 7:40 am

Actually, in a sideslip the airplane is always lined up with the runway. The pilot banks into the wind and uses opposite rudder to keep the longitudinal axis of the airplane parallel to the runway. It is called a sideslip because the airplane is flying sideways with respect to the runway, however, the wind is continually pushing back on the airplane and keeping it lined up with the runway. The airplane is flying sideways through the air and straight over the ground.

The other form of slip is the forward slip which is used to lose altitude quickly, usually on approach to land. The pilot shoves in full (or nearly full depending on the airplane) rudder to one side, then uses the ailerons to keep the airplane lined up with the runway. Again, the airplane is uncoordinated, flying sideways through the air, but straight across the ground.

This is a hard concept for many non-pilots to grasp and many student pilots have difficulty understanding the difference between motion with respect to the airmass and the ground.

Just to spit out another thing and maybe touch off a debate among the pilots, the downwind turn is no more dangerous than any other turn in the traffic pattern, even when the wind is high 
09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
 
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RE: The S Turn

Wed Mar 08, 2000 7:43 am

Bruce...

Not to beat a dead horse here but, "s" turns are a fairly common manuever. Don't know what caused it with the Atlas jet but the list is long and I'm sure they had good reason. Anything from wind changes, high/fast approach, spacing with other aircraft, flying pilot being new to the equipment, or something you couldn't see such as a airport vehicle on the far end of the rwyway missing an intended taxiway turnoff. As you can see there are many reasons for S turns and they're more fuel efficient then having to go-around. I've lost count on how many times I've S turned for one reason or another.
 
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Bruce
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Joined: Tue May 18, 1999 2:46 am

Side - Slipping

Wed Mar 08, 2000 4:41 pm

I have actually witnessed this from the ground. I've seen planes on final that did not look like they were lined up at all, coming straight in at me!! Once I got a little worried because it was coming right at me...not the runway!! But they sure were lined up....right on centerline
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens

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