Effect of Density Altitude on Crosswinds

RoscoeT said:
Wrong. Fly along straight and level and coordinated and then try to make the airplane move "laterally" (new flight path) without producing an intial turning (curving) flight path, slip or no slip. Cannot happen. Please post video. Have never seen this.
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Sorry, I'm all out of videos. And this thread. Fly safe.
 
I am thinking this thread might belong in the "Slip Zone". Admins? :)
 
FastEddieB said:
They do???

On a flight plan, maybe, but where else?
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If a pilot hears a controller say "say airspeed", the pilot must reply with what the ASI reads. If the controller says " say heading" , the pilot must comply with what his compass or DG indicates. There is no wiggle room or ambiguity in any of this. That is why everyone in the system has to use the same definitions.
 
vintage cessna said:
If a pilot hears a controller say "say airspeed", the pilot must reply with what the ASI reads. If the controller says " say heading" , the pilot must comply with what his compass or DG indicates. There is no wiggle room or ambiguity in any of this. That is why everyone in the system has to use the same definitions.
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The "wiggle room" is that if ATC asks for your heading, you must first check your (unslaved) DG against your (properly calibrated) compass and correct if off, and be sure you fly coordinated. Then you follow your (now corrected) DG.
 
MAKG1 said:
The air. You have a speed and direction (in three dimensions) within the air...
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Are you saying there is such a thing as "flight path through the air" referenced on air molecules? I'm not following you, the air is fluid and in motion, how can you define a path through it and what reference would you use to navigate?
 
Silvaire said:
Are you saying there is such a thing as "flight path through the air" referenced on air molecules? I'm not following you, the air is fluid and in motion, how can you define a path through it and what reference would you use to navigate?
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Your flight path through the air is your flight relative to the air mass surrounding your aircraft. Your direction through that airmass would be always pointed into the relative wind, if you fly coordinated.
Your TAS is measured relative to that airmass.
 
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vintage cessna said:
If a pilot hears a controller say "say airspeed", the pilot must reply with what the ASI reads.
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Of course.

A good reminder for new pilots is that many here flew for decades where the only way to know your TAS at any moment was to dig out your E6B. Or maybe if you had really good eyes and the right kind of airspeed indicator, you could dial temp opposite PA and read it there.
 
RotorDude said:
The "wiggle room" is that if ATC asks for your heading, you must first check your (unslaved) DG against your (properly calibrated) compass and correct if off, and be sure you fly coordinated. Then you follow your (now corrected) DG.
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Well, I've seen a lot of confusion on some peoples part by the ATC instruction " fly runway heading" . If one understands the definition of "heading" , there would be no confusion. But some people think ATC wants or expects the pilot to track to track the runway alignment. Yeah, and before you say it, I know ATC will be disappointed with the pilot if he side slips like some kind of crazy ape.
 
vintage cessna said:
Well, I've seen a lot of confusion on some peoples part by the ATC instruction " fly runway heading" . If one understands the definition of "heading" , there would be no confusion. But some people think ATC wants or expects the pilot to track to track the runway alignment. Yeah, and before you say it, I know ATC will be disappointed with the pilot if he side slips like some kind of crazy ape.
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Re "fly runway heading", you are right, if they use that phrase, after clearing obstructions you should turn to the runway numbers on your DG, which should be verified to match the compass (if unslaved), as always. Obviously any crosswind will drift you off, but ATC expects that.
 
RotorDude said:
Re "fly runway heading", you are right, if they use that phrase, after clearing obstructions you should turn to the runway numbers on your DG, which should be verified to match the compass (if unslaved), as always. Obviously any crosswind will drift you off, but ATC expects that.
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If a controller instructs you to fly runway heading, that means as soon as you are flying. If you feel you can't do that because of an obstruction, you need to reject the instruction and state why prior to departing.
 
I believe we've established that when told to maintain runway heading, they really want you to maintain runway track.

Pretty sure someone produced a source for that interpretation.
 
FastEddieB said:
I believe we've established that when told to maintain runway heading, they really want you to maintain runway track.

Pretty sure someone produced a source for that interpretation.
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See what I mean. They don't use the phraseology " maintain runway heading". The say "fly runway heading". If you just use what the FAA says is the definition of heading, you don't need to attempt to deduce what is meant. Of course, a certain level of airmanship is expected in flying the heading. If a controller is doing his job, anything he says has been clearly defined by the FAA so that a pilot would understand what it means.
 
FastEddieB said:
I believe we've established that when told to maintain runway heading, they really want you to maintain runway track.

Pretty sure someone produced a source for that interpretation.
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p. 2-35 of the Instrument Procedures Handbook (my bold):

Pilots cleared to “fly or maintain runway heading” are expected to fly or maintain the published heading that corresponds with the extended centerline of the departure runway (until otherwise instructed by ATC), and are not to apply drift correction
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The spin is epic.

Silvaire said:
If you enter a slip while keeping the nose on a constant heading are not now going to be moving laterally?
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You call it moving laterally, I call it turning...slipping turn, curving flight path. You can then stop the slipping turn and slip along a new flight, but you have TURNED to that new flight path via curing flight, not instantly jumped to a new "lateral" flight path as many seem to imply. If you hold the precise inputs that made you move "laterally" off your flight path, you will turn in circles until you stop it.

Silvaire said:
If you enter a slip while keeping your ground track constant are you turning?
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Of course not. I'd ask why this was so hard, but it would only make it harder.
 
FastEddieB said:
I believe we've established that when told to maintain runway heading, they really want you to maintain runway track.

Pretty sure someone produced a source for that interpretation.
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I'm not sure who established that but in reality, as you climb through possibly shifting air currents how do you maintain this "track" other than continually peer out the back window?

Heading is one and only one thing - what you see on your compass. Again, there is no alternate definition to that.
 
RoscoeT said:
...You call it moving laterally, I call it turning...
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Once again, if you are "turning" why does your heading remain constant? Hold that slip for 10 minutes, you are still on the same heading. Why do you want to call it a "turn"?
 
Silvaire said:
Hold that slip for 10 minutes, you are still on the same heading. Why do you want to call it a "turn"?
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Here's what you're missing - If you hold the exact inputs that caused that initial flight path change, that is a slipping turn that will continue in circles until you adjust your inputs. To keep your NEW "lateral" flight path constant, you must STOP the slipping turn before you've turned so far that you can no longer hold the nose on the original heading. All you've done is a slipping turn a few degrees to a new flight path, stopped the slipping turn, and then proceeded to slip along a constant new flight path with the nose still on your original heading. You have a limited angle at which you can turn onto a new flight path before your nose cannot stay on the original heading with a slip. For lots of airplanes, it might not be much more than 10 degrees. Depends on control surface effectiveness.

Think of the runway drill. Fly aligned and tracking the runway, and then angle your flight path in a 10 degree angle toward the runway. You could do that without changing your heading. You did it with a slipping turn though. Now try to make that "lateral" angle 70 degrees. You won't come close to keeping the nose on heading while changing your flight path to that degree.
 
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Silvaire said:
Once again, if you are "turning" why does your heading remain constant? Hold that slip for 10 minutes, you are still on the same heading. Why do you want to call it a "turn"?
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If you start in a coordinated flight down a straight road (zero wind), and start a bank, keeping the the nose on the road, you'll enter a slip, and drift off that road. If you keep your slip balanced (non-turning), you will start forward-slipping into a new straight course, away from the road. The slight change in direction, from down the road to the new course at some angle to it, is your turn. After that brief turn you'll be in a non-turning forward slip.
 
vintage cessna said:
See what I mean. They don't use the phraseology " maintain runway heading". The say "fly runway heading". If you just use what the FAA says is the definition of heading, you don't need to attempt to deduce what is meant. Of course, a certain level of airmanship is expected in flying the heading. If a controller is doing his job, anything he says has been clearly defined by the FAA so that a pilot would understand what it means.
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From the 2015 AIM.
RUNWAY HEADING− The magnetic direction that corresponds with the runway centerline extended, not the painted runway number. When cleared to “fly or maintain runway heading,” pilots are expected to fly or maintain the heading that corresponds with the extended centerline of the departure runway. Drift correction shall not be applied; e.g., Runway 4, actual magnetic heading of the runway centerline 044, fly 044.
 
Silvaire said:
I'm not sure who established that but in reality, as you climb through possibly shifting air currents how do you maintain this "track" other than continually peer out the back window?

Heading is one and only one thing - what you see on your compass. Again, there is no alternate definition to that.
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That's actually correct, if you use the compass itself (which you know is properly calibrated) and not an unslaved DG that's off. But ATC also expects heading to be your flight direction in coordinated flight, so if you slip you'd be confusing ATC, just like an error due to uncorrected DG drift or uncalibrated compass.
 
RotorDude said:
If you start in a coordinated flight down a straight road (zero wind), and start a bank, keeping the the nose on the road, you'll enter a slip, and drift off that road. If you keep your slip balanced (non-turning), you will start forward-slipping into a new straight course, away from the road. The slight change in direction, from down the road to the new course at some angle to it, is your turn. After that brief turn you'll be in a non-turning forward slip.
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You got it, and you must STOP that turn also...and you can't turn very far until you can no longer hold the nose on heading. Maybe only around 15 degrees in lots of airplanes. Very limited window. Again, try changing your flight path by 70 degrees in a slip and see if you can hold the nose on heading. Not.
 
Vance Breese said:
From the 2015 AIM.
RUNWAY HEADING− The magnetic direction that corresponds with the runway centerline extended, not the painted runway number. When cleared to “fly or maintain runway heading,” pilots are expected to fly or maintain the heading that corresponds with the extended centerline of the departure runway. Drift correction shall not be applied; e.g., Runway 4, actual magnetic heading of the runway centerline 044, fly 044.
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Guess I misremembered.

It is, in fact, what I always thought and taught, but I thought somewhere along the line I was corrected.
 
RoscoeT said:
You got it, and you must STOP that turn also...and you can't turn very far until you can no longer hold the nose on heading. Maybe only around 15 degrees in lots of airplanes. Very limited window. Again, try changing your flight path by 70 degrees in a slip and see if you can hold the nose on heading. Not.
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True.
 
RotorDude said:
True.
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I know you knew that- my comments weren't even directed toward you since you never had any issues on this subject. You are a winner of the comprehension award in this thread. :lol:
 
RotorDude said:
If you start in a coordinated flight down a straight road (zero wind), and start a bank, keeping the the nose on the road, you'll enter a slip, and drift off that road. If you keep your slip balanced (non-turning), you will start forward-slipping into a new straight course, away from the road. The slight change in direction, from down the road to the new course at some angle to it, is your turn. After that brief turn you'll be in a non-turning forward slip.
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So you're saying it's a turn because my track over the ground has changed? What about in straight and level flight as you fly through shifting and changing winds. With no intervention on your part your track over the ground will change. Are you going to call that a turn too? Because back before gps if you weren't flying along a VOR radial and there were sparse landmarks it might take you awhile to discover that you're now 3 miles off course.

I'm telling you that if you cross the aileron and elevator controls you are going to enter a slip. Now there is no force on Earth or in flight, there is no law of physics that says when you do that your nose has to shift off to the right or left or your heading must be altered so that your ground track doesn't change. You may purposely cause that to happen in a forward slip on final to lose altitude but you are manipulating the controls to make that happen.

Forget about the ground, you are not physically attached to the ground, you are flying in the air. With the controls crossed and heading constant you are in a slip, not a turn.
 
RoscoeT said:
... Again, try changing your flight path by 70 degrees in a slip and see if you can hold the nose on heading. Not.
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Again? Where did altering your course by 70 degrees come from? We are talking about a slip where the aircraft is flying through the air laterally in respect to the longitudinal axis. If you are doing a forward slip on final to lose altitude can you kick the nose off 70 degrees?

So what are you talking about?
 
Silvaire said:
Again? Where did altering your course by 70 degrees come from? We are talking about a slip where the aircraft is flying through the air laterally in respect to the longitudinal axis. If you are doing a forward slip on final to lose altitude can you kick the nose off 70 degrees?

So what are you talking about?
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It was an extreme example to make a point that is lost on you. Some get it, some don't. Such is life.
 
You tell us Roscoe. What physical law am I missing that says that the aircraft's ground track cannot be altered or that the heading cannot be held constant when applying the control inputs to enter a slip? Because if you don't turn the nose off the initial heading your ground track is not going to remain the same.

How about the opposite. You are on final in a crosswind, left aileron, right rudder, tracking the centerline of the runway. You are in a slip, correct? So neutralize the controls, nose still pointed down the runway. Isn't your ground track now going to change as the crosswind causes you to drift to the right of the runway?

What is it that you two aren't getting here? This is basic stuff.
 
Thousands of aviation youtube sensations and nobody can shoot a video of a proper sideslip it seems.
 
Silvaire said:
How about the opposite. You are on final in a crosswind, left aileron, right rudder, tracking the centerline of the runway. You are in a slip, correct? So neutralize the controls, nose still pointed down the runway. Isn't your ground track now going to change as the crosswind causes you to drift to the right of the runway?
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OMG, please send a video of you flying down final in a x-wind, slipped, tracking, and aligned with the runway and then NEUTRALIZE the controls. If you think that your nose will still point down the runway after neutralizing the controls, you are way beyond help here. You will continue to track the runway in a crab, but the nose will sure as hell not point "down the runway". Hint- this means the nose will swing left...which BTW is different from TURNING left.

BTW, this is the most comprehensible FALSE statement you've made in this whole thread. At least I understand where your failings stem from.
 
That's your answer?

When I was a kid my instructor had two basic coordination exercises that I practiced involving slips.

The first one was to slowly move the stick from neutral all the way to the left, back to neutral then all the way to the right while simultaneously applying opposite rudder to keep the compass heading constant. The result is a slip to the left and a slip to the right. No turning involved.

The second was the same only leading with the rudder, turning the nose off heading and using the ailerons to maintain my ground track over a straight road.

In both cases you end up with opposite aileron and rudder inputs so you tell me why one condition would be different from the other? They were both slips, the only difference being the ground track and, as I've said, there is nothing physically tethering you to the ground. I don't know why you guys seem to be hung up on that.

The other disarming thing about these discussions is that some of you are apparently incapable of grasping the concept without a YouTube video. :rolleyes:
 
Dude, stop the unintelligible jabbering and go take your Luscombe or whatever you fly (you are a pilot right??) and replicate these actions PRECISELY AS YOU DESCRIBED THEM, and I quote:

"You are on final in a crosswind, left aileron, right rudder, tracking the centerline of the runway. You are in a slip, correct? So neutralize the controls."

Neutralize simultaneously. No centering the ailerons first and skidding the nose to the right.

Now... I beg you, plead with you for the love of godamighty, tell us what the nose does.
 
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Maintain heading

Can you acknowledge that you can enter a slip without changing your heading which will result in a change to your ground track? Without turning?
 
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Silvaire said:
Now can you acknowledge that you can enter a slip without changing your heading which will result in a change to your ground track? Without turning?
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Nope. If you actually read carefully anything I wrote, you would see that I admit you can do a slipping turn to a very small flight path change (maybe 10-15 degrees) while keeping the nose aligned. Now please read the next sentence with as much care as you can muster:

But if you continue to hold the exact inputs that caused you to depart your flight path, that you would continue to turn, and your heading (nose) would show a change (continued turn) once you went beyond about 15 degrees from your original flight path and were no longer able to disguise the initial small turn with rudder. You would need to STOP the slipping turn before you reached this point. You are still turning, slipping or no slip. You will never understand this it seems. So...

Again, please stop babbling and just go do it. Anyone smart enough to get an airplane off the ground should be smart enough to take some video of what they are doing. Until that time, I guess you win because you say so...on the internet. Damn, we've gone in more circles than the Daytona 500. Though this has been more entertaining. I appreciate it.
 
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RoscoeT said:
...Again, please stop babbling and just go do it. Anyone smart enough to get an airplane off the ground should be smart enough to take some video of what they are doing. Until that time, I guess you win because you say so...
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Okay, that's all I wanted to hear LoL but apparently a video is the only thing that will convince you - so be it. I'll do that at my soonest opportunity.

Meanwhile at least I have Wikipedia on my side: :rolleyes: (I know...internet)

Sideslip
The sideslip also uses aileron and opposite rudder. In this case it is entered by lowering a wing and applying exactly enough opposite rudder so the airplane does not turn (maintaining the same heading), while maintaining safe airspeed with pitch or power.

In the sideslip condition, the airplane's longitudinal axis remains parallel to the original flightpath, but the airplane no longer flies straight along its original track. Now, the horizontal component of lift forces the airplane to move sideways toward the low wing.
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I have scoured youtube for videos of this mythical sideslip as described in this thread. It seems I'll have better luck looking for bigfoot in my backyard or the Loch Ness monster in the neighborhood swimming pool. Bueller, Bueller?? Nevermind- there's an entry on Wikipedia, last edited by Joe Bloe.
 
Other option is you could go up and do as described - cross controls without letting heading change - and show us how you'll go around in a circle. :dunno:
 
RoscoeT said:
You got it, and you must STOP that turn also...and you can't turn very far until you can no longer hold the nose on heading. Maybe only around 15 degrees in lots of airplanes. Very limited window. Again, try changing your flight path by 70 degrees in a slip and see if you can hold the nose on heading. Not.
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Why can't the heading be held? Do you have a source to reference that describes slips the way you do?
 
vintage cessna said:
Why can't the heading be held? Do you have a source to reference that describes slips the way you do?
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It can if you stop the slipping turn after a small flight path change and then continue on a straight slipping non-turning path. Crap, I keep writing as if people actually make an effort to READ. But as I posted in another thread, this is nothing but folks spinning comments attempting to prove others have no grasp of physics. Nothing more that can be done. It's been fun, but it's getting old. Keep spinning if y'all want. Ciao.
 
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