'Report 4 mile base for runway two five left' - meaning?

eman1200 said:
no you won't.
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According to those that say "the GPS says 4" and since the base leg can be anywhere from 1/4 mile off the end of the runway, to 4 miles off the end of the runway. That's anywhere on the red arc.
 
I had this happen two weekends ago and I have witnesses, one of which is in this thread. We were landing at Ryan airport and the controller told me to report a three mile base. I estimated what I thought was three miles out (since I didn't have Foreflight or anything powered up except my eyeballs) right before I needed to turn final and reported a three mile base. The controller promptly cleared me to land runway 6 left. I turned and lined up on final. So what I'm saying is that the controller at Ryan and I have the same definition of a three mile base.
 
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Timbeck2 said:
I had this happen two weekends ago and I have witnesses one of which is in this thread. We were landing at Ryan airport and the controller told me to report a three mile base. I estimated what I thought was three miles out (since I didn't have Foreflight or anything powered up except my eyeballs) right before I needed to turn final and reported a three mile base. The controller promptly cleared me to land runway 6 left. I turned base and lined up on final. So what I'm saying is that the controller at Ryan and I have the same definition of a three mile base.
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For me all legs are 1/2 mile offset at most. Downwind is 1/2 mile offset from the centerline. Base is offset 1/2 mile from end of runway. So for me, if I hear 4 mile base I'm going to be flying a base leg that's 4 miles long, and will be on 1/2 mile final when I make the turn.
 
Did he want your left leg or your right leg 4 miles from base. That could seriously impact your position report.

Of course, if your'e expecting Left Final it makes it more easier.

Seriously though. You're probably supposed to enter base however you'd like and report 4 mi from the airport, as a crow flies.
 
I see what you're saying Fred but how many times have we had to follow some yahoo flying a bomber pattern. Everyone's "offset" differs. Controller's expectations obviously differ and I can't speak for anyone but me.
 
‘Round here our controllers would want you on a perpendicular line to the runway heading, 4 miles out from the approach end.

In other words they want you no closer than 4 miles to the approach end of the runway with a squared off pattern.

No angling in, no circles, just four miles away so they can see if you’ll fit into the landing sequence by looking and seeing your sideways relative motion, easier than trying to pick you out head-on on a 4 mile final.*

*Assuming you don’t have landing lights that will light up the Sun. And I’ve noticed if you have decent LED or better lights and you angle toward the tower directly BEFORE you get to four miles, they’ll see ya, and you’ll have an instant landing clearance or traffic to follow called out.

They’re just trying to spot you out there, ‘round here anyway. Eyeballs see relative motion so they ask for the base so you have some from their vantage point.

They have radar/repeater/whatever off of DEN TRACON. I’ve noticed when it’s busy the better controllers don’t look at it. They tell the airplanes to do things that make the airplanes visible to them and the work the sequence looking out the window.
 
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Timbeck2 said:
I see what you're saying Fred but how many times have we had to follow some yahoo flying a bomber pattern. Everyone's "offset" differs. Controller's expectations obviously differ and I can't speak for anyone but me.
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Which is why the instruction is so ambigious, there is no standard answer! I can see both your way, and my way being "standard". With my way being a little bit more so. :D :D
 
denverpilot said:
‘Round here our controllers would want you on a perpendicular line to the runway heading, 4 miles out from the approach end.

In other words they want you no closer than 4 miles to the approach end of the runway with a squared off pattern.

No angling in, no circles, just four miles away so they can see if you’ll fit into the landing sequence by looking and seeing your sideways relative motion, easier than trying to pick you out head-on on a 4 mike final.*

*Assuming you don’t have landing lights that will light up the Sun. And I’ve noticed if you have decent LED or better lights and you angle toward the tower directly BEFORE you get to four miles, they’ll see ya, and you’ll have an instant landing clearance or traffic to follow called out.

They’re just trying to spot you out there, ‘round here anyway. Eyeballs see relative motion so they ask for the base so you have some from their vantage point.

They have radar/repeater/whatever off of DEN TRACON. I’ve noticed when it’s busy the better controllers don’t look at it. They tell the airplanes to do things that make the airplanes visible to them and the work the sequence looking out the window.
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So here's the ambiguous thing Nate, at what point on that perpendicular line do you report "four mile base"? What you describe is what I want as well but the reporting point seems to be an issue which is why I report four mile (or three mile as described above) just before turning on final because I anticipate getting cleared to land after I report a four mile base.
 
EdFred said:
So.....this?

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The GPS reference point for the airport is whatever the LAT/LON listed for the airport is, which is somewhere in the middle. Your GPS doesn't know how to tell you how far it is to the end of the runway.

The reference is usually halfway down the runway at an airport with a single runway, but somewhere in the middle of the complex if there are multiple runways. It's further complicated by the fact that runways are lengthened, shortened, added, or removed, and the reference point probably doesn't get changed.

Take a look at KSCH. We are frequently told to report a 2 mile left base for 22 when approaching from the E or NE. That runway is 7000' long and the reference point is more than halfway along the runway, probably about 4000' from the approach end of 22. I've never been sure what a 2 mile left base means exactly, but I know that if my GPS reads 2 then I'm a lot closer than 2 miles from the end of the runway.

ksch.jpg
 
If I were landing runway 22, my reporting point for a (lets be realistic because I don't have a scale) 2 mile base would be the word "middle" in his first sentence. Considering left traffic of course.
 
Timbeck2 said:
So here's the ambiguous thing Nate, at what point on that perpendicular line do you report "four mile base"? What you describe is what I want as well but the reporting point seems to be an issue which is why I report four mile (or three mile as described above) just before turning on final because I anticipate getting cleared to land after I report a four mile base.
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Around here they don’t seem to care where you enter that base leg, as long as you’re four miles away from the end of the runway, when you do it.

Like others have said, even controllers here, they disagree with the phraseology and where they’d expect the airplane to be.

Common sense seems to indicate if a controller is using miles as a measure, someone calculating the distance of the total ground covered by the base who ends up 1/2 mile from the runway, would probably surprise the controller a bit. If they said four miles, they’re much more likely to be looking for someone four miles out than for someone in essentially a standard pattern.

Standard pattern usually isn’t going to cause any real heartburn for most controllers though. It’s what you’d be doing at an uncontrolled field to give the best chance of seeing other aircraft, and the only oddity would be that you’re entering on the base leg, so watch out for airplanes coming along the downwind leg... that’s most likely where your traffic is going to be, as well as ahead coming in on a long final, at a controlled field.

Usually when they give us similar instructions here, what they’re doing is putting us outside the normal pattern to see if we fit in with someone doing laps, who SHOULDN’T be extending their downwind out to the four mile away point*, so we end up “side by side”, them on a closer in base than us. And then it’s “follow the Cessna off to your left, you’re number two, cleared to land behind that Cessna”.

* we have at least one well known national school here who loves to have pilot’s turning base miles off the end of the runway for whatever damn reason, and they’ll go out there so far the tower will cancel their landing clearance and then turn the aircraft behind them in the downwind in for a landing before them, otherwise the pattern will be ten miles out in no time. :)
 
Eric Gleason said:
The GPS reference point for the airport is whatever the LAT/LON listed for the airport is, which is somewhere in the middle. Your GPS doesn't know how to tell you how far it is to the end of the runway.
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EdFred said:
Maybe I have RWY27 as my way point and not the airport.
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Many people don’t realize there’s often waypoints for the approach end of the runways in their GPS until they’ve started Instrument training. :)

Makes GPS substitution easier when you use the right waypoint for substitutions of GPS for DME on an ILS, for example.

But a LOT of people don’t know that and either do it the hard way, or haven’t even been made aware of the fact that there are often waypoints just for that. :)
 
Maybe the best thing is just ask each controller that gives you an instruction like that and say "do you want me to end up on a 4-mile final or do you want me to end up on 1/2 mile final and fly a 4-mile long base leg?"
 
EdFred said:
Maybe the best thing is just ask each controller that gives you an instruction like that and say "do you want me to end up on a 4-mile final or do you want me to end up on 1/2 mile final and fly a 4-mile long base leg?"
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Exactly!!

Clarify

But you don't have to ask me. I expect you on a 4 mile final because if you call base (at any distance), just like in a normal pattern, I'm going to clear you to land.
 
EdFred said:
Maybe the best thing is just ask each controller that gives you an instruction like that and say "do you want me to end up on a 4-mile final or do you want me to end up on 1/2 mile final and fly a 4-mile long base leg?"
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Yup. This.

They’ll figure out better ways to ask for it if enough pilots are confused by ambiguous stuff. :)

The good ones around here do the “are you familiar with [landmark]?” thing.

If they get an “Affirmative” back or recognize voices and tail numbers they’ll say, “Report over [landmark] FOR a four mile left base, runway Y”.

For us, “the power lines” is a commonly used one, they’re on the ridge line south of the airport. Massive high tension lines and wires. Easy to spot.

“Your traffic is over the power lines on a straight in for runway 35R, do you have them in sight?”

Others are “Parker Road”, “Lincoln Avenue”, Arapahoe Road, etc.... all major roads and easy to see and plunk yourself right over the top of them. But non-locals don’t know them.

Then it changes to larger landmarks... “The large reservoir north of the airport” ... “Your traffic is over the shoreline of Cherry Creek Reservoir, you’re number two behind that traffic.”

The only thing I RARELY see controllers do is use the landmarks pointed out with flags by the VFR charts. The so called “VFR reporting points”

*I* have used them when navigating to a new airport to me or if a controller is trying to help me find something local I don’t know about, “I can see the X landmark (whatever the chart calls it), would that work for you?” And that works VERY well.

But I can only think of one time a controller used a landmark that was marked and named on the chart. That one was the 1500’ multiple radio towers just a few miles off of their runway on a hill.

“Do you see the radio towers at eleven to twelve o’clock? Make your base inside those towers for runway X.” Worked FABULOUS that that airport I had never been to.

Same thing with various other things, the “checkerboard water tower”, stuff like that. All those big visibility things work great.

But it’s quite rare to hear the VFR reporting points used. I don’t know why. I doubt controllers look much at VFR charts if they aren’t pilots, but I don’t know for sure.
 
Why do there have to be two mutually exclusive options? It can be both...e.g. report at the X.

Screen Shot 2018-07-27 at 1.11.44 AM.png
 
Timbeck2 said:
Ah yes, the eight mile to fly option which I really don't think a controller intends to happen. At X, how do you know that you're 4 miles from the extended center line?
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Around here on initial call up if you’re at the edge of the Delta, that’s pretty much what they’re expecting, honestly.

But like you said, where along the line do they want the report?

I usually split the difference and do it about two miles along that line.

I suspect that here, when given that instruction people fly all sorts of varied stuff and the controller is just happy they’re on a base somewhere out there. Haha.

I could ask a couple of our controllers and I bet I get two different answers. Ha.

And asking the tower chief would probably just start some strange new standardization that won’t make any sense to anyone. LOL.
 
If the dimensions of Class D airspace is a 4nm radius from the center airport, a base 4 miles from the end of the runway would place the aircraft outside the Class D.
 
Well I’m gonna keep doing what I was doing :)
 
dmspilot said:
Why do there have to be two mutually exclusive options? It can be both...e.g. report at the X.

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This is what I would expect a pilot to fly, the base leg portion of this drawing. Not the 4 mile final portion though, just a normal final leg.

Let's say this runway is E-W and the drawing is for runway 27. So IMO you'd be arriving from the south so I would say report a 4 mile base. I could say it as report 4 miles south for a base leg runway 27 too.

How does one measure 4 miles though. You know what, who cares. GPS, eyeball, pull it outa yo arse, not that critical. I certainly wouldn't expect you to report a 4 mile final, or I would have instructed you to report a 4 mile final if I wanted that.

So there. :D
 
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Why would you not fly direct to where you would be on base if you were in the pattern and on the same heading as the base leg. Report 4 miles from that point. Otherwise, you'd be flying a 4 mile base and then a 4 mile final. In which case, I would expect the tower to ask you to report a 4 mile final, which would be 4 miles out on the runway centerline.
 
Timbeck2 said:
Prior to the top of the red arc is what I would expect. You gotta say it early otherwise you blow through final. The lower part of the arc could be considered the downwind.
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So...if you were 8 miles to the SE of the nice blue picture, where would you go? To the bottom of the arc, so you're entering the arc 4 miles away on base?

I solve this by planning my flights for a straight in.
 
I agree with Tim in that the controller is expecting a 4 mile intercept from the approach end. I wouldn’t use that phraseology though. “Cessna 345, enter left base runway 25L, report 4 mile final” would be more appropriate.

One way to look at it, is if tower issues traffic. If they say “Mooney 321, traffic is a Cessna on a 4 mile left base for runway 25L” I’m looking for someone intercepting 4 miles down the runway and not someone 4 miles away from centerline but on a normal distance off the end of the runway. That’s my interpretation of it.
 
bflynn said:
So...if you were 8 miles to the SE of the nice blue picture, where would you go? To the bottom of the arc, so you're entering the arc 4 miles away on base?

I solve this by planning my flights for a straight in.
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Hey man, I didn't have anything to do with no arc. I didn't draw it, suggest it or expect it. ;)
 
You guys overthink things to an unbelievable degree. Maybe one of you should write a PhD thesis on this topic.
 
eman1200 said:
huh? your final turn should be onto final, from a base leg that you have flown on for at least 4 miles (or at least reported, as asked, on the base leg 4 miles out. you still have to turn final.
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Serious overthought!
 
There is no official interpretation. As Timbeck2 says, it depends on the controller. In many cases the folks in the tower cab cannot pick you up on the base leg visually because of terrain/obstructions so the "Report xxx" provides a clue as to where to point the binoculars.

Bob
 
This is a classic case of reading too much into an instruction. The tower is giving you two separate instructions. One is to report when you are four miles out. (Although there is room for debate, I would just wait until my GPS reads 4 miles.) Second, expect to enter the pattern on the base leg.

So, I would fly toward the point at which one would make the turn from downwind to base, if flying a normal pattern, report when I was 4 miles out, and enter the pattern at the aforementioned point. Easy-peasy.
 
Rykymus said:
This is a classic case of reading too much into an instruction. The tower is giving you two separate instructions. One is to report when you are four miles out. (Although there is room for debate, I would just wait until my GPS reads 4 miles.) Second, expect to enter the pattern on the base leg.

So, I would fly toward the point at which one would make the turn from downwind to base, if flying a normal pattern, report when I was 4 miles out, and enter the pattern at the aforementioned point. Easy-peasy.
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Yup. As a controller this is what I'd expect you to do. :thumbsup:
 
Rykymus said:
This is a classic case of reading too much into an instruction. The tower is giving you two separate instructions. One is to report when you are four miles out. (Although there is room for debate, I would just wait until my GPS reads 4 miles.) Second, expect to enter the pattern on the base leg.

So, I would fly toward the point at which one would make the turn from downwind to base, if flying a normal pattern, report when I was 4 miles out, and enter the pattern at the aforementioned point. Easy-peasy.
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What if you received the instruction to “enter a 4 mile left base.”?
 
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