Fly-By vs. Fly-Over Waypoints: The Circle That Changes Everything, Turn Anticipation, and What Your GPS Is Doing
Updated: 2 days ago
With the widespread use of GPS and RNAV procedures, the way aircraft transition between route segments has changed. Instead of navigating to a VOR, crossing overhead, and then turning, modern avionics anticipate the turn — beginning it before the waypoint so the aircraft rolls out established on the next leg without overshooting. That’s the default behavior, and it’s what makes RNAV paths smooth and efficient. But some waypoints are designed so that you must cross directly over them before turning, because the airspace beyond is where the obstacle protection lives. The difference is marked on the chart by one small detail — a circle around the waypoint star — and knowing which type you’re approaching tells you what the airplane is about to do.
This post covers fly-by and fly-over waypoints in practical depth: what a waypoint is, the two types and their exact chart symbols, how turn anticipation works and a simple rule for when to expect it, where fly-over waypoints actually appear, what the avionics do after a fly-over, the leg types behind the behavior, RF legs, why the distinction exists (protected airspace), hand-flying technique, and the checkride questions.
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What a Waypoint Is
A waypoint is a defined geographical position used for navigation and procedure design.
Waypoints may be:
GPS-defined (a latitude/longitude with a five-letter name, e.g., “ZIPPY”)
Collocated with a ground-based navaid (a VOR or NDB that also serves as an RNAV waypoint)
Charted (named and published) or database-only (computed by the avionics for a procedure)
Part of an airway, a SID, a STAR, an approach, or a direct route
The question each waypoint answers:
Where is the point? (its coordinates)
How do I transition THROUGH it to the next leg? (fly-by or fly-over)
The second question is what this post is about
Same point, two different turn behaviors
Fly-By Waypoints
Definition:
A fly-by waypoint allows the aircraft to begin turning BEFORE reaching the waypoint, so it intercepts the next course smoothly without overshooting
The aircraft does NOT pass directly over the waypoint; it cuts the corner inside the turn
The default waypoint type in RNAV
“Fly by it, don’t fly over it”
Key characteristics:
Turn anticipation is expected and designed-in
The flight path is a smooth arc that blends the inbound and outbound legs
Reduces workload and eliminates the overshoot-and-correct of turning overhead
The protected airspace is designed around the anticipated turn (inside the corner)
How avionics handle a fly-by waypoint:
The GPS/FMS knows the course change at the waypoint (the angle between the inbound and outbound legs)
It figures the aircraft’s turn radius from current groundspeed and a nominal bank angle
It works out how far BEFORE the waypoint the turn must begin so the arc rolls out exactly on the next leg
It initiates the turn at that point (and annunciates it)
The aircraft flies the arc and rolls out established on the new course, never having crossed the waypoint itself
What this improves:
Passenger comfort (no abrupt turn and correction)
Fuel efficiency (shorter path)
Lateral path accuracy (you’re on the new leg at rollout)
Workload (the automation does the geometry)
Chart depiction:
A four-pointed star at the waypoint position — with no circle around it
The default; if you see a plain star, it’s fly-by
The name is printed next to it
The absence of a circle is the cue
Common uses:
En route RNAV routes (T-routes, Q-routes) and GPS direct routes
Most SID and STAR waypoints
Most approach waypoints: IAFs, intermediate fixes, and the FAF
Step-down fixes
The vast majority of waypoints you’ll fly
Fly-Over Waypoints
Definition:
A fly-over waypoint requires the aircraft to pass DIRECTLY OVER the waypoint before initiating the turn to the next leg
No turn anticipation
The turn begins only after the waypoint is crossed
“Fly over it, then turn”
Key characteristics:
Turn anticipation is NOT allowed
The aircraft crosses the waypoint on the inbound course, then turns
Ensures the aircraft reaches a precise location before changing course
The protected airspace is designed around the overfly and the turn that follows (beyond the waypoint)
Why fly-over waypoints exist:
Where turning early would carry the aircraft toward terrain or obstacles inside the corner
Where the procedure needs the aircraft at an exact point before the next leg begins (the start of a missed approach, the end of a runway)
Where a course reversal or specific maneuver must start at a known point
Where the next leg is defined relative to the waypoint itself (a “direct to” or heading leg from that point)
Chart depiction:
The four-pointed star ENCLOSED IN A CIRCLE
The circle is the distinguishing symbol
Same star as fly-by, plus the circle
Look for the circle — that’s the whole identification
Where fly-over waypoints actually appear:
The missed approach waypoint (MAWP) on RNAV approaches — typically at or near the runway threshold, designed fly-over so you don’t begin the missed-approach turn before reaching it
The first waypoint on some SIDs — often fly-over so the aircraft continues on runway heading past that point (and past the departure end of the runway) before turning, protecting the initial climb
Specific waypoints in terrain — where an early turn would be unsafe
Waypoints where the next leg is a heading or direct-to from that point — the leg geometry requires crossing it
What is NOT typically fly-over (correcting a common misconception):
Initial approach fixes — usually fly-by
Step-down fixes — fly-by
Intermediate fixes and the FAF — fly-by
Holding fixes — holding is handled separately (below); the fix itself is often fly-by
The holding case:
When a hold is loaded at a waypoint, the avionics fly the hold ENTRY by crossing the fix, regardless of whether the waypoint is charted fly-by or fly-over — the hold geometry requires it
So you’ll see the aircraft cross a fly-by waypoint when entering a hold there
Not a contradiction; the hold leg type overrides the normal transition
The avionics know the difference
Turn Anticipation: When the Turn Actually Starts
You don’t need to calculate anything in the cockpit — the avionics do it — but having a feel for how early the turn begins explains what you’re seeing on the display and lets you catch something that looks wrong.
The two things that set the turn radius:
Groundspeed — the faster you’re moving over the ground, the bigger the circle the airplane carves, and the earlier the turn has to start
Bank angle — a steeper bank tightens the turn; the avionics assume a modest, comfortable bank, so the radius is driven mostly by speed
The avionics watch GPS groundspeed continuously, so a tailwind pushes the turn point earlier and a headwind pulls it later
A simple rule of thumb for the radius:
At a standard-rate turn, the turn radius in nautical miles is roughly your groundspeed divided by 200
At 100 knots, about half a mile; at 120 knots, about 0.6 NM; at 180 knots, about a mile; at 250 knots, about a mile and a quarter
That’s a sanity-check figure — the avionics use their own bank-angle model, so the box’s number may differ a little
Good enough to know “about when” to expect the turn
How the size of the turn matters:
A 90-degree course change starts about one turn radius before the waypoint
A smaller course change (say 60 degrees) starts closer in — a bit more than half a radius out
A bigger course change (say 120 degrees) starts farther out — nearly two radii before the waypoint
Bigger turns start earlier; small heading changes barely anticipate at all
A worked example in plain terms:
You’re at 120 knots groundspeed approaching a fly-by waypoint with a 90-degree course change
Your turn radius is about 0.6 NM, so the GPS starts the turn about 0.6 NM before the waypoint
The arc passes about a quarter mile inside the corner from the waypoint — you never cross it
You roll out established on the new leg
A faster example:
A jet at 250 knots groundspeed with a 120-degree course change
The turn radius is about 1.25 NM, and because the turn is large, the anticipation starts more than 2 miles before the waypoint
That’s why a jet’s FMS turns “so early” at big course changes — and why the procedure designers protect that much airspace inside the corner
Why this matters:
Large course changes at high speed begin a LONG way before the waypoint
If you’re hand-flying and waiting to see the waypoint sequence, you’ll be late
The avionics’ early turn is correct, not a malfunction
Trust the anticipation (and know roughly when to expect it)
How the avionics tell you:
Garmin units annunciate a turn prompt (typically a countdown) and draw the turn anticipation arc — the curved path — on the map ahead of the waypoint
The autopilot (in GPSS/roll-steering mode) follows the arc
The CDI shows the deviation from the arc, not from the straight leg
Watch for the prompt; the turn is coming
What Happens After a Fly-Over Waypoint: The Rejoin
Crossing a fly-over waypoint on the inbound course means you’re not on the outbound leg yet — the avionics have to get you there.
The geometry:
You cross the waypoint still on the inbound heading
The outbound leg starts AT the waypoint on a different course
After crossing, the aircraft turns toward the new course — but because it didn’t anticipate, it crosses the waypoint and then arcs around to intercept the outbound leg from the outside
The path overshoots the outbound leg briefly and rejoins it
What the avionics do:
Compute a turn after the waypoint that intercepts the next leg
The intercept may require a larger turn (more than the course change) to come back to the leg, then a reverse roll to track it — a mild “S” shape
Or, if the next leg is “direct to” the following waypoint, the avionics simply turn direct from wherever the fly-over turn ends
The rejoin is automatic, but it takes more airspace than a fly-by
Why the protected area is bigger:
Procedure designers protect the airspace BEYOND a fly-over waypoint for this larger, later turn
That’s the trade: fly-over gives you an exact crossing point at the cost of a bigger turn afterward
Fly-by protects inside the corner; fly-over protects beyond the point
Different shapes of protected airspace
The missed-approach example:
You reach the MAWP (fly-over) at the DA/MDA and begin the missed approach
You continue straight ahead (climbing) past the waypoint
The missed approach’s first turn (if any) begins after the waypoint, usually at a specified altitude
The airspace beyond the runway is protected for exactly this climb-then-turn
The Leg Types Behind the Behavior (ARINC 424)
The fly-by/fly-over distinction interacts with how each leg is coded in the navigation database. A little of this vocabulary explains what you see.
TF — Track to Fix:
A great-circle track from one fix to the next
The normal en route and approach leg
At a fly-by waypoint, the avionics anticipate the turn to the next TF leg; at a fly-over, they cross and rejoin
DF — Direct to Fix:
A leg that goes direct to a fix from wherever the aircraft is (no defined starting point)
Commonly follows a fly-over waypoint: cross the waypoint, then “direct to” the next fix from there
The reason fly-over waypoints often don’t need an elaborate rejoin — the next leg starts from your position
CF — Course to Fix:
A specific course that leads to a fix (like intercepting a localizer-style course)
Used where the procedure needs you to intercept and track a defined course — some departure legs, some intermediate segments, and legs following a heading or vector
The aircraft must intercept and track that exact course to the fix
(The final approach segment on an RNAV approach is normally a TF leg, not CF)
Why pilots should know this (briefly):
When the GPS “turns early,” it’s anticipating a TF-to-TF transition at a fly-by waypoint
When it crosses a waypoint and then turns direct, it’s a fly-over followed by a DF leg
The behavior isn’t arbitrary; it’s coded
You don’t need to decode the database, but recognizing the pattern builds trust in the automation
RF Legs: The Third Concept
Some modern procedures replace the fly-by/fly-over turn entirely with a defined curved path.
What an RF leg is:
Radius-to-Fix: a constant-radius arc from one fix to the next, with a defined center and radius
The aircraft flies a precise curve, not an anticipated turn at a point
The path is the same for every aircraft that flies it
Precision curved guidance
How it differs:
Fly-by: the avionics compute a turn at a waypoint (the radius varies with your speed)
RF: the procedure DEFINES the arc (the radius is fixed by the design; you fly it at a speed that works)
The curve is part of the procedure, not a product of your groundspeed
Repeatable, protected curved paths
Where RF legs appear:
RNP AR approaches (marked “Authorization Required”)
Some non-AR RNP 1 SIDs and STARs, flagged with an “RF Required” note
Threading terrain, curving around noise-sensitive areas, or building repeatable curved paths where point-to-point turns aren’t precise enough
For the GA pilot:
Flying any RF leg requires RF-capable navigation equipment (check your unit’s capabilities and AFM supplement — many current WAAS navigators support RF legs; older units don’t)
RNP AR procedures additionally require specific operator authorization
If a procedure says “RF Required” and your unit can’t fly RF legs, you can’t fly that procedure
Know what your equipment supports before loading one
Why the Distinction Exists: Protected Airspace
The deeper reason, in one place.
Obstacle clearance is built around the expected path:
Procedure designers draw protected airspace around the path the aircraft is expected to fly
At a fly-by waypoint, the expected path cuts the corner, so the protection is inside the turn — and there’s less protection in the area beyond the waypoint
At a fly-over waypoint, the expected path crosses the waypoint and turns beyond it, so the protection extends past the point — and an early turn inside the corner may NOT be protected
Fly the type that’s charted, because the protection matches it
The failure modes:
Turning early at a fly-over waypoint: you may leave protected airspace inside the corner (terrain, obstacles)
Crossing and turning late at a fly-by waypoint: you overshoot the outbound leg and may leave protected airspace on the outside
Either error puts you where the designers didn’t plan for you
Match the behavior to the symbol
The automation-management point:
Modern avionics handle both correctly — IF the procedure is loaded from the database (not built by hand from waypoints)
A hand-built route of user waypoints will treat everything as fly-by
Load the published procedure so the fly-over coding comes with it
The database carries the distinction; a manual route doesn’t
Hand-Flying Technique
What to do when you’re flying the airplane rather than the autopilot.
At a fly-by waypoint:
Watch for the turn-anticipation prompt or arc on the display
Begin the turn when the avionics indicate — or, without a prompt, roughly one turn radius before the waypoint for a 90-degree change (closer in for a smaller change, farther out for a bigger one)
Use a standard-rate turn (the geometry assumes something close to it)
Roll out on the new course; the CDI should be centered on the new leg
Don’t wait for the waypoint to sequence — by then you’re late
At a fly-over waypoint:
Maintain the inbound course until the waypoint sequences (you’re over it)
Then turn toward the next leg at standard rate
Expect to overshoot the outbound course slightly and rejoin it from the outside
If the next leg is a heading or direct-to, just turn to it after crossing
Don’t anticipate — that’s the point
Cross-checking the automation:
Before each waypoint, know its type (from the chart) and what you expect the airplane to do
If the autopilot turns early at a circled waypoint, or waits at a plain one, something is wrong (a hand-built route, a database issue, the wrong procedure loaded)
Be ready to take it and fly the charted behavior
Expectation first, then observation
Why This Matters in IFR Flying
Obstacle clearance:
Fly-over waypoints ensure terrain clearance where early turns could be unsafe
Fly-by waypoints allow efficient navigation where the airspace permits
The chart tells you which; the protection depends on your compliance
Automation management:
You must understand what the GPS or FMS is commanding and why
Misunderstanding the waypoint type leads to early turns, late turns, lateral deviations, or overriding correct automation
“Why is it turning now?” should have an answer before the turn starts
Checkride and training:
Examiners ask: “Why did the airplane turn early here?” (fly-by anticipation) and “Why must you cross this fix before turning?” (fly-over, protected airspace)
Pointing to the circle on the chart and explaining the protected area is the complete answer
Systems knowledge, not rote memorization
Common Pilot Errors
Assuming all waypoints are fly-by (and anticipating a turn at a fly-over MAWP or departure waypoint)
Failing to recognize the circled star on the chart
Believing fly-by waypoints have “no symbol” (they’re a plain star; fly-over adds the circle)
Assuming IAFs, step-down fixes, or holding fixes are fly-over (they’re generally fly-by)
Building a route from user waypoints instead of loading the procedure (losing the fly-over coding)
Hand-flying a fly-by waypoint by waiting for it to sequence (turning late, overshooting)
Overriding correct turn anticipation because it “looks early” (it’s supposed to)
Confusing the hold-entry crossing of a fly-by waypoint with fly-over behavior
Loading a procedure with “RF Required” on equipment that can’t fly RF legs
Not briefing waypoint types before the procedure
Practical Tips
Brief every waypoint’s type during the procedure review: plain star = fly-by, circled star = fly-over
Expect the MAWP and the first SID waypoint to be fly-over; expect almost everything else to be fly-by
Load procedures from the database so the coding is correct
Watch for the turn-anticipation prompt and arc; trust it
Keep the rule of thumb in your pocket — turn radius is roughly groundspeed ÷ 200 NM — to sanity-check when the turn should begin
Cross-check the airplane’s behavior against the chart at every waypoint
Be ready to hand-fly the charted behavior if the automation does something unexpected
Checkride Questions — With Answers
“What’s the difference between a fly-by and a fly-over waypoint?”
A fly-by waypoint allows turn anticipation — the aircraft begins the turn before the waypoint and cuts the corner to roll out on the next leg without crossing the point. A fly-over waypoint requires crossing directly over the waypoint before turning. Fly-by is the default.
“How are they depicted on the chart?”
Both are four-pointed stars. A fly-by waypoint is the plain star; a fly-over waypoint is the star enclosed in a circle.
“Where do fly-over waypoints typically appear?”
The missed approach waypoint on RNAV approaches, the first waypoint on some SIDs (to protect the initial climb past the runway end), and specific waypoints where an early turn would conflict with terrain or where the next leg begins from that exact point.
“Why did the airplane start turning before the waypoint?”
It’s a fly-by waypoint and the avionics are anticipating the turn — figuring the turn radius from groundspeed and starting early so the arc rolls out on the next leg. At 120 knots with a 90-degree course change, that’s a bit over half a mile early.
“Why must you cross a fly-over waypoint before turning?”
Because the protected airspace is designed beyond the waypoint for a turn that begins after crossing it; turning early inside the corner may leave protected airspace. Common at the missed approach point and on departures.
“What happens when you hold at a fly-by waypoint?”
The avionics cross the fix to enter the hold regardless of waypoint type — the hold geometry requires it. The crossing isn’t a contradiction of the fly-by designation.
“What is an RF leg?”
A radius-to-fix leg: a defined constant-radius arc between fixes, replacing the anticipated turn with a precise curved path. Found on RNP AR approaches and some non-AR RNP SIDs/STARs marked “RF Required.” Requires RF-capable equipment; AR procedures also require authorization.
Final Thoughts
Fly-by and fly-over waypoints reflect the evolution of IFR navigation from ground-based fixes you had to overfly to precision RNAV paths designed around how the aircraft actually turns. Fly-by waypoints — the plain star — let the avionics anticipate the turn, cutting the corner by a radius that grows with groundspeed, to roll out smoothly on the next leg. Fly-over waypoints — the circled star — demand that you cross the point first, because the protected airspace lives beyond it: at the missed approach point, at the start of a departure, and wherever an early turn would be unsafe.
Understanding the difference lets you fly procedures accurately, anticipate aircraft behavior before it happens, manage automation with confidence, and stay within protected airspace. In modern IFR flying, knowing how you turn is just as important as knowing where you are.
On the Written Test and Checkride
Waypoint types appear on instrument writtens and orals. The most commonly tested topics:
The definitions (fly-by anticipates; fly-over crosses first)
The chart symbols (plain star vs. circled star)
Where fly-over waypoints appear (MAWP, some SID first waypoints, terrain)
Why the distinction exists (protected airspace)
Turn anticipation and why the GPS turns early
RF legs (RNP AR and “RF Required” procedures)
Quick Reference
Waypoint:
A defined geographic position (GPS-defined or collocated with a navaid)
Two transition types: fly-by (default) and fly-over
Fly-By (default):
Turn anticipation: begin the turn BEFORE the waypoint, cut the corner, roll out on the next leg
Never cross the point
Chart: plain four-pointed star (no circle)
Uses: en route RNAV, most SID/STAR waypoints, IAFs, intermediate fixes, the FAF, step-down fixes — almost everything
Protected airspace: inside the corner
Fly-Over:
NO anticipation: cross directly over the waypoint, THEN turn
Chart: four-pointed star ENCLOSED IN A CIRCLE
Uses: the missed approach waypoint (MAWP), the first waypoint on some SIDs (protects the climb past the runway end), terrain-critical waypoints, waypoints where the next leg is a heading/direct-to from that point
NOT typically: IAFs, step-down fixes, holding fixes
Protected airspace: beyond the point (for the later, larger turn)
Holding at a Waypoint:
The avionics cross the fix to enter the hold regardless of type
Not a contradiction of fly-by
Turn Anticipation (rule of thumb):
Turn radius at standard rate ≈ groundspeed ÷ 200 NM (a sanity-check figure — the avionics use their own bank model)
100 kt ≈ half a mile; 120 kt ≈ 0.6 NM; 180 kt ≈ a mile; 250 kt ≈ a mile and a quarter
A 90° turn starts about one radius before the waypoint; smaller turns start closer in, bigger turns start farther out
Uses GROUNDSPEED (wind moves the anticipation point)
Big turns at high speed begin a long way out — that’s normal
After a Fly-Over:
Cross on the inbound course, then turn
Overshoot the outbound leg slightly and rejoin from the outside (a mild “S”), or turn direct to the next fix if the next leg is DF
Takes more airspace — which is what’s protected
Leg Types (ARINC 424):
TF (Track to Fix): normal fix-to-fix leg; fly-by anticipation between TF legs
DF (Direct to Fix): direct from present position; often follows a fly-over
CF (Course to Fix): intercept and track a specific course to a fix (some departure and intermediate legs; RNAV final segments are normally TF)
RF Legs:
Radius-to-Fix: a DEFINED constant-radius arc between fixes
Appears on RNP AR approaches AND some non-AR RNP 1 SIDs/STARs (“RF Required”)
Requires RF-capable equipment; AR procedures also require authorization
Hand-Flying:
Fly-by: turn when the avionics prompt (or about one radius before the waypoint for a 90° change); standard rate; don’t wait for sequencing
Fly-over: hold the inbound course until the waypoint sequences, then turn; expect a slight overshoot and rejoin
Automation:
Load procedures from the database (hand-built user-waypoint routes lose the fly-over coding)
Watch for the turn-anticipation prompt/arc
Expectation first, observation second; be ready to fly the charted behavior
Key Principle:
A plain star is fly-by — the avionics anticipate the turn (radius roughly groundspeed ÷ 200 NM) and cut the corner, with protected airspace inside the turn. A circled star is fly-over — you cross the point first and turn after, with protected airspace beyond it; expect this at the missed approach waypoint and the first waypoint of some SIDs, not at IAFs or step-down fixes. Read the circle, load the procedure from the database, and know what the airplane is about to do before it does it.
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Author: Nathan Hodell
CFI, CFII, MEI, ATP, Creator and CEO
Nathan is an aviation enthusiast with thousands of hours of flying and dual instruction over the past 15+ years. Through his aviation career he has been able to earn his ATP, fly as an airline pilot, own/operate flight schools, and create and host wifiCFI.