A flashing yellow arrow (FYA) is the permissive left-turn display in a separate left-turn signal face — it replaced the circular green ball as the “turn when clear” message. One four-section head (or a three-section head with a bimodal section) can run protected, permissive, or both, and can change modes by time of day.
What it means to drivers
Quote
“Vehicular traffic, on an approach to an intersection, facing a flashing YELLOW ARROW signal indication, displayed alone or in combination with another signal indication, is permitted to cautiously enter the intersection only to make the movement indicated by such arrow…” — and it shall yield to pedestrians in the crosswalk and oncoming traffic. (Sec. 4A.04, 11th Ed., Dec 2023)
So: FYA = yield, then go. Green arrow = protected, opposing traffic stopped. Steady yellow arrow = your movement is ending.
Why agencies dumped the doghouse
The 5-section “doghouse” showed permissive lefts a circular green — the same ball the through lanes see. Two problems:
- Comprehension. Drivers read the green ball as “I have the right of way.” NCHRP driver-comprehension research behind the FYA found the flashing arrow communicated “yield” far better.
- Display lock-in. A doghouse shares the circular indications with the adjacent through face, so the left can never show something different from the through — which forbids lead-lag phasing (see the trap below) and time-of-day mode changes. Section 4F.08 explicitly permits the FYA to keep flashing while the adjacent through shows red and the opposing left runs its green arrow. That independence is the whole point.
Retrofits are cheap in concept: same 4-section face runs protected-only, protected/permissive, or permissive-only without rewiring displays.
The left-turn trap (“yellow trap”), concretely
Example
Lead-lag phasing with doghouses: NB left leads, SB left lags. You’re NB, waiting to turn left on the permissive circular green. Your through signal turns yellow. You assume opposing SB traffic sees yellow too, so you commit the turn on the tail of yellow — but SB through is still green (it stays green through the SB lagging left). You turn across live opposing traffic. That’s the trap: your yellow falsely implies their yellow.
With FYA, your left face just keeps flashing yellow while your through goes yellow-then-red. No false “all clear” cue — you keep yielding. This is why FYA unlocked lead-lag phasing for coordination.
Time-of-day operation
Section 4F.02 defines four left-turn modes: permissive only, protected only, protected/permissive, and variable — the mode changes by time of day or by traffic conditions. Typical Florida arterial pattern: protected-only during peaks (heavy opposing volume = no usable gaps, so the FYA is suppressed and the head runs arrow-yellow-red only), protected/permissive midday and nights. The controller’s TOD plans drive it — check the phasing notes on the timing sheet, not just the head on the pole.
Warning
Whether a left may run permissive at all is an engineering call — opposing speed and volume, number of opposing lanes, sight distance, crash history, dual-left geometry. Agencies (FDOT districts, counties) have their own PPLT screening criteria; never set or review the mode from remembered thresholds. And never assume the mode you saw at 2 pm is the mode at 5 pm.
Where the MUTCD governs it
Chapter 4F (Steady Stop-and-Go Operation), 11th Edition: 4F.02 modes and general rules, 4F.04 permissive-only in a separate face (three-section red arrow / steady yellow arrow / FYA), 4F.07 shared-face PPLT, 4F.08 protected/permissive in a separate face (four-section, or three-section with bimodal FYA/green-arrow section). Meanings live in 4A.04; a flashing red arrow variant exists for offset lefts where every vehicle must stop first (4F.04/4F.08). Section numbers are from the Dec 2023 11th Edition #status/verify against Revision 1 (Dec 2025).
Tip
Free Part 4 PDF on the MUTCD 11th Edition page (link above). FHWA also publishes FYA outreach materials (driver-education one-pagers) you can crib for public meeting exhibits.
See also: Clearance Intervals and Ped Timing · How to Read a Signal Timing Sheet · Signal Warrants (MUTCD Ch 4C)