What is the minimum aircraft separation on final approach?
Minimum aircraft separation on final approach explained: when 2.5, 3 or 5 NM applies, plus wake turbulence and runway occupancy rules.
There is no single worldwide minimum aircraft separation on final approach. Under surveillance, 3 nautical miles (NM) is common in terminal airspace, while approved arrival streams may use 2.5 NM near the threshold. A 5 NM minimum, wake-turbulence spacing, runway occupancy or local rules may require a larger gap.
For our Aviation & Real-World Flying readers, the key distinction is between airborne separation and runway separation. Distance between radar targets does not guarantee that the runway will be clear, and a landing clearance does not remove wake-turbulence or stabilised-approach limits.
Is final-approach separation 3 NM, 2.5 NM or 5 NM?
All three figures can be correct, depending on the surveillance system, national authority, phase of approach and traffic sequence.
| Separation | Where it commonly fits | Main limitation |
|---|---|---|
| 5 NM | General ICAO surveillance minimum and operations where no smaller minimum is authorised | Local procedures may prescribe this distance even near an airport |
| 3 NM | Authority-approved terminal surveillance operations | Not a worldwide minimum or a pilot-selected target |
| 2.5 NM | Approved streams of successive aircraft established on the same final approach track, usually within 10 NM of the runway end | Requires specific monitoring, runway and traffic conditions; wake spacing still takes priority |
Under the ICAO framework, the general horizontal surveillance minimum is normally 5 NM. The responsible authority may reduce it to 3 NM where surveillance accuracy, display performance, coverage and controller procedures support the reduction. National rules can express the framework differently, so the applicable local publication and ATC procedure always control.
Our broader explanation of how 2.5, 3 and 5 NM fit into ATC separation rules covers the surrounding en-route and terminal standards.
Can ATC legally reduce separation below 3 NM?
Yes—2.5 NM can be authorised as reduced surveillance separation for a closely managed final-approach stream.
Typical approval conditions include:
- Both aircraft are established on the same final approach track close to the runway.
- The surveillance equipment provides suitable accuracy, resolution and update performance.
- Controllers monitor approach speeds so the following aircraft does not erode the minimum.
- Runway occupancy has been assessed, commonly against an average of no more than 50 seconds.
- Braking action, runway exits and surface monitoring support prompt runway vacation.
- No larger wake-turbulence minimum applies.
A mistake we see constantly is treating 3 NM—or 2.5 NM—as a spacing target for the pilot. These are conditional ATC minima. Controllers normally build a buffer because winds, speed differences and a slow runway exit can consume the planned margin; this is why controllers use speeds, vectors and sequencing instructions before aircraft reach short final.
How much is the separation in miles and seconds?
Aviation separation is stated in nautical miles, not ordinary statute miles. One nautical mile equals 1.1508 statute miles or 1.852 kilometres.
| Distance | Statute miles | Kilometres | At 120 kt groundspeed | At 140 kt groundspeed |
|---|---|---|---|---|
| 2.5 NM | 2.88 miles | 4.63 km | 75 seconds | 64 seconds |
| 3 NM | 3.45 miles | 5.56 km | 90 seconds | 77 seconds |
| 5 NM | 5.75 miles | 9.26 km | 150 seconds | 129 seconds |
| 6 NM | 6.90 miles | 11.11 km | 180 seconds | 154 seconds |
The time calculation is distance in NM ÷ groundspeed in knots × 3600. Use groundspeed rather than indicated airspeed because wind changes the interval available at the runway.
The table also assumes a stable gap. If the following aircraft is doing 140 kt over the ground and the leader 120 kt, the 20-knot closure rate consumes one nautical mile every three minutes. That is why a distance that looks acceptable several miles out can become inadequate near the threshold.
What is the minimum separation between aircraft landing on the same runway?
There is no single distance for successive landings because surveillance separation, wake separation and runway occupancy are separate tests; the controlling minimum is whichever requires the greatest spacing.
- Surveillance separation controls the distance between aircraft while both remain airborne under radar or ADS-B separation.
- Wake-turbulence separation may demand a larger distance based on the leading and following aircraft categories.
- Runway separation determines whether the following aircraft may cross the threshold while the preceding aircraft is still using the runway.
- Local restrictions may add limits for visibility, braking action, runway contamination, tailwind or unavailable exits.
Some jurisdictions allow a landing clearance to be issued before the leading aircraft has vacated if the prescribed runway separation is expected to exist when the following aircraft crosses the threshold. Clearance timing therefore does not mean the runway is already available.
What are reduced runway separation minima?
Reduced runway separation minima are locally authorised exceptions that can permit a landing aircraft to cross the threshold while the preceding aircraft remains on the runway. They are not another name for the 2.5 NM final-approach minimum.
The ICAO framework includes reference points of 600 metres, 1,500 metres and 2,400 metres along the runway for specified aircraft-category combinations. An authority must implement the procedure after a safety assessment, and conditions normally cover visibility, daylight, wake turbulence, braking action and confirmation that the leading aircraft remains in motion and will vacate without backtracking.
Those reference distances are not permission for a pilot to land behind traffic at any suitable-looking runway. If reduced runway separation has not been authorised and applied by ATC, use the normal local rule. Airports using intersecting or parallel runways may have additional geometry-based requirements, explained in our guide to simultaneous, intersecting and parallel runway operations.
How does wake turbulence change final-approach separation?
Wake turbulence overrides a smaller surveillance minimum whenever the applicable wake category and procedure require more distance.
Under the conventional ICAO HEAVY, MEDIUM and LIGHT categories, familiar examples include 5 NM for a MEDIUM aircraft behind a HEAVY, 6 NM for a LIGHT behind a HEAVY, and 5 NM for a LIGHT behind a MEDIUM. These are examples rather than a complete lookup table: some authorities use SUPER categories, recategorisation systems or aircraft-specific pairings that produce different minima.
On a visual approach, responsibility depends on the jurisdiction and clearance. A pilot instructed to follow traffic visually may become responsible for maintaining visual separation and avoiding its wake. Remaining above the larger aircraft's flight path and landing beyond its touchdown point can reduce exposure, but only when runway length, conditions and aircraft performance make that safe.
Does the 3 NM rule apply to visual or parallel approaches?
No—the familiar 3 NM figure does not automatically apply when separation is being provided visually, procedurally or under an approved parallel-approach system.
At a non-towered aerodrome, pilots do not apply 3 NM as a mandatory circuit rule. They must sequence themselves, allow for wake, communicate as required and avoid landing on an unavailable runway. In non-surveillance airspace, ATC may instead use times, levels, fixes and position reports.
Independent approaches to parallel runways use monitoring, centreline spacing and missed-approach criteria specific to that operation. The distance between two aircraft on adjacent finals cannot be judged solely against the same-stream 3 NM minimum.
What should you do if the spacing becomes too small?
Request more room early, and go around if the approach, wake spacing or runway situation is no longer safe.
- Check the closure rate. Compare groundspeeds rather than looking only at the displayed distance. Consider how long the leading aircraft will need to decelerate and reach an exit.
- Tell ATC promptly. Request additional spacing, a lower assigned speed or vectors. Do not make unapproved S-turns on final or slow below a safe stabilised speed.
- Reject unsuitable wake spacing. Advise ATC if you cannot safely accept the sequence behind larger traffic.
- Discontinue the approach when required. Go around if the runway remains unavailable, wake avoidance is doubtful, the aircraft becomes unstable or no landing clearance has been received at a controlled aerodrome.
Built-in simulator ATC and AI traffic can occasionally compress an arrival stream or leave an aircraft on the runway too long. Do not force the landing to satisfy the simulation; follow the same practical go-around decision criteria for traffic, wake and occupied runways that protect a real approach.