Which Runway Should You Use Today?

The best runway keeps the crosswind component low and the headwind component high, but wind alone doesn't decide the runway. At a towered airport, ATC assigns the runway in use based on current wind, traffic volume, and the approach in use, and pilots fly that runway unless it exceeds their aircraft's crosswind limit or personal minima, in which case they request a different one.

At a non-towered airport, the pilot makes the call. Check the windsock or automated weather, then enter every runway heading plus the wind direction and speed into the calculator above and pick the option with the lowest crosswind. If you only need to check one heading, the full crosswind calculator works just as well.

Traffic pattern direction is a real constraint, not just a preference. Most runways fly a standard left-hand pattern, but noise abatement or terrain can force a right-hand pattern on one runway and not its reciprocal, so both ends of the same strip aren't always interchangeable. Runway length, surface condition, and instrument approach availability all serve as tiebreakers once crosswind and traffic pattern rule out the unsafe choices. See runway numbers for how each number maps to a magnetic heading.

Most runways come as a reciprocal pair, like Runway 09 and Runway 27, exactly 180° apart. Only one end usually suits a given wind, and working out which one takes three steps.

Take wind from 320° at 20 kt. For Runway 09 (heading 090°): the raw difference is |090 − 320| = 230°, and because angles wrap at 360°, the shortest angle is 360 − 230 = 130°. XWC = 20 × sin(130°) = 15.3 kt. HWC = 20 × cos(130°) = −12.9 kt, a 12.9-kt tailwind.

For Runway 27 (heading 270°): the difference is |270 − 320| = 50°, already the shortest angle. XWC = 20 × sin(50°) = 15.3 kt. HWC = 20 × cos(50°) = 12.9 kt headwind.

The crosswind is identical on both ends, 15.3 kt, but Runway 27 turns the same wind into a 12.9-kt headwind instead of a tailwind, making it the clear choice. For a quick visual estimate instead of the math, see the crosswind component chart.

Busy airports rarely pick a runway on wind alone. Noise abatement rules often lock in a preferential runway over a residential area until the tailwind component crosses a fixed threshold, commonly 10 kt, regardless of a smaller crosswind on the other end. London Heathrow, for example, lands on 27R and departs from 27L under normal westerly flow, and only swaps to the easterly runways once the tailwind limit is reached.

Instrument approach availability shifts the balance in poor weather. When cloud or visibility drops, ATC and pilots both favor the runway with an ILS or other precision approach, even if it carries a few more knots of crosswind than the alternative, because a stabilized instrument approach lowers overall risk more than a slightly better crosswind number.

Traffic pattern direction adds a third constraint. Parallel or crossing runways sometimes fly opposite pattern directions to keep departures and arrivals separated, so the runway with the best wind isn't always the one that's open. Always check ATC instructions or the ATIS broadcast before assuming the calculator's top pick is available.

ATIS (Automatic Terminal Information Service) broadcasts the wind, altimeter setting, and runway in use in one repeating loop, updated hourly or whenever conditions change enough to matter. A typical broadcast sounds like: "Information Bravo, wind 250 at 12, visibility 10, few clouds at 5,000, temperature 22, dew point 14, altimeter 30.12, landing and departing runway 27, advise on initial contact you have information Bravo."

Pull two numbers from that: the wind group (250 at 12) and the runway in use (27). Run them through the calculator: θ = |270 − 250| = 20°, XWC = 12 × sin(20°) = 4.1 kt, HWC = 12 × cos(20°) = 11.3 kt. A light crosswind with a solid headwind, well within limits for almost any aircraft.

ATIS updates hourly at most airports, so reverify the wind on initial contact with the tower or on CTAF at a non-towered field. If the reported wind has shifted since the last ATIS letter, recompute before committing to the approach. For an automated report without a spoken loop, the METAR decoder pulls the same wind group directly from the raw text.

Sometimes every runway at the field shows a crosswind at or above the aircraft's demonstrated limit. Three options remain, in order of preference.

First, check whether a nearby airport has a runway better aligned with the current wind. A short diversion to a field with an extra 30° of alignment can turn a marginal 18-kt crosswind into a comfortable 10-kt one. Second, if fuel and time allow, hold or wait: surface wind at many airports backs or veers 20 to 30° over a few hours as a front passes or a sea breeze develops, and a short delay can bring the wind back within limits. Third, if diverting or waiting isn't possible, choose the widest and longest runway with the best surface condition, since extra width and length forgive more drift and a longer stopping distance if the touchdown wanders off centerline. Never treat the demonstrated crosswind limit as a target to reach; leave a margin, especially with gusts in the forecast.