Boeing Fld/King County International to St. Louis Lambert International BFI → STL
1,482 nautical miles (1,706 statute miles) east on a straight line, true course 099°, about 084° magnetic at the departure end (variation 15E). At 120 knots that is 9 h 30 min at the quickest height in today's winds (39,000 ft, a 36-knot tailwind), arriving about 12:15 pm CDT (17:15 UTC). For planning, not a briefing: the legal preflight briefing comes from Flight Service (1-800-WX-BRIEF) or the FAA's own tools. Airlines fly this pair: 6 flights in the DOT's last twelve reported months, the route's page.
The route the straight line, the warnings crossed, restrictions, pilot reports and the airports along the way · click a mark for its words
Green, blue, red and purple airport dots are the flying conditions reported there now (VFR, marginal VFR, IFR, low IFR); grey means no report. Red areas are SIGMETs, orange areas AIRMETs, hatched red areas temporary flight restrictions. Map tiles: OpenFreeMap, data © OpenStreetMap contributors.
Warnings the route crosses SIGMETs and AIRMETs whose area the line passes through or comes within 25 nm of
- SIGMET C13C: thunderstorms (a convective SIGMET) up to 30,000 ft, moving from the southwest at 40 knots, until 1:55 am PDT (08:55 UTC). Near the route, 856 nm along the route.
as issued
WSUS32 KKCI 120655 MKCC WST 120655 CONVECTIVE SIGMET 13C VALID UNTIL 0855Z SD FROM 50NW DPR-30ESE DPR-20SE RAP-50WNW RAP-50NW DPR AREA TS MOV FROM 22040KT. TOPS TO FL300.
- AIRMET TANGO 1W: moderate turbulence above 18,000 ft from 18,000 ft to 39,000 ft, from 11:00 pm PDT (06:00 UTC). Over the first 179 nm of the route.
- AIRMET ZULU 2C: moderate icing up to 23,000 ft, from 11:00 pm PDT (06:00 UTC). Over the route from 119 to 537 nm out.
- AIRMET SIERRA 1E: mountains obscured by cloud (due to mountains obscured by clouds, precipitation, mist), from 11:00 pm PDT (06:00 UTC). Over the route from 219 to 657 nm out.
- AIRMET TANGO 1W: moderate turbulence above 18,000 ft from 18,000 ft to 36,000 ft, from 11:00 pm PDT (06:00 UTC). Over the route from 269 to 458 nm out.
- AIRMET SIERRA 4E: low cloud or poor visibility (IFR conditions) (due to ceilings below 1,000 ft, visibility below 3 miles, precipitation, mist), from 11:00 pm PDT (06:00 UTC). Over the route from 308 to 1005 nm out.
- AIRMET ZULU 2C: moderate icing up to 23,000 ft, from 11:00 pm PDT (06:00 UTC). Over the route from 547 to 716 nm out.
- AIRMET TANGO 4W: moderate turbulence below 18,000 ft up to 18,000 ft, from 11:00 pm PDT (06:00 UTC). Over the route from 597 to 756 nm out.
- AIRMET TANGO 4W: moderate turbulence above 18,000 ft from 18,000 ft to 38,000 ft, from 11:00 pm PDT (06:00 UTC). Over the route from 607 to 826 nm out.
- AIRMET TANGO 1W: low-level wind shear (due to air speed loss or gain of 20 knots or more below 2,000 ft above the ground), from 11:00 pm PDT (06:00 UTC). Over the route from 637 to 816 nm out.
- AIRMET TANGO 3W: low-level wind shear (due to air speed loss or gain of 20 knots or more below 2,000 ft above the ground), from 11:00 pm PDT (06:00 UTC). Over the route from 945 to 1393 nm out.
A SIGMET warns of weather hazardous to all aircraft; an AIRMET of weather that matters to small aircraft and to flying without instruments. "From 60 to 180 nm out" is measured along the route from BFI.
Pilot reports along the route within 50 nm of the line, last three hours, the serious ones first
Not fetched just now.
Winds aloft along the route, and the time en route the forecast for use 02:00–09:00 UTC · at 120 knots true airspeed
The eastbound cruising heights for this course (VFR: odd thousands plus 500 ft; above 18,000 ft the forecast levels), with the wind averaged along the line from the 15 forecast points nearest it (SEA, YKM, GEG, LWS, DLN, BIL, RAP, PIR, ONL, GRI, OMA, DSM, MKC, COU, STL). A plus sign is a headwind, a minus sign a tailwind.
| Height | Average wind | Head- or tailwind | Temperature | Ground speed | Time en route | Arrival |
|---|---|---|---|---|---|---|
| 5,500 ft | 200° at 11 kt | +1 kt | 15 °C | 119 kt | 12 h 27 min | 3:12 pm CDT (20:12 UTC) |
| 7,500 ft | 210° at 9 kt | 0 | 7 °C | 120 kt | 12 h 21 min | 3:06 pm CDT (20:06 UTC) |
| 9,500 ft | 220° at 10 kt | −2 kt | 3 °C | 122 kt | 12 h 09 min | 2:54 pm CDT (19:54 UTC) |
| 11,500 ft | 220° at 14 kt | −4 kt | 1 °C | 124 kt | 11 h 57 min | 2:42 pm CDT (19:42 UTC) |
| 13,500 ft | 220° at 16 kt | −6 kt | -3 °C | 126 kt | 11 h 46 min | 2:31 pm CDT (19:31 UTC) |
| 15,500 ft | 230° at 18 kt | −7 kt | -7 °C | 127 kt | 11 h 40 min | 2:25 pm CDT (19:25 UTC) |
| 17,500 ft | 230° at 20 kt | −8 kt | -11 °C | 128 kt | 11 h 35 min | 2:20 pm CDT (19:20 UTC) |
| 18,000 ft FL180 | 230° at 20 kt | −9 kt | -12 °C | 129 kt | 11 h 29 min | 2:14 pm CDT (19:14 UTC) |
| 24,000 ft FL240 | 230° at 23 kt | −10 kt | -23 °C | 130 kt | 11 h 24 min | 2:09 pm CDT (19:09 UTC) |
| 30,000 ft FL300 | 240° at 32 kt | −19 kt | -35 °C | 139 kt | 10 h 40 min | 1:25 pm CDT (18:25 UTC) |
| 34,000 ft FL340 | 250° at 42 kt | −32 kt | -39 °C | 152 kt | 9 h 45 min | 12:30 pm CDT (17:30 UTC) |
| 39,000 ft FL390 | 250° at 47 kt | −36 kt | -45 °C | 156 kt | 9 h 30 min | 12:15 pm CDT (17:15 UTC) |
Based on data from the 12th at 00:00 UTC; valid on the 12th at 06:00 UTC for use 02:00 to 09:00 UTC; temperatures above 24,000 ft are below zero. Heights are above sea level; a height is left out when the forecast has no wind for it over most of the line (the ground is higher). Ground speed is the airspeed less the headwind; the time en route is for the straight line and ignores climb, descent and routing around weather.
The forecast points as issued
| Point | From | 3,000 | 6,000 | 9,000 | 12,000 | 18,000 | 24,000 | 30,000 | 34,000 | 39,000 |
|---|---|---|---|---|---|---|---|---|---|---|
| SEA | used from 0 nm out; 25 nm from the line | 050/7 | 050/11 1° | 050/12 -5° | 030/31 -7° | 010/61 -15° | 010/69 -26° | 360/73 -40° | 360/62 -47° | 330/21 -43° |
| YKM | used from 50 nm out; 45 nm from the line | 070/10 | 040/15 -1° | 020/27 -8° | 030/25 -13° | 020/48 -20° | 010/83 -27° | 010/77 -37° | 010/49 -40° | 350/14 -41° |
| GEG | used from 149 nm out; 44 nm from the line | 080/16 -2° | 050/17 -7° | 080/9 -10° | 190/33 -21° | 180/31 -32° | L/V -35° | L/V -37° | 270/8 -40° | |
| LWS | used from 199 nm out; 27 nm from the line | 070/10 | 080/12 -2° | 030/12 -6° | 080/7 -10° | 170/34 -21° | 160/46 -32° | 200/33 -35° | 220/22 -35° | 230/18 -38° |
| DLN | used from 348 nm out; 68 nm from the line | 090/6 -6° | 240/22 -4° | 210/34 -16° | 210/62 -25° | 210/66 -34° | 210/82 -36° | 220/77 -42° | ||
| BIL | used from 497 nm out; 64 nm from the line | 080/13 | 180/9 -2° | 210/38 0° | 220/51 -11° | 210/46 -22° | 210/58 -35° | 230/73 -39° | 230/72 -45° | |
| RAP | used from 696 nm out; 111 nm from the line | 180/23 12° | 200/38 13° | 210/38 6° | 220/28 -10° | 230/34 -21° | 230/37 -36° | 250/52 -38° | 250/59 -46° | |
| PIR | used from 895 nm out; 90 nm from the line | 170/22 19° | 190/25 13° | 210/32 6° | 240/23 -9° | 250/32 -21° | 250/38 -36° | 260/44 -40° | 260/52 -47° | |
| ONL | used from 945 nm out; 74 nm from the line | 210/31 20° | 230/27 13° | 230/18 7° | 220/19 -8° | 240/26 -20° | 250/44 -35° | 270/52 -39° | 260/57 -47° | |
| GRI | used from 1094 nm out; 63 nm from the line | 230/35 21° | 230/23 13° | 220/20 7° | 240/25 -8° | 240/37 -20° | 250/49 -33° | 260/57 -38° | 260/58 -47° | |
| OMA | used from 1144 nm out; 19 nm from the line | 220/47 | 240/33 19° | 250/18 11° | 230/17 6° | 260/29 -8° | 250/33 -19° | 250/51 -33° | 260/61 -40° | 270/62 -49° |
| DSM | used from 1244 nm out; 69 nm from the line | 230/40 | 250/33 17° | 250/18 12° | 240/17 5° | 260/28 -8° | 270/34 -19° | 260/41 -33° | 260/55 -41° | 270/62 -51° |
| MKC | used from 1293 nm out; 81 nm from the line | 220/44 | 250/28 18° | 250/18 13° | 240/12 6° | 280/24 -6° | 240/34 -18° | 260/47 -30° | 260/51 -40° | 270/58 -50° |
| COU | used from 1343 nm out; 55 nm from the line | 230/31 | 230/30 15° | 260/16 11° | 270/14 6° | 260/24 -6° | 270/27 -18° | 270/37 -32° | 280/49 -41° | 290/56 -51° |
| STL | used from 1443 nm out; 20 nm from the line | 250/24 | 250/24 16° | 260/23 9° | 270/16 6° | 260/25 -6° | 270/29 -19° | 290/34 -33° | 290/48 -41° | 290/54 -51° |
The weather now: both ends and the airports along the way public airports with a weather report within 25 nm of the line, one for each stretch
| Airport | Where | Conditions | Wind | Visibility | Ceiling | Elevation | Reported |
|---|---|---|---|---|---|---|---|
| BFI Seattle, WA | departure | no report just now | 21 ft | ||||
| MWH Moses Lake, WA | 119 nm out, 4 nm northeast of the line, tower | no report just now | 1,188 ft | ||||
| PUW Pullman/Moscow, WA | 219 nm out, 6 nm southwest of the line | no report just now | 2,566 ft | ||||
| BTM Butte, MT | 418 nm out, 6 nm southwest of the line | no report just now | 5,550 ft | ||||
| BZN Bozeman, MT | 468 nm out, 4 nm east of the line, tower | no report just now | 4,473 ft | ||||
| SHR Sheridan, WY | 657 nm out, 1 nm northeast of the line | no report just now | 4,021 ft | ||||
| RAP Rapid City, SD | 826 nm out, 23 nm northeast of the line, tower | no report just now | 3,203 ft | ||||
| RBE Bassett, NE | 1005 nm out, 3 nm northeast of the line | no report just now | 2,349 ft | ||||
| OMA Omaha, NE | 1184 nm out, 9 nm northeast of the line, tower | no report just now | 984 ft | ||||
| ICL Clarinda, IA | 1234 nm out, 5 nm south of the line | no report just now | 995 ft | ||||
| MBY Moberly, MO | 1383 nm out, 13 nm southwest of the line | no report just now | 866 ft | ||||
| STL St Louis, MO | destination | no report just now | 617 ft |
The highest airport on this list sits at 5,550 ft; the ground between airports is higher still. Check the sectional chart for the terrain and the minimum safe heights along the line.
At STL when you get there the forecast at the estimated arrival, 12:15 pm CDT (17:15 UTC)
STL has no terminal forecast; use the nearest airport that does.
Temporary flight restrictions on the line or within 25 nm of it
- 6/7634 CENTRALIA, MO, Monday, October 12, 2026 UTC 21 nm from the route, 1403 nm along the route · a hazard on the ground (fire-fighting, a chemical spill, rescue work) · today · ZKC
Daylight
Sunset at BFI 6:25 pm PDT (01:25 UTC), at STL 6:27 pm CDT (23:27 UTC) (civil twilight ends 6:54 pm CDT (23:54 UTC)).
Each restriction opens the FAA's own page with the exact area, heights and times. Ordinary notices to air missions (closed runways, lights out) are not shown: the FAA's notice search is not open to sites like this one at this time.
Radar and forecast charts for the regions crossed government pictures, the latest each time the page loads
Sources: the Aviation Weather Center's data service (SIGMETs, AIRMETs, graphical AIRMETs, pilot reports, winds and temperatures aloft, observations and terminal forecasts), the National Weather Service radar, the Weather Prediction Center's charts, the FAA's temporary flight restriction list and shapes, and the FAA's airport file for the positions, elevations and magnetic variation. Fetched when the page is viewed and kept a few minutes. Each leg is the straight line between its two airports; airways, terrain and airspace are not considered. The airports in detail: Boeing Fld/King County International, St. Louis Lambert International.