Denver International to Helena Regional DEN → HLN
516 nautical miles (593 statute miles) northwest on a straight line, true course 324°, about 316° magnetic at the departure end (variation 8E). At 120 knots that is 3 h 56 min at the quickest height in today's winds (30,000 ft, a 11-knot tailwind), arriving about 8:42 am MDT (14:42 UTC). Right now DEN is VFR, wind from the southwest (230°) at 11 knots; HLN is marginal VFR, wind from the west (270°) at 7 knots. 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: 1,617 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
- AIRMET TANGO 4W: moderate turbulence above 18,000 ft (due to mountain wave) from 34,000 ft to 43,000 ft. Over the first 208 nm of the route.
- AIRMET TANGO 2W: moderate turbulence below 18,000 ft (due to mountain wave) up to 22,000 ft. Over the first 178 nm of the route.
- 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). Near the route, at the departure end.
- 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). Over the route from 69 to 188 nm out.
- AIRMET SIERRA 1E: mountains obscured by cloud (due to mountains obscured by clouds, precipitation, mist). Over the last 397 nm of the route.
- AIRMET TANGO 5W: strong surface winds (30 knots or more) (due to sustained surface winds greater than 30 knots). Over the route from 139 to 198 nm out.
- AIRMET ZULU 2C: moderate icing up to 23,000 ft. Over the route from 208 to 406 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). Over the last 228 nm of the route.
- AIRMET ZULU 2C: moderate icing up to 18,000 ft. Over the last 99 nm of the route.
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 DEN.
Pilot reports along the route within 50 nm of the line, last three hours, the serious ones first
- B737 descending, 3 nm south, 2:10 am MDT (08:10 UTC): light chop turbulence. At the departure end, 3 nm south of the line.
as filed, and in English
DEN UA /OV DEN/TM 0810/FLDURD/TP B737/TB LGT CHOP
- Report
- a routine report filed through DEN
- Where
- over DEN
- Time
- 08:10 UTC
- Height
- during the descent
- Aircraft
- B737
- Turbulence
- light chop
- B763 at 23,000 ft, 24 nm southwest, 4:26 am MDT (10:26 UTC): light chop turbulence, remarks: zdvwc. 30 nm along the route, 24 nm southwest of the line.
as filed, and in English
DEN UA /OV DEN278037/TM 1026/FL230/TP B763/TB OCNL LGT CHOP/RM ZDVWC
- Report
- a routine report filed through DEN
- Where
- 37 nm west (278°) of DEN
- Time
- 10:26 UTC
- Height
- at 23,000 ft
- Aircraft
- B763
- Turbulence
- occasional light chop
- Remarks
- zdvwc
- BE9L at 17,000 ft, 35 nm northeast, 3:42 am MDT (09:42 UTC): light rime icing from 15,000 ft to 17,000 ft, 0 °C, remarks: zdvwc. 208 nm along the route, 35 nm northeast of the line.
as filed, and in English
CPR UA /OV DDY250025/TM 0942/FL170/TP BE9L/TA 00/IC LGT RIME 150-170/RM ZDVWC
- Report
- a routine report filed through CPR
- Where
- 25 nm west (250°) of DDY
- Time
- 09:42 UTC
- Height
- at 17,000 ft
- Aircraft
- BE9L
- Temperature
- 0 °C
- Icing
- light rime from 15,000 ft to 17,000 ft
- Remarks
- zdvwc
Winds aloft along the route, and the time en route the forecast for use 08:00–15:00 UTC · at 120 knots true airspeed
The westbound cruising heights for this course (VFR: even thousands plus 500 ft; above 18,000 ft the forecast levels), with the wind averaged along the line from the 6 forecast points nearest it (DEN, BFF, LND, BIL, DLN, GTF). A plus sign is a headwind, a minus sign a tailwind.
| Height | Average wind | Head- or tailwind | Temperature | Ground speed | Time en route | Arrival |
|---|---|---|---|---|---|---|
| 8,500 ft | 250° at 14 kt | +5 kt | 3 °C | 115 kt | 4 h 29 min | 9:15 am MDT (15:15 UTC) |
| 10,500 ft | 240° at 19 kt | +4 kt | 2 °C | 116 kt | 4 h 27 min | 9:13 am MDT (15:13 UTC) |
| 12,500 ft | 240° at 25 kt | +1 kt | -1 °C | 119 kt | 4 h 20 min | 9:06 am MDT (15:06 UTC) |
| 14,500 ft | 230° at 29 kt | −2 kt | -5 °C | 122 kt | 4 h 14 min | 9:00 am MDT (15:00 UTC) |
| 16,500 ft | 220° at 33 kt | −5 kt | -10 °C | 125 kt | 4 h 08 min | 8:54 am MDT (14:54 UTC) |
| 18,000 ft FL180 | 220° at 37 kt | −7 kt | -13 °C | 127 kt | 4 h 04 min | 8:50 am MDT (14:50 UTC) |
| 24,000 ft FL240 | 220° at 48 kt | −8 kt | -24 °C | 128 kt | 4 h 02 min | 8:48 am MDT (14:48 UTC) |
| 30,000 ft FL300 | 220° at 57 kt | −11 kt | -32 °C | 131 kt | 3 h 56 min | 8:42 am MDT (14:42 UTC) |
| 34,000 ft FL340 | 220° at 62 kt | −10 kt | -37 °C | 130 kt | 3 h 58 min | 8:44 am MDT (14:44 UTC) |
| 39,000 ft FL390 | 220° at 62 kt | −8 kt | -45 °C | 128 kt | 4 h 02 min | 8:48 am MDT (14:48 UTC) |
Based on data from the 12th at 06:00 UTC; valid on the 12th at 12:00 UTC for use 08:00 to 15:00 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 |
|---|---|---|---|---|---|---|---|---|---|---|
| DEN | used from 0 nm out; 25 nm from the line | 270/24 11° | 230/13 5° | 230/48 -8° | 230/46 -20° | 230/63 -30° | 240/78 -36° | 240/78 -48° | ||
| BFF | used from 99 nm out; 123 nm from the line | 280/28 | 260/39 11° | 240/34 5° | 210/38 -11° | 210/52 -22° | 230/61 -31° | 230/61 -36° | 240/56 -45° | |
| LND | used from 149 nm out; 87 nm from the line | 240/10 3° | 240/30 0° | 220/42 -13° | 230/52 -23° | 220/54 -33° | 220/52 -36° | 220/53 -44° | ||
| BIL | used from 347 nm out; 81 nm from the line | 300/14 | 270/19 -2° | 260/26 -2° | 220/28 -13° | 210/51 -25° | 220/56 -33° | 220/61 -39° | 220/72 -45° | |
| DLN | used from 397 nm out; 86 nm from the line | 190/10 -4° | 220/23 -4° | 210/21 -18° | 210/43 -28° | 210/60 -33° | 210/72 -37° | 210/67 -44° | ||
| GTF | used from 496 nm out; 63 nm from the line | L/V | L/V -7° | 240/8 -8° | 240/30 -14° | 240/40 -28° | 210/52 -38° | 210/76 -38° | 220/72 -43° |
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 |
|---|---|---|---|---|---|---|---|
| DEN Denver, CO | departure | VFR | from the southwest (230°) at 11 knots | 10+ mi | none | 5,433 ft | 3:53 am MDT (09:53 UTC) |
| FNL Fort Collins/Loveland, CO | 40 nm out, 8 nm northeast of the line, tower | VFR | from the south (190°) at 7 knots | 10+ mi | none | 5,020 ft | 09:56 UTC |
| LAR Laramie, WY | 99 nm out, 15 nm northeast of the line | VFR | from the west-southwest (250°) at 13 knots | 10+ mi | none | 7,283 ft | 09:53 UTC |
| SAA Saratoga, WY | 139 nm out, 23 nm southwest of the line | reported, no category | from the south-southeast (150°) at 13 knots, gusting to 19 | 10+ mi | none | 7,014 ft | 10:30 UTC |
| RWL Rawlins, WY | 159 nm out, 23 nm southwest of the line | VFR | from the south (180°) at 5 knots | 10+ mi | none | 6,816 ft | 13:53 UTC |
| HSG Thermopolis, WY | 288 nm out, 7 nm east of the line | marginal VFR Sky: scattered clouds at 1,300 feet, a broken layer at 2,700 feet, overcast at 3,200 feet | from the north-northeast (030°) at 5 knots | 10+ mi | 2,700 ft | 4,891 ft | 10:35 UTC |
| COD Cody, WY | 337 nm out, 16 nm northeast of the line | marginal VFR Sky: scattered clouds at 1,100 feet, overcast at 1,800 feet | from the north (010°) at 10 knots | 10+ mi | 1,800 ft | 5,102 ft | 10:15 UTC |
| BZN Bozeman, MT | 456 nm out, 6 nm southwest of the line, tower | low IFR Sky: overcast at 200 feet Weather: mist | from the south (170°) at 4 knots | 6 mi | 200 ft | 4,473 ft | 09:56 UTC |
| HLN Helena, MT | destination | marginal VFR Sky: a broken layer at 2,300 feet, overcast at 4,500 feet | from the west (270°) at 7 knots | 10+ mi | 2,300 ft | 3,877 ft | 4:22 am MDT (10:22 UTC) |
The highest airport on this list sits at 7,283 ft; the ground between airports is higher still. Check the sectional chart for the terrain and the minimum safe heights along the line.
At HLN when you get there the forecast at the estimated arrival, 8:42 am MDT (14:42 UTC)
Wind light and variable, visibility more than 6 miles, overcast at 1,500 feet marginal VFR
The whole forecast for HLN
- From Mon 12:00 am MDT (06:00 UTC): wind from the west-northwest at 14 knots, visibility 3 miles, light snow, overcast at 3,500 feet
- At times between Mon 12:00 am MDT (06:00 UTC) and 3:00 am MDT (09:00 UTC): visibility 1 mile, light snow, overcast at 1,500 feet
- From Mon 3:00 am MDT (09:00 UTC): wind light and variable, visibility more than 6 miles, overcast at 1,500 feet
- 30% chance between Mon 3:00 am MDT (09:00 UTC) and 6:00 am MDT (12:00 UTC): visibility 3 miles, light snow, overcast at 1,000 feet
- From Mon 3:00 pm MDT (21:00 UTC): wind light and variable, visibility more than 6 miles, scattered clouds at 1,500 feet, scattered clouds at 3,500 feet
The forecast for DEN, the departure
- From Mon 3:00 am MDT (09:00 UTC): wind from the south at 15 knots, visibility more than 6 miles, clear skies
- From Mon 10:00 am MDT (16:00 UTC): wind from the southwest at 14 knots, gusting to 21, visibility more than 6 miles, clear skies
- From Mon 4:00 pm MDT (22:00 UTC): wind from the south at 9 knots, visibility more than 6 miles, clear skies
- From Mon 7:00 pm MDT (01:00 UTC): wind from the northeast at 8 knots, visibility more than 6 miles, a few clouds at 15,000 feet
- From Mon 11:00 pm MDT (05:00 UTC): wind from the north at 10 knots, visibility more than 6 miles, a few clouds at 3,000 feet
Temporary flight restrictions on the line or within 25 nm of it
No temporary flight restriction on or near this route right now.
Daylight
Sunset at DEN 6:22 pm MDT (00:22 UTC), at HLN 6:45 pm MDT (00:45 UTC) (civil twilight ends 7:15 pm MDT (01:15 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: Denver International, Helena Regional.