Intro
Denver International is a big Class B airport on the western plains just east of the Front Range. It is used by United, Frontier, and Southwest as a scissor hub for connections throughout North America. Due to the geography, the air is usually bumpy and weather can switch around quickly, leading to frequent arrival and runway changes. Knowing about Denver’s setup, weather, and threats will make your time there less stressful.
Geography
Denver is located on the western plains about 50 miles east of the Front Range at 5400 feet MSL. The area near it is pretty flat, but the mountains have an outsize impact on the weather and operation.
Denver's geography has a large impact on its weather.
Weather
The Front Range plays a major role in Denver’s weather. Westerly winds aloft usually lead to turbulence in the lee of the mountains, so climbs and descents can be assumed to be bumpy on most days. As the air swirls down from the mountains, it can spiral and lead to winds from just about any direction at the surface. Expect frequent wind shifts, updrafts, and downdrafts on final and re-crab as needed. Fight the airspeed losses, but avoid chasing the bug if you have a gain in the puffs.
Cold fronts often lead to thunderstorms, as the mountains provide a good lifting action. Check your prog chart before you launch. Cold-front thunderstorms will lead to reroutes as inbounds and outbounds get routed around them. Plan extra fuel even if the TAF says weather at the field will be fine.
Cold fronts often lead to thunderstorms, as the mountains provide a good lifting action. Check your prog chart before you launch. Cold-front thunderstorms will lead to reroutes as inbounds and outbounds get routed around them. Plan extra fuel even if the TAF says weather at the field will be fine.
A word of caution on Colorado Springs as an alternate: many others have that same alternate, so COS gets swamped when everyone decides to bug out of Denver. Either fold early or plan to sit there for a while. If Denver’s going to be bad for a while, an early divert to someplace further out for a gas-n-go might save you time versus being #27 in line for fuel at COS when Denver opens back up.
The wind shift at the surface will lead to delays as the field gets flipped around. Approach will prioritize anybody getting close to bingo fuel, so departure rates will go down. If there’s projected to be a strong westerly or easterly, they might switch arrivals to the pair of east-west runways. This reduces arrival capacity, so expect flow delays.
If you see wind shifts in the TAF near your push time, expect new taxi instructions. I like to grab numbers for several different runways and set up secondary flight plans to reduce workload on taxi. It’s usually a good idea to have wind shear numbers on hand, as that can crop up quickly.
Summer airmass thunderstorms are frequent, and have similar mitigation to the cold front storms, though they usually don’t show up in a line. In any case, it’s a good idea to have ADS-B or internet weather up on your iPad when you’re several hundred miles out to get a better picture of what’s going on beyond the range of your weather radar.
Winter weather consists of snow storms that blow in from the south. If you see a low-pressure system coming north from Albuquerque, you may get a few days of snow. There will be a long list of snowtams: start annotating your charts early and expect things to change.
Outside of those issues, Denver is usually pretty clear.
The wind shift at the surface will lead to delays as the field gets flipped around. Approach will prioritize anybody getting close to bingo fuel, so departure rates will go down. If there’s projected to be a strong westerly or easterly, they might switch arrivals to the pair of east-west runways. This reduces arrival capacity, so expect flow delays.
If you see wind shifts in the TAF near your push time, expect new taxi instructions. I like to grab numbers for several different runways and set up secondary flight plans to reduce workload on taxi. It’s usually a good idea to have wind shear numbers on hand, as that can crop up quickly.
Summer airmass thunderstorms are frequent, and have similar mitigation to the cold front storms, though they usually don’t show up in a line. In any case, it’s a good idea to have ADS-B or internet weather up on your iPad when you’re several hundred miles out to get a better picture of what’s going on beyond the range of your weather radar.
Winter weather consists of snow storms that blow in from the south. If you see a low-pressure system coming north from Albuquerque, you may get a few days of snow. There will be a long list of snowtams: start annotating your charts early and expect things to change.
Outside of those issues, Denver is usually pretty clear.
Airport layout and ground ops
Ground ops are mercifully simple at Denver.
Denver’s layout, being a clean-sheet design, is mercifully straightforward. The airport is laid out with runways going out from the main terminal area in a throwing-star pattern, which leads to short taxi times when you're not in the middle of a departure bank. Terminals count up from A at the south end, and gate numbering is odds north, evens south, increasing eastward. Taxilanes between them correspond to where they are relative to the terminal, so CS means “Charlie South” and is south of the Charlie gates. Typical traffic flow is westbound on the southern lanes in each alley (AA, AN, BN) and eastbound on the northern lanes (AS, BS, CS) Knowing just that, I could take your ramp chart away and give you a gate assignment, and you could get there without issues 95% of the time (SFO’s planners should have taken notes). With the thin air and a heavy airplane, you sometimes need to plan a two-engine taxi if you’re going uphill, e.g. ED to the terminal from 17L, or up EE going to 17L.
Arrivals |
Denver has a handful of arrivals that come in from the four corners of the map. Each corner has two commonly-used STARs with about 20-30 miles of spacing. If thunderstorms are in the forecast, expect the following:
- The windward STAR (e.g. LONGZ) gets closed and you get rerouted to the leeward STAR (FLATI).
- The storm drifts into the leeward STAR (FLATI), and traffic gets sent to the windward STAR (LONGZ) again.
Green arrow: you get routed around the weather.
|
When the weather moves downrange, traffic gets sent back to windward.
|
This is why it’s important to check your prog charts and have weather displayed a few hundred miles out so that you can anticipate the changes. If an entire corner gets shut down (e.g. cold front storms), you’ll get a 50+ mile reroute to a different corner. Setting up secondary flight plans will help you calculate fuel requirements early and reduce the scrambling later.
Guessing your runway assignment is part art, part science: the STARs list a “select runway __” and they’ve gotten better about sticking to that about 60% of the time. If you’re on one of the STARs that borders a different assignment (e.g. CLASH north flow), you have a much higher chance of getting shuffled across if the downwind is full from the AALLE and LAWGR.
Guessing your runway assignment is part art, part science: the STARs list a “select runway __” and they’ve gotten better about sticking to that about 60% of the time. If you’re on one of the STARs that borders a different assignment (e.g. CLASH north flow), you have a much higher chance of getting shuffled across if the downwind is full from the AALLE and LAWGR.
Default assignments: 60% of the time, it works all the time. The rest of the time you need to guess and have a secondary flight plan ready.
If there’s a closure or something else is going on, I like to look at what’s on the ATIS and then divide up the approach regions, then put the next most likely guess in the secondary. That usually covers 90% of the cases.
Dividing and guessing on your secondary should get you up to about 90% that at least one plan will work out.
|
Dividing and guessing on your secondary should get you up to about 90%. Then you get 16R off the CLASH. It happens.
|
Just when you think you’ve figured it out, they’ll give you the RNAV Z 16R off the CLASH.
Depending on which direction they’re landing, you’ll either get dropped off on a downwind or a base leg approach transition. If it’s VMC, expect them to cut you inside that transition for a visual, reducing your track distance. Keep in mind that you will need about 30% more track distance to slow down in the thin air. I like to descend a bit earlier than normal so that I can trade speed back for altitude when they give me “Denver speeds,” usually 210, then 190, and 170 to the FAF.
The RNAV Y 16R has a slight offset. If you have a strong left crosswind, you may get a similar visual illusion to Salt Lake’s LDA35 and see 16L off your nose. Point at both when you break out to be sure, then stick right.
If you’re used to sea-level airports and you plan to flare at the same height, the thinner air won’t arrest your descent as well and you’ll have a firm touchdown. Here’s how to adjust for that. Likewise, your increased ground speed will result in a quadratic increase in deceleration energy. Especially in the summer, it’s a good idea to plan reversers and light braking to avoid cooking your brakes.
Depending on which direction they’re landing, you’ll either get dropped off on a downwind or a base leg approach transition. If it’s VMC, expect them to cut you inside that transition for a visual, reducing your track distance. Keep in mind that you will need about 30% more track distance to slow down in the thin air. I like to descend a bit earlier than normal so that I can trade speed back for altitude when they give me “Denver speeds,” usually 210, then 190, and 170 to the FAF.
The RNAV Y 16R has a slight offset. If you have a strong left crosswind, you may get a similar visual illusion to Salt Lake’s LDA35 and see 16L off your nose. Point at both when you break out to be sure, then stick right.
If you’re used to sea-level airports and you plan to flare at the same height, the thinner air won’t arrest your descent as well and you’ll have a firm touchdown. Here’s how to adjust for that. Likewise, your increased ground speed will result in a quadratic increase in deceleration energy. Especially in the summer, it’s a good idea to plan reversers and light braking to avoid cooking your brakes.
Departures
Similar to the STARs, the SIDs radiate out in every possible direction and have diverging tracks so that they can reassign you based on weather. If you’re performance limited and need to go slow (<270 KIAS) in the climb, tell Clearance ahead of time so that they can either build a gap or vector you off track a bit so you don’t hold up traffic.
There’s a website that shows which runways are feeding which SID at any given time. Check your company charts for this. The last few times I went, it was about 70-80% as advertised. The remainder of the time, we guessed and put in a secondary flight plan to reduce workload. Sometimes they catch you with a curveball and you tell them you need a few minutes.
One common Denver thing is combining tower frequencies, typically the whole west side on 35.3 and the east side on 24.3. If you pre-planned the tower freq for the specific departure runway (e.g. 8 or 25), listen for the combined one to ensure you’re not off freq when they say “Monitor tower on [freq].”
There’s a website that shows which runways are feeding which SID at any given time. Check your company charts for this. The last few times I went, it was about 70-80% as advertised. The remainder of the time, we guessed and put in a secondary flight plan to reduce workload. Sometimes they catch you with a curveball and you tell them you need a few minutes.
One common Denver thing is combining tower frequencies, typically the whole west side on 35.3 and the east side on 24.3. If you pre-planned the tower freq for the specific departure runway (e.g. 8 or 25), listen for the combined one to ensure you’re not off freq when they say “Monitor tower on [freq].”
GA Traffic and Bravo Shelves
There’s a lot of GA traffic in the Denver area that likes to fly in the Southeast Practice Area around at 8000-9000 feet. The Southeast Practice area is just outside and below the Bravo shelves, so keep an eye out if you’re on the CLASH or NIIXX. The “Strait of Gibraltar” between Denver’s Bravo and Rocky Mountain on the west side should be less of an issue unless you’re getting vectored to runway 7, but it’s worth knowing about as well. The Colorado Pilots Association has a ForeFlight overlay that you can add to your charts for better SA.
If your MFD doesn’t depict airspace, try to draw range rings in the box to help with awareness. This can also help if they vector you below the shelf to avoid busting the 200-knot speed limit.
If your MFD doesn’t depict airspace, try to draw range rings in the box to help with awareness. This can also help if they vector you below the shelf to avoid busting the 200-knot speed limit.
Heavy GA traffic is worth paying attention to, especially on COS-DEN flights at low altitude.
Conclusions
Denver provides a number of challenges to pilots, most notably the squirrelly winds, hot & high conditions, thunderstorms and consequent frequent arrival changes, and bumpy rides. Knowing these threats and how to prepare for them on any given day will make your life easier when it comes time to execute.