The Trench
Overview (Thanks to Wikipedia & Chuck Jarecki)
The Rocky Mountain Trench, also known as the Valley of a Thousand Peaks or simply the Trench, is a large valley on the western side of the northern part of North America’s Rocky Mountains. The Trench is both visually and cartographically a striking physiographic feature extending approximately 1,600 km (1,000 mi) from Flathead Lake, Montana to the Liard River, just south of the British Columbia–Yukon border near Watson Lake, Yukon. The trench bottom is 3–16 km (1.9–9.9 mi) wide and is 600–900 m (2,000–3,000 ft) above sea level. The general orientation of the Trench is an almost straight 150/330° geographic north vector and has become convenient as a visual guide for aviators heading north or south. More information on “The Trench” on Wikipedia here.
The Trench is visible from space, as seen here from the International Space Station 
Comprehensive Airstrip List
KML file for import into your ForeFlight or Garmin app: Most up-to-date strip list: link
Here is a large-format satellite image of the Trench with all the airstrips that I’m aware of shown (plus Sifton Pass–high point–is shown). Zoom in to see detail. This is simply a composite image of what you can view the the below Caltopo link.
Link to interactive CalTopo map (read only) I created (link here)–Note: CalTopo is an excellent map source!
To document airstrips along the Trench, I scanned topographic maps, an old brochure on the Trench (posted by “KG” on BackCountryPilot.org–images here & here), and did numerous Google searches. There is at least one unnamed strip as noted on the maps above; There might be others (please let me know if you have info on more).
Here is a PDF of all airstrips I documented along the Trench (PDF link here). Note: This list does not include Watson Lake, Mackenzie, Prince George or Quesnel—those are well documented many other places on-line.
Included as links in the above airstrip list are satellite images of each airstrip. Enjoy!
This description starts at Mackenzie CYZY. Alternate fuel can be had far less expensively at Quesnel, Vanderhoof (self serve) or Macbride. Other route pages on this website, describe how to get to either Watson Lake CYQH or Mackenzie from points N or S.
Video Presentation (Webinar) on “The Trench” Route
I recently did a webinar on “The Trench.” Link here (about 50 minutes).
Trench Slide Show
Here’s a web-based slide show of numerous pictures along the route (South to North). Link
Fuel & New FBO at Mackenzie
Mackenzie CYZY fuel 2022 update: New FBO building. Picture of FBO You can camp on the side of the building, but the building is locked up after hours. Port-a-potty available outside (as of late summer 2022).
Note: As of summer 2022 FBO was only open Tuesday – Saturday, 8 am to 5 pm. Call out after hours as well as Sunday & Monday. A big corporation manages the FBO/fuel concession for the city. Staff was changing every few months in 2022. We’ll see what 2023 offers in terms of staff and hours.
Avoid Prince George for fuel
Avoid Prince George for fuel. Much more expensive than other nearby airports. Even the fuel truck staff advised me to only put on minimum needed to get to next closest fuel stop. There is a surcharge (!!) if one takes more than 49.9 liters too (last time I was there)! I’ve not received any feedback from 2022 re the situation improving at Prince George.
Other Fuel Sources
Apparently 90 octane MOGAS is available on an emergency basis at Fort Graham CBW3. Contact info is listed as Finlay River Outfitters (link)
Rumor has it one might be able to get MOGAS at Ft Ware. Not confirmed nor have I ever heard of anyone trying there.
Might be able to get emergency fuel at either Terminus (link) or Scoop Lake lodges (link) –prior contact HIGHLY suggested if there is any doubt.
Long Distance
Depending on your aircraft range and cruise speed, you may not be able to do the Trench due to adverse winds. Weather (low clouds) can change dramatically in the long distance (342 nm). Check with Flight Service for updated forecasts. Recognize there aren’t any reporting points between Watson Lake and Mackenzie, so Flight Service is often guessing as much as you are.
There are weather cams at Ft Ware (link), Tsay Keh (link), Mackenzie (link) and [unofficial] Watson Lake (link).
Plan enough fuel to allow turning around up to 1/2 or even 2/3 of the way. Obviously your best information might be other pilots in route who have reported conditions to Flight Service. Sifton Pass is the highest point along the Trench (marked on above map) at 3,320’—This is a common choke point for low weather.
126.7 is generally the in-route radio frequency.
Alternate Airstrips Enroute
While there are a number of gravel strips (link), along the route, there are no services. No fuel. In a pinch, you might be able to purchase some auto fuel at Ft Ware. Many websites advise against landing at Ft Ware due to unfriendly locals. Friend landed FT Ware in 2022 and was able to pour fuel bags into his plane with no problems (other than a curious black bear)!
Beach Landing Options
Though you’re flying along Williston Lake for about 156 miles, there are logging camps and roads along many sections. Also, Williston Lake is actually a huge reservoir. Due to lower snowmelt in recent years, the lake (2019) was very low. There are miles upon miles of beach/shoreline available to set down in an emergency along most of the lake (depending on lake level–again in 2019 it was very low; 2022 was high).
Villages with airstrips are noted on the above linked maps. Note that these are remote villages. No services as far as I know.
Note: Though I have not experienced this myself, I have read several pilot reports indicating that landing at the native fields (e.g. Ft Ware) can be problematic. Some of the locals apparently do not welcome non-native visitors (rumors; No personal experiences or reports).
Northern Section of the Trench
Once past Ft Ware you are following a river valley and what was once referred to as the Davie Trail (link to more historical info). I have seen the occasional remote cabin by one or two of the smaller lakes. For instance, Fox Lake has a small cabin.
Occasionally, especially later in the season, there are short gravel bars where one might set down if needed in an emergency. Other than those occasional options, there are relatively long sections with no landing options.
Watson Lake Comments
Watson Lake (pictures link) has self-service fuel. It seems they have intermittent pump credit card issues. Last time there I had to get a special card in the office from the person who operates the radio. The FBO is manned perhaps 18+ hours/day. There is good WiFi and a phone to call Flight Service if you don’t want to use your cell phone.
Inside the FBO there are a lot of historical pictures from when Watson Lake was a major hub on the Lend Lease aircraft route from the U.S. to Russia. Link to history here and here. The original WW-II (massive) hangar (pictures link) is neat to see–Note: You cannot enter the hangar! Even though the door was open when we were last there, the folks working inside were decidedly unfriendly.
Camping At Watson Lake
Camping is available with water at the gazebo NW of the terminal building. On arrival or departure, if you look closely, there are still the remains of a WW-II bomber on the far W shore underwater that crashed on takeoff.
Camping at Watson Lake is quiet. Few airplanes stop here late in the day. If I had to sit at Watson Lake for more than a day or two due to weather it would be “challenging.”
Side Trip
Suggestion by Chuck Jarecki. If you find yourself SW of Prince George there is the old gold mining town of Barkerville (historical info). If you want to visit an interesting place, although a bit touristy, fly over to Barkerville. This town became the gold mining center of B.C. when gold was discovered in 1862. There 125 heritage buildings that have been restored. You can even try gold panning. The visitor center is informative.
Getting there from the Trench: about 30 NM down the Frazer River from McBride, change course to 200o and fly about 40 NM to the Barkerville airstrip. Enroute, you will pass over the northwest corner of Bowron Lakes Provincial Park where there is a primitive landing strip with nearby cabins to rent.
From the Barkerville airstrip it is about a mile walk to the town.
If you do not want to camp at Barkerville or stay in local lodging, another option is to fly west to Quesnel (CYQZ). There is a nice pilots’ camp ground at the airport and a shower is available in the “terminal”. There is self-serve fuel available. If you do not wish to camp, there is the Airport Inn Motel nearby. They offer airport shuttle. (250-992-5942).
Continuing Your Trip
From Watson Lake I highly recommend you proceed along Hwy 1 along the Swift River toward Teslin then into Carcross. Pictures travelling from Watson Lake to Carcross (link).
Continuing along the Alaska Hwy covered here.
Continuing on to Carcross & Skagway covered here.