A few days ago I went out to Pegasus preparing for flight ops to work on a troublesome weather computer exhibiting strange networking problems. Driving back from Pegasus I got caught in a Herbie and it went from Condition 2 to Condition 1 in all of 10 seconds. During the ensuing seven hours waiting, aligning with the convoy, and finally getting back to station, I was inspired by a comparison.
Every year, Denver get’s beautiful snow storms. They are likely increasing with frequency, but are more erratic than even in my childhood. Yet those days that Denver get’s dumped on by 2 feet of snow in a few hours (even in May), brings the city to a crawl. I have many memories of getting stuck in snow, in snow traffic, or being hindered by snow in Denver. Mostly overridden by the bright sunshine that happens less than a day later, but I do remember those times where I got stuck in a snow bank and waiting for rescue.
Of course in Denver, if we get stuck we call a 4 wheel drive vehicle–a truck or a SUV–to come pull us out. Increased traction and better torque, whalla, you are sweaty and covered in snow, but your front wheel drive car is now back on the road.
Here in McMurdo we have a similar arrangement, but it’s at a different level. We start in a 4 wheel vehicle and not just an all wheel drive thing with snow tires. That’d be a vehicle Fleet Operations (Fleetops) would tell the Vehicle Maintenance Facility (VMF) not to check out. No, we start in a lifted van with double wide tires that is generally driven in 4wd High. It has 4wd Low, the fluids are low temperature rated including the fuel, they are check for Preventive Maintenance (PM’ed in the vernacular) very regularly, and are the staple of our transport fleet.
What we call for a tow is a CAT Challenger or a Case Quad Track. Think tracked farm vehicle… as that’s actually what they are. Of course they are somewhat modified but mostly it’s just different low temp fluids and heaters for the oil and battery. Again, increased traction, torque, and in the case of Winter, much better lighting, plus often a GPS.
Of course there’s a reason for the different level. What Denver mostly drives on is pavement. Even on the worst day, you can generally get a grip on it if you move enough snow. Unless of course there’s ice on it. Which of course generally what we drive on to Pegasus, or rather a combination of compacted snow with patches of varying types of ice. They don’t call Pegasus the Blue Ice runway for no reason. Which incidentally they do actually land wheeled planes on the ice, of course they have thrust reversers or prop feathering in addition to brakes. The Ross Ice Shelf, which is the majority of what we are on driving to Pegasus, is a glacier that’s between 50 and 200 feet thick. New accumulation yearly and what is blown here from other parts of the continent is what we generally drive on, make snow caves out of (for happy camper), and what Pegasus is covered by (which is compacted or removed).
To give you reference, Condition 3 (think green for go) is Winds less than 48 knots, and Visibility greater than or equal to ¼ mile, and Wind chill temperature warmer than -75°F. Condition 2 (think yellow for yield) is Winds 48 to 55 knots sustained for one minute, or Visibility less than ¼ mile, but greater than or equal to 100 feet sustained for one minute, or Wind chill -75°F to -100°F sustained for one minute. Condition 1 (think red for STOP!) is Winds greater than 55 knots sustained for one minute, or Visibility less than 100 feet sustained for one minute, or Wind chill greater than -100°F sustained for one minute.
Now perhaps you can see that when it goes from Condition 2 (visibility) to Condition 1 (visibility & wind) in 10 seconds that it’s not just about being able to grip the road, but it’s also about dealing with a white out. I’ve dealt with a whiteout in Colorado a few times. You slow down, look for the reflective markers on the side of the road or the stripe on the road, and either move along slowly (hoping you don’t get hit from behind) or pull off (hope you don’t get stuck and hope you don’t get sideswiped by a jerk in a 4wd). Similar here, but all we have are flags every 25 yards with a bit of reflectivity on them and there is no way to differentiate the road. It’s white… and white. You can feel the difference if you are on top of it, as fleetops drags the road to compact it and keep it more clear of snow. However in low visibility if you see a flag you can get disoriented and wonder aloud “is that flag the inside or outside of the lane?” Add to this that you don’t really want to stop if you are at all close to getting stuck. 4 wheeler aficionados may know this, but momentum is your friend. Run across a drift caused by a herbie on an area that was just dragged can still be dicey, better to stay moving and get through it slowly but consistently. Just don’t burn the tranny out.
All of this is why next time you drive from DIA back home and get stuck in a snowstorm you can think about getting stuck in a herbie in Antarctica on your way home. It might be 25 miles to get back Downtown and take you 2-3 hours, but remember if you get stuck at Pegasus at mile marker 12 it can take 7 hours to get home. Even if you have a Magic Carpet…