Thirty-three Gusting Thirty-nine

I flew up north this morning. Not as far north as Aviatrix is, but well north-west of Calgary. Some people might call it Rocky Mountain House but pilots would likely refer to it as CYRM. It was a long slog up there. A really long slog. The winds aloft were forecast to be 330 at 43 knots and based on our groundspeed of 73 knots, I don’t think that forecast was far off. And I was too busy battling the light to moderate chop to muck around with the GPS to calculate the actual winds.

But the best thing about a consistent headwind is that it becomes a tailwind on the return flight. The same route that was a 1.3 hour flight going there, was a mere 45 minutes on the return. The bad news though is that the winds at Calgary/Springbank (CYBW) had increased from ”20 gusting 30” to ”33 gusting 39”. At 30 degrees off the runway, with some fluxuation, that put me dangerously close to exceeding the aircraft’s maximum crosswind component of 17 knots. And, in fact, the maximum would be exceeded during the gusts.

For students, or even licenced pilots, who are are unaware, don’t understand or simply don’t use the correct crosswind landing technique, the notion of a maximum crosswind component may be lost on them. When a pilot improperly employs the use of crabbing on short final in order to return the aircraft to solid ground, kicking the rudder at the last second to bring the aircraft in line with the runway, a maximum crosswind component doesn’t really exist. Or there’s no need for it to exist. If they kick within the last couple feet the aircraft will drift, but on a reasonably wide runway they can get away with that simply by ensuring that they start the kick with the aircraft on the wind side of the centre line. That way the drift simply brings them inline with the centre of the runway and at the very least they have some room to play with. So in a sense, the maximum crosswind component for a ‘kick’ method landing is really related to the width of the runway because for pilots employing this method, the higher the crosswind, the more they’ll drift.

Ultimately though, as Sam points out in his Slipping and Sliding, Kicking and Screaming post, the crabbing method can be dangerous, not only to the airplane structure but to the crew’s health should a runway excursion occur. But with the proper side slip technique, you bank in the direction of the wind and keep the aircraft aligned with the runway using opposite rudder. Here’s where the maximum crosswind component comes in; you can counter any crosswind using this technique but the higher the crosswind, the more bank required. And at some point, your angle of bank will be such that should you continue this all the way to the ground, your wingtip will contact the ground first. And to overstate the obvious, having your wingtip contact anything but air at anytime is a bad thing, but when that wingtip is the first thing to contact the ground on a landing, well, it’s not likely that things will end very well. It’s impossible to tell from the report as to when during landing this Delta aircraft wing strike happened, but I’d say they were lucky. In any case, the maximum crosswind component should make sense now.

So what did I do for my landing in this extreme crosswind? Although this was my first landing with a crosswinds anywhere close to the maximum crosswind component, I planned to do what I always do: side slip on final to correct for the crosswind. I did, however, request an extended downwind. That way I could ensure I would have a little extra time to stabilize my final approach. Although anticipated the tailwind I’d have on the left base for runway 34, my turn to base and turn to final were still one fluid movement. I then myself up in a side slip for the two mile final, during which I time I was able to monitor frequency of the gusting and how much more slip was required. I maintained the slip all the way to the threshold, at which point, unable to ensure I wouldn’t strike the wingtip, I transitioned to a bit of a combination; a partial crab of no more than perhaps two or three degrees with a slip to offset the rest of the crosswind.

I have so much time on the Warrior (though likely not as much as David so perhaps he can comment) that I am never surprised by the touchdown; it’s like having a built in radar altimeter. That said, I’m not entirely sure that it was the best method and I’m not sure that I would recommend it to anyone else unless they too were intimate with their aircraft. But the plane is home safe and without any undo stresses placed on the aircraft or it’s pilot. What I would recommend, however, to any pilot put into any situation on landing that they aren’t used to, is to setup for a long, stabilized final approach. Forget that rule about turning base when the threshold is 45 degrees off your wing in the circuit (or pattern) and instead ask for an extended downwind and thus an extended final. If it’s good enough for the big boys, I don’t see why us bug smashers shouldn’t use it also.

1 comment »

1. By David Megginson 2 days later:

   
   
   The technique you used at the end is similar to what I do. Once I run out of rudder authority in a slip to keep the nose lined up on the centreline (usually around 17 kt crosswind), I actually ease up on the rudder and fly in *more* of a crab, so that I have some room free in the rudder to kick the nose straight just before I touch down. Personally, I wouldn't bother with the long final. The winds and gusts are drastically different even at at 200 ft than they will be close to the ground (heck, they'll be different at 20 feet), so there is zero value in setting up the slip until you're below building/treetop level -- just crab until you cross the fence and set up your slip when you're over the numbers (being prepared to overshoot, of course). I often find that a brutal lion on 1/2 mile final has turned into a pussycat by the time I'm skimming a few feet above the runway. Some people deal with a crosswind by touching down fast with no flaps. Certainly, extra speed helps with the crosswind correction, but it also increases your risk of losing control on the rollout because there's less weight on the wheels at first. I always land full flaps, because I figure landing slowly in a crab and leaving a bit of rubber on the asphalt wouldn't be nearly so bad as careening off the runway at 80 knots (~150 km/h!) and likely nosing over or bending a wing.