I really enjoy those YouTube posts of airliners landing in strong crosswinds. I just watched a good one of 15 minutes worth of landings at Amsterdam Schiphol. Most were twins but there was an A380 and 747 in there too. The thing that strikes me is how many landings are with the crab still in. Only a few of the pilots push the airplane straight before touchdown as we used to call it. Most of the pilots who do push are flying Boeings. The Airbus guys seem to all just land in a crab. I never thought that was a good idea, or even possible, in light airplanes.
Gusty crosswind landings are always a challenge and I always thought they were sort of fun and the reward of a good touchdown in those conditions was satisfying. I watched another video of an airliner that was taken in the cockpit and the pilot was really wrestling with the controls. To me, part of the challenge was to deal with turbulence as smoothly as possible with only the essential control movements.
Occasionally when flying in bumpy air with a pilot who was fighting the controls, I would ask for the controls and hold them as still as possible. That could even be stock still. The turbulence would calm down a bit when this was done and the airplane didn’t do anything crazy.
Low-level turbulence is a given on a windy day, or even on a hot day. That accounts for but a small portion of a cross-country flight and I always thought that anticipating and dealing with turbulence other than the low-level stuff was far more interesting and educational. If I had passengers, I wanted to know enough to explain in advance what we would encounter during the flight. If it wasn’t as anticipated, I wanted to be able to tell passengers why that happened.
I worked at this with no passengers, too, but with a bit less emphasis on keeping the ride as smooth as possible. Like all pilots I would rather have smooth air all the way but it was just more important with passengers. If flying IFR in clouds, the fact that turbulence there makes many riders uneasy and uncomfortable has to be acknowledged, and even some pilots riding as passengers get antsy in bumpy clouds. Even some pilots who are flying are unnerved by such conditions, especially if they are not anticipated.
All this suggests that the potential for turbulence should be an integral part of pre- and in-flight weather study. And I found over the years that experience is the best teacher because with turbulence what you feel is what you get.
My en route turbulent education started one spring day in 1953. I was 19, flying the PA-12 Super Cruiser that I had bought when I was 18. My big plan was to fly from Camden, Arkansas, to New York. I was a VFR pilot, as were all others around the airport, and, when considering weather, fronts were the big deal. They were considered almost impenetrable when the flying was limited to VFR.
Things looked good this day because a cold front had just passed. The surface wind was a bit whippy but I was used to that. Soon after takeoff, flying in clear air, I encountered turbulence that felt like it was going to turn my Cruiser inside out. Me too.
It took only a minute of this to convince me to turn around and return to base. I had quickly decided that I didn’t know enough about weather to fly a trip of that length. Such wisdom for a 19-year old.
At the time, I didn’t put comments about conditions in my log entries so can’t share that. I do remember that the decision to return and land was made less than 30 minutes after departure.
I later learned that the turbulence was associated with wind shear along the slope of the front and that if I had waited for few hours after frontal passage, things would have calmed down. Over the next 55 years I learned that again, and again, and again.
One of the best lessons that I learned (and obviously forgot several times) about this came from an article in the May, 1964 Air Facts. It was actually the transcript of a speech on Short Haul Transport in Rough Terrain by Captain Donald H. Rieger of Piedmont Airlines. The original Piedmont flew the eastern mountains in DC-3s and later YS-11s and Martin 404s and if their pilots hadn’t seen most everything in the way of turbulence, then nobody had.
He spoke of pre-frontal, frontal and post-frontal weather as being the real turbulence generators on Piedmont’s routes. Then he offered an observation that I haven’t seen anywhere else.
We do have one post-frontal turbulence phenomenon that may be worth mentioning. During the winter months we have some periods of very warm weather at which time the mountain valleys become filled with warm, moist air. If a fast-moving cold front being pushed by very cold Arctic air moves across the mountains at this time, the cold air will overrun the warm air trapped in the valleys. Mother Nature, in an effort to return things to a natural balance, becomes impatient and the cold, dry air descending rapidly through the rising, warm, moist air can generate a band of severe turbulence that will cover the entire mountain range.
He went on to tell of control difficulties, seat belt burns and other injuries as well as pilots so sore the next morning they couldn’t get out of bed.
Captain Rieger also told of the difficulty in forecasting this condition because there are so many variables. The observation that struck me as most helpful is that the conditions last until the valleys give up the warm, moist air and things calm down after a period of six to 12 hours.
Fast forward many years to January 29, 1993, when Pete Bedell and I were flying my P210 from Winchester, Va., to Asheville, N. C., to visit with my father. We’d be dealing with Captain Rieger’s mountains and, you guessed it, a cold front passed through as we were driving to the airport.
Winchester is not far to the east of the mountains so we’d be starting over the rough terrain soon after takeoff. The result was pretty spectacular. As the airplane bounced around we encountered downdrafts that made it feel like all the air had been sucked out of the area. I could visualize that cold air swooping down into those valleys, scouring out the warm air, and then swooping back up, ever stronger, to harass my little airplane.
The clouds were about as ripped up as I had seen, too. Pete was flying and he’s more used to a stronger-climbing Baron so he was taken by what the downdrafts were doing to the P210’s rather puny rate-of-climb.
As we flew toward Asheville, the conditions moderated and the trip back that afternoon was in normal post-frontal conditions with smooth air at FL190 and manageable up and downdrafts.
My logbook for that leg showed two plus 45, from W16 to AVL, comment: Strongest UDDFs in a long time. Unable to maintain altitude.
On another trip to Asheville that was launched right after a cold frontal passage, I got tired of dealing with the downdrafts and landed for some lunch while it calmed down. I also wanted more fuel. The groundspeed was varying so much, from 80 to 160 knots, that it was impossible to come up with even a wild guess about the time to go until reaching AVL.
I flew that route hundreds of times and while it was often possible to offset the route to one side or another, to maximize the updraft time and minimize the downdraft time, that didn’t work that day.
My logbook for that first leg showed two plus 35 from HGR to PSK, comment: Extreme UDDFs, landed PSK for more fuel – wind abated after a pause for lunch.
Because I flew to and from Asheville so many times I learned a lot there about wind-induced turbulence in mountainous terrain. In fact, I did it so many times that I felt like I knew where the really big bumps were located.
The elephant in the room at AVL is always Mount Mitchell, at 6,684 the highest peak east of the Rockies, not far northeast of AVL. Coming in from the northeast my strategy was to stay on the west side of the mountain. This meant filing to an intersection that was on the Rwy 16 localizer about 15 miles north-northwest of the airport. (The localizer is gone now, replaced by a GPS approach to the runway and the pavement has become Rwy 17.)
That worked like a charm when the wind was from the usual strong directions, from southwest around through northwest. Then one day I was headed to AVL when there was a strong southeasterly flow caused by a tropical disturbance. I think smoke was coming out of my ears before I finally formulated an IFR arrival plan that would avoid the area west of the big mountain.
A really memorable trip was notable for just a little turbulence where a lot of turbulence had been anticipated. I’ll give the log entry for the trip first and then tell you about it. The leg time was three plus 05 from IXD (Kansas City) to HGR, comment: Fast. Over low and front, top groundspeed 324.6, new record. That was a bit of sweet revenge for the seven hours it had taken to get to IXD a couple of days before.
The fast trip was in my P210 at FL210 and the groundspeed reflected a maximum tailwind if about 140 knots. That would certainly qualify it as a jet core or jet streak which is an area of extremely high wind within a strong jet stream flow, in this case from slightly north of west to begin to southwest a bit later.
Because there is plenty of wind shear in the transition zone from the garden-variety strong wind aloft into and out of the jet streak, this is the stuff of which notable clear air turbulence is made. I had always heard the turbulence is more pronounced on the cold side of the streak and I started off this leg on that cold side. The air was not smooth but it was just jiggly as I watched the groundspeed work its way up to that 324.6 mark.
It stayed there for just a bit but I knew that it would soon be time to descend and also that I would soon be starting to fly out of the jet streak.
The descent would be complicated by the decreasing tailwind. That 324.6 groundspeed would have to work back to a more reasonable value and that meant the airplane would have to decelerate by that amount at the same time I was trying to descend. With the power back to the gear horn threshold and with the airspeed slightly below the top of the green, I was not getting much rate of descent. I had told the controller I needed to start down early and he understood and was quite helpful.
I was locked and loaded for turbulence as I flew out of the streak but, again, it was not there. The air was a bit more jiggly than it had been when flying into the streak but it was nothing more than light chop.
Clearly, this day any seat belt burns would have come from my continuous tightening of the belts in anticipation of bumps that never came.
A lower and lighter airplane like mine actually does better in most forms of clear air turbulence than the much heavier and faster jet airliners. The slower you are flying in strong wind shear conditions, the less vigorous the bumps. That is because the changes in wind are addressed more gradually.
I did once encounter jet streak turbulence that convinced me to stay low, below the streak, even though a better tailwind would have been available at a higher altitude. There was no hazard, just a desire for a smoother ride.
Another place where wind shear turbulence can jostle the airplane, sometimes with great enthusiasm, is along frontal slopes, where cold and warm air is doing battle.
Here I am going to discuss what, to an aviator, is a relatively rare thing to encounter but something that can be memorable. When you look at the dates on the next two log entries, you can see that flying through an occluding front is not something that slips quickly from memory.
The first entry is from 11/26/1976. N2254L, BE-24, MSL to MEM, one plus 50 enroute. I made no comment entry after this flight because, quite frankly, I didn’t know what was going on but when it takes almost two hours to cover 117.8 nautical miles something is quite definitely going on.
I was flying the Beech Sierra for a pilot report and the mission of the day was to get from Asheville, N. C. to Little Rock. It turned into a long day with six hours required to cover the 500 miles.
AVL to MSL was slow but nothing special and I made the stop to buy gas because of a rapidly deteriorating groundspeed. MSL was reporting nine hundred overcast and five miles so I flew the ILS to runway 27 and landed on that runway with a crosswind from the left and maybe even a little downwind component.
Headed toward Little Rock out of MSL, and flying in clouds, the air was churning weirdly. The autopilot was going nuts over the bumps so I hand flew. It might have been a slug but the Sierra was a stable airplane and a good ride in turbulence.
It was showery with occasional bursts but the controller said he didn’t see anything really bad. While the turbulence was jarring, there were no up or downdrafts so I knew there was nothing convective in there. The amount of drift was obscene. This was before GPS but the DME was telling a tale of extremely low groundspeeds. The landing at MEM was on Rwy 27 with a howling crosswind from the left. I stopped there because I was, as we say in that part of the country, woe out. I needed a time out after flying through the chaos of an occluding front without knowing that was what it was. There was no mention of such in the briefing but it did show on later weather charts.
Research and a consultation with my weather guru enlightened me and I was convinced that this was something to avoid.
Jump now to 04/06/1988 and a day that was to take me from Trenton, N.J., to Wichita. The pertinent log entry for the first leg that day read: N40RC, TTN-OSU, Three plus 25, Comment: Divert to OSU due wx. One plus 30 wx delay. The weather synopsis suggested a strong surface low just north of the route but did not suggest or show an occlusion. That was for Mother Nature to know and me to find out.
I was below the clouds for a while and could look up and see that they were angry clouds indeed. There was a lot of churning. The ceiling lowered as I flew west and I was soon in those clouds, enjoying a lot of churning.
Dayton was my original plan for a fuel stop but as I neared there the flying was quite uncomfortable. There was no convective activity and my Stormscope was clear. One airline pilot said, though, that cells are popping up all over. When I realized I was going to be in a long line for the ILS at Dayton, and much to the relief of the Dayton controller, I said I’d divert back to The Ohio State University airport at Columbus.
When I got back to OSU, I landed on Rwy 14 into a quite strong and gusty southeast wind. The surface wind at Dayton, not far to the west, had been strong and gusty out of the southwest. That indicated that the occlusion was between the two points. After an hour and a half on the ground, conditions seemed to have calmed and I actually had a smooth but slow trip on to Wichita.
Maybe I had learned something because on a number of subsequent trips I deviated pretty far south to stay a greater distance away from a strong surface low. Occlusions are most common closer to the center of the low.
Perhaps there is a reason that occluded fronts on a weather map and bruises are the same color.