Last Sunday (July 31) I had a very hard landing while flying the NCSA Grob 103 (N3981C) at KTRK. Several members of the club have asked me what happened, and since I think my experience can help others avoid a similar situation, here is a description of what happened.
First, let's be clear: cause of the event was pilot error. I'd love to say otherwise, but I cannot. I blew it.
The short version is that, despite being aware of the hazards and the weather conditions, and actively thinking about them throughout setting up the landing and the downwind leg, somewhere between turning base and landing I managed to let the airspeed bleed off so that my final approach was made without sufficient airspeed margin. The more detailed description is as follows:
The landing took place on runway 20 at approximately 2:20 pm, at the end of a flight of approximately 38 minutes duration. I was flying from the back seat; I had a passenger on her first flight in a small aircraft in the front seat.
The general conditions of the day were that the valley was filled with smoke from nearby fires, there was a southwesterly wind varying from 10 to 20 knots on the ground, and the air was somewhat turbulent aloft. The smoke affected the visibility, so that nearby mountains were visible in outline, but not detail, and from 10,000 feet directly over the airport the town of Truckee was easily located but hard to make out in detail; locally, however, (within several miles) visibility was fine and was no factor.
My passenger became somewhat nauseous as we climbed through 10,000 feet in bumpy thermals, and asked me to fly straight instead of turning; I accommodated her wish, flying a long back-and-forth pattern through the house thermal over the frog pond, losing a bit of altitude on each pass until I was down to 8300 feet or so, and informed her we would have to thermal or land. She asked me to land, so I headed back to the initial point.
The area around the North Star parking lot was solid lift, and I had to use full spoilers to drop to pattern altitude for entry on the 45. I closed the spoilers before I entered the pattern; realizing I wanted to preserve my altitude. While maneuvering toward the pattern entry I tuned in AWOS. Wind conditions were reported as “240 at 10 knots, gusting 21 knots”. The wind was at 40 degrees to the runway heading, and I realized this meant the crosswind and parallel components would be similar in strength and would likely be somewhat less than 10 knots. In a gust, though, the crosswind component could be noticeably higher, even as much as 16 kts or so.
I consciously applied the adage of adding “1/2 the wind speed” to the book approach speed of 55 knots. I split the difference between wind and wind+gust and decided to add 7 knots to the approach speed, making my approach speed 62 knots. I also reminded myself to make a high approach and turn downwind-to-base “inside the spillway” (Martis Lake Reservoir has a spillway northeast of the approach end of runway 20; the plan was to make the turn between the end of the runway and the spillway.)
There was no traffic in the pattern; a tow plane and glider departed from runway 20 as I entered the downwind leg and was no factor, and a general aviation aircraft was at the threshold of runway 29; they radioed to me that they would hold their takeoff roll until I either crossed runway 29 or rolled to a stop on runway 20; again, they were no factor.
I made several radio calls: that I was about to enter the pattern, upon entering the 45, upon turning downwind, upon turning base, and upon turning final. It was just after I called the turn to base that the general aviation aircraft holding on 29 called me and we had our brief conversation.
I made my turn to base leg inside the spillway, as planned**. I opened my spoilers on the base leg, but as I turned final I felt I was getting low too fast and closed them. I felt my speed was ok*, but I do not recall actually checking it at that time.
Then things got dramatic. As I crossed the cliff at the end of runway 20 I encountered either a sudden lull in the wind or a rotor over the cliff’s edge; whichever it was, the practical effect was sudden loss of airspeed and, without sufficient airspeed margin, a loss of lift. The aircraft dropped “like a stone.” It was a sickening feeling to sense it dropping so fast and realizing I had essentially no control over what it would do.
But I knew what was obviously what was going to happen- a hard landing was in my very near future!
We landed very hard on the main wheel, at or just barely beyond chevrons marking the displaced threshold. I rolled to a stop on the apron where the tow planes normally park. The landing was hard, but I did not feel the tail wheel hit, and I do not think it did. Nor do I think the nose wheel hit; it felt like I came down squarely on the main wheel. I do remember being a bit surprised that we did not bounce back into the air noticeably.
So how did this happen? I believe the cause of the hard landing is that I allowed my airspeed to bleed off during the base leg and the turn to final, and hence did not have sufficient margin on the airspeed to compensate for any gusts, lulls, or wind shear that I might encounter (and that, obviously, I did encounter). This was exacerbated because, despite my best intentions, I did not come in on a high, steep approach. I allowed myself to come in too slowly, and lower than I had planned.
As I said when I started: pilot error.
I wrote all the words above Monday, while the incident was still fresh in my mind. Tuesday morning I carefully examined my IGC file using OLC, skylines.aero, and Doarama, and discovered, to my surprise, that:
* 1) I was flying even more slowly than I had recalled on my final approach. The GPS ground speed on my downwind leg was 70kts, on base leg 62 kts, and on the final approach 45 knots. If I assume 10 kts of wind at 240 degrees the airspeed values become more like 63 kts on downwind (essentially as I had planned) but only 52 knots through most of the final leg. I also saw that I allowed the speed to further bleed off to 38 kts (GPS ground speed) just at the threshold. If the wind were still at 10 kts that would have been 45 kts of air speed, barely above stall speed, as I crossed the threshold about 50 feet above the ground. If I hit a lull (or the wind was blocked by the trees, which is what I think actually happened) I would have been at or below stall speed! That is what I believe occurred; I stalled the aircraft while still well above the ground, and down we went. I still had forward momentum, of course, so still rolled out along the runway after the landing.
**2) moreover, although I started my turn to base "inside the spillway," I did not crab and I let the wind blow me into a rounded base leg rather than a square one, drifting downwind so the base leg was actually outside, rather than inside the spillway, making my final leg somewhat longer than I planned.
3) The analysis confirmed something I had realized just after the incident, namely that I should have flown the entire pattern higher, and that I had lost sufficient altitude on the downwind leg that I should have made my base turn considerably earlier, probably when I was even with the numbers. I had actually made two turns between NorthStar and the Initial Point (the so-called Lone Pine) specifically to burn off altitude with the goal of entering the pattern around 7400 feet, 1500 feet above ground. But I made the turns too far out from the IP and was in sink from where I made the turns all the way to the IP, so that when I reached the turn to downwind I was already down to 6800 feet, just 900 above terrain! I did observe during the downwind leg that I was lower than I wanted to be; however, for some reason, I did not correct for it appropriately with an earlier turn to base.
In short, I was too low and too slow and I did not recognize and correct for those facts.
= = =
So, what is my corrective plan for the future?
First, whenever I fly in future I will strive to be more attentive to my landing plan, making sure I am following it and also making sure that it is working; I’ll be much quicker to make an adjustment, such as making the base turn sooner.
That's in general. A more specific corrective plan involves what I will change about flying at Truckee. I talked with Mike Mayo shortly after the incident – when I told him my airspeed plan had been 62 kts (approach plus half the wind), he observed that the "approach speed" in the POH was selected with nice, smooth-air, open field German landing strips primarily in mind, and not for the kind of roiling conditions commonly found in Truckee (and other gliderports in the Western USA) and that his approach at Truckee is to always come in at least at 70 kts, if not 80 kts, precisely because of the rotor and tree-line effect on runway 20. As he pointed out, runway 20 is a long runway, and coming in with plenty of airspeed at worst means the ground crew has to drive the golf cart a long way to get you. His comments make sense to me, so I will elevate my basic approach speed for KTRK from 55 to 65 in a G103 and then add for the wind speed from there. This would have made my target speed for this landing 72 kts. I will also follow my plan of entering the pattern at a higher altitude than I did. In conversation with Larry this afternoon, he observed that he likes to hit the Lone Pine IP at least 1500 feet AGL; in fact, that had been my plan, but I actually was 600 feet lower than that when arrived at the IP. I think, with the long runway to use, a higher, steeper, faster approach has now become my normal plan for Truckee, with modifications for specific conditions as necessary.
Finally, there is a very frustrating side note to all this. I was well aware of Bill Gawthrop’s crash at Truckee two years ago. Like many pilots, I have studied his trace and I have read with interest not only his description of the event but also the lengthy discussions and analyses of his accident on rec.aviation.soaring. I was very much aware of the mistakes Bill made, and I actually thought about them as I was setting up for the landing pattern.
And yet, I still came very, very close to replicating his experience.
Having a plan is only useful if you follow it while it is working, recognize when it isn't, and take decisive remedial action when necessary.
You can see the trace of the flight at Skylines.aero, at:
I've also put together a Doarama visualization of the last few minutes of the flight only, which may be seen at:
I also posted it on OLC, so another trace can be seen at:
Friday, August 5, 2016
Wednesday, August 3, 2016
On July 16th, 2016 I had the distinct pleasure of sharing a 503 km cross country flight with Tim Gardner as my XC mentor. The flight was a raffle prize generously donated by Laurie Harden of Soaring NV at the Pacific Soaring Council awards banquet last winter.
Thank you Laurie and Tim!
|The Soaring NV flight line|
My soaring cross country experience started last summer and since then I have logged a little over a dozen flights in the 200-300 km range and I was thrilled when they pulled my name out of the hat for this cross country mentoring flight up at Minden in a Duo Discus.
I scheduled the flight and watched the weather with great anticipation as our date approached. It is a 4 hour drive to the Minden airport from my house in San Carlos, CA. But this was well worth the effort given the huge learning opportunity I was looking at. I arrived at KMEV at 10am and met the staff at Soaring NV. They were polite and professional and I felt right at home.
Tim showed up shortly thereafter and we discussed the weather, TFRs (what would flying the Sierra be without at least 1 forest fire TFR), airport procedures, and chose our route of flight and outer turn-point. Based on the forecast we opted to fly South to the Whites and get to at least Bishop before turning back and we agreed that 4pm would be the latest we should turn back in order to make it home before the lift shut down.
|Inside Soaring NV|
Lucas was working the line and helped up get the glider ready and out to the line. We were number two for tow and were in the air at noon. We took a 3,000’ tow because it was completely blue, the local lift wasn’t very good for getting out of the valley the day before and the forecast for today was about the same. Our first climb got us 13,500’ and the optimism to run down the Pine Nuts and try for the altitude needed for the jump to the next range. But we got stuck at the end of Pine Nuts waiting for the lift to get organized.
After thrashing around for over a half hour working week/disorganized lift we made it to just over 14,000’ near Farias Wheel Airport and headed South to the Pine Grove mountains where some clouds were starting to form. A couple thermals later we were over 17,000’ and charging on past Baron Hilton’s Ranch and Lucky Boy Pass (I took this as a good sign). All along the way Tim was pointing out airports, waypoints, decision points and xc strategy. I was impressed and grateful for his wealth of knowledge and teaching style.
|Southbound into the blue|
|Soaking up the adventure with an excellent teacher|
Now we were cooking and making good time. We worked a couple thermals along the way and were able to stay above 15,000 and with over 17,000’ had a comfortable altitude cushion for the 35 km jump to our next goal, Boundary Peak and the White Mountain range. The flight thus far was an incredible experience and I was a sponge absorbing all the information along the way. My prior cross country flights were in the area to the North and West of Minden between Truckee, Air Sailing and Nervino and this was this was my first time flying out of Minden and to the South. As we approached the Whites I was awe struck. Tim said that soaring the Whites is a great experience, but all that much better when you have to fly a hundred miles to get there.
|Heading back to White Mountain|
We started off ridge running all the way to White Mountain where Tim showed me how to thermal a canyon from below ridge top. I let Tim take the controls for this lift and was impressed with his skill and a bit nervous every time we turned into the ridge as this is a skill I had not yet developed. We were climbing like the proverbial bat out of Hell when Tim asked if I could see any hikers on the ridge-top path. There were about a dozen and Tim decided it he wanted to give them a photo opportunity. So it was time for full spoilers and we spiraled down a couple thousand feet back down to the ridge were he gave them a high speed pass “up close and personal”. Here is a link to a video of the fly by:
|"This is Maverick, requesting permission to buzz the tower..."|
Now it was back to my turn to get that altitude back and off we went South across the valley, over Bishop and beyond to just pass Coyote Flats. We got there low, at around 11,000’, and it was a struggle getting back up. Another glider was reporting a strong convergence over the Sierra to the South and West of our position and asked if we wanted him to wait so we could join him. We could see the cloud streets from where we were. However, it was going to take us too much time to climb out so we told him to keep going as we again struggled, waiting for the thermals to cycle.
Our persistence paid off but it was now around 3:30 pm and close to our agreed upon turn-back time. Since the clouds to the North were starting to dissipate we agreed to head back and had to make our next decision. Do we cross the valley back over to the Whites where the lift was still strong and marked by a cloud street all the way back to Boundary peak or head off on the more direct path toward Mono Lake.
|Cu markers ahead|
Although we saw only two cloud markers we decided to go direct to Mono Lake. It was 35 km to our next good climb and then we crossed a big blue patch with no lift for about another 55 km. This lift was a bit disorganized but we again persisted and got the altitude we needed for the next jump to Mono Lake.
|Looking at the Sierra from the east|
We chose well and reached just South/East of Mono Lake at 14,000’, found a climb to 17,000’, and were off on our next jump North.
Running the gauntlet direct to Mono Lake, Sierra to the left and Whites to the right
|Time to go, Sierra on your hip, go fast!|
Our next struggle was above the old ghost town of Bodi in weak/disorganized lift with only 1 knot on the averager. Our second thermal in that area was much better and at about 15,000’ we encountered wave and were blessed with smooth 6-8 knots lift to 17,999 and had final glide in the bag. Our glide back was a straight shot of 95 km at 120-130 knots ground speed and was very satisfying after such a challenging day.
By the numbers we did 503 km, soared for 5.5 hours at an average ground speed of 90 km/hr, and used 41 thermals to get around the task. It was an amazing experience and I would recommend it to anyone wanting to kick-start their cross country soaring training.
Here is the trace of the flight, which can be found in more detail at https://skylines.aero/flights/66975/
And lastly, I cannot end this tale of good fortune without again praising the staff, tow pilots, instructors and line kids and fleet of SoaringNV. This type of one-on-one training cannot be passed up.
So give a big Hello to Laurie and the rest of the crew from me next time you are out at SoaringNV and take them up on their offer, whatever it may be. You will be glad you did.