Here's a Challenge

I'd finished all of the Juneau Hub flights, so I decided to start the Alaska postal circuits. I started with the circuit out of Anchorage. For reasons I'll explain in a subsequent post, I found myself doing this in the newest version of the Aerosoft DHC-6 Twin Otter. For my money, this DHC-6 is not an easy plane to fly. It is particularly prone to engine fires and you have to watch your start procedures and engine gauges like a hawk. I gather this feature was added to enhance the realism of the model. On top of that, I would say that it's moderately difficult to control. The engines spool up and down slowly, the aircraft is kind of twitchy and tends to wallow at slow speeds. It may well be that these features mimic the real aircraft; they certainly require additional skill and attention. On the other hand, the engines are powerful, it has good cruise speed for a bush aircraft and has tricycle gear, tundra tires and a reversible prop, all good attributes for short bush strips.

So, I was optimistic leaving Anchorage that I could complete the circuit in the times called for. The first landing at South Gasline (AK39) went OK. The strip is laid out along the gasline, so it's easy to line up on final, once you decide which is the strip and which is the service road. It wasn't the prettiest landing I've ever made, but I didn't break the airplane or trim the vegetation. So, I figured I'd get better with practice.

However, the next leg was over the mountains to Whittier (PAWR). I've been in there before and I remembered that it was problematic. On top of that, there is no ATIS or AWOS, so I wasn't sure what I was getting myself into. Not to worry though, because it's not like you get a choice. Whittier is located right on the water of the Passage Canal. In fact the runway, a 1480' gravel strip actually protrudes into the water, and, at least in FSX, it features a small, steep hill towards it's western end. Behind the western end is a steep, winding valley leading up to the Portage Glacier. So, you have to approach from the east and land on Rwy 22, because there is no plausible approach to Rwy 4 from the west. Even the approach to Rwy 22 can be difficult, because the Passage Canal itself is narrow and set between two high ridges. On top of that, you had better make it on the first try, because in the official airport description it says.."Go Around Unlikely".

I was fortunate to get a break in the overcast which allowed me to fly down to the water with good visibility going eastbound. I then made a turn within the gorge and started westbound up toward the strip. The visibility was pretty good and I could set a docked cruise ship on the southern shoreline as I approached the strip. However, the wind was not propitious: 096/19/24. If you recall your high school trig (or have an EB6), you can figure out this means a tailwind of about 8 Kts., and a crosswind of about 17 Kts. These numbers would be problematic under the best of circumstances. The crosswind means that you have to crab into the wind to hold the runway centerline on approach and then use the rudder to line the aircraft up with the runway just before touchdown so that you don't collapse the gear and roll the aircraft. On top of that, the tailwind means that you will be landing almost 10 Kts. faster than usual at stall speed. This isn't good news, particularly on a short strip.

But, I thought it was worth a shot, or maybe ten shots. However, I just could not successfully land the Otter under these conditions. As I usually do, I saved the flight on approach, so that on a crash FSX would revert to the approach and I could try again. It was simply too hard to hold the runway centerline, manage the altitude and airspeed and touch down on the end of the runway, anywhere near the centerline (the runway is only 60' wide) with the aircraft pointed down the runway. I could meet all of those conditions but one or two. Sometimes, I landed long, sometimes I was on the side of the runway, sometimes the aircraft wasn't level when I touched down, and even when I was close, my high speed meant that the nose would go into the strip when I reached the steep hill towards the west end One time, I managed all of the above, but was left of the centerline and clipped some trees just off the runway.

So, I swapped out the Twin Otter for the trusty DHC-2 Beaver with tundra tires and made it on the first attempt. Maybe that's because the Beaver isn't as "twitchy" as the Otter. But maybe it's really just a matter of using the right equipment.

After I gave up, I went to the complete set of manuals provided with the Aerosoft DHC-6. There I learned that a 9000 Lb. Otter with a 10 Kt. tailwind requires a landing distance of 1880' So maybe it wasn't all about my flying skills. Maybe I just needed an additional 400' of runway, and no hill in the middle.

So, the moral of this story is similar to theme of my last few posts. It was not realistic to attempt this landing and (I suspect) a professional pilot would probably never even try. First of all, an experienced bush pilot would probably not have left Anchorage with an intent to land at Whittier, because, even with no tailwind, the Twin Otter requires 120' more runway than is available at Whittier, and a pro should know that. But suppose that our pilot has long experience flying the Otter and knows he can beat the performance tables. He still wouldn't try because he would know that he couldn't do a go around at Whittier. So, it would be a foolish thing to try unless you were absolutely certain you could do it on the first attempt. But suppose he thought he could pull that off. When he got there and discovered that he'd have a 17 Kt. crosswind on final, he'd abort the landing attempt and return to Anchorage.

So, my sense of practicing realism in this hobby would require that we know the capabilities of the aircraft we are flying, that we know our own capabilities in handling the aircraft and, when conditions are bad, we call it off and return to base. I didn't meet any of those conditions before this flight and the outcome demonstrates the almost certain consequences of failing to meet them.

Mike

Interestingly, the AK39 - PAWR flight was my most recent CFIT incident. I'm still trying to find a 'reasonable' margin of error using navigational instruments to identify where to safely descend between mountain peaks.

Needless to say, I came up short here aiming for the bay where PAWR is. The problem is that there is a lack of exactness when you try to fly a radial and drop out of the clouds a certain distance from the VOR.

In this case - considering the target area and the alternate route - flying the long route around the mountain through Turn Again Arm, I chose the long route and made it successfully. Still, I jumped over the last hill at the wrong point and ended up in the adjoining bay. The topography was adequate to recognize what I had done and I easily followed the shoreline around to the correct bay - landing my trusty beaver successfully on my second life.

I also had trouble finding AK39 because I didn't recognize that it was just the wide spot in the gas line (or roadway - whichever it is). Finally figured it out - but wasted too much fuel trying to find it and had to return to PANC for enough fuel to make the PAWR leg.

I agree with all of the above George.

John, I gave up with the DHC-6 and took the DHC-2 from AK39 to PAWR this afternoon. Like you, I stayed under the ceiling and flew around the north end of the Kenai Mountains and then down the Turnagain Arm to the Portage Visitor Center and then up and over the Portage Pass to Whittier. I was at the Portage Visitor Center in Sept. of 1990, but I don't recall knowing then that there was a tunnel under the pass to Whittier. It was late and we were on our way down to Kenai, so we wouldn't have had time for a side trip anyway.

Even with the trusty and easy-to-fly Beaver, it took me three shots to nail the landing. But, if you manage the throttle well, you can touch down just past the threshold and roll the tail dragger to a stop before you reach the hill on the runway. Great flight.

Yes...Whittier is one of my most favorite destinations - and easy to land with on with the beaver, but you do have to be low along the water and touch down as close to the 'numbers' as possible.

I've now moved on to the turbo prop segment of the postal flights without gps. I consider all of my flights a combination of instrument and visual flights (Most of the flights I either don't have the necessary weather to disregard my instruments, or I'm still in too much of a hurry to fly through the various valleys to my destination. I try to fly direct - over the mountains, and use the instruments to drop down below the clouds in a safe area near my destination so that I can follow the final valleys or river to my location.

This last group of postal flights certainly qualifies, as they are generally far apart and over significant mountainous terrain.

My first flight (PAKT to PAJN) I turned off the GPS - something I can actually do with the MU-2. I then followed the VOR to Sister's Island and from there followed the VOR/DME approach plate. This was necessary since the weather was broken at 6000 and 5000 feet, which pretty much left a lot of clouds considering that the approach to Sisters Is. was at 5600 minimum.

From Sisters Is. I set a course away from the VOR 7 degrees for 12 miles that would take me to the Lynn Intersection and an initial approach fix for localizer approach to PAJN, descending according to the approach plate. As the clouds cleared, I could see I was on track with my approach, and when I saw the 12 Mi from Sisters Is appear on my gauge, I shifted again to a 71 degree heading for the offset approach to Rwy 8 at PAJN. At this point I also switched from HDG to APP mode and, as expected (hoped for), the localizer needle came alive and I clicked the APP button and honed in on the localizer, descending according to the approach plate for a safe landing at PAJN.

Along the way - when the clouds parted enough for visual reference, I was able to verify my location based on my distance along the Sister's IS radial and the underlying terrain based on my VFR chart. I flew at 8500, which was a safe altitude for my flight path - as long as I followed that radial - although it did take me a while to move far enough westward to pick it up and lock it into the auto pilot.

What a fun way to fly!

John

John,

I've made just that sort of quasi IFR approach to PAJN 8 a number of times. In fact, I use that approach even when I could land VFR, just to practice the procedure. The big problem of course is the lack of a glide slope on the LDA approach. It's a matter of adjusting your rate of descent to your airspeed, something which is not that easy to do without an autothrottle.

I've been trying to fly "pure" VFR on the Anchorage postal flights and, as usual, the problem is finding the destination airstrip without using the GPS. The information on the destination available through Sky Vector gives the distance and radial from the nearby VORs to the airstrip. This provides pretty good guidance to your destination, as long as the vector from the VOR to your destination does not make a small angle to your course. In that event, both the radial and the DME are weak discriminators of your position. If that angle is close to 90 degrees, a single VOR is adequate.

In any event, it seems to be a matter of maintaining sufficient altitude that you can visually search a large area for the strip, because dead reckoning is not adequate to hold a sufficiently accurate course that you will fetch up the strip. On top of that, some of those small strips are very hard to see from the air, particularly without use of an outside view.

So, I've got a ways to go before I have developed my technique to the point at which I do not ever have to "peek" at my GPS.

Mike

Mike,

When you say pure VFR, does that mean you don't set your radio for any VOR and fly only by what's out your window?

I think an additional handicap is the way FSX generates scenery - at least with my settings. Much of the scenery isn't generated until I get close enough to it.

John