Aleutian Adventures

It will not come as a surprise for you to learn that the winter weather in the Aleutians is not optimal for air operations. I am still working away at the Alaska Marine Highway Tour from Bellingham, Washington to Atka, Alaska in my DHC6 Twin Otter. As I write, I am newly arrived in Sand point (PASD), at the end of 25 of the 29 legs of this tour. As I have begun working my way southwest out the Aleutian archipelago, I have had to say goodbye to ATC with radar control and airstrips with ILS approaches. On good days, in clear and still conditions, this has been OK. Other times, not so much.

Last Monday, I made a flight from King Salmon (PAKN) to Port Heiden (PAPH). When I left PAKN, Port Heiden was reporting 5 SM and CLR; not a problem. The wind was not looking quite so good at 030/27G31 KT. Still, PAPH has two runways (14/32 & 6/24), so that stiff crosswind promised to be just 24 degrees off the bearing of Rwy 06 (054 deg.). However, as I approached PAPH, the weather deteriorated to 014/27 with a ceiling of 3300' BKN. But, Rwy 06 was still the best choice, 40 degrees off the wind, compared to 54 degrees for Rwy 32. I had to abort my initial approach to Rwy 06 because I was unable to hold the runway center-line on final. I went around and made another effort, crabing (yawing) at about 15 degrees to stay on the center-line all the way down to the runway.
<img src="coppermine/albums/userpics/10009/22/MYJETLINE-PC-2020-jan-27-006.jpg" alt="Approaching Rwy 0 at PAPH" width="1000" height="625">

This gets tricky just as you land, as you need to kick in enough cross-rudder rudder to line the gear up with the runway before touching down and do it without letting that wind get under your windward wing and flip you over.

<img src="coppermine/albums/userpics/10009/22/MYJETLINE-PC-2020-jan-27-007.jpg" alt="Just above touchdown." width="1000" height="625">
If you compute the crosswind component of a 27 KT wind 40 degrees off the runway, you will find that it's almost 21 KT. I thought that might exceed the published capabilities of the aircraft, but apparently those spec are not published by the manufacturer, as the literature only talks about the demonstrated crosswind capability/ Apparently, it dpends mainly on the skill of the pilot.

In the event, I didn't get completely lined up before the wheels hit, but the DHC6 sim let me get away with it. It's not so clear that the real aircraft would have been so forgiving. There is another, probably better way to make this sort of severe crosswind landing. It's called the low wing approach. I haven't really practiced this, but as I understand it, you use the ailerons to bank toward the wind, lowering the windward wing. Ordinarily, this would put you into a continuing turn in that direction, but you buck this out by applying reverse rudder, causing the aircraft to yaw to lee. In theory, this will allow you to keep the aircraft's longitudinal axis aligned with the runway, while simultaneously holding the runway center-line. I was sorry afterward that I had not stored the approach part of the flight so that I could re fly the landing using other techniques. Maybe next time.


This afternoon, I took the Twotter from Port Heiden to Sand Point (PASD). Sand Point is a small strip with a collocated NDB. There are two published approaches, an NDB approach and an RNAV(GPS) approach. In these cases, I usually opt for the NDB for a couple of reasons. First of all, most RNAV approaches require a more extensive navigational suite that is available on a bush aircraft, and the GPS we find in many of our sim aircraft is more of an "applique" than a real instrument, in that it is not native to the aircraft. The preflight weather was 150/07 KT, 7 SM, SCT 1200'. This sounded OK, so I took off assuming that I'd be making the NDB approach. As I neared PASD, they were reporting 147/11, 5 SM in snow, and a ceiling of 1000' OVC. Whoops! A quick check of the IAP showed NDB approach minimums of 1900' and 1.25 SM. So, PASD was below minimums! Actually, this happens a lot less often than you might think. But, there it was. As an alternative to returning to PAPH, I had a quick look at the GPS approach. To my surprise, the minimums for that approach were 720' and 1.0 SM. Possible,so I elected to push on with the GPS approach.

However, there is a problem with the GPS on my Twotter. It uses an outdated navigational database, so the way-points on the published IAP and on my GPS are not the same. In fact, it's not even always clear that it is the same approach. Nonetheless, I make the assumption that they're close enough and try to use the GPS approach. However, since I don't know which named way-point on the GPS approach corresponds to which way-point on the IAP, I just select the "vectors to final" option on the GPS. I know that will steer me to the final approach fix (FAF) on the older (GPS) approach and I just assume that corresponds to about the same distance from the runway and altitude as on the published approach. (I know never "ass-u-me"). Even then, I have learned that you don't want to use the GPS to guide the autopilot to the FAF, because that will leave you insufficient time, distance and altitude to make a clean approach. Instead, I use the HDG mode and the GPS map to direct me to a point on the final approach course, but more distant from the runway than the FAF. As I intercept that line, I turn to the inbound approach heading and engage the GPS in the autopilot "LOC" mode. Once the autopilot captures that course, it's "just" a matter of managing your altitude and airspeed down to the MAP - frequently easier said than done.

So, I made the GPS approach to PASD in IMC, maintaining the MSA of 5200' within 25 NM of PASD to ensure that I had no risk of flying into the terrain as I approached the FAF without ATC support. That worked pretty well and, as I approached the FAF the overcast broke just long enough to allow me to see the VASI on the end of the runway.

<img src="coppermine/albums/userpics/10009/22/MYJETLINE-PC-2020-feb-2-003.jpg" alt="At the FAF for PASD" width="1000" height="625">

However, I rarely do these things exactly right - that's what keeps me interested. This time, I did not go far enough outbound of the FAF to make the necessary altitude from the MSA of 5200' and the FAF altitude of 2300'. As you can see from the photograph above, upon reaching the FAF, I was still at 4511' even though I had been descending at 2000 fpm. The reasons for this error: insufficient patience. Happens all the time. So, I employed another trick - the poor man's holding pattern descent. To do this I leave the autopilot set to capture the FAF altitude, switch back to HDG mode and turn 180 degrees left to proceed outbound on the approach course until I capture the FAF altitude. Whereupon I tun back onto the approach course and recapture the GPS course in LOC mode. Then, upon reaching the FAF, I can commence the right rate of descent to descend the glide path to the MAP and, upon arriving there, make a decision to land or go missed.

So, this maneuver looked like this.

<img src="coppermine/albums/userpics/10009/22/MYJETLINE-PC-2020-feb-2-015.jpg" alt="The poor man's holding pattern" width="1000" height="625">

Of course this is easier said than done, since as you begin descending you speed up and have to adjust the rate of descent accordingly, then you have to throttle back, deploy flaps, etc., etc. The result is that it's not that easy to fly down the glideslope in IMC without an ILS or an autothrottle. But, I set my radar altimeter alarm at the MDA or 720' and heard it go off, just as I broke through the overcast and had a clean shot at the runway. As you can see, I was a bit high crossing the threshold and had to go through that uncomfortable process of trying to get her down with some runway left without upsetting your passengers. Unfortunately, John seems to have found some of the most easily scared airline customers in Alaska to staff SPAACARS with the result that here is often some screaming going on as I execute my flair. More annoyingly, he then sees fit to dock my check. Next time I'm having the flight attendant pass out tranquilizers to those sissies.

<img src="coppermine/albums/userpics/10009/22/MYJETLINE-PC-2020-feb-2-008.jpg" alt="Still a bit too high" width="1000" height="625">



<img src="coppermine/albums/userpics/10009/22/MYJETLINE-PC-2020-feb-2-011.jpg" alt="Down safely. Quiet in back." width="1000" height="625">
But, all's well that ends well. Quiet down in back there, or I'm going to put you all out here and let you walk back to the terminal.

Hah, very nice Mike - as was your Homer Alaska adventure. And yes...those passengers are very spoiled. A bit of bumpy weather in a thunderstorm and you would have thought they were being tortured back there. How distracting for pilots trying to concentrate on landing a plane in less than ideal weather. Perhaps the algorithm I found was more appropriate for larger aircraft than smaller ones. It seems to be more sensitive when flying smaller planes that are more likely to be buffeted about - with passengers usually more accepting of that behavior.

John<br /><br /><!-- editby --><br /><br /><em>edited by: jer029, Feb 03, 2020 - 07:10 AM</em><!-- end editby -->