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Wednesday, February 4, 2009

Flying with vision (kind of)

After losing the signal for the back course for runway 35 at Mesquite, I raised my foggles and looked around fro the first time. I could see what had happened – I didn’t turn in fast enough, and the back course signal is quite narrow and weak at that range. I thought about starting over, but “D” suggested that we weren’t too far from Lancaster airport, and we could get cheap fuel there.

So I turned on the GPS for the first time. GPS has revolutionized instrument flying – certainly it has changed mine. I deliberately learned without GPS, but then upgraded my panel in the summer of 2008 with a Garmin 430W, and had it coupled to my autopilot. When this means is that I could enter the designated letters for Lancaster “KLNC”, and on the screen the GOPS showed where I was, where the airport was, what course to fly, how long it would take, and drew a nice purple line on the map display. All I had to do was to program the autopilot for follow the line, hold our altitude, and then…… nothing.

Well, not quite. I still had to find the instrument approaches in the FAA instrument procedures book, but I could have flown without that if I’d wanted to. As we got within 10 miles, I selected the GPS RNAV approach for runway 31, and told Charlie to fly directly to the initial approach fix called VIYUN. These names are usually something that can be pronounced – my favorite near Hope AK is “MEEOW”. I turned Charlie onto the final approach course, and let the autopilot fly the whole approach, except that I had to work the throttle to stay on the glideslope. Piece of cake. GPS makes everything easy.

We landed, and fueled up at the FBO. Nice fuel prices – I’ll be back for more soon!

Taking off, I selected direct PQF, a non-directional beacon (NDB) that is the initial approach fix for Rockwall airport, and tuned 248 on the Automatic Direction Finder (ADF), and instrument that is rapidly going out of style, replaced by GPS. Over the beacon, I entered a right hand holding pattern. I chose not to select the NDB approach on the GPS – it makes all approaches the same (“follow the purple line”). Instead I flew an old school by the needle NDB approach – the hardest part is that you have to time the last leg while descending and correcting for wind drift. But it went well and we crossed over the airport at 900 feet above the runway. I won't say I didn't sneak a glance at the moving map on the GPS.....

After climbing back up to 3000 ft, for the 5th approach I tuned in the Variable Omni range (VOR) at Bonham (a.k.a. BYP, on 114.6 MHz), slaved the Distance Measuring Equipment (DME), and set course to intercept the approach around 10 miles from the VOR. You can do that by flying an arc of constant radius around a VOR (or ILS), because the DME tells you if you are getting to close, or too far away. If the leg is part of a published approach, you can also slect it on the GPS, but that is once again just “following the purple line”. This was more fun.

Once the CDI (yes, the same one) showed we were crossing the 212 degree radial from BYP, I turned to a heading of 212, and then nudged about 5 degrees of wind correction to 217 degrees. Descending to 2200 ft once the DME showed 12 miles from Bonham, I called the tower at McKinney to let them know where we were. “McKinney tower, Sundowner xxx, on the VOR approach at 13 miles DME, request the VOR approach”.

“Sundowner xxx, cleared for the VOR DME approach, maintain VFR, no separation services provided. Wind 350 at 15 kts, runway 35 in use. Altimeter 30.06. How will this approach end?”

“Cleared the VOR approach, 30.06, Sundowner xxx. We’ll knock it of at 22 DME, then head south and intercept the GPS approach at ONEME.” “Roger xxx”.

Once the DMW read 22 and we were at the minimum descent altitude (MDA), I turned to a heading of 180, and climbed back up to 3000. I selected the GPS 35 approach on the GPS, and hand flew parallel to the purple line until opposite the little white triangle that represented the total mythical waypoint called “ONEME”, before turning right, then right again to follow the purple line.

“Mckinney tower, Sundowner xxx, at ONEME, request the GPS 35 approach, landing”.

“Sundowner xxx, cleared for the GPS 35 approach, maintain VFR, no separation services provided. Cleared to land number 3”.

Since I was number 3, and I was still under the foggles, I asked “D” to keep and eye open for numbers 1 and 2. GPS approaches are so easy. I hand flew this one, a WAAS approach which means it displays on a CDI like an ILS, with the same vertical and horizontal needles. The glideslope, like ILS, goes all the way to the runway, although I have to have the runway in sight at 300 feet in order to legally land. I did (with an instructor) one time fly the approach blind all the way down to 50 ft.

At 300 feet I pull off the foggles and squint at the sunlight. Pull back the power, lift the nose, lower the flaps, check the fuel one last time (I did my short pre-landing checklist at ONEME, my fixed habit – always do the checklist at the Intermediate approach fix (IAF). Touching down on the runway, 6 different approaches in bag in 2 hours of flying, I am legally current.

Strange, it feels just the same as not being current….

Flying Blind

It’s almost been 6 months since my last real instrument approach.

That one was an Instrument Landing System (ILS) approach to Erie PA, when I was visiting my parents over the summer. I flew my Sundowner from Nashua NH to Erie PA, climbing over some building cumulus cloud near Buffalo NY that took me up to 10,000 ft. As we neared the shoreline of Lake Erie, the clouds stopped, like a giant wall of orange tinted white as the sun lowered towards the Western Horizon.

Erie was reporting no ceiling (clouds), but poor visibility. So I intercepted the extended centerline (called the localizer) and descended as cleared until capturing the glide slope around 4000 feet. I followed the beam to land on runway 24. But that was in July 2008.

The FAA requires that before you can file and fly under instrument conditions, you must be “current”, which means you must have completed 6 instrument approaches and flown holds and intercepted a VOR radial within the last 6 months. So to remain current, I had to do some blind flying.

My Friend “D” owns the only other Sundowner based at TKI. It’s been in shop for a while, after a mishap with a hanger door, so he was more than happy to volunteer to be my safety pilot. Let me explain that.

When flying to currency, you can either fly in real instrument conditions (which can be hard to find in North Texas), or you fly “under the hood” – in my case, a set of goggles that fit over my spectacles, and are fogged so that I can only see downwards. So all I can see are the airplane instruments, I can’t see out. The safety pilot’s job is, well, safety. His or her job is to look for other airplanes, and to take control if the safety of flight is in doubt.

So a few Saturdays ago, “D” and I climbed into “Charlie”, my sundowner, for a few approaches. We took off from McKinney airport at 9:30am into some severe blue weather – no clouds, clear visibility due to strong winds from the North – a Texas “Blue Norther” (cold front) has blown through the night before, dashing away all the airborne pollutants and dumping them into the Gulf somewhere. I climbed in the blind to 2,500, tuned in the ILS approach for runway 17 at Mesquite and waited to intercept the glideslope.

The ILS displays on an instrument called the CDI, or “course deviation indicator”. The CDI is round, and has a vertical needle that shows which direction to fly to intercept the extended runway centerline, called the "localizer". The ILS version also has a horizontal needle for the glideslope. The pilot’s goal on an ILS is to keep the needles crossed in the center of the dial, by following the needles – if the needle is to the right, turn slightly right. If the horizontal needle is low, increase your descent rate until it is back in the center. You can fly very accurately on the ILS – airliners can even use it to land completely blind. My airplane can descend as low as 200 feet above the runway using my system.

The only problem was that with the wind from the north, we were approaching the wrong end of the runway! So I abandoned the approach a bit higher than normal to stay out of the way of departing airplanes, and climbed back to 2,500 over the runway to set up for the back course approach to runway 35.

The ILS is set up for an approach to a specific end of a runway. Some runways have an ILS for each end, usually those that host airline traffic. At some airports, you can use the back side of the ILS to fly an approach – it’s tough to do because everything is reversed – instead of flying towards the needles, you must remember to turn away from them. Some airplanes have a button that can reverse the CDI sensing – mine does not. In the real world I would probably use my autopilot on a BC approach, because it can set up to fly it with reverse sensing, but for practice, I did it the hard way.

Too hard in fact. I lost the signal right on the turn in from the course reversal turn. I did this approach perfectly when I was doing my test ride back in October 2007. But the rules don’t say you have complete the whole approach for it to count, so when I abandoned the approach at 2000 feet, that was 2 down. I needed 6.