Fire in the Cockpit

My Bonanza finally came out of annual after 3 weeks, but not intact.  While it was in the hangar, one of the mechanics was working on some electrical issue, and turned on the avionics - at which point my Garmin 430W started to smoke and the circuit breaker popped.

Fortunately, this happened on the ground, not in the air where it would have been much more serious.  The shop took out the 430W, and sent it to the Garmin dealer at TKI, who sent it to Garmin for repair.  After 10 days or so, I got a nice surprise - Garmin repaired it for free, probably since they had just upgraded it from 430 to 430W last summer, although if they hadn't touched the power supply it might have been in a gray area from a warranty standpoint.  I will only have to pay for shipping.

So on Monday, hopefully I will get my Bonanza back intact, after a month of being down for annual.  Not quite the experience I was hoping for!

I want my Baby Back.....

It's annual inspection time.  Once every 12 months, a privately owned aircraft in the United States must under go a detailed safety inspection, just like a car in most states.

Of course, it's a much more detailed and lengthy inspection, especially for an aircraft that the shop you choose hasn't seen before and has no history with.  That's the case with my Bonanza, which has been laid up in the hangar for 3 weeks and counting.  All the insides are outside, it's up on jacks so that the shop can test the retractable gear, and all the spark plugs are out (all 12).  The shop also has to check and make sure that all applicable FAA Airworthiness Directives (ADs) have been met, which can take some time on a 45 year old airplane.

Commercial aircraft undergo a similar check, but since they fly more, they must be inspected every 100 hours of flight.  I've flown my Bonanza nearly 80 hours since last April when I bought it - slightly higher than the average private airplane, but not much.  Airliners typically have A, B and C checks - the C check happens on the ramp and takes very little time.  The A check means putting it in a hangar for a week or two, and stripping it down, often replacing engines and other major assemblies.

The annual is also time to take care of those niggling "squawks" that you list as the year goes on - internal lights that won't work and can't be fixed simply, small brake fluid or fuel or oil leaks, things not big enough to warrant immediate attention, but that need to be fixed.  So my airplane has been "out of service" for for 22 days and counting.  Thank goodness I'm instructing, or I would have been grounded for almost a month.

But I want my baby back........

Instructing

It's different from just being a pilot, or from being a student.  You would think that would be obvious and not need comment, but just as the actual fact of being married is different from your expectations, being the CFI responsible for not only the safety of flight, but also efficient transfer of knowledge, is very different from what you might think.

I've done some instructing before.  Prior to even having an instructor's license I taught my oldest daughter (Thing 1) the basics of aircraft control, and even had her able to fly a full traffic pattern and approach, everything except the final moments of touchdown on the runway.  Then she lost interest and hasn't flown since.  I have an instrument student "D", but he can already fly safely.  My responsibility is only instructional - to teach him how to fly and navigate only using instruments.

My new basic student, "D2" already has 30 hours or so, and has had 2 prior instructors.  He's not happy with how quickly they were progressing, I suspect because he is a perfectionist, and since I know the other 2 instructors, who are the same way, I can see how they would keep on polishing and polishing the same skill over and over, and not move on once it became "good enough".  In this sense, good enough means he can perform the skill to PPL standards most of the time.  I believe once we add further skills, the current stuff will become second nature and just need practice before the test.

So yesterday we started on traffic patterns and landings.  If we'd had an office space or a desk, we could have (and should have) gone over the traffic pattern procedures with him in advance, but since I hadn't flown with him before I didn't know if he was good enough yet.  Well, he is, so we did 3 circuits at Mesquite.  By the 3rd one he was picking it up, but it was starting to get dark and the cloud base was dropping. So tomorrow it's back to pattern work, but this time with a thorough pre-flight briefing since I can have a firm plan.. 

We're both learning here.

Interference

I keep my Bonanza at a small, private field in McKinney TX, called AeroCountry (T31).  It has one runway, a strange combination of grass and concrete.  The Northern end is 1,300 feet of grass, the Southern end is 3,000 feet of concrete, for a total length 4,300 feet.  The join is pretty well done - I've landed on the grass and taxied onto the concrete and there's just a small bump.

No instrument approaches, however.  Many of the aircraft there are smaller experimental types, and some exotic aerobatic aircraft (the hangar next to mine holds a Yak 26).  Until recently, the runway was too narrow to meet the FAA requirements to have an IAP (Instrument Approach Procedure), but when a developer wanted to buy the East side of the airport and put up luxury condos and attached private hangars, part of the deal was that he would pay to re-develop the runway, making it wider.  Now we can have an IAP developed, and I'm pushing the owners council to ask the FAA to make a GPS IAP for us.  Otherwise in bad weather I have to land at Collin County Regional (KTKI), about 8 miles away.

Of course in order to fly a GPS approach, the aircraft must have a working GPS unit, certified for IFR operations.  My Bonanza has a Garmin GNS 430W, certified for precision approaches down to 300 feet AGL (or down to 200 in ILS mode), an Apollo panel mounted GPS without WAAS (for navigation and non-precision approaches, I usually just leave it turned off), and a handheld Garmin 496 in a mount, which is used for navigation, backup, and Nexrad weather radar display.

The trouble is, that they all have to receive satellite signals, and these signals come in on a variety of microwave frequencies, around 1.5 GHz.  Paradoxically, the most capable of the 3 GPS units in my Bonanza is also the most sensitive to interference - the 430W needs 5 working satellite signals to be able to support a precision approach.  The 496 only needs 3, but it can't be used for approaches.  And somewhere near T31 is an interferer that is blanking out all GPS use.

Garmin GNS 430 W

Some of the pilots thought that someone had put up a 1.5GHz base station on a nearby water tower that doubles as a cell site, having read about the issues with Lightsquared and the FCC.  Others suspected a nearby radar test range owned by Raytheon.  And a few suspected a microwave relay tower furtehr to the southwest owned by AT&T.  Since I work in wireless telecommunications and am an FAA licensed flight instructor, I know how to work with both the FAA and the FCC and have the contacts to make something happen.

Eventually the FCC agreed this was their baby, and sent out a technician to track down the source.  He drove around where the pilots said we all lost GPS, and found nothing.  So he called me, and I agreed to take up my airplane and try to narrow down the source.  I took off one Saturday with a friend in the right hand seat, and we flew all around the field at 600 to 700 feet AGL (the FAA requires at least 500 feet clearance above or laterally from any obstacle, building, person or vehicle).  We flew various legs around the field, and proved that the source was not the cell tower, the radar range, or the communications tower.  It appeared to be a circle centered near a road intersection.

Based on where we lost GPS lock, the FCC drew up a map showing the 2 circular patterns that best fit the data, and concluded that interferer is near the intersection of Westridge and Independence roads, in a newly built neighborhood.  They asked me to do some more runs from the West and South to confirm the circle's radius, but now suddenly the interferer has gone, after 4 months.  Vanished. Poof!

The FCC's best guess is that it's a bad HDTV adapter in someone's home.  It seems that some can fail in a way that radiates in the GPS bands - at least one model has been recalled, but there are still some out there.  I wish we had found it - it worries me that the GPS blank spot could come back at any time.  Unless the perpetrator knew what he was doing and realized that someone in an airplane was trying to track him or her down - Chinese spy satellite radio, anybody?  Although the usage pattern is closer to that of the TV adapter, staying on for days and weeks at a time - maybe they went out and bought an HDTV and threw out the old analog one.  Still, before we can get a GPS IAP, it needs to be resolved.

This is why your instrument instructor told you to monitor the GPS unit's satellite lock throughout an approach - it can just vanish.  Then what will you do?