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Aviation Safety


Dave Fry, WVFC CFI and Aviation Safety Counselor

And Yet More Spaghetti

Good pasta is right at the top of my list of vices.  I don’t much care if it comes with a simple marinara sauce, or shrimp, lemon zest, and fennel, chicken curry and fresh broccoli, or any of a hundred other sauces.  Spaghetti, ziti, farfalle, gemmeli, cellentani, rotini, bucatini, fettuccini, linguini, fusilli, lasagna, penne, radiatori, rigatoni, vermicelli or macaroni – I’m into all of them.  Or if done right, they’re into me.

However, there is one kind I’m less than fond of, and that’s the kind that sometimes hits the fan while you’re flying.  The longer you fly, the more likely you are to sample some of the more exotic and rare varieties that seem to occur in airplanes.  And the more complex the plane and the more complex the systems, the more likely they are to go wrong from time to time.  I mean, take something simple like an anvil, very little is going to go wrong.  The same thing with hammers and screwdrivers.  But as soon as you start adding moving parts, complex systems, or even worse, computers, an entire universe of potential spaghetti sources opens up.

Here’s an example.

I was flying a Citation M2 back from Austin, Texas and through careful planning, I had another type-rated pilot, Wes Irish, in the cockpit.

As often happens in aviation, it was a somewhat longer day than we had planned.  The original plan was to leave Austin at 1600, fly to Rocky Mountain Metro (between Denver and Boulder) to pick up another passenger, then fly back to San Jose, where we would drop off all five pax and continue on to Hayward to put the plane to bed.  We actually departed Austin a bit after 1900, but the good news was that we were flying back to San Jose without the stop in Colorado, and without some of the passengers – Yippee, more fuel!  But we still had to stop once on the way home., and both legs of the flight were night flights.

Two hours out of Albuquerque, we were cruising at flight level 360, when the spaghetti began to hit the fan.  It started with an Amber Caution that we had lost our ADS-B capability.  While this doesn’t qualify as a “non-event”, most of us have seen worse.  In this case, a quick trip into the Emergency Procedures checklist informed us that we should switch transponders, which wasn’t exactly a surprise, so we proceeded to do so.

At this point, I should probably say a thing or two about how one does CRM in a two-crew environment.  It is specifically briefed during the pre-takeoff crew briefing, but the normal procedure is that when the spaghetti (or other substances) hits the fan, the Pilot Flying (PF) flies the plane and the Pilot Not Flying (PNF) handles the radios and reads the checklists.  This isn’t to say that the PF isn’t involved in the process.  What happens is that the PNF finds the correct checklist, does a quick review of the procedure, and either tells the PF about it or reads it directly to the PF.  When both pilots have agreed on the checklist and the course of action one of them carries out the checklist procedure.

In this case, the procedure was simple - switch to the other transponder, which we did.  And it solved the problem for about 10 seconds (just long enough for us to congratulate ourselves on successfully handling the problem) at which point, we got the message again, indicating that ADS-B had rolled over and died on both sides.  Unfortunately, the messages we had dealt with at this point weren’t the real problem; they were only symptoms of something worse.   The next message told us that we had lost our Terrain warning capability.  Now, the good news is that at 36,000 feet there really isn’t a lot of terrain that is going to cause the pilot concern.  The bad news is that as you descend, which you WILL do at some point, more and more of the local terrain begins to become a factor.  I had an entire course on such things in grad school – boundary value problems, and the ground is the ultimate boundary. 

But wait, sports fans, there’s more.  After referring to the checklist again and discovering there was nothing we could do about the Terrain system, another Amber Caution came up advising that both Attitude and Heading Reference Systems (AHRS) were using GPS 1.  It’s just advisory, since there’s nothing the pilot can do about it aside from checking the appropriate circuit breakers, which we did, only to find that none had popped.  Good news, again, the plane can fly just fine on a single GPS.

Of course, it doesn’t do so well when it’s trying to navigate with no GPS guidance, which was the next message – GPS NOT USED.  Normally, when there is a loss of GPS signal, there will be red Xs at various points on the PFD, but we didn’t have that.  Remembering that aviation is a team sport, we reported the loss of GPS guidance to ATC, which accommodated the issue by giving us vectors all the way from the Sierras to the downwind for San Jose.  I wondered at the time how accommodating they would have been if we’d had the problems during rush hour instead of at 10 PM.

During all of this Wes had both the presence of mind and the cycles to take a bunch of pictures of the various panels showing the Cautions and the Messages.  They helped immeasurably during the conversations I had with Cessna and Garmin over the next couple of days.

The funny thing is that after 10 or 15 minutes of this, the process reversed itself and we ended the flight with a fully capable airplane and no Amber Cautions.  We were still left with a CONFIG ERROR, which we were unable to clear.  I felt marginally better when the factory guy was also unable to clear the problem.  Well, maybe “vindicated” is a better term, since we apparently hadn’t missed anything obvious in our procedures.  On the other hand, the plane was still a sick puppy in need of a good veterinarian.

Now, let’s step back and look at the big picture.  This kind of stuff (or similar or worse) can happen at any time.  Heck, we’ve even had engine problems in club planes, and have had (at one time or another) every system on our planes quit.  Sometimes these things happen when the pilot isn’t busy, sometimes when the pilot is swamped.  If you KNEW something like this was going to happen on a particular flight, what would you do – aside from letting someone else take the plane?  I know what I’d do; I’d make sure I had a qualified pilot along with me.  Of course, I’d train specifically for as many of the gotchas as I could at least once a year.  And since I don’t know when something like this will happen (but I know that WILL happen at some point), I have a qualified pilot along with me whenever the passenger load allows.  I’d be crazy not to.  If you want to extrapolate that to infer that ANY jet pilot would be crazy not to have a qualified pilot along on every flight – well, I didn’t SAY that.

I will say, though, most pasta dishes are better when they’re shared.