Archive for the ‘Safety’ Category

A Quiet Evening (on the ground)

Wednesday, June 10th, 2015

Screenshot HGR to MtA stationary front had settled over New England with low ceilings, fog, and rain. I had just finished a safety presentation to the Flying Physician Association’s Annual meeting in Hanover, New Hampshire. We discussed some of the safety aspects of medical reform (most of the docs are in favor) and loss of control (most of the docs are against it).

My summertime strategy is always to be airborne early to beat the inevitable summertime convection. Got to the aircraft well ahead of schedule (about 10:00 a.m.—that’s not early but business got in the way) and, glory be, received a cleared-as-filed clearance. But just as soon as it was loaded into the GPS, the amendment clarified what Boston Center really wanted had more waypoints and fixes than ants on a Tennessee anthill. Fine—another few minutes of button pushing and I taxied out.

Non-radar environments mean one airplane in and one out, or more often, three or four in and outbound traffic can just relax. It got so “relaxed” the tower apologetically suggested I shut down and call back in a bit. Finally, airborne 40 minutes later with 30 knots on the nose—but just clouds and rain—made for a good ride.

Down the line in Pennsylvania, however, datalink weather was showing that I was late to the party as the atmosphere was beginning to go vertical. Two hours earlier this would have been a non-issue. The showers and a few cells were well-scattered, but once Mother Nature starts to boil the ride can be uncomfortable (or worse) even when there is no precipitation nearby.

The other data point is that the stuff can build from nothing to nasty in a short time (minutes), and the latency of datalink pictures doesn’t always serve us well. Just about the time you’re fairly sure what’s going on, it’s changed significantly (see the Air Safety Institute’s Accident Case Study: Time Lapse video).

At 8,000 feet there were short glimpses of towering cumulus clouds followed by bouncy periods of blinding white inside. Above 14,000 the view would have been a lot better, but that’s a stretch for my normally-exasperated aircraft and there was no O2 on board. Ten degrees left, then 15 degrees right, coordinate with ATC, and avoid the big ugly ones.

Altitude hold on autopilots can put significant stress on the airframe where hand flying provides a softer touch in these circumstances. Get a block altitude from ATC if unable to maintain plus or minus 150 feet. In retractables, the landing gear will stabilize the machine and act as a speed brake in descents. No flaps allowed—they lower the G tolerance of the airframe. The goal is to stay well below maneuvering speed by at least 20 to 30 knots as adjusted for the actual weight. Much easier on the airframe and the passengers although the natural inclination is to get out of there!!! Slow and easy does it.

The fuel stop at Hagerstown, Maryland, was a pleasant respite, and a long look at the FBO’s radar (see image at top) showed there was no realistic strategic avoidance through Virginia or North Carolina to my destination in South Carolina. Secure the beast and get a hotel. Widely scattered aluminum will not be in tonight’s forecast.

On the bright side, it’s an adventure. Met some local color in the bar—Ernest Hemingway spent much time in such establishments, and look at the literature he produced (but there’s no danger of that here!!).

Well before bedtime, moderate to heavy rain cascaded over the parking lot with periodic peals of thunder. It was a good call to stay put. Glad I put a plastic bag over the copilot seat: door seal leaks! What we tolerate from our pricey machines is a lot more in some respects than from the cheapest automobile.

Next morning it was Déjà Vu all over again: rain, fog, low ceilings—but no ATC delays. The early morning strategy made all the difference as the convection started to build in from the west over Raleigh. This time, however, a 20-degree heading change to go down the east side missed the whole mess. That’s where datalink really shines. Landed at 11:00 a.m. and by early afternoon it’s Groundhog Day (the movie) in the Southeast—no easy diversions.

This also illustrates a reality in flying light aircraft. We operate in weather windows, and life has to accommodate that or you may not be happy with the results. Anyone with a good convection story and timing of the flight?

As we get into thunderstorm season proper, remember that whatever it’s doing now, in ten minutes it will be different (often worse). We know that thunderstorms and airplanes don’t mix, so avoid these violent storms by checking out the tools at your disposal in the Air Safety Institute’s Thunderstorm Avoidance Safety Spotlight.

Slip Sliding Away—but a really great touchdown !!

Wednesday, May 27th, 2015

slip slidingNot the way songwriter Paul Simon intended, this week’s blog is about stopping on the available runway. The accident statistics show pilots are much attracted to the far end of a landing runway. There are multiple reasons: Excess speed is one, and water is another. Water is a universal lubricant and one of its less endearing qualities is that it makes stopping difficult or impossible.

A friend who’s in the automotive body shop business always smiles when it rains because it means the work will be steady in the near future. Unless you fly only when the runways are perfectly dry there’s one word to know—hydroplaning! There are multiple kinds of hydroplaning that make for good cocktail party talk, but what’s important is that when enough water gets between the rubber and the runway you’re not stopping anytime soon.

A short hangar story from this spring: The night IFR approach was routine, and the runway was in sight at least three miles out. I’ve learned over the years that excess speed on landing only leads to wasted runway behind me, so I had settled comfortably into about 80 knots on short final with just a little power on the Bonanza. The landing light had thoughtfully sacrificed itself on the approach, so a blackout touchdown was in the offing. (That’s only fair when remembering all the blackouts inflicted upon students during night checkouts to simulate just such a happening.)

It was one of those rare (for me) satisfying touchdowns where the wheels just kiss the pavement and you’re not really sure the aircraft is down. That’s because it wasn’t—the airplane made just the slightest of swishing movements and things felt “fluid.” A minor touch of rudder and brake revealed tentative pavement contact at best. Just let gravity work it’s miracle as the speed bleeds off and then get on the brakes, gently.

We rolled slowly to the end of the 3,700-foot ungrooved strip using aerodynamic braking until the tires had a solid grip. Learned the next day there’d been heavy rain just an hour or so before our arrival with some standing water on the pavement. Couldn’t have seen it in the dark even if the landing light had worked. Grooved runways dissipate water very well but small airports usually don’t have them. They also don’t have braking action reports unless somebody happened to land just before and said something on the CTAF.

The formula for dynamic hydroplaning is the square root of the main gear tire pressure in PSI multiplied by 8.6. Probably best to memorize the computed number for the aircraft you normally fly unless you’re really quick with a calculator or abacus on the rollout! The mains in my aircraft are inflated to 36 to 40 pounds, so that equates to 51.5 to 54.4 knots—call it 55 knots. That means dissipating roughly 20 knots before the brakes begin to work dependably on a watery runway.


We haven’t discussed reverted rubber or viscous hydroplaning—my hunch is that dynamic is the one that is most likely to be encountered. The others occur under special circumstances, but the bad news is that they can affect braking at significantly slower speeds.

Contaminated landing distance performance is a subject most light aircraft POHs avoid. We’ve spoken before about the “optimistic” nature of POH numbers. They are absolute performance numbers: The pros don’t use them, and why the FAA tests our ability to measure it to the nearest 10 feet, or calculate fuel burn to a gallon or three, is a mystery.

The Air Safety Institute recommends the “50-50 method” in computing takeoff and landing distance. Whatever the book says the test pilot could do over the 50′ obstacle—add 50 percent to that. Under the ambient conditions that evening, the POH landing distance for my aircraft on a paved, level, dry runway was about 1,500′. Add the margin and a more realistic dry runway number is 2,300′. Now factor in water’s lubricity and it’s smart to double the number to 3,000′. Any downslope to the runway, density altitude, clearing the obstacle by a few extra feet, or an extra five knots for comfort will add up quickly. Your mileage will vary so be conservative!

We’re only talking about the longitudinal aspect of landing—not what a blustering crosswind might do if the tires are not in full contact with the runway. The demonstrated crosswind component means nothing at that point. Then a really wide runway—or better, one where the wind is right down the slot—is much the desired option. Anyone else with a hydroplane story?

Free educational programs from the Air Safety Institute—like this Mastering Takeoffs and Landings safety advisor and the Takeoffs and Landings safety videos series—are available to all thanks to support from pilots everywhere. Help us to keep educating pilots on safety issues by donating to the AOPA Foundation today.

Pissing genies and the aircraft electric

Wednesday, May 6th, 2015

genie-blogWith apologies for the headline, writer Earnest K. Gann eloquently stated that, “Somewhere in the heavens there is a great invisible genie who every so often lets down his pants and pisses all over the pillars of science.” Despite advanced and redundant systems we remain as vulnerable as ever.

Engines and certain mechanical systems were often the reason of a cancelled flight but perhaps not so much anymore. It’s software and the millions of lines of code that lie embedded in the magic that run the show and periodically cancel it as well. For GA, this is instructive.

The Boeing 787 has an AD against it now with the unusual warning that the beast needs to be totally powered down at least once every 284 days. Never knew it needed to stay plugged in for that long, and the electric bill must be impressive. Apparently there’s a troll hiding in the code, which if not appeased will simultaneously take down all four of the aircraft’s generators. Quadruple simultaneous failures are so irritating.

For your consideration: Some years ago I had to scrub a trip because, immediately after engine start, the tower couldn’t hear my transmissions. I could hear them just fine. This was a new aircraft with a full glass panel and lots of redundancy. Taxied down to the local avionics shop where they proceeded to run various tests. After several hours of troubleshooting they still hadn’t found the problem. Next day, pulling various boards, swapping things around and reseating cards, the fault mysteriously cleared. The genie had wandered off to rain on someone else’s parade.

On a day VFR flight in an old technology aircraft, I was unable to transmit while approaching class Delta airspace. Neither comm radio worked. Tried swapping headsets, using different push-to-talk switches, even the hand-held mike. Nothing. For the first time in two decades of carrying a handheld radio—and not storing dead batteries in it, as my friend Rod Machado likes to remind us—that seemed like it might be the salvation. Didn’t work.

The dreaded light gun signals were a distinct possibility. You remember—the alternating red and green that says the airport restaurant is closed on Monday, the green that advises avgas is less than $5 per gallon and the flashing red that reminds us not to forget Mother’s Day—or something like that.

But then, inspiration. Perhaps the rubber duck antenna just didn’t have the punch. This aircraft was equipped with a coax connector to one of the aircraft antennas. Plugged that hummer in and voila… the tower could hear us, confirmed the airport restaurant was open, and provided landing clearance.

Despite having perfectly good radios there was a single point failure in the system and the genie found it. The transmit relay failed, and the ship’s radios were struck mute. I recently installed a separate comm antenna and coax on my aircraft as a hedge against such an occurrence because genies are a persistent bunch.

The latest genie sighting was a doozy! American Airlines’ iPad app crashed, and despite dual pads in every cockpit, the crews couldn’t access their charts. Dozens of flights were cancelled or delayed. What a mess! Address one problem and then the genie finds another way to get you. The more things change… Ask Boeing or Airbus.

One more thought: Remember never to drop the aircraft to deal with troublesome genies. Distraction is almost always a key link in the accident chain.

What’s your genie story and how did you resolve it?