Archive for the ‘Safety’ Category

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?

Placards needed or are we idiots?

Wednesday, April 22nd, 2015

Placard blurred A36 Seat Back

Most of the placards plastered on my aircraft are just there, like wall paper, and I usually look right through them. But while communing with the aircraft one rainy afternoon in the hangar, I got to thinking about why they existed—did the FAA require them or did the manufacturer get sued for not telling someone to do or not do something? Some seemed legitimate and others were laughable.

Several remind us of FARs or good operating practice. Perhaps they do no harm but it goes to familiarity with the machine and actually thinking about what we’re doing. Aircraft are like chainsaws—they do what they do very well but must be treated with much respect.

This collection is from my Bonanza: Check local listings for aircraft you fly.

Verify door is properly latched before Takeoff

Duh, seems self-evident. Many aircraft have a double latch, and they both must be engaged or the door will come open. In my Bonanza door experience, the top latch popped open about an hour into the flight. Fortunately it was in Florida on a nice day with only 20 minutes to our destination. The bottom latch held, but it was breezy and noisy. Passenger had closed the door—now I always close it unless it’s a Bonanza passenger who knows what will happen, but I still verify.

The second instance was shortly after door maintenance: It closed properly but popped after two hours as we entered the traffic pattern (won’t go back to that shop!). No problem: Just fly and do not drop the aircraft to attempt closing the door, because closing is not an option. They open doors in flight test knowing that it’s bound to happen. While inconvenient and sometimes somewhat expensive, production aircraft will be completely controllable.

The A36 aft utility doors are a different matter. There is an annunciator light directly in front of the pilot to remind us that a door(s) may be departing the aircraft if not latched. Again, the aircraft will fly just fine, and A36s without aft doors are regularly used as photo platforms. But located on the aft cabin wall, where you probably wouldn’t notice it:

When utility doors are removed–No smoking, all loose objects must be secured. Personnel not secured in seat by safety belts must wear parachutes

“Excuse me Captain, I seem to have set the back of the airplane on fire…was just having a little smoke…” or “My prized anvil collection just went overboard—can we go back and get it?” or “Has anybody seen your mother-in-law lately? She was here just a minute ago.” Kidding aside, there must be some sad history to this placard. Seems like this would be obvious but…

Fuel selectors fall into the “basket of snakes” category for me. Handle them very carefully because engines get fussy when not fed.

Position selector in detents only–No fuel flow between detents

This placard is placed directly on the selector, so if you went to the trouble of reading it presumably you’d know to put the pointer in a detent. Just reaching down and moving the handle is not a good idea, but then you wouldn’t see the placard. Hmmmm.

Left–Right & Off not in same positions on all Bonanzas

Those fun-loving Beech engineers are always changing things up. Again, this goes to knowing your aircraft. “Your honor, my client crashed because—well—he put the fuel selector where he always positioned it. It was a different airplane but the blinking engine just stopped—how was he to know that ‘OFF’ wasn’t the right tank?”

Fuel selectors should command your undivided attention. That means LOOK even though you’ve moved them a thousand times.

We could go on for much longer but here’s a final reminder:

Shoulder harness must be worn at pilot positions for Takeoff and Landing. Seat back must not be in full back position

The first part of this is a reminder of what’s in the regulation. If the aircraft is so equipped, you’re smart and legal to wear the harness. As for the second part—any flight operation would be by braille as the pilot would be staring at the ceiling of the aircraft. There either was an idiot who tried it or the attorneys just think we’re idiots. Either way, it’s not a vote of confidence.

Any good placards on your aircraft you’d like to share?