Archive for May, 2014

Hail , Hail, the Gang’s all here

Tuesday, May 27th, 2014

This is not a club you want to join—the “Busted Windshield, Dented Airframe Society.” Last week an airliner bound for Philly had its lights punched out by hail. It doesn’t happen that often, but it’s really expensive.

A picture being worth a few thousand blog words helps with the motivation to keep a healthy distance from the good ‘ole big ones!

hail windshield

          Figure 1

From the Skybrary website, Figure 1 and Figure 2 are pictures from an Airbus 321 flown by a foreign carrier over Korea that encountered severe hail: The windshield wiped out and radome was ruined (gone actually). Damage was also noted on the leading edges of the wings and empennage.

Side effects included the inability to look out the front of the aircraft—landing was a bit challenging. A huge amount of noise in the cockpit made communication very difficult.

hail radome

          Figure 2

Suspect the discussion with the chief pilot wasn’t exactly career enhancing. Failure to keep up with the weather, no warning from ATC, and cutting it too close were cited. The tough part about this is that most of the time there isn’t any hail. However, the answer that “It always worked before” won’t always buy you a sympathetic audience with the boss or your insurance agent.

 

hail shaft

          Figure 3

Figure 3 is a low altitude shot of a possible hail shaft. (Although it could be rain, we didn’t get close enough to test!) This was taken on the trip from STL to FDK referenced in last week’s blog. We were a good 15 miles away (as best we could estimate) from the storm at 5,000. VFR pilots take note—this isn’t just a problem for the IFR dudes and dudettes!

 

As we get into thunderstorm season proper, remember that whatever it’s doing now, in ten minutes it will be different (often worse). A reminder that the Air Safety Institute’s Storm Week begins on June 8, and the live “Datalink: Cockpit Weather Do’s and Don’ts” webinar will be held June 11 at 7:00 p.m. EDT. 

Tiptoeing ‘round the Boomers

Wednesday, May 21st, 2014
Boomers Fig 1

                    Figure 1

Last week the Weather Channel was predicting Meteorological Apocalypse as they almost always do whenever a strong cold front hits the Midwest. A 25-degree temperature spread across the air masses often makes for a few tornadoes and copious thunderstorm activity.

A business meeting in Kansas City offered the chance to fly from the East coast with a friend in his Cessna 441. We launched early afternoon for the 3.5-hour ride. At 30,000 feet the view was impressive, and it was obvious from several hundred miles away that “direct” was no longer in the cards. We climbed to FL340 for a better view. Not many 32-year-old turboprops can do that.

In Figure 1, you’ll note a significant northwest deviation as we worked around the end of the first line. Datalink radar told the story as did ATC. Visually, however, it looked better down to the southwest. That’s because the line was trailing away from us and was hidden by the closer storms. Got to watch those illusions or get taken for a ride!

Boomers Fig 2

                    Figure 2

Arrival into MKC required onboard radar because the flight was in and out of lower clouds and much closer to the cells. Timing is everything. FlightAware’s snapshot at 2:50 pm is a midflight picture—not actually what was happening when we arrived. It shows us going through a cell, which we did not (Figure 2).You may notice a “buttonhook” sort of turn as we got onto the downwind. Tracon asked if we’d like a scenic detour since heavy rain was moving across the final approach course. It’s bad karma to be on final in heavy precip, so a 5-minute delay allowed a much less exciting arrival.

The return trip two days later was equally interesting but in a completely different chariot—another friend’s Cessna Caravan. Since many of us don’t routinely fly the flight levels, it’s fun to compare the differences. It was VFR, low and slow, to St. Louis for a three-hour business stop.

 

Boomers Fig 3

                    Figure 3

The mid-afternoon launch had us into the backside of the front, which had meandered into the Ohio Valley (Figure 3). Again, the image shows the mid-trip picture, so the cells are not exactly as they appear at the time of our passing.

The first part of the trip, being in the cold sector, precluded cruising at the odd 5,000 feet altitude due to icing—4,000 worked well until the temperatures warmed eastbound.

Late afternoon is about the worst time to tackle something that requires heat as an engine, but there we were. In convective weather one should never rely on just one source of information. We had five: visual (much of the time), datalink, onboard radar, lightning detection, and ATC (the ARTCC duplicates datalink, but most tracons have real time weather). Each has its strength and weakness, but collectively they provide a good picture of where not to go. The whole trick is not to get painted into a corner, and a wide yellow stripe down your back doesn’t hurt either!

One point about deviations: On the return trip, even though there appear to be significant deviations (and there were), the mileage didn’t change much—699 nm direct, 757 nm as filed, 761 nm as flown. Those were quality miles, and despite all the vertical clouds light turbulence was all we encountered and not enough rain to wash the bugs off.

Join the Air Safety Institute during Storm Week, June 8-14. Each day during Storm Week look for ASI’s convective-weather related safety products, including a  new “Flying the Weather” video, and register now for our “Datalink: Cockpit Weather Do’s and Don’ts” webinar to be held on June 11, 2014, at 7:00 p.m. ET, as we discuss important safety considerations when flying with cockpit weather.

Learn how to keep thunderstorms at bay with ASI’s “Weather Wise: Thunderstorms and ATC” course, which explains the finer nuances of how to effectively communicate with ATC, how controllers describe precipitation, and what radar services they can offer.

Air Pockets or Worse !

Wednesday, May 14th, 2014

wavesToo many airlines think we can’t handle the truth, and so the flight crew refers to “bumps” rather than turbulence. You’ll even hear media types occasionally mention “air pockets,” a long outdated terminology. For light GA, turbulence is often uncomfortable and occasionally dangerous.

The Air Safety Institute, working with the FAA and the NTSB, is highlighting turbulence this month as part of our 2014 weather education campaign. Turbulence comes in a variety of forms and can be merely aggravating or really bad news.

Convective turbulence from thunderstorms is probably the worst and disassembles aircraft about six times a year. It often takes the form of the pilot first losing control, and then the hardware starts to come apart after all speed limits are exceeded.

But sometimes the bounces are in the form of waves and rotors. If you’ve done much flying in any sort of mountainous or hilly terrain you’ve likely experienced the wave—sometimes visible with lenticular clouds but not always, especially when the air is dry.

My first exposures to the wave were perplexing at best. In cruise flight with the autopilot in “altitude hold,” the airspeed was going up and the A/P was trimming nose down. Pretty cool—free lunch? You know the deal on lunches, because a few miles down the road just the opposite happened as the nose went up and the airspeed just went to pot. Thinking a navigational error had placed me into the Bermuda Triangle I called ATC to ask for a block altitude. It was, of course, the smooth part of the down wave.

However, altitudes below the smoothness can be a dentist’s delight—rough enough to jar loose fillings. Airspeed control is the key, and on descent in those types of conditions one should be well acquainted with VAmaneuvering speed. VA is one of those counter-intuitive concepts. As the gross weight declines, the slower the maneuvering speed. The published number in the handbook or on the placard is appropriate at max gross. If you’re lighter than that—slow down.

Airspeed bumps around a good bit in turbulence, and if everything is stable “right at” VA, a gust can increase the speed by 10 knots in the blink of an eye. When flying an older aircraft there is no comfort knowing that if the bozo that flew it before you exceeded VA, and got into heavy turbulence, some of the margins built into the structure when new have been used up. How much? Good question. Slow down.

Pay attention to pireps and Center Weather Advisories—the loss of a modified Cessna P210 is instructional. Even moderate winds over big mountains deserve to be treated with great respect. Maybe there’s something to this air pocket thing after all.