A Flight Not Taken

Most pilots can’t resist reading reports of accidents and near-accidents. Features like “I Learned About Flying From That” and “Never Again” in Flying Magazine and AOPA Pilot are, as AOPA puts it, “one of the most widely read sections in the magazine…presented to allow pilots to learn from the experiences of others.”

Sometimes, however, stories about flights not taken are just as valuable, if less dramatic. A case in point: a Pilots N Paws mission that I’d planned to undertake today.

The plan (still) is to fly from Boeing Field (KBFI) in Seattle to pick up a dog in Roseburg, OR (KRBG) and deliver it to a shelter near Bremerton, WA (KPWT). The typical route for the 280 nm trip south (view it at SkyVector.com here) is one I’ve flown countless times in a variety of aircraft. It’s not an especially challenging cross-country trip, especially in my A36 Bonanza, but winter weather in the Pacific Northwest is, to be charitable, changeable and fickle.

I watched the forecasts for several days, paying close attention to the forecast discussions from the National Weather Services offices in Seattle and Medford to get a sense of the overall trends. This time of year, I also keep an eye on the icing predictions and reports at the Aviation Digital Data Service website. The forecasts suggested high pressure and good VFR weather. No AIRMETs for icing marred the picture, and all of the airports I planned to use were forecast to remain in basic VMC all day. Some clouds were expected en route, so I filed IFR flight plans for the trips down and back.

When I updated my official weather briefing early in the morning, the big picture hadn’t changed. Reports showed a few more clouds than expected the night before, but the forecasts still looked good, and there were no warnings about ice. I collected my flying gear, loaded the car, checked in with the folks at both ends of the flight, and got ready for the drive to the airport.

Then my spidy-sense nagged me to check the weather again. I returned to ADDS, and the Supplementary Icing Information page confirmed my concern. It showed a high probability of significant ice, including the dreaded supercooled large droplet (SLD) variety, along the route, especially around and south of Portland. PIREPS from early-morning flights confirmed ice encounters at the altitudes I had planned to fly.

My airplane is not, as pilots say, FIKI-approved. That is, I can’t legally “fly in known icing” conditions. Forecasts of ice are notoriously inaccurate, but pilot reports of in-flight icing are definitive.

I canceled my flight plans, informed my Pilots N Paws contacts that the mission was off–again–and settled in at my desk to polish my presentations for this weekend’s Northwest Aviation Conference and Trade Show.

Later, when the mail arrived, I experienced one of those coincidences that people often attribute to some sort of cosmic “woo.” The day’s haul included the March 2012 issue of AOPA Pilot magazine. After looking at the pictures (yes, I do look at the pictures), I turned to my favorite running feature, “License to Learn,” by my friend Rod Machado. That installment is titled “Decide to decide again.” Rod describes how his intuition sometimes gives him pause, and he chooses not to begin (or continue) a flight–sometimes even after starting the airplane’s engine and when doing so means staying in less-than-five-star hotels.

Could I have made the flight uneventfully? Probably. But the mostly sunny skies promised in the forecasts never materialized. In the end, I’m glad to have taken a few minutes to write this blog post rather than a feature for “Never Again.” It’s not a great story to tell over a beer. Stories need conflict, tension, and a dramatic arc. “There I was” isn’t as compelling as “here I stayed.” But today I didn’t need to learn another lesson the hard way.

New Definitions for Icing PIREPs

The February 9, 2012 edition of the AIM includes an update to section 7-1-21: PIREPS Relating to Airframe Icing. According to the FAA:

This change addresses the change to the icing intensity definitions, quantifiable icing rates, and an updated replacement for current terminology. It would also help satisfy NTSB Safety recommendations A­96­51 and ­060.

The updated definitions are:

1. Light. The rate of ice accumulation requires occasional cycling of manual deicing systems** to minimize ice accumulations on the airframe. A representative accumulation rate for reference purposes is 1/4 inch to one inch (0.6 to 2.5 cm) per hour (See TBL 7-1-7)  on the unprotected part of the outer wing. The pilot should consider exiting the condition.

2. Moderate. The rate of ice accumulation requires frequent cycling of manual deicing systems** to minimize ice accumulations on the airframe. A representative accumulation rate for reference purposes is 1 to 3 inches (2.5 to 7.5 cm) per hour (See TBL 7-1-7)  on the unprotected part of the outer wing. The pilot should consider exiting the condition as soon as possible.

3. Heavy.  The rate of ice accumulation requires maximum use of the ice protection systems to minimize ice accumulations on the airframe. A representative accumulation rate for reference purposes is more than 3 inches (7.5 cm) per hour (See TBL 7-1-7)  on the unprotected part of the outer wing. Immediate exit from the conditions should be considered.

4.  Severe. The rate of ice accumulation is such that ice protection systems fail to remove the accumulation of ice and ice accumulates in locations not normally prone to icing, such as areas aft of protected surfaces and any other areas identified by the manufacturer. Immediate exit from the condition is necessary.

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