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What Your Aircraft Feels

June 4, 2012/in Personal stories/by studentpltnews

A few years ago, at one of the local airports, there was an aircraft accident. Two guys took off in their Grumman Tiger on a beautiful, summer afternoon. The sun was shining and the winds were calm. They lifted off, barely clearing the fence at the end of the 3,700 foot runway. The pilot then […]

Is Corrective Vision Surgery for you?

May 28, 2012/in Tips and technique/by studentpltnews

It’s estimated that some 55% of civilian pilots use some form of vision correction, most notably, glasses or contact lenses. But advances in corrective surgery are making laser procedures more and more attractive to pilots. However, it’s not without risks when it comes to your vision and your medical certification. It’s easy to be sold […]

What Your Aircraft Feels

June 4, 2012/in Personal stories/by studentpltnews

Is Corrective Vision Surgery for you?

May 28, 2012/in Tips and technique/by studentpltnews

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What Your Aircraft Feels

June 4, 2012/in Personal stories/by studentpltnews

The pilot decided to land in the field underneath him. After quickly reducing the power to idle, he put the plane on the ground. The plane was out of control. He struck a wing and flipped upside down. The pilots struggled to open the canopy before the plane would catch fire. The good news is they escaped with minor injuries. They were lucky though; it could have ended much worse.

After the accident, the pilot stated he didn’t understand what was wrong with the airplane. Was it an engine problem? Why did it take so much runway to lift off the ground? Why couldn’t they clear the trees way off the end of the runway? He and his flying buddy had made successful takeoffs every flight in the months leading up to this accident.

But as I mentioned before, unfortunately, it was a beautiful, hot, early summer afternoon. The density altitude was relatively high (around 3,000 feet) and there was no wind to “help” the airplane off the ground. The aircraft was near max gross weight as they usually are. They didn’t understand the dramatic effect that the elevated density altitude would have on their takeoff distance. It also decreased their climb performance which is reflected in their inability to clear an obstacle. This lack of appreciation and understanding almost cost them their lives.

Density altitude is pressure altitude corrected for non-standard temperature. Of all your various altitudes that you’ll learn about (absolute, true, or pressure), density altitude is the most important when it comes to aircraft performance. It’s the altitude your aircraft “feels” while flying. The aircraft feels or behaves as if it were at its density altitude because hot days with high density altitude adversely affects the performance of the wings, the propeller, and the engine (rule of thumb: add about 12% to your takeoff distance for every 1000 feet density altitude, about 36% for the flight we’ve discussed). Added to this, the pilots had no headwind to help decrease their takeoff distance (10 knot headwind decreases distance by about 10%), and they were taking off uphill (1% upslope increases takeoff distance about 8%). You can see how this adds up.

Even though the pilots had made this takeoff successfully in the fall, winter, and spring leading up to the accident, they did not account for that hot, 3000 foot density altitude day at max gross weight on an upsloping runway with no headwind to help them. This resulted in a much longer takeoff roll with decreased climb performance. They should have recognized the airplane wasn’t performing nearly to what it had for them on past flights and aborted the takeoff.

With summer right around the corner, it only takes a few minutes to check your performance calculations. See how the hotter temperatures affect your airplane’s performance in all phases of flight. Note that most operating handbooks base their takeoff and landing distances on shortfield technique. If you plan a normal takeoff roll, the numbers in the POH will not work. Also, try to plan your flights earlier in the day when you can take advantage of the cooler temperatures and better performance.

Is Corrective Vision Surgery for you?

May 28, 2012/in Tips and technique/by studentpltnews

It’s easy to be sold by the burgeoning number of television & radio advertisements for quick, painless, worry-free corrective vision procedures. After all, this is capitalism at work and medical practices specializing in these procedures need to turn a profit. I’m not suggesting that the motivation of most physicians performing these procedures is less than honest, but it would be naïve to assume other influences aren’t present. What this means to you is to proceed with caution and consider the entire process.

There are a number of variations of laser eye procedures and the variations seem to be growing, but all include a laser resurfacing procedure which changes the way light focuses on the retina to form an image in the brain. A list of approved surgeries and FAA guidance can be found here. The most popular procedure today is LASIK — Laser-Assisted In-Situ Keratomileusis.

The following selection criteria are used for LASIK:

Age 18 years or older
Stable refractive error (less than .50 diopters [D] change within the last year) correctable to 20/40 or better
Less than – 15.00 D of myopia and up to 6 to 7 D of astigmatism
Less than + 6.00 D of hyperopia and less than 6 D of astigmatism
No gender restriction, with the exception of pregnancy
Pupil size less than or equal to 6 mm (in normal room lighting)
Realistic expectations of final results (with a complete understanding of the benefits, as well as the possible risks)

Advances in the equipment and techniques used to perform these procedures have made complications less frequent. The technological advancements coupled with proper patient selection (not everyone is a candidate for corrective surgery) also have made any potential side effects (varying vision acuity, haloes, glare, etc.) less severe.

The Medical — FAA requires that you stop flying after a vision correction procedure until it has been determined that your vision meets the standards of your medical and that there are no adverse side effects. The recovery process also needs to be at a point where eye drops are no longer required. Pilots should report to FAA using form 8500-7 (Report of Eye Evaluation). The report can be submitted directly to the Medical Certification Division or to your AME at your next exam.

If the procedure was done 2 years ago or longer, the FAA may accept the Examiner’s eye evaluation and an airman statement regarding the absence of adverse side effects.

Find the right specialist — it’s important to find a reputable facility and eye care specialist to perform a vision correction procedure. Consult the eye care specialist to determine whether you’re indeed a candidate and then consider the risks versus rewards. It’s important that you possess normal ocular health and be free of pre-existing conditions to provide the best likelihood of success.

For more information, read the FAA brochure Information for Pilots Considering Laser Eye Surgery.

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What Your Aircraft Feels

Is Corrective Vision Surgery for you?

What Your Aircraft Feels

Is Corrective Vision Surgery for you?

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What Your Aircraft Feels

Is Corrective Vision Surgery for you?

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