AVmail: Jun. 27, 2005
Reader mail this week about the Pinnacle and Payne Stewart crashes, why we fly and more.
Thank you for posting the various links regarding the Pinnacle crash (NewsWire, Jun. 16). As a CRJ captain myself, I find all information on the subject to be a matter of my own professional safety. That said, I have to ask why there is a 20-minute gap on the CVR reported in the Salt Lake Tribune link. At 09:54, they're afraid they're losing it. At 10:14, they're in their last seconds before crashing. My coworkers and I have turned this scenario over many, many times, debating and questioning every possible human and mechanical factor that may have acted on this crash. Those 20 minutes of conversation would shed a lot of light on the speculation!
A large part of the public docket, including what appears to be the full CVR transcript, is available here.
Features and Columns Editor
Regarding Frank Nelson's comment, "That's especially important since they appear to condone airline pilots flying while inebriated," (AVmail, Jun. 20).
ALPA never has condoned inebriated flying, at least since 1957 when I became a member and they certainly don't now. ALPA has a very effective corrective program to allow pilots who have alcohol problems to correct the problem and return to active flying.
Where did you get your information that they apparently did? In NATOPS perhaps?
Learjet 35 Accident
This Learjet accident involved golfer Payne Stewart (NewsWire, May 9). I believe all the litigation is over. I was curious about the probable cause. As an aviation insurance claims rep., retired, I handled at least two partial-damage claims on Learjet 35 aircraft manufactured the 70s that suffered from corrosion around the aft bulkhead. In the early Lears, lead-acid batteries were used. I didn't note any mention of this in the NTSB investigation. Perhaps some of your subscribers may have knowledge of this early problem, which may not have been corrected in all cases.
You could have put the last choice as "All of the above" in this week's question (QOTW, Jun. 23). Back in the mid-60s when I soloed I can still remember the takeoff (what I thought) and the landing, as if I did it today. My feelings were every one of the options, and then some. I do remember saying, "I'm free."
Average Speed Error
Unfortunately you have an error in the calculated average speed for the L-39 "Wild Child" round-trip speed record (NewsWire, Jun. 23). I don't know if the error is yours or the NAA's, but your reported average speed of 463.25 mph was calculated as the average of the two leg's speeds of 561.2 mph and 463.25 mph. This is incorrect because you cannot average the speed of two legs in this manner. The correct calculation takes the total distance flown (2 x 373.82 miles) divided by the total time (0:39:58 + 1:01:24 = 1:41:22), which gives an average speed of 442.5 mph. This is 20.7 mph slower than the number you reported.
That was basic, ground-school math that I forgot. Thanks for setting us straight.
POTW -- Shutter Speed And Turning Props
You ran a couple nice pictures this week that would have been even better if the photographers had used a slower shutter speed and panned the shots (POTW, Jun. 23).
Why? So it doesn't look like the props are stopped.
Compare the B-25 and Sun 'n Fun photos with the pictures of the C-152 and the C-170. Yes, I know a slower speed risks blurring the primary subject as well as the prop -- but that's what separates the good photographers from the great ones.
I'd recommend a shutter speed that allows the prop to rotate at least three blade widths at its tip. More (slower shutter speed) is better.
For a propeller with six-inch blade width, 60" diameter, turning 2100 RPM, the maximum shutter speed would be 1/350.