AVmail: Oct. 23, 2006

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New York Cirrus Accident Analysis

Regarding the Lidle accident, the Oct. 16 AVwebFlash stated that, "Some analysts suggested gusty winds blowing between the Manhattan skyscrapers contributed to the accident, but winds were out of the east and Manhattan's skyscrapers were to the aircraft's west."

Wind certainly did have a lot to do with the Lidle accident, and particularly because the winds were out of the east.

An aircraft flying at 120 MPH [sic] (cruise speed in a Cirrus is about 150-160 MPH) requires a turn diameter of about 2,000 feet when the bank angle is 45 degrees. Of course, a bank angle of 45 degrees is considered a steep turn in any aircraft, not just a Cirrus. If the turn is steepened beyond 45 degrees (while maintaining altitude), the diameter of the turn is decreased, but the stall speed goes up (non-linearly, by the way). If the turn is steepened enough, the aircraft can enter an accelerated stall. If the turn is not perfectly coordinated near an accelerated-stall condition, the outside (of the turn) wing could stall before the inside wing. This causes an unbalanced lift situation and the aircraft will thus roll out of the turn on its own. Control inputs are useless until after recovery.

The wind definitely aggravated the situation. The wind was out of the ENE at 13, gusts to 22. Since the aircraft was flying north and entered a left turn (one that would have to be completed within a 2000-foot diameter), the existing wind direction and speed would require much more than a 45-degree bank angle to complete the turn safely. The strong east wind would have had a tendency to blow the aircraft into any tall buildings to its west. And through a forest of tall buildings the wind speed could have been much greater than reported, due to funneling effects between the buildings.

By the time they realized they weren't going to make the turn, they were probably being blown right into a forest of tall buildings. In attempting to dodge the buildings within the forest, they probably entered an accelerated stall and lost control of the aircraft.

Had the turn been initiated to the right from the west side of the "canyon," it would have been much easier to complete the turn safely.

My son and I took mountain flying lessons in Idaho years ago. We had it drilled into our heads through several real, in-canyon training situations about the difficulty of safely making turns in narrow canyons. The best way to make a safe turn in a narrow canyon is to slow down to a minimally safe airspeed before initiating the turn and then apply full flaps and full power upon entering the turn. Many pilots are not aware of the amount of turn diameter required at higher airspeeds because typical training is not done in canyons.

Jim Morris


My background is as a pilot and CFI for 35 years. I have also flown the NYC VFR corridor, albeit not often. Noting a recent CAP accident where two high-time pilots flew into a California mountainside on a VFR day while checking out some newly installed glass cockpit equipment, it seems likely to me that both Cory Lidle and his CFI, Tyler Stanger, were more worried about airspace incursion, rather than giving the required 500 ft. space between them and the surrounding buildings. Breaking the mantra of aviate, navigate, then communicate, they were both heads-down, looking at the virtual reality of the GPS and not the reality outside their windows. A case might be made here where today's pilot worries about airspace limitations was a contributory cause of the accident.

Rob Duncan


I cannot imagine anyone wanting to fly in that environment without all the assistance available for the asking from ATC (Question of the Week, Oct. 19). It might be interesting to know how many of the "Yes" answers are from instrument rated pilots or pilots flying from controlled airfields, i.e., that group of pilots who are on the radio with ATC every time they fly.

Fred Wedemeier


NTSB Safety Alert

Reference your latest story on the NTSB Safety Alert regarding "Thunderstorm Encounters (AVwebFlash, Oct. 16) ...

The NTSB should be ashamed of the lack of useful material contained in the alert. Yes, thunderstorms do kill people. Yes, you had better not put your life in the hands of ATC when it comes to avoiding them. Bottom line-It's not their job.

However, only a mention of Flight Watch (read as Flight Service) in passing? A general aviation pilot in a situation with thunderstorms along the route needs to use all of the information available to him/her. What about Flight Service? The personnel at your local FSS have the tools and training to help pilots, using real time radar, a system that overlays the aircraft route on the radar, along with numerous other weather resources. That's our job.

The information contained in the NTSB alert just proves that they know very little about general aviation and Flight Service.

Dale Walker


I left general aviation 30 years ago. After completing an airline career I am back in the thick of it, and one change has been very apparent.

I have found that it is routine for ATC to describe any and all precip. as "severe precipitation" in warning GA pilots away from it. In the vast majority of cases, such a description proves to be neither accurate nor warranted. In one startling case, I had an approach controller inform me, in the same breath, that she was painting severe precip. over my destination airport ... and that another a/c on an instrument approach was calling "Runway in sight" and canceling IFR on three-mile final.

This is the classic "cry wolf" scenario, and if it is as widespread as it appears to be, then it is no wonder that pilots are ignoring such warnings and, occasionally, getting into real trouble that might have been avoided.

In 1977, the most frequent comment on wx from a controller was, "My radar does not paint wx well." Now, that has become, "Caution, severe wx ahead." I maintain that the latter trend is far more dangerous than no info at all.

Kim Welch


Bluewater Petition On Lead Elimination

As the co-author of Bluewater's petition asking the EPA to eliminate lead from avgas, I found your commentary on it quite curious (AVwebFlash, Oct. 16). First of all, you wondered where I got the information allowing me to assert that 70% of general aviation aircraft can use unleaded auto gas. However, that bit of information is clearly attributed to an article from Aviation Week & Space Technology in footnote 42. Of course, the vast majority of those 70% do not have certificates allowing them to use auto gas, but they have the capability to do so.

Second, you state that ethanol-based fuels are banned from use in aircraft. That is simply not the case. While it is true that ethanol is not widely used as an aviation fuel, the FAA has issued supplemental type certificates for several planes that run on ethanol-based fuel. Indeed, the first STC for such a plane was issued in 1999. For more information, see here.

Ultimately, the concern over lead in avgas comes from the lack of action by the EPA to fully eliminate it from mobile sources. Lead is a toxic substance that is not safe even in small doses. The EPA did great work removing lead from auto fuel; now they should finish what they started and mandate its removal from avgas. In the EPA's response to public commentary, they stated they could not do so because there were no viable alternatives to leaded avgas. As noted in the petition, that simply is not the case. Since alternatives to leaded avgas presently exist, the EPA has an opportunity to push forward on this issue.

I hope you take a more detailed look at the petition for further discussion.

David Zizmor


No Piston?

It's happened. Today's AVweb had nothing but Jet-A burning hardware from top to bottom (AVwebFlash, Oct. 18). Yikes. Is AVweb going the way of Flying Magazine and AOPA?

I'd hate to see you ignore your (and all of GA's) roots: the piston GA fleet. It may not be as glamorous, but at least it's relatable to more of us (your readers) than this turbofan monotony.

Rich Chiappe

AVweb Replies:

The AVwebFlash you received last Tuesday and Wednesday were special issues, direct from Orlando, Fla., and the National Business Aviation Association (NBAA) Annual Meeting and Convention. As always, AVweb's team at NBAA worked hard to bring you and other readers the "latest and greatest" from one of the aviation industry's leading trade shows. Other examples of these efforts include our reports from EAA's AirVenture Oshkosh and Sun 'n Fun. Next month, AVweb will report from the AOPA convention in Palm Springs.

In this instance, you're absolutely right: Nothing but kerosene queens. That was the market in Orlando, and that was the news stories we wrote. The next day, of course, AVwebFlash provided a mix of news from NBAA and elsewhere in the aviation world, including Jet A burners as well as those that drink 100LL.

At AOPA next month, you can bet our coverage will reflect the show's orientation and will have far more piston-aircraft news than has been the case with our NBAA coverage. Stay tuned.

Jeb Burnside
Newswriter, Editor


Central Oregon Labor

I find it amusing that the corporations in Bend, Oreg., are not able to find skilled labor (AVwebFlash, On The Fly, Oct. 19). In this day and age of outsourcing to cheap labor in foreign countries, most of our kids have learned that the only way to make decent wages is to have a college degree and aspire to a management position. Skilled labor is not valued or rewarded by the corporate world. You never stated how much the jobs that go begging pay and how much the whining management of these companies make. You reap what you sow.

Curt Randoll


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