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Hi Gang
I received a large number of responses to my posting both on RAS (25) and privately and would like to respond to some of the issues. Firstly I would like to reiterate that the reason for my posting was to make pilots aware of not paying attention to critical considerations, situations can quickly get out of hand. We seem to have here in Minden at least one destruction of an aircraft (Carat and ASW26) every 2 years and almost the same number of deaths in situations where if the pilots had flown reasonably in wave these accidents could have been avoided. I came close and it was a wake up call. Enough! I would like to discuss communications with ATC especially around Reno which is an International Airport. My rule of thumb is never to burden them with chit chat but to communicate when necessary. When flying in wave I monitor Reno Approach ( 2 frequencies - one from the south and one from the north) and if close to 18k I do not communicate. If flying anywhere close to approaches or flyways I speak to them and give them my intentions. This works well and if there are several gliders flying doing the same this doesbad not over burden them. When I got into my situation I was monitoring Reno Approach and there were no other aircraft in my vicinity. I knew I would have to fly higher for a very short time so should I have called them and declared an emergency? I think not! What would I have said: "This is an ultalight vehicle (FAA definition of my flying machine), 8 miles NV of Reno declaring an emergency, squawking 0440, request operation to 19k from present altitude." What would ATC have said in response: :You are what? Repeat request and say N number." Would this have started a useful interchange of ideas. I think not. No I had to as safely as possible fix my mess and get down to below 18k. Lets talk reporting altitudes to ATC. Below is a private response to a question concerning altitudes: "Thanks for your reply. The actual difference in indicated altitudes between the transponder and the pressure altitude altimeter that day was very small because barometric air pressure was close to the standard value. You are correct that up to Class A air space altitudes are given based on surface pressures. Above 18k all altitudes must be given using the standard pressure. So there can be a dilemma. There is a region of uncertainty around 18k. If the transponder says 18.2k (my Becker transponder displays its altitude) and the pressure altitude reading says 17.8k and ATC asks what altitude you are what do you say? OK. So what happens in practice? When I am close to Reno monitoring ATC and ATC informs another aircraft of my presence they always use my transponder altitude using an expression like this: "Glider at your 3 o'clock indicating one five thousand one hundred feet" ATC never corrects my transponder altitude below 18k to actual altitude. So in extreme conditions there can be errors of several hundred feet between what is reported and reality. The solution? GPS, GPS, and GPS! " And finally VNE at altitude. IAS has to be adjusted for altitude to give TAS. It is generally accepted that rule of thumb reckoning for every 1000 feet above sea level TAS has to be increased by 1.5% although at high altitudes 30k it is closer to 2% (Check site given below. It has an excellent article). So how do sailplane manufacturers rate their machines? In general fairly close to the above. Eric Greenwell in a previous posting gives the IAS for the ASW26 and I have checked the same for my Stemme S10-VT and in private correspondence I find other sailplanes are similarly placarded. This does not answer my original question about the sensitivity of flutter to altitude and true air speed. No one, including me, to date has been able to identify any meaningful articles on the subject. Dave http://tvnz.co.nz/view/video_popup_windows_skin/1519472 |
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