Ah the 50' rule. It has been around for more years than stated and has been a contributing factor in many a prang I bet. I know of one in the early 70's where the glider pilot had a predilection and acceptance of the 50' rule, landed over that fictitious obstacle and could not fit into the outlanding paddock [at Emu Plains]. There was an option of missing the non-existent obstacle, clear the 4' fence, and land across the diagonal with 40% more landing run!
At the time I landed as close as I dared over a fence at Forbes airfield and paced out my touchdown to be 220' from the fence. Critical in a short outlanding, and worse if one adds and unnecessary 50' at 30:1! My google-fu found " Douglas Bader, British WWII air ace). Rules are for the guidance of wise men and the blind obedience of fools. (Solon, the Lawmaker of Athens, d. 559BCE)" ... Some unnecessary rules have been around for millennia. It may come from an instructor who could gauge that clearance of a fence because 50' is a soft conversion of a 15 meter wingspan. Sitting safely on a chair at the pie cart the instructor can visualize that and use it to berate the pilot who considered he had a short landing well under control. But in any event is the rule necessary? We all know the advantages of not hitting the far fence at 5 knots over going through the near fence at 50 knots. Those who don't are not around to tell! So, clear all obstacles is the key, and land as safely as you can. Finally, appreciate that the younger set probably have a good appreciation of metrics, but may not relate to Knots and feet. My 'two bobs' worth, but you can call it 20 cents. Alan Wilson Canberra -----Original Message----- From: aus-soaring-boun...@lists.internode.on.net [mailto:aus-soaring-boun...@lists.internode.on.net] On Behalf Of Peter F Bradshaw Sent: Friday, 19 October, 2012 2:24 AM To: Discussion of issues relating to Soaring in Australia. Subject: Re: [Aus-soaring] 50' obstacle clearance rule Hi; Irrespective of whether it is 50' or not I find it hard to believe that the figure is given in a system which people under 40 have no heuristic knowledge of. On Mon, 15 Oct 2012, Mark Newton wrote: > > Hi folks. > > My google-fu is failing me, but at least one of you can probably help. > > I've long accepted that the rule for obstacle clearance is 50'. > > However, the GFA instructor handbook describes it as a wingspan, and > the B certificate oral exam calls 50' a "recommended" minimum, so I'm > trying to go back to sources to find the origin of the rule. > > And I can't seem to find it written down anywhere. > > I'm beginning to suspect that my long-term acceptance of the 50' > rule is wrong, and that the real limit is, shall we say, more > "operationally fluid" than that. > > Wondering if the strict mention of 50' that I've seen at clubs all > over Australia is actually more of a tradition, perhaps derived from a > misunderstanding of certified light aircraft performance charts which > give minimum takeoff distances including clearance of a 50' > obstacle. > > Does anyone have a cite to the regulations? > > (while you're at it, providing a cite to a current GFA or non-exempted > CASA regulation which states what GFA annual check entails, whether > it's required to be signed out in a logbook, or whether an instructor > is even required to be present, would help to settle a long-standing > argument :) > > - mark Cheers -- Peter F Bradshaw: http://www.exadios.com (public keys available there). Personal site: http://personal.exadios.com "I love truth, and the way the government still uses it occasionally to keep us guessing." - Sam Kekovich. _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
