Pietenpol-List: Kitplanes Nov 2006
Posted: Tue Sep 19, 2006 8:51 pm
Original Posted By: "jimcarriere"
>FAR 91.121 states, in part, that the altimeter is set to "...the elevation of the departure airport or an appropriate altimeter setting available before departure..." For at least the following three reasons this is the proper procedure:1) The altimeter references your location in the third dimension of space. In a radio-equipped environment, reported altitude provides a better chance of separation between aircraft. If I report that I am over the airport at 3,500 feet, I mean above sea level, as reported by reading my altimeter, set to the current altimeter setting or field elevation before departure.2) Elevation figures on sectional charts provide an MSL figure in bold type, which is close to what a pilot will observe with a properly set altimeter. The smaller numeral is the above ground level heighth of the obstruction. Remember, the top number is where you're going to hit it, and the bottom number is how far you're going to fall.3) Consider what you will do if, after you depart the airport with the altimeter zeroed, the airport is closed behind you and you cannot legally (or safely) return to it. Your altimeter now reports a garbage in-garbage out altitude as you divert to your alternate field. The elevation difference between my home field and the closest alternate is nearly 300 feet. And there are unlighted towers in between them.Sorry for the long and pedantic first post. But as Gary said a day or two ago, we need to be safe out there. And I'm speaking from the perspective of someone who has lost a friend when he flew into a tower in the scud with possibly a mis-set altimeter. Thanks for making me dust off my FAR-AIM!Mark SmithGround Instructor and List-Lurker________________________________________________________________________________Subject: Pietenpol-List: Kitplanes Nov 2006
>FAR 91.121 states, in part, that the altimeter is set to "...the elevation of the departure airport or an appropriate altimeter setting available before departure..." For at least the following three reasons this is the proper procedure:1) The altimeter references your location in the third dimension of space. In a radio-equipped environment, reported altitude provides a better chance of separation between aircraft. If I report that I am over the airport at 3,500 feet, I mean above sea level, as reported by reading my altimeter, set to the current altimeter setting or field elevation before departure.2) Elevation figures on sectional charts provide an MSL figure in bold type, which is close to what a pilot will observe with a properly set altimeter. The smaller numeral is the above ground level heighth of the obstruction. Remember, the top number is where you're going to hit it, and the bottom number is how far you're going to fall.3) Consider what you will do if, after you depart the airport with the altimeter zeroed, the airport is closed behind you and you cannot legally (or safely) return to it. Your altimeter now reports a garbage in-garbage out altitude as you divert to your alternate field. The elevation difference between my home field and the closest alternate is nearly 300 feet. And there are unlighted towers in between them.Sorry for the long and pedantic first post. But as Gary said a day or two ago, we need to be safe out there. And I'm speaking from the perspective of someone who has lost a friend when he flew into a tower in the scud with possibly a mis-set altimeter. Thanks for making me dust off my FAR-AIM!Mark SmithGround Instructor and List-Lurker________________________________________________________________________________Subject: Pietenpol-List: Kitplanes Nov 2006