Return-Path: Received: from mail.his.com ([205.177.25.9]) by truman.olsusa.com (Post.Office MTA v3.5.1 release 219 ID# 0-52269U2500L250S0V35) with ESMTP id com for ; Sun, 28 Feb 1999 11:14:02 -0500 Received: from hk53 (pm8-206.his.com [205.252.121.206]) by mail.his.com (8.8.5/8.8.5) with SMTP id LAA14642 for ; Sun, 28 Feb 1999 11:15:51 -0500 (EST) Message-ID: <000301be6335$26a64540$ce79fccd@hk53> Reply-To: "Avionics Systems" From: "Avionics Systems" To: Subject: Radar altimeters Date: Sun, 28 Feb 1999 11:12:32 -0500 X-Mailing-List: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> All radar altimeters have an altitude warning that can be set with the DH (Decision Height) bug. The unit gives an aural warning, and illuminates a DH light. Some units have a gear logic input so it knows when the gear is up or down. The best unit we've seen for small aircraft is the Bendix/King KRA-10. Trimble made a line of both alalog and digital radar altimeters, but every one we tried had problems like warnings at the wrong altitude, constantly resetting itself, total blackouts, etc. Other owners of the Trimble units confirmed the same types of problems. An acquaintance was working on a homemade radar altimeter for his Venture that uses the distance sensor from a Polaroid camera to judge distance to the runway, then give an aural countdown in feet above the runway. The system was even tested successfully, but the limitation was the short range of the sensor. I don't think the project went farther than that. David Buckwalter Avionics Systems