Story ID: 
Retrofit altimeter chosen for Challenger 
By: Charles Alcock
Caption: Bombardier has selected Revue Thommen’s AD20 two-inch electronic standby altimeter as a retrofit option for the Challenger 601-3A/3R and 604.
Word Count: 169
Bombardier has selected Revue Thommen’s AD20 two-inch electronic standby altimeter as a retrofit option for the Challenger 601-3A/3R and 604. According to the Swiss avionics specialist, the AD20 is the first electronic standby altimeter designed to RTCA DO-178B standards with software level A required for installation on Part 25-certified jets.The new altimeter promises operators enhanced features that are not available with mechanical standby instruments, as well as improved reliability. It provides both a dedicated digital liquid crystal display and an analog pointer, and features high-intensity backlighting for daylight conditions. The altitude can be displayed in both imperial and metric formats, and the unit can work at lower barometric settings. The equipment’s built-in test capability ensures that everything is functioning correctly each time the aircraft is powered up.The AD20 can be installed under Bombardier’s optional service bulletins SB 604-34-056 and SB 601-0595, which were released in June 2008. More details are available at Bombardier’s customer service Web site, www.cic.bombardier.com.