Part 135 Mode S Exemptions Expire March 1, 2007
The FAA is proposing that there be no more installations of Mode C transponders in Part 135 aircraft after March 1, 2007, and that all transponder replacements after that date be with Mode S devices. The agency issued a Notice of Proposed Rulemaking (NPRM) on Oct. 7 saying that exemptions to the rules requiring all new transponder installations be Mode S will terminate on March 1, 2007, and it will not grant any exemptions after that date. However, if, under an exemption, the Mode C is installed before March 1, 2007, the equipment can continue to be repaired to keep it in service after that date. When it's finally irreparable, it must be replaced with Mode S.