how long can you record on a cassette tape
Compact Cassette Tape length usually is measured in minutes of total playing time. The most popular varieties are C46 (23 minutes per side), C60 (30 minutes per side), C90, and C120. The C46 and C60 lengths typically are 15 to 16 micrometers (0.59 to 0.63 mils) thick, but C90s are 10 to 11 µm (0.39 to 0.43 mils) and (the less common) C120s are just 9 µm (0.35 mils) thick, rendering them more susceptible to stretching or breakage. BASF declared the C60 with 88 meters (289 feet).[clarification needed] Some vendors are more generous than others, providing 132 or 135 meters (433 or 443 feet) rather than 129 meters (423 feet) of tape for a C90 cassette. Even C180 tapes were available at one time, but these were extremely thin and fragile and suffered from such effects as print-through, which made them unsuitable for general use. 150 minute length is still available from Maxell (UR 150), Sony (CDixI 150) and TDK (TDK AE 150).
Flight recorder The United States' first CVR rules were passed in 1964, requiring all turbine and piston aircraft with four or more engines to have CVRs by March 1, 1967.[37] As of 2008[update] it is an FAA requirement that the CVR recording duration is a minimum of two hours,[27] following the NTSB recommendation that it should be increased from its previously-mandated 30-minute duration.[38] As of 2014[update], the United States requires flight data recorders and cockpit voice recorders on aircraft that have 20 or more passenger seats, or those that have six or more passenger seats, are turbine-powered, and require two pilots.[39]