Question regarding the ELT.

[WhySoTough]

Is the Emergency Locator Transmitter fitted with both the CVR and DFDR?
Does it send a signal for 48 hours or is it 30 days.
I been reading a lot of mixed things.

Thanks n advance:ok:

[jamesleaman]

From my previous training when I did some Cabin Crew work, the ELT sends signals on 3 Frequencies, for as long as the battery life permits, normally closer to 48 hours than 30 days!

I've never heard an ELT to contain the Cockpit Voice Recorder or Flight Recorder unless your talking about something completely different.

[mad_jock]

The black boxes do have various location devices fitted to them some work under water and others above water. But which ones are fitted is dependent on the make and model.

When you talk about ELT people tend to presume that you are talking about the Aircraft ELT which is hardwired into big things and portable ones in smaller aircraft.

[aviofreek]

ELT, CVR and DFDR are three completly different things.

Emergency Location Transmitter is a part of aircraft emergency equipment and transmits a signal on three emergency frequencies (by operating a switch in a cockpit or upon a crash G-switch closes and ELT operates automatically). 121.5 Mhz (which is normally picked up by the closest ATSU/SAR), 243 MHz also picked up by SAR, 406 MHz picked up by satellite. They have a built-in test program also which enables the pilot/engineer to test it for proper operation without triggering SAR

CVR and FDR (DFDR) are recorders and that's exactlly what they do. Record data. They do not transmit anything. They are, however, equiped with ULB (underwater location beacon). It's a small metal cylinder that transmits an ultrasound "ping" (only) when submerged into water. The ULB is only used to locate the CVR/FDR if the aircraft crashed into the water, as they can get displaced quite far from the original crash site due to currents...