ELT Jammed my comms yesterday

[Furball]

Yea I know, its not a 407 but who cares. Somehow, during a smooth flight from Montauk to Islip yesterday, that little piece of soup telephone cable that goes from the ACK switch up front to the ELT came out of its housing on the ELT. So the damn thing started going off. I checked the ACK light - nothing came up. Since I was next to Spadaro and all their craziness I thought it was someone who planted a 152 hard - not unusual for that airport or their tenants.

Anyway, the kicker was - I could transmit just fine, but I had 9/10th bleedover from the damn ELT. I couldn't hear a damn thing from ATC until their signal strength burned through the ELT's signal. It was on all frequencies - and I literally had to be next to the tower they were transmitting to hear what they were saying.

So here's the thing - will the 407 have the same radio jamming feature as the UHF/VHF version? Can I just soupcan the UHF/VHF since its no longer monitored anyway? I'd rather not have a lostcomm emergency by a box sitting in the back seat that no one listens to and jams everything incoming.

My cat's name is Mittens.

[Widewing]

Back in 1994, I designed the crash sensor used in many, maybe most ELTs meeting the requirements of RTCA DO-183 (121.5/243 MHz), EUROCAE ED62 (121.5/243 MHz and 406 MHz) and RTCA DO-204 (406 MHz). We manufacture about 30,000 sensors annually.

The DO-204 requirement unifies U.S. and EUROCAE specifications in regard to the crash sensor response curve. DO-183 has contained specification error since it was released. Essentially, DO-183 calls for no-trigger when exposed to 22g of vibration at 44Hz. However, its dynamic response curve shows that the Delta V generated at that amplitude and frequency falls right into the may-operate area of the crash response curve Delta V. In other words, the ELT must not trigger and yet trigger to the exact same velocity change...  

This required that I design the sensor to operate in the upper half of the g/time curve to avoid unwanted tripping during FAA qualification vibration testing (Delta V response requirements for DO-183 are 3 ft/sec/sec no fire, 4 ft/sec/sec must fire). This nearly doubled the cost of the sensor and increased cost of the ELT to the user. EUROCAE recognized this screw-up and shifted the g/time curve upwards, as well as static g value. Thus, they specified 4 ft/sec/sec no fire and 5 ft/sec/sec must fire. Static g sensing increased from 2.0g +/- 0.3g to 2.3g +/- .03g. With the adoption of the 406 MHz frequency, the RTCA DO-204 spec adopted the EUROCAE g/time curve.

We are currently finishing up development of an improved sensor, which will be installed in Kannad ELTs before the end of this year, with several other manufacturers coming online with it soon after. We see little demand for DO-183 sensors, but the demand for DO-204 (406 MHz) sensors is booming.

We have been trying to get the FAA to look at the all aspect sensors we currently supply for the Navy. Current ELTs sense a crash in the forward direction only. These new all aspect sensors will sense a crash in any direction, even backwards. We are retrofitting these sensors to the units installed in E-2Cs and C-2As, with identical sensor packs being used for their emergency lighting as well.


My regards,

Widewing

[Chalenge]

I think less than half of the soaring guys use ELTs at all but they are obviously a good idea along with PLBs and not just for aviators. You appear more interesting every day Widewing.