Friday, March 27, 2009

Thoughts on the ELT

The installation of an Emergency Location Transmitter (ELT) was mandated by Congress in 1973 in the aftermath of the disappearance of Rep. Hale Boggs' flight in Alaska. N631S still has installed the ELT that was delivered with the airplane in 1977.

Like most airplanes of a certain age, this ELT is designed to be activated by the deceleration forces associated with a crash and to broadcast a signal on the designated emergency frequency, 121.5 MHz. For some time, this signal could have been detected by an orbiting satellite that would provide location information to search-and-rescue (SAR) agencies who would then further localize the signal and effect a rescue. At least that was how it was supposed to work.

In fact, the 121.5 MHz ELT's are quite unreliable. They cannot be counted on to activate in the event of an accident. In fact they are so bad that they are being superceded by a new generation of ELT's that will operate at 406 MHz and will provide much improved performance. (These new units will also emit a signal at 121.5 MHz so that the SAR folks can deal with the last stages of the search without needing to procure all new direction-finding receivers.)

As part of this transition to the 406 MHz technology, the orbiting SAR satellite stopped "listening" for 121.5 MHz signals on February 1, 2009. Now, if you crash and your old 121.5 MHz unit activates (a very big if) you are dependent on passing aircraft monitoring that frequency to detect you.

So, what are the options?
  • Upgrade to a 406 MHz ELT and enjoy the benefits of the new technology. This will set you back about $2,000 (including cost of installation) for a basic unit or about $5,000 for one that is coupled to your GPS and will, when activated, broadcast the lat-lon of your crash site.
  • Keep the old 121.5 MHz unit in the airplane, for what it's worth, and invest about $500 in a 406 MHz Personal Locater Beacon (PLB) to carry with you on every flight. The drawback of the PLB is that you have to be conscious and capable of activating it manually -- it has no self-activation mechanism.
  • Just keep the old 121.5 MHz unit. It complies with US regulations (though not with Canadian nor Mexican regs) but you probably should not count on it to get you rescued with any speed.
If money were no object, I'd be having a 406 MHz unit installed in N631S right now. Even with money being a rather significant object, if my missions involved extensive flights over mountainous or desolate terrain, I'd be upgrading to a 406 MHz system.

But with virtually all of my flying being done in the "civilized" environs of the Northeast and under IFR (therefore in virtually constant contact with Air Traffic Control), I feel comfortable keeping the old unit in place, and maybe acquiring a PLB. Thus, during the current annual inspection we are replacing the ELT's battery as the regs require. It's just a brick, but it's a legally necessary brick.

I'll discuss PLB's in a later post.

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