Thoughts on emergency locator transmitters

As the search for aviator Steve Fossett continues, I've been thinking about the ways we try to track down missing people.

One of the leading independent experts on ELTs (emergency locator transmitters) is Doug Ritter, editor of the Equipped to Survive Web site. Ritter has written extensively about ELTs, which are installed on aircraft; EPIRBs, or emergency position-indicating radio beacons, which are carried on boats; and PLBs, or personal locator beacons, which are carried by individuals. If you have any interest in the subject, you should check out his Web site.

Ritter's most recent blog post, dated Thursday, concerns a recent memo from the chairman of the National Transportation Safety Board to the administrator of the Federal Aviation Administration. In the memo, he recommends that the new style of 406MHz ELT be mandated for use on all aircraft, replacing the existing mandate for 121.5MHz ELTs.

The issue is that the international COSPAS-SARSAT satellite system will stop processing 121.5MHz alerts in 2009, so the ELTs that are currently required will no longer serve their intended purpose. As the NTSB and Ritter point out, they don't work very well right now anyway.

I don't know whether Fossett's airplane had the new or old style of ELT, but that isn't actually what I want to talk about here.

It occurred to me that the whole idea of an ELT that transmits only in an emergency should be revisited.

Cell phones continuously announce themselves to the cell phone network as their owners move around. These announcements are very short and efficient, since there isn't much to say; they consume very little of the system's available bandwidth.

Similarly, I'm thinking that ELTs should periodically transmit their current position, direction and velocity. If these announcements happened every five minutes or so, a lost airplane could be located fairly quickly even after a sudden catastrophe, like running into the side of a mountain.

It's possible that these periodic transmissions would overload the existing COSPAS-SARSAT network, but perhaps these satellites can be replaced with more capable units over time. For example, beamforming techniques could be used to improve sensitivity in areas of heavy air traffic. Increasing the effectiveness of this system could save a lot of lives, which justifies some increase in cost.

The ELT should be self-contained, with its own UPS (uninterruptible power supply) and GPS receiver so that it can independently monitor the aircraft's motion. Once an aircraft departs from its normal flight envelope-- sudden descent, for example, or a roll maneuver in an airplane not designed for acrobatics--the ELT could begin transmitting more frequent updates.

This all comes to mind because I've been having similar thoughts about how the new 700 MHz public-service band should be used. This is the same band in which several companies, including Frontline Wireless, hope to create so-called Open Communication public wide-area networks. (On August 21, I blogged about Reed Hundt's overly political speech about Frontline Wireless at the Hot Chips conference.)

I'd like to see ELT-like capabilities used in this new band, along with various other new operating modes...but that's a subject for a future post.

[salsaman100]

Aircraft ELT's and Continuous Tracking

We already have transponders (radar tracking devices) with altitude encoding, and the availability of filing flight plans with the FAA. Don't need big brother in the cockpit anymore than we already have. Also, there are many older aircraft without electrical systems and do not have a way to power equipment with continuous electrical requirements. Might work better as a voluntary system and not a requirement.

What happens when I stop for lunch, park the airplane some place that blocks the satellite signal (hangar, tree, buildings), and search and rescue is sent out? Continuous tracking may not be the answer.

[Peter N. Glaskowsky]

Just to be clear

I wouldn't want the system to act solely on the basis of a loss of signal.

Anyway, if the previous readings declined smoothly to 0 AGL and 3 knots, it's probably reasonable to suppose that the pilot survived whatever happened next. :-)

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[willie61]

A nice idea.....but...

Steve uses some clear logic about incorporation of new ELT tech, but a little clairfaction here..Current ELTs of which are being used on Steve's A/C are self contained/battery powered units with 3 settings OFF/ ON/ AUTO. The AUTO setting responds to a "G" shock (or crash) to start transmitting on 2 feq's (one military / one civi). These units can also be quickly pulled out of the A/C to be set to ON to send a signal.
The problem with the issue of new tech goes back to the nature of aviation certification itself- a very long process which cannot; and often in cases should not, respond as quickly as other tech based businesses with the latest -greatest idea. The system does need to be changed, and frankly those of us who have been directly effected by the industry often pull our hair out with the stupid nature of a gov run system.
Also the idea of adding components (the UPS idea) violates a basic idea of system engineering - the more components in a system, the more expensive and the more likely it will fail.

GPS systems have become a wonder for all of us and have a big role to play here as a potential solution; but just as with the major airlines, until people are killed or harmed , there is often a push back on spending money on a solution.

The certification process with the FAA is often the problem here; that and equally the issue expressing opinions while not knowing the said industry. We are all guilty of such flaws. Often the devil is in the details.