What happens after an airplane crashes? How will rescuers find you?
Let’s dig into the “Beeps & Squeaks” that will tell the world where you are (hopefully).
To begin, the pilots will have been radioing their position for as long as they can when a crash is inevitable. If you are lucky enough to be in radar contact, ATC will know your last position when you disappear. But, not everywhere has radar coverage, pilots may not get a radio call off & that leaves a lot of ground to cover.
Enter the “Emergency Locator Transmitter”. We call it an E.L.T. for short.
The ELT has been around for a very long time. In its earliest form, it just emitted a continuous radio signal that sounds like an alarm & transmits continuously on a “Guard” emergency frequency. The civilian frequency is 121.5 MHz, while the military is 243.0 MHz.
Commercial pilots are generally required to continuously monitor 121.5 & report any ELTs they hear. ATC can then use other pilot reports & the intensity to kind of triangulate a general position. Sometimes they will ask random jets if they can hear it.
Search & Rescue teams have specialized equipment that will lead them even closer to this “beacon”.
ELTs can be triggered manually by the pilot, or automatically if a certain amount of G’s were encountered, indicating a crash (it’s sometimes possible to set it off by landing really hard).
The ELT mounted in the jet won’t do you much good if you land in water & the jet sinks, though – radio waves don’t travel well through water. So, portable ELTs are in brackets on the jet – usually near a door – that the flight attendants can grab & throw in the raft. They have various forms, but are usually yellow or orange & about the size of a walkie-talkie. They are operated manually & can transmit the beacon, or be used to talk on the Guard frequency, w/ a continuous use battery life of around 24 hours.
This was the best we had for many years, but in the wake of MH370, new technology began to become widespread.
The Global Aeronautical Distress & Safety System (GADSS) became the best choice. This system tracks the airplane’s systems & its position, transmitting every 15 minutes back to the airline. If certain systems start to fail, that’s updated to every minute.
Then GADSS ELT-DT (Distress Tracking) came along. It’s similar, but has more data & controls the ELT. It can turn on the ELT well before a crash, if things look bad enough, and the ELTs are now no longer dependent on exceeding a G limit to activate.
Now, another technology emerged to improve the ELTs. The COSPAS-SARSAT program, an international effort, built little modules that hitched rides on satellites (the satellites have other primary jobs) which could detect & triangulate an ELT signal…but they eventually stopped tracking the 121.5 & 243.0 beacons because of the high number of false alarms in Cessnas & such.
They moved to a specific ELT frequency – 406.0 MHz – that reduced the number of false alarms. Still, in 2017, there were 8,898 ELTs in the U.S. alone on this satellite frequency, 98% of which were false alarms. It’s a problem.
Anyway, both the jet’s ELT & the portable ones transmit on civilian, military & satellite frequencies simultaneously. They are pretty reliable, but they can fail…so even if I didn’t land on water, I’d try to grab an ELT when escaping, just to be sure.
The ELTs are built to similar standards as the “Black Box”. Which is actually two boxes, one recording voice & sound in the cockpit, the other airplane performance. Those can withstand 3,400 G’s. While the black boxes can survive being under about 14,000’ of water or more, there’s no point for the ELT. The black boxes use a different frequency to “ping” continuously for 30 days or more, which travels better through water.
In the U.S., the Air Force Rescue Coordination Center (AFRCC) is responsible for responding to ELTs. That might mean a search, but it’s usually screening false alarms.
That’s all my space. Hope it helps!