This document discusses underwater locator beacons (ULBs) that are attached to flight recorders and aircraft to help locate crash sites underwater. It explains that ULBs emit ultrasonic pings once per second at 37.5 kHz when submerged in water. The beacons are designed to survive crashes and have a high recovery rate. Recommendations are made to increase their transmission duration and add frequencies to improve localization of wreckage. Maintenance, testing, battery replacement, and mounting procedures are also outlined.

2. LESSON OBJECTIVE
AT THE END THE OF THE LESSON,THE STUDENT
SHOULD BE ABLE TO CORRECTLY EXPLAIN;-
1.THE PRINCIPLES OF OPERATION OF AIRCRAFT
UNDER WATER LOCATOR BEACON
2. DEFFERENT TYPES OF UNDERWATER
SYSTEMS.
3.MAINTENANCE AND TESTING OF UWLS
4.UWLS MOUNTING REQUIREMENTS

3. LESSON SCOPE
1.ANALYSIS OF UNDERWATER LOCATOR
SYSTEM

4. EMERGENCY
INTRODUCTION.
• DEFINITION.
An underwater locator beacon (ULB)
or underwater acoustic beacon, is a device fitted
to aviation flight recorderssuch as the cockpit voice
recorder (CVR) and flight data recorder (FDR). ULBs
are also sometimes required to be attached
directly to an aircraft fuselage. ULBs are triggered
by water immersion; most emit an ultrasonic 10ms
pulse once per second at 37.5 kHz ± 1kHz.

5. ULB CONT-----
The device is designed not only to survive accidents, but to function
correctly after impact. Research by the French Bureau d'Enquêtes et
d'Analyses pour la Sécurité de l'Aviation Civile (BEA) has shown that it
has had a 90% survival rate spanning 27 air accidents over the sea. The
ULBs fitted in Air France Flight 447, which crashed on 1 June 2009,
were certified to transmit on 37.5 kHz for minimum 30 days at 4°C
temperature.

6. ULB CONT---------------
• Investigating the crash, the BEA recommended that
FDR ULBs' transmission period be increased to 90 days
and that "airplanes performing public transport flights
over maritime areas to be equipped with an
additional ULB capable of transmitting on a frequency
(for example between 8.5 kHz and 9.5 kHz) and for a
duration adapted to the pre-localisation of wreckage"
(i.e. with increased range).

7. POWER SOURCE AND ACTIVATION
A beacon is typically supplied with electrical power by
a lithium battery, which needs to be replaced after
several (DK120/six) years. Once the beacon becomes
immersed into water, a built-in "water switch" activates
it (water closing an electric circuit), and the beacon
starts emitting its "pings"; the battery power should be
sufficient for at least 30 days after the activation. The
minimum battery voltage is 2.97 Volts and the
maximum battery voltage is 3.5 Volts.

8. MAXIMUM DETECTION RANGE
•A 37.5 kHz (160.5 dB re 1 μPa) pinger can be
detectable 1–2 kilometres (0.62–1.24 mi) from
the surface in normal conditions and 4–5
kilometres (2.5–3.1 mi) in good conditions.

9. MAINTENANCE
Upon completion of each deployment, take these steps to assure
continued reliable performance from the ULB-350 Beacon.
• Wash the exterior of the equipment with fresh water and mild
detergent. Pay particular attention to cleaning film build-up from
the transducer face.
• Make sure the equipment has been thoroughly dried before
storage.
• Inspect all O-rings for damage and wear. Replace O-rings every
12 to 18 months.

10. REPLACING THE ULB-350 BATTERIES
The batteries in the ULB-350 transponder should be replaced after
each use to insure maximum operational life. To change the ULB-350
batteries follow this procedure:
• Gently loosen and remove the end cap assembly from the housing by
turning counter clockwise
• Remove the old battery and install the new battery as shown. Note
the battery terminal orientation before making connection. Insure the
battery terminals are fully seated into the battery connector.

11. BLACK BOX FINDER

12. ULB MOUNTING

13. ULB MOUNTING CONT---------

14. ULB CONT-------
• "Black boxes", which are in fact orange or red, will also survive in the
sea at depths of 20,000ft (6,096m)
• Commercial aircraft have an Underwater locator beacon fitted to the
recorders which will start emitting a continuous ultrasonic "ping"
when they come into contact with sea water.

15. ULB CONT------
• The signal can reach the surface from depths of 14,000ft, but crash
investigators are using submarines and other underwater listening
devices to locate Flight 447's black box in case it is transmitting from
below that depth.
• "The issue is that the pinger - which is transmitting once a second as a
locator beacon - will begin to fade after 30 days," says Mr Reavis. "The
signal will start to drop and it will be much more difficult to find."

16. Q&A
OK, what did I not make perfectly clear?

17. LESSON OBJECTIVE
AT THE END THE OF THE LESSON,THE
STUDENT SHOULD BE ABLE TO CORRECTLY;-
1. EXPLAIN WHAT IS ADS-B
2. WHAT IS FIS-B.
3. WHAT IS TIS-B

18. REFERENCE
STUDENTS NOTES

19. TAKE HOME

20. Q1.Define what is ADS-B.
Q2.Define what is TIS-B.
Q3. Q6.Define what is FIS-B?

21. LINK