Aural Null Procedures Air Search Module 9 of CASARA ELT Training Plan

Aural Null Using aircraft communications radio

Aural Null Procedure AProcedure B

AURAL NULL PROCEDURE In the event that your homer is not working, you must know Aural Null methods, “A”, and “B”. The only equipment you need is: VHF receiver clock map pen

Signal Reception Beware of a difference of signal reception on the nose of the search aircraft, as compared to the signal off of the tail. Signal strength may vary enough between the two so as to make the results inaccurate. If this occurs it is recommended that readings be taken off of the nose. It will mean flying out of the signal, then making a 180 degree turn and coming back on the same track. When flying back towards the signal, take your readings once the signal is heard again. Signal Detected Signal Faded

Descend to minimum reception altitude. Disable squelch if possible and adjust radio volume to minimum reception. When signal detected:

Fly a constant heading and draw a track made good on the map. Pinpoint your position on map. Once signal is lost, do a 180º turn and mark the spot (A) where the signal is acquired again. Maintain constant altitude and volume setting at all times. When signal detected: AURAL NULL PROCEDURE “A”

When signal fades out Fly along the same track and pinpoint position of fade out (B), do another 180º. Calculate mid-point of track made good (C). From this mid-point plot at 90 degrees, a new desired track which extends on both sides of track made good. Return to mid point and fly either direction to make good, the new track.

When signal strength fades out, plot this point on your map (D) –Reverse course, signal will build and then fade. Plot point at which signal fades (E) When signal fades out

ELT Location In theory, the ELT should be located at the mid point of the second track Terrain, obstructions and aircraft wreckage can skew the points and make finding the ELT more difficult.

Signal Detected Mark Position And heading Draw Track line A B Signal FadedMake 180 deg turnSignal DetectedMark Position Calculate Halfway pt. Mark Calculated Halfway pt. C Draw Track line 90 deg to 1 st track line Fly to Calculated Halfway pt. turn left or right and fly until signal fade Signal fadedMake 180 deg turnSignal DetectedMark PositionDFly track until signal fade Signal fadedMake 180 deg turnSignal DetectedMark Position E Fly to Calculated Halfway pt. Calculated ELT Location

Are there any questions?

AURAL NULL PROCEDURE “B” This method has both an advantage, and disadvantage: –ADVANTAGE: It is faster than Procedure “A” –DISADVANTAGE: It requires sufficient cockpit space to adequately plot the information Requires: –VHF receiver - pen- dividers –map - ruler triangle

AURAL NULL PROCEDURE “B Position of the aircraft is plotted as soon as the signal is heard Continue on same heading for a short distance Turn 90 0 either left or right, and proceed until the signal fades. Note this position Turn aircraft and again plot where the signal is heard, and where it fades

Approximate position of ELT is plotted by: –drawing chord lines between each set of “signal heard” and “signal fades” positions –Drawing perpendicular bisectors of each chord AURAL NULL PROCEDURE “B Aircraft proceeds to the point where the perpendicular bisectors intersect. The ELT should be there

Are there any questions?

That’s All For Now Have a pleasant flight!

“THAT OTHERS MAY LIVE” THANK YOU CASARA